View Full Version : Can top-grade, critical components make a Frankengun a winner?
Or does it have to be a through-and-through Colt/BCM/DD/Knight's/etc.?
To me the most critical components are the barrel, BCG, and FCG. Talking about the basic weapon itself, not add-ons like red dots or other glass.
Case in point: perhaps my favorite carbine is built on an 80% lower, engraved as I wanted it to be. The bare upper is a Del-Ton. The barrel is a Colt SOCOM, the BCG is an LMT Enhanced one, the handguard is a KMR, and the FCG is a Geissele SD-C. I also put Knight's anti-rotation pins on it to prevent the ovalling of those holes over time.
My close second is built on a complete BCM ELW upper with KMR. It too has an LMT Enhanced BCG and Geissele SD-C. The lower is a no-name brand I can't even recall off the top of my head.
Now, I do have through-and-through name brand/top tier guns. I am of the opinion, however, that with top-grade critical components you can build a Frankengun that is perfectly suitable as a go-to piece. This assumes that the lower and upper are within specs, and so are the little pins and springs (other than the FCG itself) in the LPK.
Fire away (pun intended).........:cool:
Of course, some of my best have been frankenguns. Besides, the critical parts all come from the same handful of sources and are simply re-branded. I trust myself more to do a more thorough assembly than someone trying to crank out as many rifles as they can in a given period of time.
SniperOverwatch
09-29-16, 14:47
The term "frankengun" is something of a pejorative and not really a fair term for all builds. Frankly, most of the builds you see on sites like this are probably good enough quality not to be frankenguns.
Cuz man, I've SEEN some frankenguns!! :lol:
Here in North Carolina there is this guy, a 1911 guru. He is like 80-something, and was an armorer for the Army back in the 40s and 50s before he became a competitive shooter. He knows everything--everything--about the 1911. Anywho, he told me one time in a discussion about modifications, a 1911 is a machine. If it is built to spec, it will run. It has to. It doesn't know any other way.
To take that argument further, I would think that if specs are, well, within spec, then, yes.
I've built two Frankenguns from the best parts available in the past--a 5.56 and a 7.62/.308.
I won't ever be doing it again.
Due to cost or function? ...curious.
SniperOverwatch
09-29-16, 14:55
Here in North Carolina there is this guy, a 1911 guru. He is like 80-something, and was an armorer for the Army back in the 40s and 50s before he became a competitive shooter. He knows everything--everything--about the 1911. Anywho, he told me one time in a discussion about modifications, a 1911 is a machine. If it is built to spec, it will run. It has to. It doesn't know any other way.
To take that argument further, I would think that if specs are, well, within spec, then, yes.
Very well said. I concur heartily.
Doc Safari
09-29-16, 14:58
I've built two Frankenguns from the best parts available in the past--a 5.56 and a 7.62/.308.
I won't ever be doing it again.
Reasons?
Due to cost or function? ...curious.
Not to speak for him but the cost of parting it together can add up real quick.
Alternatively, he won't do it again because he doesn't need to!
Component quality, assembly quality and proper tools and specifications are core components of a good build. Some guys can do great AR's from scratch. some who think they're good builders, aren't.
I wouldn't thumb my nose at a "frankengun" that was built with top shelf components once I performed an inspection and all the safety and function checks. Any issues at all would be a huge red flag though. One area I'd be circumspect about though is if the builder assembled the upper, because it's almost impossible to ensure all the correct procedures and specs were adhered to without disassembly of the upper.
I have one that consists of a Noveske lower with BCM RE assembly (properly staked), DD LPK w/Geissele SSA, BCM factory assembled upper and BCG with Magpul furniture. Is that a frankengun? If it is, then there's obviously more than one level of frankengun! :)
Not to speak for him but the cost of parting it together can add up real quick.
Alternatively, he won't do it again because he doesn't need to!
You're precisely right.
At the time I did both builds we didn't have the options we had today. My .308 shot great but at the end of the day I had over 3,500 in it. If I DID have a problem it would have been up to me to figure out. These days you can get a KAC SR-25 for not much more though so there is absolutely no reason to get stuck with a Frankengun.
The 5.56 ran fine but wasn't as accurate as it should have been. I never noticed as I had only ever used M855 in it but the guy that bought it from me was never able to get better than 2.5" groups out of it. I probably had 1500-2000 in it, can't quite remember. It was when 1/7 mid-length CHF barrels were just becoming available. The entire upper was BCM/DD/LMT.
You're precisely right.
At the time I did both builds we didn't have the options we had today. My .308 shot great but at the end of the day I had over 3,500 in it. If I DID have a problem it would have been up to me to figure out. These days you can get a KAC SR-25 for not much more though so there is absolutely no reason to get stuck with a Frankengun.
The 5.56 ran fine but wasn't as accurate as it should have been. I never noticed as I had only ever used M855 in it but the guy that bought it from me was never able to get better than 2.5" groups out of it. I probably had 1500-2000 in it, can't quite remember. It was when 1/7 mid-length CHF barrels were just becoming available. The entire upper was BCM/DD/LMT.
That sounds about right for CHF barrel.
mkmckinley
09-29-16, 15:49
I think the biggest failure point in "top-grade frankenguns" is probably the person putting it together. If you buy components that are in-spec and put the together following the right procedure there's no reason a home-built gun won't be just as reliable as a factory-built one. You also have to be able to recognize when something's not fitting right or a part's out of spec. Someone with a pair of vice grips and punches sitting at their kitchen table isn't going to be able to do this as well as someone like IG who's built thousands of rifles. I also think that must be why large frame ARs can cause trouble as there's less of a "spec" for parts to conform to.
ColtSeavers
09-29-16, 15:52
If it's assembled from quality parts, by a compitent person and put together properly, then I see no reason why a frankengun cannot be a winner.
I think the biggest failure point in "top-grade frankenguns" is probably the person putting it together. If you buy components that are in-spec and put the together following the right procedure there's no reason a home-built gun won't be just as reliable as a factory-built one. You also have to be able to recognize when something's not fitting right or a part's out of spec. Someone with a pair of vice grips and punches sitting at their kitchen table isn't going to be able to do this as well as someone like IG who's built thousands of rifles. I also think that must be why large frame ARs can cause trouble as there's less of a "spec" for parts to conform to.
I agree with this. If you give 2 identical sets of parts to 2 different people and have them build the guns, you could end up with 2 guns that look the same, but function very differently (or don't function).
But I'll add a slightly different spin on this. I believe it's a "the chain is only as strong as the weakest link" situation. You can have some really good components. But, if you made one poor part choice or assembled just one thing incorrectly, it could make your whole gun function poorly or shoot very inaccurately. One important thing is for you (or the builder) to have a good understanding of what parts/features/assembly methods make a difference, and what parts/features/assembly methods do not.
I absolutely believe someone can make an AR from parts which will be significantly "better" than an off the shelf top tier AR.
Joe Mamma
I agree with this. If you give 2 identical sets of parts to 2 different people and have them build the guns, you could end up with 2 guns that look the same, but function very differently (or don't function).Agreed. And not just a matter of two different people, but also two different levels of experience for the same person.
Years ago, for my first build, I read posts on this forum, used good quality parts, and built it to the best of my ability and experience. It was less expensive than a factory-built gun, but only because I lucked out on some parts from an acquaintance, and it ran without any problems. Over time, and a lot more reading of posts on this forum, and more familiarity with the platform, my skillset improved. Eventually, I disassembled that earlier build and rebuilt it. Since it never gave me any problems, I cannot definitely say it's better now. But I do know I made some fine-tuning to it, what you might call "closer" attention to detail. I suspect any small issues it may have originally had are now gone, so I likely resolved any potential problems that might have arisen over time.
Building an AR isn't rocket science, but it's also not like slapping Legos together either.
I have one that consists of a Noveske lower with BCM RE assembly (properly staked), DD LPK w/Geissele SSA, BCM factory assembled upper and BCG with Magpul furniture. Is that a frankengun? If it is, then there's obviously more than one level of frankengun! :)So ... do frankenguns have their own tier levels? :D
sevenhelmet
09-29-16, 16:46
I got into ARs by assembling my own. On the first, I only did the lower, but I got bolder and assembled the upper and lower on my 2nd, after doing a ton of reading and getting the tools I needed. I think even my wife was impressed that it worked when I was finished. Are my builds better than a good quality AR? I don't know, probably not. I will say the barrel, BCG, and FCGs are top-notch. They're also both 100% reliable, more accurate than I am, and have features I like. The only downside was cost (it would have been cheaper to retrofit a Colt/BCM for both), and if someone asked me when brand of guns they are, I wouldn't have an easy answer. But I like them because they work and they're 100% mine.
Sevenhelmet, if you're like me, you probably also discovered that the building process, when led by an informed perspective and with quality in mind (as opposed to being slapped together), taught you a lot about the platform that you couldn't learn just through reading. I now have a much better idea of the quality differences people are talking about between makers and parts, and a much better idea of how the gun functions and why.
sevenhelmet
09-29-16, 17:05
Sevenhelmet, if you're like me, you probably also discovered that the building process, when led by an informed perspective and with quality in mind (as opposed to being slapped together), taught you a lot about the platform that you couldn't learn just through reading. I now have a much better idea of the quality differences people are talking about between makers and parts, and a much better idea of how the gun functions and why.
Sure did! That was a big benefit for me- I enjoy taking things apart to see how they work, and learning how to fix them. The AR is a fantastic platform for that- everything is so easily accessible.
My buddy is a retired SGM from 5th SFG and is a gunsmith, having worked on firearms for decades. I have him actually put the parts together I have accumulated and I just look over his shoulder and generally aggravate him! He can troubleshoot and AR (so can I) like nobody's business. I have to say, for instance, that he doesn't care for Anderson lowers. Now the one or two I've had he didn't have any problems with but other's he has. He has one of those little plastic containers divided into sections with just about all the small pins/springs/detents/etc. you can need, but I always buy a LPK (last few have been Stag with Geisseles being the FCG) so I'm not scrounging his parts.
Like someone mentioned above, if I was asked what "brand" it was it'd be like that old Johnny Cash song "One Piece At a Time"!
Technically, any arsenal reworked M4 or M16 is a "franken-gun"...
You don't honestly think Anniston segregates Colt bolts and bolt carriers, etc, from the FN ones, from the replacement contract ones from third sources; and then meticulously puts them back together with matching parts?
As long as your stock of parts is quality, the aggregate of those parts will be quality...(assuming there is quality in the assembly work).
Who supplies "quality" parts is another debate entirely.
Coming from the world of FALs (where, I believe, the term "frankengun"originated), a rifle doesn't qualify as a frankengun unless a Dremel was involved and the project baptized with the blood of the builder.
In all seriousness, along with barrel, bolt and FCG, springs are very important, especially the extractor, action and hammer springs. Any of those three start to fail and your rifle is going to have problems no matter how good the rest of the parts or carefully the rifle is assembled
If done right, a custom build can be great. Mine is. It's exactly what I wanted, is of high quality and assembled well.
If it's made of good components and assembled well, and function verified, it's good to go imo. You can ussually get same function for less, but they have their place.
sevenhelmet
09-29-16, 20:45
Like someone mentioned above, if I was asked what "brand" it was it'd be like that old Johnny Cash song "One Piece At a Time"!
This definitely occurred to me! And since my receivers are Spike's, my ARs (technically they are ST-15s) are probably considered "crap", or someone will probably make a dick joke. And the buffers are Spikes T-2... oh no! Ban me now!!!! :D But I don't really GAF- nobody who has shot them has ever said they're crap. Quite the opposite. I'm still a fan of homebuilt ARs- as long as the builder has realistic expectations and isn't just trying to cut corners and "out cheap" the mass-producers.
ETA: I agree with the assessment that "Frankengun" probably involves a dremel, a soldering iron, and maybe duct tape. Exhibit A is the "Gunsmithing Hall of Shame" thread.
Dionysusigma
09-29-16, 20:47
For whatever it's worth, every single AR I've ever owned (lost count over the years) has been a FrankenGun. The only issues I've ever had were 1) magazine-related (very early Magpuls, C-Products, and Thermold), 2) a velcro-mounted brass catcher bouncing casings back into the ejection port, 3) indecision as to where I was going with a particular build, and 4) running low on funds when I finally did decide what I wanted.
Complete factory builds, in my opinion, only hold their resale value better than FrankenGuns. If that's not a concern, "piecing one together" is just fine - especially to get every last specification you want.
I've built and bought. Personally I've had great luck building, but a close friend of mine had some issues with his. I don't remember what the issues were but the rifle was not reliable at all. He called the various manufactures, and was basically told by each that it was the other guys fault.
When you build your own you are the warranty department. I only build if there isn't a rifle offered by a top shelf company in the configuration I want.
Sent from my SM-G930V using Tapatalk
Imo it's vastly superior. I can't think of a single AR I wouldn't change something on. Imo factory builds always stick to the norms and there's always somebody doing something a little better than normal. Why wouldn't you do a rifle exactly how you want is my POV. Most importantly you know every part and how well it's put together. I've found most people these days want the most for doing the least. No thanks. I'll do it myself.
Interested to hear what makes one assembly good and another bad. All of the pieces pretty much either snap together, have a simple to tap in roll pin, or have a nut that you just torque to spec with a torque wrench. An AR is unbelievably simple to put together correctly. What are people doing to have a "poorly assembled" AR?
Interested to hear what makes one assembly good and another bad. All of the pieces pretty much either snap together, have a simple to tap in roll pin, or have a nut that you just torque to spec with a torque wrench. An AR is unbelievably simple to put together correctly. What are people doing to have a "poorly assembled" AR?
Because they lack the fundamental knowledge, manual dexterity, proper tools, etc.
Interested to hear what makes one assembly good and another bad. All of the pieces pretty much either snap together, have a simple to tap in roll pin, or have a nut that you just torque to spec with a torque wrench. An AR is unbelievably simple to put together correctly. What are people doing to have a "poorly assembled" AR?Here are a few I've seen: a factory Bushmaster barrel assembly with an off-center-drilled FSB [use of an improperly made FSB], a factory Stag bolt carrier with an improperly staked gas key [improper staking], an uncentered gas tube [a couple of home builds I've seen], and unstaked castle nuts. Note that not all of the assembly errors were made by the home builder ... until the home builder decided to use the poorly assembled parts in his build. I've also seen castle nuts installed with the teeth facing the wrong way. I know some people do that on purpose, claiming it reduces snagging on clothing. I can't say whether that works on not, but it's fine if you do it on purpose. However, if you do it because you weren't paying attention, I consider that an error, because you should be paying attention.
sevenhelmet
09-30-16, 09:06
Interested to hear what makes one assembly good and another bad. All of the pieces pretty much either snap together, have a simple to tap in roll pin, or have a nut that you just torque to spec with a torque wrench. An AR is unbelievably simple to put together correctly. What are people doing to have a "poorly assembled" AR?
Parts selection is where the battle is won or lost most of the time, IME. Tolerance stacking can be an issue with sub-par parts, so ensuring parts are in spec is important (just knowing what the spec is and how to check can be a research project in itself for the uninitiated.) Barrel to upper receiver fit is very important for maintaining accuracy as the gun warms up. Too loose/tight, or uneven coatings will cause the POI to drift unpredictably. Gas system length, port sizing, and buffer weight all need to be balanced or the firearm may not function reliably or at all. Poor tooling can lead to gritty or loose movement of the trigger, safety, bolt release, CH, etc. All things that can contribute to various firearm failures or less-than-optimal accuracy.
I'm sure there is more, but those are just a few things I picked up along the way.
Or does it have to be a through-and-through Colt/BCM/DD/Knight's/etc.?
To me the most critical components are the barrel, BCG, and FCG. Talking about the basic weapon itself, not add-ons like red dots or other glass.
Case in point: perhaps my favorite carbine is built on an 80% lower, engraved as I wanted it to be. The bare upper is a Del-Ton. The barrel is a Colt SOCOM, the BCG is an LMT Enhanced one, the handguard is a KMR, and the FCG is a Geissele SD-C. I also put Knight's anti-rotation pins on it to prevent the ovalling of those holes over time.
My close second is built on a complete BCM ELW upper with KMR. It too has an LMT Enhanced BCG and Geissele SD-C. The lower is a no-name brand I can't even recall off the top of my head.
Now, I do have through-and-through name brand/top tier guns. I am of the opinion, however, that with top-grade critical components you can build a Frankengun that is perfectly suitable as a go-to piece. This assumes that the lower and upper are within specs, and so are the little pins and springs (other than the FCG itself) in the LPK.
Fire away (pun intended).........:cool:
Is there a cost saving to the approach or is it done for chits and giggles to more or less build to your liking? Problem for me mostly is I don't feel knowledgeable to decide what's critical and what's not per se, and hence would just default to brands known to be GTG. When I was dedicated 1911 shooter, I did take what's considered base quality guns and make some mods to get an improved gun, but don't think it really saved me any $ in the end from just starting with a better 1911.
Is there a cost saving to the approach or is it done for chits and giggles to more or less build to your liking?
Oh I wouldn't say it's a cost-saving thing, as the cost of the individual components can at times exceed just buying a complete weapon. But yeah, it is basically building it to your liking. For instance with the one that has the Colt SOCOM barrel on it......I had the barrel sitting in my parts cupboard new in wrap from Grant. Had it well over a year. Decided WTH, I'll put one together based off of this. Had my buddy cut down the FSB so I could put a KMR on it. Had an 80% lower already so bought a Geissele and LMT Enhanced BCG (damn are those things expensive!). I have two containers of parts so dug out a buffer tube, H2 buffer with spring, stock, and an Aimpoint T-2 that had been on another gun I sold previously. I picked up the Del-Ton upper from Midsouth Shooters Supply (about 15 minutes from my house) and viola! Oh, almost forgot the set of Troy BUIS I ordered. All in all (not counting the T-2) I have about $1500 in it. The T-2 pushes it up over $2K. So you see it is right up there with, or maybe a little more than, a DD.
Anywho, he told me one time in a discussion about modifications, a 1911 is a machine. If it is built to spec, it will run. It has to. It doesn't know any other way.
To take that argument further, I would think that if specs are, well, within spec, then, yes.
Not so, as besides being in spec, the greatest bearing on reliability and longevity is WHERE the individual parts are related to those specs. Case in point learned when I was in GE Aircraft Engines's machinist/engineering program.
Ford Motors made and sold a car under the Ford badge while Mazda sold the same car under their badge – both made to the same prints and same specs. The failure rate on the Ford-made transmissions, even though each part was made in spec, greatly exceeded the failure rate for the Mazda product, by a factor or 10 or more, IIRC. And again - all parts were within ‘spec’.
But upon dissection, each individual part within the Ford parts was all over the place within the design tolerance envelope, while for the Mazda parts, each and every part A was at X size, +/- the machine capability production tolerances, while Part B was at Y size, +/- , and so on. It was in effect, the meshing or stack-up of tolerances between the mating parts that had the largest bearing on the usefulness and ‘Quality’ if you will, of the final product.
So while I agree 100% that parts need to be made in spec, there is actually more to it than that on the design side. If the tolerances do not correctly identify which parts can be (or should be) on the high side or which can be on low side for example, is when variation can occur. Such variation can lead to factors, e.g., stress, wear, fatigue, etc., not correctly calculated in the overall design envelope (whether correctly captured in the tolerance scheme or not) causing failures to occur at an alarming rate.
Specs are one thing and are indicative of but one glaring example of ‘why?’ reverse engineering efforts can fail; like years ago when the Russians would steal our military products and reverse engineer them, only to have them fail miserably. Measuring a sample of one or just a sampling of parts gives no direction to the overall dimensional needs of the final design, in terms of what it will eventually mean to functionality, reliability or longevity.
Oh I wouldn't say it's a cost-saving thing, as the cost of the individual components can at times exceed just buying a complete weapon. But yeah, it is basically building it to your liking. For instance with the one that has the Colt SOCOM barrel on it......I had the barrel sitting in my parts cupboard new in wrap from Grant. Had it well over a year. Decided WTH, I'll put one together based off of this. Had my buddy cut down the FSB so I could put a KMR on it. Had an 80% lower already so bought a Geissele and LMT Enhanced BCG (damn are those things expensive!). I have two containers of parts so dug out a buffer tube, H2 buffer with spring, stock, and an Aimpoint T-2 that had been on another gun I sold previously. I picked up the Del-Ton upper from Midsouth Shooters Supply (about 15 minutes from my house) and viola! Oh, almost forgot the set of Troy BUIS I ordered. All in all (not counting the T-2) I have about $1500 in it. The T-2 pushes it up over $2K. So you see it is right up there with, or maybe a little more than, a DD.
This is why I'm so glad for the 6920OEM2.
There isn't a factory made gun that comes with my favorite forend, grip AND stock.
All my future rifles will be 6920OEMs where I finish the build or factory KAC guns.
This is why I'm so glad for the 6920OEM2.
There isn't a factory made gun that comes with my favorite forend, grip AND stock.
All my future rifles will be 6920OEMs where I finish the build or factory KAC guns.
You nailed it. I might even add barrel to the list (profile, gas system length), but yeah I customize everything.
Lefty, what you're talking about is control. To produce a good product, it must be within tolerance AND in control. If the parts are within tolerance but some on the high side, some on the low side and some in the middle of the tolerance range, your process isn't in control.
If a product is engineered correctly and the manufacturing process is right, there will be no problems with tolerance stack up so long as the parts are all within tolerance, even if they are out of control.
For example, the print calls out for 11 holes to be drilled 1 inch apart +/- .010". 11 holes 1 inch apart means the last hole will be 10 inches +/- .010" from the first. In order to hold that tolerance, the distance of each hole must be measured from the first hole and only the first hole and held to a tolerance of +/- .010" without tolerance stack up. If you were to measure the distance from the first hole to the second, then the distance from the second to the third and so on, the tolerance from the second hole is added to the third and the third to the fourth and so on. While the distance between each hole is within tolerance, by the time you get to the last hole, its location could be off by .10", ten times the allowable tolerance.
That's what "tolerance stack up" really means
There is a difference between a frankengun, and a custom build.
Lefty, what you're talking about is control. To produce a good product, it must be within tolerance AND in control. If the parts are within tolerance but some on the high side, some on the low side and some in the middle of the tolerance range, your process isn't in control.
If a product is engineered correctly and the manufacturing process is right, there will be no problems with tolerance stack up so long as the parts are all within tolerance, even if they are out of control.
For example, the print calls out for 11 holes to be drilled 1 inch apart +/- .010". 11 holes 1 inch apart means the last hole will be 10 inches +/- .010" from the first. In order to hold that tolerance, the distance of each hole must be measured from the first hole and only the first hole and held to a tolerance of +/- .010" without tolerance stack up. If you were to measure the distance from the first hole to the second, then the distance from the second to the third and so on, the tolerance from the second hole is added to the third and the third to the fourth and so on. While the distance between each hole is within tolerance, by the time you get to the last hole, its location could be off by .10", ten times the allowable tolerance.
That's what "tolerance stack up" really means
BOLD - No, it does not mean that. (And unfortunately, many an engineer doesn't know this either, so you're not alone.)
If the drawing states that '11 holes to be drilled 1 inch apart +/- .010"' (assuming in a straight line), then the allowable tolerance on the distance from the first hole to the last hole is +/-.100" by definition. This is because you have defined the distance between the holes can be up to 1.010" for each.
If 11 holes have to be drilled and the distance from the first hole to the last hole cannot be more that .010" then what you wrote as a drawing is incorrect, and the drawing needs to changed to address the problem. That's a design problem, not a tolerance problem. If the distance from the first to last hole needs to be 10 inches +/-.010", then the drawing should state something like:
"distance from first to last hole 10 +/-.010", 9 holes between equally spaced to within +/-.010", or call out the distance from the first hole to each subsequent hole individually, 1.000 +/-.010", 2.000 +/- .010", 3.000 +/-.010", etc....
If your control is loose, and things wander around inside the tolerance, and this causes problems, then the design is bad. As stated, if everything is within tolerance, things should work correctly, If -
. . . the tolerances do not correctly identify which parts can be (or should be) on the high side or which can be on low side for example, is when variation can occur. Such variation can lead to factors, e.g., stress, wear, fatigue, etc., not correctly calculated in the overall design envelope (whether correctly captured in the tolerance scheme or not) causing failures to occur at an alarming rate.
Then the design is bad and should be changed.
On that note, what is the difference between these four length call-outs:
1) 1.634 +/-.006"
2) 1.628 +.012/-0"
3) 1.640 +0/-.012"
4) 1.628" - 1.640"
Hint, there is a big difference.
The part you bolded is the short version. The way most aviation prints are spec'd, the standard practice is that the tolerance of each hole is the distance from the first hole +/- and the distance from the first hole to the last hole is usually the most critical in the run. (Actually, the location of the first and last hole of the run are the most critical.) Many hole patterns on McDonnell-Douglas prints would spec the example I used as "fastener holes are 10 equal spaces" with a dimension line showing 10.00" from the first hole to the eleventh. There would be a note defining what the tolerance will be for a dimension spec'd to two places which, if I recall, is +/- .005"
How to avoid tolerance stacking is one of the first and most important things they taught us. As Lefty pointed out, there's more to manufacturing than just holding a part to spec. The process must be in control and good standard practices and training employees on what the standard practices are, is essential to controlling the process
Yes, but this on a drawing: '11 holes to be drilled 1 inch apart +/- .010"'
Means this:
distance from the first hole to the second hole: .990" to 1.010'
distance from the first hole to the third hole: 1.980" to 2.020"
distance from the first hole to the forth hole: 2.970" to 3.030"
etc.
If you wrote '11 holes to be drilled 1 inch apart +/- .010"' and on the mating part's drawing wrote:'11 studs to be positioned 1 inch apart +/- .010"', the thing would never fit together, unless the holes were .200" bigger in diameter than the studs.
Also, if one does state: '"distance from first to last hole 10 +/-.010", 9 holes between equally spaced to within +/-.010"', what will the maximum distance going to be between holes? It won't be 1.010"....
If the TDP is done right, then the holding to spec is sufficient, as the TDP (the specifications) should have sufficient information in it to make parts that work, regardless of the process used to make them, and, if the process is critical, it should be part of the specification.
The example given by Lefty is an example of poor design practices (specifically, poor drawings) because of the issues that can be resolved by the 4 dimension call-outs I noted in my previous post.
As I said- standard practice and notes on the print explain how the holes are to be spaced and from which point each hole will be measured from. If standard practices and print notes are followed, there will be no tolerance stacking. McDonnell-Douglas and Boeing both have a tech manual defining standard practices which must be followed. I have personally used those manuals. Any company worth it's salt has defined standard practices and yes, they will be part of any TDP of any company that holds a government contract.
ETA- I agree with you that If all applicable notes and standard practices are followed and the part is made to spec and tolerance stacking occurs, there is a problem with either the design or the documentation
There is a difference between a frankengun, and a custom build.
I like that, really. It's a good way to look at it. Almost profound! :)
I just built my first from the ground up. It has an Aero upper and lower, Colt SOCOM barrel, Colt BCG, White Oak lower parts, ALG ACT trigger, BCM receiver extension, with a B5 SOPMOD stock on it. Nothing fancy, but what little I have shot it so far indicates it is going to be a trouble-free rifle. I would say it is nearly as good as a Colt or BCM (of which I have both.) At least I hope it will be. It cost right at $1000 to build it, so I didn't save any money, but that wasn't the objective in the first place. I just wanted to do one.
I need to bookmark this thread :D
In view of the expertise of members exhibited in this thread, I'd say my experience is limited by comparison. What I have learned has been aptly stated here: reverse engineering causes problems. Without correct specs and tolerances, reverse engineered parts are hit and miss parts.
Having a bucket of good parts that work great in their own system randomly placed for selection for other builds is not an ideal way to make them with that randomness. Sure, some can be great, others can be total flops.
There are good reasons that certain components are associated with the others.
My favorite carbines I run are made from LMT, DD, and Colt components. With occasionally ALG thrown in. And usually magpul furniture.
I used to build lowers, now just start with LMT complete lowers, can't build equiv for less.
Usually DD CHF barrels. Colt Delta ring, barrel nut, etc. DD, LMT, or Colt BCG. (Though recently I tried a tool craft, looks good!)
Four or Five mfgs, Franken gun or custom build, it's zackly what I want.
Those could be examples that work well enough together. The parts are not identical Legos that work the others the same.
All of my frankenguns use quality barrels, bcg, and triggers (BCM, Geisselse, Noveske, DD and LMT) and most have ended up costing more than my BCM and DD factory rifles while not being noticeably better but they are definitely quality guns I'd bet my life on.
I only own "frankenguns" now. People talk about spending more on these custom built guns than a factory gun but i think most forget that even though the factory complete rifles are top notch rifles from top tier companies, they still come with parts that are basic and will more than likely be swapped out, like triggers, charging handles, BUIS, etc. by the time you buy an off the rack "Daniel Defense" at $1700 for instance, add a couple hundred dollar trigger, a $100 charging handle, Foregrip or your flavor (angle or pistol), sights, and an optic you are going to come in pretty close to or more than what building it from scratch would be.
Also building a gun is more than just that. It is the best way to learn exactly how the platform works and gives you the knowledge to be able to diagnose your own issues if you have any.
As for reliability, my guns run 100%. I used top tier parts, for example my last build consists of:
-Spikes Tactical "Honey Badger" Lower Receiver
-Geissele SD-E Trigger
-BCM Lower Parts Kit
-Vltor A5 Buffer System
-MFT Minimalist Stock
-Magpul MOE+ rubber over old pistol grip
-Magpul Bad Lever
-KNS anti roll pin setup
-BAD Badass Safety
-Magpul Enhanced trigger guard
-Aero gen 2 Upper receiver
-BCM Gunfighter Charging Handle
-Larue Tactical 16" Stealth Barrel "this thing is sick accurate"
-BCM KMR 15" keyMod rail
-BCM Low Pro Gas Block
-Daniel Defense mid length gas tube
-Spikes Tactical M16 BCG
-Surefire ProComp Muzzle Break
-Magpul Pro BUIS
-Trijicon MRO sitting on Larue quick release mount
This gun runs great and was so much more fun to put together than it is to walk in a store and walk out with a complete gun. And to be honest if someone has a gun like this and needs to sell it they are probably better off to disassemble it and sell it off peice by peice which is the only downside. Most folks who have a couple thousand to buy a gun are going to buy a complete factory rifle or they are going to do their own build. So my advice would be if you are going to build a gun, the or five, make sure to take your time and build exactly what you want so you have in the end a gun you will want to keep for a long time.
On another note, what's up with people being so intimidated by building an upper? If you know how to use a torque wrench and thread a nut the right way it's actually easier in my opinion than a lower. A lower can be tedious thing to put together without marking up your brand new receiver. I just don't get why folks are so afraid of building uppers.
dylank0723
09-30-16, 23:45
I only own "frankenguns" now. People talk about spending more on these custom built guns than a factory gun but i think most forget that even though the factory complete rifles are top notch rifles from top tier companies, they still come with parts that are basic and will more than likely be swapped out, like triggers, charging handles, BUIS, etc. by the time you buy an off the rack "Daniel Defense" at $1700 for instance, add a couple hundred dollar trigger, a $100 charging handle, Foregrip or your flavor (angle or pistol), sights, and an optic you are going to come in pretty close to or more than what building it from scratch would be.
Also building a gun is more than just that. It is the best way to learn exactly how the platform works and gives you the knowledge to be able to diagnose your own issues if you have any.
As for reliability, my guns run 100%. I used top tier parts, for example my last build consists of:
-Spikes Tactical "Honey Badger" Lower Receiver
-Geissele SD-E Trigger
-BCM Lower Parts Kit
-Vltor A5 Buffer System
-MFT Minimalist Stock
-Magpul MOE+ rubber over old pistol grip
-Magpul Bad Lever
-KNS anti roll pin setup
-BAD Badass Safety
-Magpul Enhanced trigger guard
-Aero gen 2 Upper receiver
-BCM Gunfighter Charging Handle
-Larue Tactical 16" Stealth Barrel "this thing is sick accurate"
-BCM KMR 15" keyMod rail
-BCM Low Pro Gas Block
-Daniel Defense mid length gas tube
-Spikes Tactical M16 BCG
-Surefire ProComp Muzzle Break
-Magpul Pro BUIS
-Trijicon MRO sitting on Larue quick release mount
This gun runs great and was so much more fun to put together than it is to walk in a store and walk out with a complete gun. And to be honest if someone has a gun like this and needs to sell it they are probably better off to disassemble it and sell it off peice by peice which is the only downside. Most folks who have a couple thousand to buy a gun are going to buy a complete factory rifle or they are going to do their own build. So my advice would be if you are going to build a gun, the or five, make sure to take your time and build exactly what you want so you have in the end a gun you will want to keep for a long time.
On another note, what's up with people being so intimidated by building an upper? If you know how to use a torque wrench and thread a nut the right way it's actually easier in my opinion than a lower. A lower can be tedious thing to put together without marking up your brand new receiver. I just don't get why folks are so afraid of building uppers.
building the lower is what i'm nervous about, too many small parts for me to lose lol
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Just buy right the first time.
Some dude hassles me for getting pricey high grade lowers and parts telling me that I am just paying for a logo, Anderson/Spikes/PSA is just as good, x company is going out of business, etc.
Yet none of my home builds nor store boughts have died yet. I want the "dumbest" guns possible. Eveything is just so, I can put em away, and come back still intact ready to go.
I want the rifle that does rifle things. Not a Jalopy like from Archie comics where something is always screwing up on me or being a pain in the butt.
Why do we rationalize these things? Why?
It's the gun equivalent of, pardon the analogy, being Captain Save A Ho. It cant be done, wastes time and money, and just...just...ugh.
One man's opinon.
I need to bookmark this thread :D
In view of the expertise of members exhibited in this thread, I'd say my experience is limited by comparison. What I have learned has been aptly stated here: reverse engineering causes problems. Without correct specs and tolerances, reverse engineered parts are hit and miss parts.
Reverse engineering can be successful if the people doing the engineering are well versed in the type of design being reverse engineered.
H&K could probably reverse engineer an FN design fairly well, as they understand gun design and can fill in the blank spots with their experience. Ford Motor Company would have a harder time, as they have little prior experience to draw on.
Reverse engineering can be successful if the people doing the engineering are well versed in the type of design being reverse engineered. H&K could probably reverse engineer an FN design fairly well, as they understand gun design and can fill in the blank spots with their experience.
THIS ... wish I had thought that through and had included something similar in my original response!
building the lower is what i'm nervous about, too many small parts for me to lose lol
LMT L7C2 complete lower. Should be able to get ordered via a local FFL for $330-350.
My last one was $330 out the door from my local guy. My earlier ones were $276 otd.
You may be able to build a cheaper one, but you won't be able to build a better one for that price. (Don't bother commenting about spikes blems, etc)
Or do the same with BCM.
You can change everything else on the carbine later, but you can't change the lower easily. An AP or Spikes will always be a low end franken gun by definition. And will have virtually no resale value, probably 25-30% of the cost of the parts.
All that said, you'd still be better off with a Colt OEM unless you just have to have a middie or LW barrel, etc
Sent from my PRC-104 using phonetics
Yes, but this on a drawing: '11 holes to be drilled 1 inch apart +/- .010"'
Means this:
distance from the first hole to the second hole: .990" to 1.010'
distance from the first hole to the third hole: 1.980" to 2.020"
distance from the first hole to the forth hole: 2.970" to 3.030"
etc.
If you wrote '11 holes to be drilled 1 inch apart +/- .010"' and on the mating part's drawing wrote:'11 studs to be positioned 1 inch apart +/- .010"', the thing would never fit together, unless the holes were .200" bigger in diameter than the studs.
Also, if one does state: '"distance from first to last hole 10 +/-.010", 9 holes between equally spaced to within +/-.010"', what will the maximum distance going to be between holes? It won't be 1.010"....
If the TDP is done right, then the holding to spec is sufficient, as the TDP (the specifications) should have sufficient information in it to make parts that work, regardless of the process used to make them, and, if the process is critical, it should be part of the specification.
The example given by Lefty is an example of poor design practices (specifically, poor drawings) because of the issues that can be resolved by the 4 dimension call-outs I noted in my previous post.
I design a lot of sheet aluminum parts for our products and these issues aren't that hard to work around. A typical drawing will have a the tolerances noted with -
All dimensions +- .010"
Tolerances not to accumulate.
Critical dimensions are shown and referenced from an absolute zero point, or from another point where the relationship is critical. Dimensions less critical can be derived from others but again the line Tolerances not to accumulate resolves the potential issues with things like repetitive hole patterns.
This stuff isn't rocket surgery. It's basic engineering and drafting...
All dimensions +- .010"
Tolerances not to accumulate.
There is a problem with that statement. And to be honest, I find that sloppy drafting/engineering.
Using the example from above the 11 holes 1 inch apart +/- .010", what is the allowable tolerance?
If the distance between the 1st and 2nd hole is 0.995" what is the allowable distance between the 2nd and 3rd hole? 1.000 +/-.010, putting it as close as 1.985"? Or, is it 1.000 +/-.005", keeping the 3rd hole in the 2.000 +/- .010 range? Now, what about the 4th hole, you're going to have to go down to .0025" if the distance between the 1st and 4th holes has to be 3.000 +/-.010. By the 5th hole your allowable tolerance is down to a thousandths.
If the distance between the 1st and 5th hole has to be 4.000 +/-.010", then put that on the drawing. So, you have ten dimensions rather than one dimension, use two sheets, if you need more room. If the dimension is critical, then the dimension should be addressed on the drawing. And, if there is a possibility of tolerance stacking that will cause problems, it should be eliminated. Good, confusion-proof drawing lead to better products.
For example, on the AR lower drawing, the distance from the datum plane to the hammer pin hole is given +/-.002. The distance between the hammer pin hole and the trigger pin hole is the critical distance, and needs to be within .0015", so that is the distance given, not the distance from the datum plane*. However, on the bolt, every critical dimension is referenced of the back side of the locking lugs, so there is no confusion or possibility of tolerance stacking. It also tells the machinist (in the old days) how to make the part - he goes from the datum plane to the hammer pin hole and drills it, he zeros the machine and goes to the trigger pin hole and then drills that. Now the holes are properly located, no question, no error. No need to know Armalite's proprietary manufacturing process specification.
And, in my experience with engineering drawings, the ARDEC drawings for the M16/M4 are much better in this regard to anything I have seen from the aerospace industry. The aerospace industry generally makes drawings with their own "this is how we read drawings/make stuff" processes in mind. The ARDEC drawings are done so that it doesn't matter how you read them, if you plop a part down under a faro-arm and get readings that say it is "to print", it will fit and work.
That's one reason GM and FN could stand up production so quickly, with so few headaches.
______________________
*Actually, if the trigger pin hole were referenced off the datum plane, it would be impossible to hold the hammer/trigger pin holes spacing to .0015" tolerance.
LMT L7C2 complete lower. Should be able to get ordered via a local FFL for $330-350.
My last one was $330 out the door from my local guy. My earlier ones were $276 otd.
You may be able to build a cheaper one, but you won't be able to build a better one for that price. (Don't bother commenting about spikes blems, etc)
Or do the same with BCM.
You can change everything else on the carbine later, but you can't change the lower easily. An AP or Spikes will always be a low end franken gun by definition. And will have virtually no resale value, probably 25-30% of the cost of the parts.
All that said, you'd still be better off with a Colt OEM unless you just have to have a middie or LW barrel, etc
Sent from my PRC-104 using phonetics
First people are ripping folks for wanting these inexpensive ARs like the Smith Sport and Ruger AR556 and now Spikes lowers are being lumped in the "low end Frankenstein gun" range. Low end is taking a $49 Anderson receiver and throwing a bunch of random parts on it from entry level companies. I would hardly call Spikes an entry level low end AR company.
So just because you bought an LMT Lower that makes your Frankenstein gun a top tier rifle and because I use Spikes Tactical Lower receivers on my rifles with nothing but high end, extremely well known and GTG parts from companies like Geiselle, BCM, LaRue Tactical, and Battle Arms Development, that means my rifles are bottom of the barrel low end garbage that are only worth 25% of the cost? So basically that means that my latest build Is worth around $650. Even though it's got a $300 Geissele trigger, $200 BCM rail, $400 SS Match Grade Barrel, etc, etc, etc. But because I built it up on a Spikes Lower receiver it's shit. Cmon man, get real here. I get that Franken guns are not going to hold their value like a factory gun. But losing 75% because you feel like bashing Spikes and Aero is ridiculous and is just not true. I did a lot of research before putting my guns together. I spent a ton of money to make sure I have high quality rifles that run 100%, which is what this forum pushes for right? Supposed to be professional grade equipment because that's what we talk about and represent here. So don't take the brand whoring over the edge now and start shitting on people's guns that they spent thousands of dollars putting together. I get shitting on the entry level stuff and trying to steer people towards quality, but you're just taking it too far now. I'm sure there are lots of guys here toting duty, Proffesional grade weapondry that was built on a Spikes or even Aero Lower receiver and I'm sure they don't want to hear that there stuff is shit either.
I would hardly call Spikes an entry level low end AR company.
Snip
Proffesional grade weapondry that was built on a Spikes or even Aero Lower receiver and I'm sure they don't want to hear that there stuff is shit either.
Some quick questions:
1) how many militaries are using spikes rifles/carbines?
2) how many militaries are using spikes anything?
3) what is the ratio of complete rifles to stripped lowers sold by spikes?
AP and Spikes primarily cater to the do it yourselfer selling pieces parts. I have an AP lower, it's OK. I consider it as good as the spikes I've seen. Which will probably offend you.
Thus the low end franken gun comment. You may chose to pour a ton of money in parts into yours. Have at it. Then go and try to trade it in or sell it. You'll find out quickly what I'm talking about. You'll be far better off parting out the expensive stuff
The guy said he was apprehensive about building a lower, so I made a suggestion.
You going to tell me you can buy a complete non-blem spikes lower for less? And that it is as good or better than LMT? And will retain its value as well?
There is a problem with that statement. And to be honest, I find that sloppy drafting/engineering.
Using the example from above the 11 holes 1 inch apart +/- .010", what is the allowable tolerance?
If the distance between the 1st and 2nd hole is 0.995" what is the allowable distance between the 2nd and 3rd hole? 1.000 +/-.010, putting it as close as 1.985"? Or, is it 1.000 +/-.005", keeping the 3rd hole in the 2.000 +/- .010 range? Now, what about the 4th hole, you're going to have to go down to .0025" if the distance between the 1st and 4th holes has to be 3.000 +/-.010. By the 5th hole your allowable tolerance is down to a thousandths.
If the distance between the 1st and 5th hole has to be 4.000 +/-.010", then put that on the drawing. So, you have ten dimensions rather than one dimension, use two sheets, if you need more room. If the dimension is critical, then the dimension should be addressed on the drawing. And, if there is a possibility of tolerance stacking that will cause problems, it should be eliminated. Good, confusion-proof drawing lead to better products.
For example, on the AR lower drawing, the distance from the datum plane to the hammer pin hole is given +/-.002. The distance between the hammer pin hole and the trigger pin hole is the critical distance, and needs to be within .0015", so that is the distance given, not the distance from the datum plane*. However, on the bolt, every critical dimension is referenced of the back side of the locking lugs, so there is no confusion or possibility of tolerance stacking. It also tells the machinist (in the old days) how to make the part - he goes from the datum plane to the hammer pin hole and drills it, he zeros the machine and goes to the trigger pin hole and then drills that. Now the holes are properly located, no question, no error. No need to know Armalite's proprietary manufacturing process specification.
And, in my experience with engineering drawings, the ARDEC drawings for the M16/M4 are much better in this regard to anything I have seen from the aerospace industry. The aerospace industry generally makes drawings with their own "this is how we read drawings/make stuff" processes in mind. The ARDEC drawings are done so that it doesn't matter how you read them, if you plop a part down under a faro-arm and get readings that say it is "to print", it will fit and work.
That's one reason GM and FN could stand up production so quickly, with so few headaches.
______________________
*Actually, if the trigger pin hole were referenced off the datum plane, it would be impossible to hold the hammer/trigger pin holes spacing to .0015" tolerance.
I know some about the old days. 40 years ago I spent my days standing in front of Bridgeport or a Lodge and Shipley lathe along with a lot of other tools that were older than I was. Back then the cellophane on a cigarette pack was .002"-.003" thick and you could use it as an edge finder if the shop was too cheap to have a real one. ;)
Dimensioning like I stated isn't done to allow me to be sloppy or lazy. There are good reasons for it. The critical dimensions are always listed as I stated elsewhere in my post -> Critical dimensions are shown and referenced from an absolute zero point, or from another point where the relationship is critical. The rest is left up to manufacturing/fabrication so that when machinery is selected and fixturing designed it will build the part properly. As often as not it's not our company doing that work and I have no control over their production or process. I'm leaving it up to them to determine the best way to build the part and I don't care much how they do to. I just want to get something from them that will work.
For example, if I list every dimension for a part with multiple holes in a pattern that are positioned from a reference it doesn't make the part any more accurately than if I call out the placement of one hole, the pattern dimensions, and use 'tolerances not to accumulate.' It just makes the drawing more difficult to read and worse, it adds to the number of dimensions that are assumed to be critical when in fact they really aren't. What's more making a change is substantially easier if I minimize critical dimensions. If I need to change one dimension or the pattern or it's position I can do that with a single dimensional change and I'm done. It's instantly obvious what changed from a glance at the drawing and it's a single change to the path when the part is built.
Here's a couple more that I wonder if you'll object to but I use all the time. pattern centered left/right on part Or holes centered top/bottom on part Why would I do this? Because any tolerance in overall dimension will fall out and my pattern will still be where I want it and within tolerance even if the referenced part is borderline or even outside of tolerance.
The last paragraph becomes extremely important when you're building parts that are fabrications based on parts manufactured by others. Often those parts are borderline or even out of tolerance. But I can still use them if I can place my modifications in the proper place on their parts. Best example being machining holes in an existing enclosure to fit parts that we fabricate or that are fabricated by others. Think pre-manufactured enclosure we buy and modify for use with a custom printed wiring board I design along with some other mechanical parts.
That's a common type of product construction for us. Off the shelf enclosure + modifications to it + PCB + fabricated parts by a 3rd party + our production assembly to completion.
AR content -> I only recently looked at some prints for the AR15 for the first time and was duly impressed. It's clear how to build the parts and overall they give the impression of something that was built for manufacturing. This just added to my previous impression of Eugene Stoner, that he was indeed a genius.
There is a difference between a frankengun, and a custom build.
Stick hit the nail on the head.
A frankengun is the crap you see over on the TOS that has a bunch of airsoft parts on it.
I only build. I have not bought a complete lower or upper since 2005.
Knowledge and tools are the key. Without them you better buy a complete rifle. If you actually know what you are doing you can assemble a much better product for a much better price then anything on the market.
There is a problem with that statement. And to be honest, I find that sloppy drafting/engineering.
Using the example from above the 11 holes 1 inch apart +/- .010", what is the allowable tolerance?
Simple. +/- .010 as measured from the first hole. Anyone who knows how to read a blueprint will follow the flag notes and the standard practices and will know that
If the distance between the 1st and 2nd hole is 0.995" what is the allowable distance between the 2nd and 3rd hole?
You do not measure the distance from the second hole to the third. You measure the distance from the first hole to the third. ALL the hole in the run are measured from the first. IF you measure the second hole to the third, then the third to the fourth and so on, you will induce tolerance stacking[/quote]
If the distance between the 1st and 5th hole has to be 4.000 +/-.010", then put that on the drawing. So, you have ten dimensions rather than one
This method might work for some detail drawings, but can also make some drawings too busy and harder to read and interpret, especially when it's a sub-assembly or assembly drawing
For example, on the AR lower drawing, the distance from the datum plane to the hammer pin hole is given +/-.002. The distance between the hammer pin hole and the trigger pin hole is the critical distance, and needs to be within .0015", so that is the distance given, not the distance from the datum plane*. However, on the bolt, every critical dimension is referenced of the back side of the locking lugs, so there is no confusion or possibility of tolerance stacking. It also tells the machinist (in the old days) how to make the part - he goes from the datum plane to the hammer pin hole and drills it, he zeros the machine and goes to the trigger pin hole and then drills that. Now the holes are properly located, no question, no error. No need to know Armalite's proprietary manufacturing process specification.
That's what I said. You lay out the first hole in the run, which in your example is the hammer hole. Then, from the first hole, you layout where the second hole will be. That's how you layout the two holes in a two hole run
And, in my experience with engineering drawings, the ARDEC drawings for the M16/M4 are much better in this regard to anything I have seen from the aerospace industry. The aerospace industry generally makes drawings with their own "this is how we read drawings/make stuff" processes in mind. The ARDEC drawings are done so that it doesn't matter how you read them, if you plop a part down under a faro-arm and get readings that say it is "to print", it will fit and work.
The AR is a much simpler machine than an aircraft and therefore AR prints are also simpler. However, aviation detail prints aren't any more complicated than a detail print for the AR. Looking at the following AR prints, I'm not seeing any practical difference from prints I use for aircraft
http://i1286.photobucket.com/albums/a601/AVIDavid1982/AR15_Bolt_zpsc8021783.png
http://i238.photobucket.com/albums/ff236/thomvinson/AR-15LowerBlueprint.jpg
I know what "Tolerance Stacking" is. The example I used about laying out holes is simple to understand and clearly explains how tolerance stacking occurs. No reason to make it more complicated than it is
I know what "Tolerance Stacking" is. The example I used about laying out holes is simple to understand and clearly explains how tolerance stacking occurs. No reason to make it more complicated than it is.
Over the years I've been lucky. I've been on all sides of this. I've been the guy out in the shop that needed to make the part, the guy that needed to design the tooling and manufacturing processes to get the part built, and the guy who designed the part in the first place.
What you posted above and this statement - Anyone who knows how to read a blueprint will follow the flag notes and the standard practices and will know pretty well sum it up.
Complication is a funny thing. It can make you feel smug, like you really have a handle on some complex problem or process. But it costs you $$ at the production end and makes people wonder wth you were thinking. I enjoy more than anything hearing from a tooling shop - The guy that designed this part understood how it would be built. As if he was spending his own money. Because mostly I've worked for small companies and it really was my money.
There are no US Army Ordnance drawings for National Match M16s and M9 pistols, or match 5.56 and 9mm ammunition. Yet all service teams must shoot them at Camp Perry.
Every single one is a custom-built Frankengun.
Marine Reserve Staff Sergeant Harry Harrison won the President's Rifle Match with an out-of-the-box Armalite National Match AR -- a factory-built Frankengun.
The second part of the equation is the shooter has to point the weapon. Indian, not the arrow.
Maybe I missed it skimming through or my lack of sleep, but I didn't seem to catch a post detailing datum points and why they are important. That understanding can help some better learn more about tolerances in general. If everybody used the same points as a reference, then things could be easier for a combination of components. Problem is with that is they are not using the same.
When you combine components with different points of reference, your building blocks may not build what could be required.
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