View Full Version : Several questions: trying to spec a 16" SPR-like upper
I'm trying to spec a 16" midlength upper with the intention of creating a precision rifle with SPR-like performance. Main uses will be: precision shooting at the range, occasional varmint hunting out to 500 yards (however, I have a 20" hb upper that does well at long ranges), and as a fighting gun (though I have another 16" mid setup for that). The issue is that I know some individual pieces and parts I want, but after reading old threads here on M4c, I haven't figured out how everything will fit together. So I have a few questions about what to get.
Here are the basic specs that I think I want.
-Barrel: 16" SS, 5.56 or Wylde chamber ok.
-Comp/FH: Battle Comp. Looks like best all-around option going.
-Receiver: VLTOR MUR. Besides the obvious quality of the VLTOR, one advantage is that you can get the "1a" version of the receiver, which positions the forward assist farther forward than on a standard receiver, which is useful for LH shooters using an ambi charging handle (that's me).
-Ambi controls: Planning to get the Troy ambi CH (available soon), the Troy ambi safety selecter, and the Troy ambi mag release.
-BCG: Have a BCM semiauto BCG.
-Handguard: DD 12" lite rail. I have longer arms, and it looks like the lite rail gives the best overall combination of a good sight radius, light weight, longer gripping surface, and free-floating stability.
-Sights: KAC 200-600m micro rear, something like DD or Troy rail-mounted front sight.
-Gas block: Not sure, what do I want to do here.
Questions:
1. For the barrel: Should I go to 18"? I've read all the "SPR" and "Mk12" threads, plus some others on ballistics, and it seems that the extra 2" doesn't buy all that much extra velocity/performance, and only makes the rifle more cumbersome.
2. For the handguard: Is there a better all-around rail I should look at? Should I consider the VLTOR rail that goes with the MUR receiver (the VIS?), or is the DD a better all-around choice to help keep weight down?
3. For the comp/fh: Will the choice of comp/fh affect my shooting (velocity or accuracy) at longer ranges? Would I want something other than the B.C. for a precision/SPR upper?
4. For the BCG: Would I likely get noticeably better accuracy than the BCM BCG if I instead get a fitted BCG from the maker of my upper?
5. For the gas block: given the rail and sight options I selected, what kind of gas block setup would be the best choice for this upper?
I think you'll be just fine with a BCM bolt carrier group.
I have a 16" midlength with a 12" DD rail on it (older M4 rail, not a Lite rail). I think it's a great combination. The Lite rail will help keep your weight down.
If you already have a longer rifle and you're concerned about weight, I'd stick with the 16". It should do everything you need it to.
This is my carbine - I have an OPS Inc muzzle brake and can on it. (15th model, not the 12th used on the SPR)
http://i2.photobucket.com/albums/y41/boltcatch/can2.jpg
http://i2.photobucket.com/albums/y41/boltcatch/carb5.jpg
eightmillimeter
04-18-11, 02:40
White Oak Armament at www.whiteoakarmament.com makes a squad designated marksman barrel that is 18 inches. It is your choice of 1:7 or 1:8 and a wylde chamber. It comes machined for their in house FSB but if you ask they will turn the end down to .75 to fit all the std gas blocks. I would say to go with any 18 inch barrel since you already have a 16 inch midlength and it sounds like you are trying to scratch the SPR itch with this one. This one's a tad heavy so get the lightest rail you can but you will love the accuracy.
If you simply need an excuse to build another AR, go for it! Either barrel length will work well- or you could do something really off the wall and split the difference with a 17" barrel!
But if you are really trying to fill a niche, you have to ask your self- what will this new rifle do that the ones you already have won't? With a few simple changes, your 16" middy will do fine in this role. So would your 20" by cutting the barrel back to 18" (unless your 20" is a dedicated to service rifle matches).
I think a 16" barrel will be handier for defense use and will still get you out to 500 yards. Choice of optics will be as important- if not more so- than choice of barrel length, to fit these dual roles
Your build sounds a lot like the one I have bouncing around in my head.
Grant is having a sale on the Vltor rifle length VIS for $574 or $560 in his open box sale. That is the best price I have seen and if you ever wanted one this would be the time. Pair that up with a BCM 16in stainless and a Vltor lowpro gas block and you’re off to a good start.
Sounds like a 'Recce-style' build in the works. SPR-ish performance can be realized in a 16" package. There are a variety of 16" barrels out there that will offer above-average mechanical accuracy potential, including the BCM SS410 barrel you mentioned. Personally, I would opt for .223 Wylde, or other chamber cut with accuracy potential in mind as opposed to a straight-up 5.56 NATO chamber. My understanding is the Bravo Co SS410 barrels have a 5.56 NATO Match chamber, which is different from your basic 5.56 NATO chamber; but I don't know how/in what way.
If you're serious about achieving 'precision' from the rifle, finding the right bullet that your barrel likes best will take some work. A better, lighter trigger than your standard mil spec FCG will probably help, as will free-floating the barrel with your choice of handguard. Beyond that, components don't figure as much into the mechanical accuracy potential of the rifle.
As for the accuracy potential of you - use whatever works. If you're a lefty, why not build the upper on a Stag lefty receiver? Might be worth a look, anyways.
Some good points--that's what I like about M4c.
boltcatch -- nice rig.
8mm -- Yeah I'm a WOA fan, already have their CMP match upper, scary accurate. I'm still weighing the benefits of 18" vs 16".
Mistwolf -- Valid point. With my current setup, it's questionable whether I really "need" another AR. Going with your point, I could take my current 20" SS, which already has a Wylde chamber, cut it back to 18" and thread it, and it'd probably do a great job.
5pins -- thanks for the tip on the receivers from Grant. Anybody know -- if I get a VLTOR MUR receiver that does NOT have the 1a configuration that I need, how hard is it to swap that part out?
hikeeba -- Didn't know about the 5.56 match chambers at BCM. Do they get similar performance to a Wylde? Are the trade-offs simply that the 5.56 match is going to run 5.56 ammo more "reliably" than the Wylde, but the Wylde maybe gives more accuracy potential?
hikeeba -- Didn't know about the 5.56 match chambers at BCM. Do they get similar performance to a Wylde? Are the trade-offs simply that the 5.56 match is going to run 5.56 ammo more "reliably" than the Wylde, but the Wylde maybe gives more accuracy potential?
I recently did a very similar project to what you are planning - I generally use the rifle for 3 gun and action rifle matches, but also enjoy some shooting for accuracy 500-600 yards off the bench with it. When I was choosing a barrel I id a fair bit of researching the net for what exactly is the difference between a 5.56 NATO Match/USMC SAM-R chamber as offered by BCM and the more common Wylde - best I could come up with is that it is a variation on the same theme but was developed by the USMC competition team as opposed to development by Bill Wylde. I didn't uncover any particular specs or schematics but my guess is that if there is a difference in the chamber, the difference in dimensions will probably be within a gnats cocks width of each other.
The barrel I went with was Nordic Components Lilja barrel - it is actually 16.5 inches and nicely lightweight as they machine it down quite a way under the handguards (more so than the BCM barrel which I was also considering). Can't say enough good things about it; superbly machined by Lilja, soft shooting, incredibly accurate with no deviation in POA/POI hot or cold, yet reliable with any kind of ammo I want to put through it from match ammo through Brown Bear crap. If you hunt around the Brian Eno's website you might find a 10% off coupon for it - makes it a very good deal....that is in stock. Also comes with a gas tube.
http://shop.nordiccomp.com/Lilja-Nordic-AR-Rifle-Barrel-Stainless-16-BBL-223-16M-LN.htm
Thanks for the info on the chambering background.
As for my own questions about handguard/rail options, I found some more good threads including one comparing the Troy and VTAC 13" handguards. These both look like great, lighter-weight options that would be worth considering to keep weight down. I haven't gotten a chance to try either of these in person, but have seen them on the M&P Vtac models in a store.
http://www.m4carbine.net/showthread.php?t=46575
Also, I noticed that Noveske's 16" Recon build with the stainless barrel comes with the VLTOR receiver and has most of what I want, though it's $1400. Centurion has a similar SPR setup in an 18" barrel for close to the same price, when you factor in the BCG cost. Despite the daunting cost of these uppers, I know they're quality and I'll probably have about the same money in them by the time I'm done anyway. So I'm wondering if I'm better off just going with a quality builder like one of these two.
...Anybody know -- if I get a VLTOR MUR receiver that does NOT have the 1a configuration that I need, how hard is it to swap that part out?...
VLTOR states that a MUR upper can be configured with or without forward assist, however, they also state once assembled, the configuration cannot be changed
hikeeba -- Didn't know about the 5.56 match chambers at BCM. Do they get similar performance to a Wylde? Are the trade-offs simply that the 5.56 match is going to run 5.56 ammo more "reliably" than the Wylde, but the Wylde maybe gives more accuracy potential?
SA80Dan came up with the same info I found when doing the research for the build project I did last year. I also could not find actual specs on the 5.56 NATO Match/USMC SAM-R chamber. I will speculate that because it was developed with accuracy potential in mind, it will be closer to a .223 Wylde chamber than it is to a regular 5.56 chamber. I don't think Bravo Co's 5.56 NATO Match/USMC SAM-R spec chamber will run 5.56 ammo more reliably than a .223 Wylde chamber. Like the .223 Wylde chamber, it should do well with good 5.56 or .223 ammo. And based on what I've read about the BCM SS410 barrels, I'd say the SAM-R spec chamber is on par with the .223 Wylde chamber as far as accuracy potential goes.
I waffled back and forth between the BCM SS410 barrels and Ranier Arms' UltraMatch barrels for my build project, but ultimately ended up with a barrel from Superior Barrels (16.1" 'Recce' barrel). The Superior Barrels barrel is chambered in .223 Wylde and has a 1/7 twist. There were a lot of little things that added up to my decision to go with Superior Barrels, but probably the biggest factors were John and Matt; the guys that own/run/are the company. They're two great, regular guys who really love to shoot. Anyhoo, I'm still trying to feel out the barrel as far as what it likes best (bullet weight), but I am more than pleased with what I've been able to do with it so far. Just thinking about shooting it makes me smile.
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