Found this online today. Figured some of you may find it interesting.
http://www.ewp.rpi.edu/hartford/~ern...inalReport.pdf
I disagree with parts of his conclusion, but his analysis of piston systems is interesting.
Cheers.
Found this online today. Figured some of you may find it interesting.
http://www.ewp.rpi.edu/hartford/~ern...inalReport.pdf
I disagree with parts of his conclusion, but his analysis of piston systems is interesting.
Cheers.
Nice find. The abstract and a quick scan of the weapon system description has me curious. I will have to read this more thoroughly when I have a little more time.
Very interesting. The internal stresses from the offset of the piston surprise me that they are 10x more than an internal piston/di design.
This is an intriguing find, looking forward to reviewing it this evening.
I disagree with the main premises and naming of the Stoner/AR15 and AR10 gas system as "direct impingement", however, I find the engineering discussion refreshing.
False Premise #1: Fouling in the AR15 design causes malfunctions. I think most of the members of this site are aware that real world results simply don't support this. Insert Filthy 14 link, or any of my personal guns that I just lube, maybe scrub off the bolt face and extractor pocket, bore snake, and lube. There is a stronger case to be made that fouling increases the gas seal around the bolt tail inside the carrier chamber/bolt bore.
False Premise #2: Maybe I'm just Murphy's best friend every time I run low or high volume with AK's, but I have yet to make it through one single range session or course with an AK, without all kinds of malf's. The only exceptions to this have been with Valmet Rk62's, Rk92's, and Rk95's, fed Finnish Defense Forces, high quality brass-cased ammo, from Finnish high quality polymer waffle mags. All the others have experienced seized cases, FTFeed, FTFire, broken components just from shooting, & double feeds. We're talking a time span covering the 1990's to present, some range sessions seeing 11,500 rounds through 8 guns.
In short, I don't want my AR15's to do anything the AK does, handle in any way the AK handles, or resemble an AK in any way, shape, or form.
For terminology, the AR15 and Stoner's patent describe the gas system as a true expanding gas system:
http://www.google.com/patents/US2951424Quote:
It is another object of this invention to utilize the energy of the expanding gas developed by the firing of the weapon, for actuating the automatic rifle mechanism directly by use of a metered amount of the gas coming from the barrel. This invention is a true expanding gas system instead of the conventional impinging gas system.
He handed in a thesis with an improper use of "platform." Nice.
The horrible abuse of weapons we were forced to perform is the last thing I will do on my personal guns. I noticed a big difference in weapons maintenance between units where maintenance was driven by competent gun guys, versus units where it was white gloved so garrison-oriented officers and NCO's would have a warm and fuzzy, while countless hours were wasted with soldiers sitting around well into the night stripping weapons of all the lubricants, only to be rejected at the Platoon CP or arms room window by some sadist with a pinky finger shaped like a dental tool...(If you were an 11 series, you know what I'm talking about.)
Wipe it down, scrub bolt with toothbrush to remove any brass shavings, clean the bore, light-to-moderate coat of oil, turn it in. No big deal. Guns ran better as well. If you learned how to clean weapons in 82nd, or most other Infantry units, it was most likely a really bad cleaning regimen. I was in 325th AIR, so I know. We did the same crap in Korea, Fort Lewis, Benning...pretty much every conventional unit is populated by people who call the shots from Division down to Brigade and Battalion levels that know jack and squat about proper weapons maintenance. White glove ruled the day. White gloving weapons should be a floggable offense in my opinion.
Yep, I was a grunt, and yep, it was "white glove" shit. I don't disagree there. It doesn't take a surgical scrub to remove built up carbon off the bolt tail or back of the carrier (inside). Hell, I have a couple little tools that are available now that do it REAL quick, especially to what one would consider a "functional" level. Even the old tried and true (but slower) process of an old bore brush rubbed a few times back and forth will take off excessive carbon buildup. If all you're looking for is functionality then that would suffice.
ETA---it is Cretan-like cleaning procedures that harm more than help. There's nothing wrong with a squeaky clean weapon if you want it that way.....it's how you do it. Power tools are heading in the wrong direction for sure!
Interesting read. Laughed a little at Figure 5: Some Typical Gas Port Locations for Varying Barrel Lengths (4) where the read arrow points to the "Gas Hole" under the FSB.
Noah
I just realized it's only a 48 page thesis!! I expected 100+ pages when I first opened it.
I'm finding technical inaccuracies and flawed wording throughout, most notably his presentation of figure 17. A final bullet velocity of... 5 ft/sec? Something doesn't make sense there.
I wonder what grade this report received.
Where are you seeing that? He lists the velocities at round 3k I thought.
I think the major issues are his assumptions about the performance of the AR and the AK in the real world. But honestly, those are pretty widespread misconceptions, and as a scientist myself, even my colleges who shoot would likely answer in similar fashion. These are long standing myths that will only be dispelled with time. Also, I'm sure that the those conclusions were supported by the literature he cited, assuming he practiced good science. I think we need new literature. There are some on this forum who believe the AK is a vastly superior system with it's piston design, I'm sure.
I can't help but feel a few hours on this forum would have really helped with the direction of his conclusions, but sadly, academia doesn't take kindly to gun board citations :P
Most likely turned into a group of progressive professors that have no clue what the guy is talking about anyhow, it's amazing the BS you can sneak past the academic types...
Maybe he does, but I'm looking at the "M-16 Internal Ballistics" chart (Figure 17, top of page 20) with multiple scales on the left hand side. The velocity scale is in single digit ft/sec. Something is off there. The author makes a lot of assumptions as the foundation for his conclusions, which, in my opinion, negates much of the technical value in this report. Many of his assumptions on construction of the M-16/AR-15 are faulty and show limited knowledge of the platform, indicating more research would have been helpful, as you also pointed out. In addition, he places the AK-47 on a pedestal, but provides no data to support his conclusion that it is more reliable than the AR-15, again showing a formed opinion with no research or testing to back it up. This thesis struck me as an opinion paper with a limited amount of supporting data, rather than a scientific evaluation of the AR-15/M-16- (terms which he uses interchangeably, which is arguably an improper generalization).
It's definitely not ignorance, I described most of my colleagues; they're people who've never actually had a real job (which I thankfully have, given my current position) and wouldn't know a charging handle from a carry handle.
What an interesting read. As an (chemical) engineer, I still remember a bit about thermodynamics and physics, and appreciate the math application.
I googled your user name and "AK" and read some of your posts. You have a pretty high post count on the other site and I did some reading on some of your posts about the AK47 guns. You make good points and I think I agree with you. I've never heard that point about the gas seal on the bolt tail before but it makes sense.
I will save my money for guns that are reliable. I've used more AK variants than most people even know exist, and they malf all the time. Most of them have been real AKM's, AKS-47's, AKMS's, MPKiMS-74's, Maadi AKM's, Arsenal's, Yugo's, Russian AK's of varying types (some of which won't even feed from 30rd mags, would only work with 75rd drums), NORK AK's (I though Eastern European AK's were bad, holy balsa wood & recycled tin can!). The more I shoot them, the less I like AK's.
The high quality ones are collector's items in the US, if we're talking Valmet, and you can't import the SAKO's. They still are boat anchors with terrible ergo's, very nose heavy. Beautiful machining, redesigned gas system (piston head, gas tube-high quality), but still nose heavy.
The premise that we should be trying to emulate the "AK's reliability" just does not jive with what I have seen spanning decades now running AK's in high volume. Maybe if you use brass-cased ammo, and segregate your magazines into ones that work in that particular AK. I still have yet to make it through a range session with an AK that hasn't malf'd, usually several times.
The Finns have run recent multiple-years long studies on AK vs. AR15 performance in high volume courses, many of which are in extreme cold conditions. Most of the "AR15's" over there are "vismods", and most of the "AK's" are really Valmet or SAKO's, with some Chinese and Arsenals in the margins. They have experienced the same number of malf's between both systems, and the Valmet's and SAKO's don't malf that I've ever seen, so that leaves the primary source of the malf's coming from the foreign guns.
So look-alike XM15-E2s guns, with a few other off-brands, malf as much as garbage AK's. And water is wet. We all know how well an imitation AR works in high volume. Some will for a while, and others will crap the bed within the first few mags, especially with bad chambers, bad extractors, improper gas ports, misaligned gas tubes, etc.
I will take a quality TDP AR15 against an AK any day for reliability. If you had told me that when I was a kid after stepping out from the theater, having just watched Red Dawn, I would have thought you were on crack. The reality I have seen in high volume between real military guns, properly built guns from BCM, and all the variants of AK's is substantially in favor of the AR15. The field is level if you include garbage look-alike AR15's in terms of reliability. Expect stoppages, broken parts, and sad faces from both. One will still be more ergonomic as it fails, and easy to change out parts. The other will just quit.
LRRPF52 thank you for your insight.