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