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Posted: 9/2/2013 3:45:25 AM EDT
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What color spring should I get? (white, red, blue) Springco link
I have four different configuration with non adjustable gas blocks that I want to optimize. PSA 16" carbine gas length std carbine buffer -observed overgassing cartridge ejection at 1oclock BCM 16" carbine gas length H buffer-never fired Rainer 16" medcon barrel mid-gas length, H buffer- perfect cartridge ejection at 3:30 oclock Noveske 18" intermediate gas length , no buffer yet- future purchase |
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The "chart" that shows over/under gassed variations is overused and poorly understood. It's useful ONLY if you're having a problem, and then it only suggests a direction to look for things in. Further, it oversimplifies things to "over gassed" or "under gassed" when in reality it's a system involving the gas port size and location, buffer mass and spring tension. Bravo for actually picking up on this - a lot of people immediately assume, because of "the chart," that there's something wrong with their gas port when that is almost certainly not the case.
Your gun is only "overgassed" if it ALWAYS ejects EVERY load way too far forward AND operates roughly and violently with every load. What load did you observe this 1:00 ejection with? It could be that it was just a much hotter load than your PSA was tweaked for. If anything, I'd go with a heavier buffer first, though the spring option costs less. Try your BCM's H-buffer in the PSA and see what happens with it. I would expect that the PSA's gas port is within specs just as the BCM's should be, so if the H-buffer works well with the PSA, you're likely to see it work fine with the BCM asd well. The midlength gas system on the Rainier upper and the H-buffer in its lower aren't giving you "perfect" or "ideal" ejection. Ejecting at 3:30 means that the gas system and buffer/spring combination are cycling the rifle relatively slowly and not tossing the brass backward enough to hit the brass deflector. With a lighter load, or a standard load with a heavier bullet, you could get short-stroking at times. Try the Rainier with your PSA's standard carbine buffer and see where it throws the brass. You may be surprised to see it going more toward 2:30, but I'd prefer that over a 3:30-4:00 ejection pattern for reliability. In short, unless every round you try, hot or mild, gives you a problem with its ejection, i.e. doesn't fully eject, or ejects straight forward and beats your shoulder up in the process, it's not really necessary to worry about which direction your gun ejects in. It ejects every time, right? That's not a problem. |
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Quoted:
What color spring should I get? (white, red, blue) Springco link I have four different configuration with non adjustable gas blocks that I want to optimize. PSA 16" carbine gas length std carbine buffer -observed overgassing cartridge ejection at 1oclock Not sure BCM 16" carbine gas length H buffer-never fired Shoot it first, don't fix it if its not broken Rainer 16" medcon barrel mid-gas length, H buffer- perfect cartridge ejection at 3:30 oclock Leave it Noveske 18" intermediate gas length , no buffer yet- future purchase Blue |
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Forgot mention that it all configuration I was firing only bulk Lake City XM855 (Palmetto Armory)
I have four different configuration with non adjustable gas blocks that I want to optimize. PSA 16" carbine gas length, std carbine buffer - observed overgassing cartridge ejection at 1 o' 'lock BCM 16" carbine gas length, H buffer - never fired Rainer 16" medcon barrel, mid-gas length, H buffer - perfect cartridge ejection at 3:30 o'clock Noveske 18" intermediate gas length, no buffer yet - future purchase |
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Call Allen at Tactical Springs (Sprinco USA), and he can help you out with any questions you may have.
For your carbine gas setups; as long as your gas port measures 0.625" / 0.63" you can use a blue spring & H2 buffer, 5-coil extractor w/ black insert and viton o-ring with either a 16" or 14.5" barrel. I also picked up an ejector spring from them being they cyrogenically treat both their extractor and ejector springs. As for my action/buffer blue spring I also requested one that was cryogenically treated. The 5-coil extractor w/ black insert and viton o-ring does not eat up your cases either as long as your bolt is not unlocking early. This setup works with American Eagle .223 55gr FMJ and 5.56mm 62gr M855. As I mentioned earlier this setup will work as long as your gas port measures 0.0625" / 0.63". I ended up choosing these specific springs after reading Mike Pannone's article. http://www.defensereview.com/the-big-m4-myth-fouling-caused-by-the-direct-impingement-gas-system-makes-the-m4-unreliable/ |
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