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Posted: 3/30/2013 1:50:15 PM EDT
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In a thread in the ammo forum, I explained that my newish Stag Mod 1 was failing to extract-only with Privi brass casings-and actually tearing the rim of the casings. The casings were easily tapped out of the chamber with a rod, but would probably have dropped out if I had tapped the butt with the bolt to the rear. The most popular idea expressed for the problem is overgassing. Suggestions included replacing the buffer with an H or H2 buffer to slow the extraction process. No mention was made of the buffer spring. Should this be replaced at the same time, and, if so, with what spring. On general principle, I'm putting in a #40 o-ring on the extractor spring. Any other thoughts are appreciated. It is my understanding from a lot of reading that the Privi ammo is pretty decent stuff, and no one else has complained about any FTE problems. Is switching to a heavier buffer going to cause problems with other ammo? I'm an AR noobie-my last AR was issued to me in Nam-but I understand the system fairly well. Again, all comments are appreciated.
Tom |
| Similar thing happening to me. I'm also an AR newbie and first round (PMC .223) had the rim sheared off by the ejector. Casings were easily extracted, with a cleaning rod. After a thorough cleaning, the same PMC ammo was ejecting, but with almost sheared rims. I.M.G. 5.56 ammo from 1991 works better, but still shows damage to the rims. Clearly overcycling, but is this a buffer weight issue or an over-sized gas port? |
| PRVI ammo is good stuff. No, you do not need to change the buffer spring when you change the bufffer. And yes, a heavier buffer to slow down the cycling will very likely fix your issue. It's either going to be overgassing and you need a heavier buffer, or there may be a burr in your chamber somewhere that is causing problems. |
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If the case rims are being bent/torn badly on the pull, then the extractor spring is fine, and an added #60 O ring around the spring to add spring tension is not needed.
Since you are talking H buffer, then you have a carbine receiver extension in play. The free length of the spring should be around 10.5" and if appears the the recoil spring had been clipped, or weak, then the problem at hand could just be a weak recoil spring. When all else fails and you don't have a replacement carbine recoil spring, borrow someone else for quick testing. If the spring is fine, then buy a H3 buffer, and here is why. A standard buffer has three steel inserts in it, while a H-3 has three tungsten inserts instead (all the same size, but the tungsten inserts are heaver). Between the standard buffer you have, and the new H3 buffer, you can swap out the inserts between the two to come up with any buffer(s) needed. To swap the inserts in the buffers, just punch out the buffer bumper cross pins, and pull the bumpers. |
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Quoted:
If it is overgassed, the best solution is an adjustable gas block. Heavier buffers,etc. are just a band-aid, and not a real fix. Not to mention the added benifits, ie. less recoil and less gas/carbon in upper, less wear and tear etc. Although I like the idea somewhat of adjustable gas blocks for guns that you need to readjust the gas system, such as suppressed to non suppressed, I have yet to find one that has a good repeat adjustablity seating to move the dial from one setting to the next, then back again (number detent style, instead of one with just a normal and advert fixed setting instead). Here, it just faster and simple to just change out the buffer instead, with say a standard buffer for unsuppressed, the other up to a H3 if need instead. Granted that the ops problem may be a gas port too large, this has yet to be determined, and may be a simple as just a weak recoil or hammer spring,or even a cheap knock off shot type buffer that is causing the problem and just need to be replaced instead. Also to add, since this rifle is not going to be supressed, if it is a gas port size problem, should be able to resolve the problem with a single increased mass buffer to solve the problem for all types through the rig. Lastly since no one brought it up, are we sure that the barrel is chambered 5.56 Nato, and not just 223 rem and causing the higher working pressure problem instead???? |
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