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Posted: 12/2/2008 4:08:51 PM EDT
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LMT 16" with LMT bolt is ripping case rim and on FTE with south african 5.56.
Cleaned chamber and had two more in ninty rounds. cases tap out easy with rod. Any suggestions? |
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Either rough/tight chamber, or gas port too large.
Start with going to a heavier buffer if a carbine stock, and if that does not cure the problem, then it's time to either ride out the problem (chamber) through live fire to polish the chamber, or just polish the chamber by hand. Or, just send the barrel back to be checked/corrected by the factory. |
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Buy a H-3 buffer.
Between the standard unit you have, and the new one, you can make a H-1, and H-2 as well. The difference of the buffers is that there are three discs in the buffer. On the standard unit, all three are steel. On the H-3, all are tungsten. So a H-1 is one tungsten disco, and two steel. To get to the discos, you just punch out the roll pin on the bumper to pull the bumper off the back of the buffer. When re-stacking, make sure to install the disc buffers correctly (back end towards the bumper does not get a buffer, but the between the front disc and front of the buffer, you install a disc, and between them as well). Bottom line is run the heaviest config you can that will still allow the bolt to be locked back on the last shot out of the mag. |
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DANO, what does the H-Buffer have to do with an extractor ripping case rims?
Could it be a overly powerful extractor spring (if installed)? See how strong the extractor is by trying to flick it OUT with your finger? Is there an O-ring around the extractor spring? Enlighten me, please. |
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The problem is his chamber it retaining the spent case too much at ejection.
It's either the chamber is too rough/reamer chattered, or the action is trying to unlock with the barrel residual pressure still to high to allow the case to be pulled (spent case still too high pressure bonded to the chamber wall). In the case of the later, more buffer weight will slow the block unlock down, and allow the barrel residual pressure to drop more before the spent case is pulled from the chamber. By loosening the tension of the extractor, his questionable ejections would just end up with the case still in the chamber, but the extractor loosing grip on the rim. Since his rims are being bent, and not the extractor dropping the case, the extractor and it's tension are fine, its that the spent case just won't come out of the chamber cleanly being the problem at hand. This leads us back to either chamber conditions, or too much gas pressure in the barrel at unlock being the problem at hand. As for telling if the extractor spring it too tensioned, then yes a bent rim will be the problem, but it will be the case rim is bent forward during loading, and not backwards during the extraction. To get a better idea of barrel port pressures, and gas action dwell time, read the tacked post in this forum "How it Works". |
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