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Posted: 1/12/2016 1:39:41 PM EDT
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I recently built my first AR-15. I used a 6.5 Grendel barrel, with .223 parts The issue I'm having is after I fire a round it ejects spent cartridge. Then is doesn't load the new one properly. It dents the cartridge in two places and jambs.
Do I need a stronger buffer and spring? any ideas would be greatly appreciated. |
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The problem you are running into is called bolt over round, Being that either the B/C did not stroke all the way back, or the mag did not get the top round all they way up for the bolt to strip the round correctly.
So with the rifle cleaned, including the chamber scrubbed with a chamber brush with CLP, then the upper receiver bearing ares lubed to begin with. Start off by pulling the charging handle all the way back and see where the face of the bolt stops against the back of the ejection port window. The face of the bolt should stop 1/8" to 1/4" in front of the back edge of the ejection port window, and the last inch'ish of the charging handle should not be harder in pull tension that the middle of the handle pull. Next, pull the bolt off the carrrier and using only the carrier with key, dry fit it into the upper receiver to make sure that the carrier is not binding in any way, and when the carrier gets about a inch from touching the back of the face of the barrel extension, the gas tube is correctly aligned to make up with the carrier key. Now with this out of the way, load only a single round into a mag, insert the mag and charge the round, and while leaving the empty mag in the well, fire the rifle to see if the bolt is locking back on the bolt catch (catch in front of the bolt, and not just catching the bottom of the carrier instead. If the bolt does not lock back, then start checking the gas block to barrel and gas tube to gas block for any leaks. Hence CLP around the seams, then using a piece of tubing on the end of the gas tube, charge the gas tube with about 100lbs of air pressure. On the B/C, CLP around the base of the key to the carrier, then hold the bolt in which charging the front of the key with 100lbs of air pressure. Granted that the air will be coming out of the bore, and the B/C will leak in other areas, the block to barrel/gas tube, and key to carrier should have no leaks. If the bolt does lock back, then we needed suspect that its the mag the problem instead. Here, start with pulling the mag apart to CLP clean it, and make sure that the mag catch assembly end threaded section is flush with the face of the mag release button. Also to note, you should be using 6.5 Grendel mags since you can run into problems trying to use 223 mags instead. |
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I've had to open the gas ports slightly and some 6.8SPC and 6.5 Grendel rifles I own to get them to function.
You didn't mention what ammo you are using? I personally have had extreme accuracy using Sierra's 107 grain Match King seated at 2.250" using 26.0 grains of VihtaVuori N530 powder. Lapua brass. I like the lighter bullets and they probably produce more port pressure then heavier ones because of the larger powder charges. If you are shooting some economy commercial load I would try some USA made brass cased ammo before modifying the rifle. |
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