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Posted: 8/2/2026 5:33:10 PM EDT
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Hey guys, Built a .300 BLK pistol, Faxon BCG, Odin Works 10.5inch barrel and Odin Works Adjustable Gas Block, Wolfman Suppressor. Firing S&B 220 grain. I was having major failure to feed, next round nose up with the bolt rammed about halfway into the case. Played with the gas adjustment, opened things up a bit and got it to run better but had a light primer strike. Closed GB 1/8 turn and then ran 4 Magpul Pmags worth of action a week ago. Today I had 3 feed failures in 9 rounds. I have a standard carbine buffer (3.6 ounces on the kitchen scale), not sure what spring. Ordered the Odin Works heavy adjustable buffer and Sprinco white spring. Am I on the right track? Thanks |
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Sounds like you have an H1 buffer. Std carbine buffer is 3.0 oz Typically with subs a mil spec spring rate and 3.0 oz carbine buffer run just fine. Typically you don't want to go heavier or higher spring rate unless you're running hot supersonic loads |
“All things are said already, but since no one is listening, it is always necessary to start again.”
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I'd be running a carbine weight buffer with gas block wide open and adjust from there. Palmetto is now making their branded 300blk ammo for a fair price I think...I haven't priced 300blk ammo for quite sometime. https://palmettostatearmory.com/300-blackout-ammo.html?manufacturer_v2=Palmetto+State+Armory ETA: I've used Velocity brand 5.56 ammo without issue. This stuff is a bit cheaper. https://republicammunition.com/product/300-blackout-220gr-tmj/ |
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No your doing it backwards for subsonics With subs you shouldn’t be turning down any gas. Leave that thing open. Like others said, you will more than likely need a carbine buffer and standard spring. Also, I love Magpul and all but I have had bad luck running their 30 round “300 BLK” magazines at full capacity, I only have a few of them from when they first came out though. Try a GI or Lancer. Not familiar with that ammo particularly but I’ve not been impressed with other Ammo Inc loads S&B is a good “cheap” choice though |
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Hey guys - did not touch the gas system today - but I did some swapping of parts and now I feel like I'm in a different rabbit hole. Swapped the .300 BLK lower for a .223 Pistol lower that I had and ran the problematic upper and it failed to feed on the 11th round (third mag). the lower had a 3-ounce buffer and I don't know what spring. Put lowers back and then swapped the Bootleg BCG from a .300 BLK rifle into the pistol and it ran 3 magazines of 6 rounds each with no issue. Aha, maybe the Faxon BCG is bad! So, I put that bad boy into the rifle, it ran 4 mags (6 each) just fine. So, is it possible that the pistol just runs better with a Bootleg than a Faxon? Seems unsatisfying, but if it is a thing..... Would need to run a few hundred rounds before I trust the gun. Still on the table is swapping the buffer and spring and opening up the gas system. Any new insight with this new data? |
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Could be a head space thing, but will bank that its a leak in the B/C, either at the key to top of carrier, or problems with tail of the bolt to channel in the carrier that may be binding. Also, take a good look at the gas rings. The are stamp cut, so one side of the rings will be rounded, while the other side will have sharp edges. When re-installing the gas rings, make sure to put the sharp edges side of all three rings, towards the tail of the bolt. The other one to check, without bolt on carrier, dry fit the carrier into the upper, to make sure gas tube is aligned with it. The gas tube enters the carrier key when the front of the carrier is about an inch from it face touching the back face of the barrel extension. If gas tube needs to be tweaked to align, bend gas tube over center of the barrel to tweak is end, not grabbing the tube where it protrudes in to the receiver to just bend the end of the tube alone. |
Posted By PlaymoreMinds:
'Twas not the <cough> sweet and innocent <cough> PlaymoreMinds...
<---skips away in frilly skirts to Candyland, leaving gutters and snorkels FAR behind.
'Twas not the <cough> sweet and innocent <cough> PlaymoreMinds...
<---skips away in frilly skirts to Candyland, leaving gutters and snorkels FAR behind.
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Originally Posted By csacksteder: Hey guys - did not touch the gas system today - but I did some swapping of parts and now I feel like I'm in a different rabbit hole. Swapped the .300 BLK lower for a .223 Pistol lower that I had and ran the problematic upper and it failed to feed on the 11th round (third mag). the lower had a 3-ounce buffer and I don't know what spring. Put lowers back and then swapped the Bootleg BCG from a .300 BLK rifle into the pistol and it ran 3 magazines of 6 rounds each with no issue. Aha, maybe the Faxon BCG is bad! So, I put that bad boy into the rifle, it ran 4 mags (6 each) just fine. So, is it possible that the pistol just runs better with a Bootleg than a Faxon? Seems unsatisfying, but if it is a thing..... Would need to run a few hundred rounds before I trust the gun. Still on the table is swapping the buffer and spring and opening up the gas system. Any new insight with this new data? You should get some Lancer 300 blk mags if you're running subs. The way the ogive of the sub bullets are won't want to be reliable in regular 5.56 mags. The little ribs inside the magazine are in a different position on the 300 blk ones. |
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