AR-15 Subsonic Feeding Problem

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AR-15 Subsonic Feeding Problem

Post by promptcritical » Sun Jan 23, 2022 4:16 am

I built up a 300 BLK using Wilson Combat parts (11.3” barrel & pistol gas. Unsuppressed-suppressors are not an option here).

It will feed supersonic rounds just fine and I’m using 300 BLK pmags (I’ve also tried 5.56 pmags with the same results).

When shooting subs it jams after 3-4 rounds (rounds don’t feed into the chamber and are stuck with the tip in the barrel extension and other end of the case resting on the next round in the magazine).

The ammo is Hornady Sub-x in 190 & 220 grain (only subs I can find locally).

I’ve tried all combinations of light and heavy buffers (from 2 to 4 oz) and strong and weak buffer springs (all of Sprinco’s different springs).

Anyone have a suggestion (Ammo or rifle)? (It’s my home defense weapon and I’m not good at reloading yet, so that is not an option).

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Re: AR-15 Subsonic Feeding Problem

Post by dpete » Sun Apr 17, 2022 1:38 pm

How big is the gas port in the barrel? My 8" barrel SBR had the same issue until I opened up the gas port to .108". Its primarily a sub gun and for shooting supers I can turn down the gas with the adjustable gas block if needed. The other thing to check is if the subs are rubbing on the side wall ribs of the mags. I know the 300 BLK Pmags are different internally than the 5.56 mags but its something easy to check.

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