Owner/Instructor at Semper Paratus Arms
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Master Armorer/R&D at SIONICS Weapon Systems- http://sionicsweaponsystems.com
I have also experienced feed issues with D&H mags.
They are relegated to "practice mag" status, if they're used at all.
Add-I've never experienced feed issues with IMI m193 with Pmags and Brownells mags.
I've shot several cases of it.
Last edited by gaijin; 04-25-17 at 10:15.
Mark all of your mags for identification. When a pattern emerges, you won't be pulling your hair out in frustration.
I had failures to feed that were a result of a loose gas key (Centurion Parts), what would happen is occasionally the carrier wouldn't travel rearward enough to get the bolt behind the next round, it was the BCG leading edge that caught the next round resulting in a hard angle into the chamber with the bolt jamming into the side of the cartridge. Sometimes it would cycle fine, sometimes it would not go back far enough to strip the next round, and sometimes it would strip the round with the BCG and the bolt would smash the round. Usually there wasn't enough energy to lock the bolt back last round either, very inconsistent until the gas key was tightened down. Gas key might not be your problem but I'm still thinking it's an undergassed situation causing your trouble.
My mags of choice are Okay mfg, NHMTG mostly with my favorite the 20 rnd variety. DH stamping places a folded metal edge into the side of the cartridge of one of the top rounds, though honestly I never had any feeding issues in my limited use.
I experienced feeding issues with a pair of NHMTG 20 round mags which ended up being the springs were installed upside down which compromised the follower. Flip and installed correctly and that problem went away.
IMG_20160321_162342_523.jpg
Last edited by LMT/556; 04-25-17 at 14:47.
A gas issue is possible, however, the FTF's happened using two different carriers, an LMT enhanced and a Sionics carrier. ALso, the weakest ammo, the PMC Bronze, cycled 100%. It's the hottest ammo, the IMI 556 that wouldn't feed.I had failures to feed that were a result of a loose gas key (Centurion Parts), what would happen is occasionally the carrier wouldn't travel rearward enough to get the bolt behind the next round, it was the BCG leading edge that caught the next round resulting in a hard angle into the chamber with the bolt jamming into the side of the cartridge. Sometimes it would cycle fine, sometimes it would not go back far enough to strip the next round, and sometimes it would strip the round with the BCG and the bolt would smash the round. Usually there wasn't enough energy to lock the bolt back last round either, very inconsistent until the gas key was tightened down. Gas key might not be your problem but I'm still thinking it's an undergassed situation causing your trouble.
I have some of the Okay mags too, and will try them with the IMI 556 to see how they do. I'll also try the IMI 556 in a different rifle with the DH mags to see if they still cause the feed ramp slamming.My mags of choice are Okay mfg, NHMTG mostly with my favorite the 20 rnd variety. DH stamping places a folded metal edge into the side of the cartridge of one of the top rounds, though honestly I never had any feeding issues in my limited use.
Interesting to me that I only get the failures with the DH mags and the IMI 556. DH mags with PMC Bronze, GECO and AE all fed without issue.
NC
I run my 11.5" RGP with a significantly restricted SLR gas block, A5H4 buffer, LMT e-carrier, and tubbs AR10 flat wire spring (roughly the same strength as a sprinco green, which I also have). I use either gen 3 pmags or Lancers.
Mine works fine using IMI 55gr or Federal Brown box XM193.... suppressed or unsuppressed. Just adding this for a data point.
I think you're on the right track with looking at the mags, brother.
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"That thing looks about as enjoyable as a bowl of exploding dicks." - Magic_Salad0892
"The body cannot go where the mind has not already been."
So I went out for another function test today. Tried IMI in DH, Lancer, Okay and Pmags. As the gun got hotter, I started to have more trouble with the failures to feed. It occurred in the DH and Okay mags. I used these same mags, with this ammo, in my other SBR, with BCM built upper. No feed issues in the BCM. I do not believe it is the mags, though, the feed problem and subsequent slamming into the feed ramp only happens with IMI 556. I tried Federal XM193 and had no issue. I find this perplexing.
I did some more sleuthing tonight after a frustrating range trip and it appears the feed ramps in the barrel extension are further out than the feed ramps on the Mega receiver. I changed upper receivers to a forged Sionics. Interestingly, the feed ramps on the Sionics receiver are further out than the barrel extension, though this would obviously seem like the better situation. In comparison, the BCM factory upper feed ramps between the receiver and barrel extension mate seamlessly.
I hope to get to the range early next week and test again to see if this change solves the problem.
NC
IMI's powder selection may have an effect here, slightly too fast or slow for your config with the short barrel and reduced port.
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