Ar Pistol - FTF

[mikelowrey]

Hey guys,

REeently build ar pistol, went to shoot a while back about 200 rounds, everything went good. Went today and about 200 rounds as well were shot, but a bit faster, started getting some FTF every 5 rounds, then every round...

Upper: Orion Guns 7.5 with no name bcg
Anderson lower
Shockwave blade with their own buffer, spring, tube (blade kit that comes everything included)
Only brass not steel

What could it be? thanks

[DrillBabyDrill]

Failure to (feed or fire)?

Feed is most likely extractor or extractor spring issue. You can try a bolt off another build if you have one.

Fire might be an out of spec firing pin.

Those are your mostly likely problems and what I would check 1st before looking into gas or spring/buffer issues.

Sent from my SM-G930V using Tapatalk

[mikelowrey]

Failure to (feed or fire)?

Feed is most likely extractor or extractor spring issue. You can try a bolt off another build if you have one.

Fire might be an out of spec firing pin.

Those are your mostly likely problems and what I would check 1st before looking into gas or spring/buffer issues.

Sent from my SM-G930V using Tapatalk

Thank you and sorry, is failure to feed. Basically what it does is, it shoots and expels the casing but it doesn't load the next one, so I have to rack it again and pull the trigger. Do you think I might a heavier buffer spring besides the extractor one which I will check out?

[Smokin338]

Did you try different mags as well ?? Also on a 7.5" I would be at a H2, if not H3 buffer...

[mikelowrey]

Did you try different mags as well ?? Also on a 7.5" I would be at a H2, if not H3 buffer...

good point: the first time I went I shot with metal mags, no problem. but this time I was trying a pmag, when I go back again, I will try that and see. thanks

[MistWolf]

It sounds like your AR is short stroking. To find out if your AR is short stroking, first test an empty magazine to make sure it will lock back the BCG when manually pulling back on the charging handle. Then, load a single round in the mag. Lock the mag in the AR, charge the AR and fire the round. If the BCG does not lock back, your AR is short stroking

[feraldog]

yep, what mistwolf said sounds right. if it doesn't lock back empty mags, its short stroking.

might be caused by too heavy a buffer, or weak ammo, or heavy recoil spring, or rough interior of buffer tube, or pressure too low because of small port hole or port-to-muzzle being so short, or, gas tube port hole is misaligned with port hole, or gas tube is fouled, or key is loose, or gas rings are screwed up, or bolt too dry/fouled, or....


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