AR Problem - failure to feed from mag while firing, but not manually?

AR/M4 AR General Discussion
1

OK, here’s the scoop. I have a 6.5 CSS with 20" barrel, 7.62x39 bolt, adjustable gas tube, built on a Eagle Arms lower. It has a Magpul PRS stock with rifle buffer and spring.

When I load up my mag and use the charging handle or bolt release, it loads a round into battery every time. I pull the trigger, it goes BOOM, ejects spent casing every time. However, using multiple and various mags, a new round never chambers - it just stays in the mag. Now, if I put an empty mag in and pull back the charging handle and release, it will hold open the bolt. But if I have one round in the mag, pull the handle, chamber the last round, then fire it will eject the empty case but won’t lock back the bolt on the empty mag.

So, am I correct in assuming that either:

1 - I’m not getting enough gas to throw the bolt far back enough to get past the rim of the next round so as to chamber it? I don’t know about this theory since ejecting is no problem.

2 - My rifle spring or rifle buffer is too much (too heavy weight buffer or too stiff of a spring) to allow for full cycle.

3 - something else?

I am using reloads which perform very well, seem to be well within proper pressures, etc. The adjustable gas tube is almost fully open, so I’m getting 100% gas.

Thanks for the help!

2

Check the OAL of your reloads and make sure the noe of the ronds aren’t rubbing or binding against the inside of the mags. There needs to be a bit of free space in front of the nose.

3

You need to find at least one more mag to check function. It sounds like a mag problem.

ETA: Oops missed the part about various mags. Sounds like over function. Turn the gas down.

4

This would indicate short stroke.

5

What he said. I have noticed this when going from 556 to cheap 223. get a lighter buffer. Also get another magazine, and number them. Note any failures that occur and which magazine it was, as well as ammo type.

TC

6

So your running 6.5 on it and have an adjustable gas tube. Adjust the gas tube to allow more gas to flow to the carrier.

7

I’ve got the gas open all the way.

Tried 3 different mags - all did the same thing.

OAL is fine and in spec.

I’m starting to wonder if maybe my handloads are too weak to cycle everything properly.

Going to get some factory ammo and give that a whirl to see if things work better.

8

Just some ideas, not in any specific order:

  1. Too much recoil spring tension and/or buffer weight.

  2. Leaky gas carrier key.

  3. Worn rings.

  4. Not enough gas.

  5. Pitted/dirty chamber.

  6. Too much spring tension in the magazine. (Red springs…)

  7. Leak around the gas manifold/gas tube.

Basically anything having to deal with not enough gas or anything that would retard the reward movement of the bolt/carrier.

9

As you posted on THR & TFL, it’s from the light loads and fire forming the brass.

10

stop using reloads you should feed your weapon at least current military loads or a good main stream load you spent good money on the weapon you shouls feed it good food.

11

Thanks - got some Hornady loads coming in and will try those out - if they work fine that tells me it is my reloads. If not, I’ll check out the other things suggested here.