Ejection Routes Inconsistent

[masterdrago]

You could just be covering up the symptoms of a bad extractor.
Have you replaced it?

No, I've not replaced the extractor. I keep thinking that something is either moving too fast or too slow and sometimes forcing the new round out of the magazine at some odd angle and ramming it in canted. The big scratch marks indicate it has come into contact with possibly the feed ramps in a bad way - fast, slow?

[26 Inf]

No, I've not replaced the extractor. I keep thinking that something is either moving too fast or too slow and sometimes forcing the new round out of the magazine at some odd angle and ramming it in canted. The big scratch marks indicate it has come into contact with possibly the feed ramps in a bad way - fast, slow?

First of all, in my scolding voice, the extractor is one of the more inexpensive parts to replace, why not?

Let me walk you through this, in my understanding:

When the cartridge fires, the elastic case material (brass - steel is also used, but not as elastic as brass) expands and firmly adheres to the walls of the chamber, as the pressure builds, pushing the projectile down the barrel.

The gas is diverted from the pressure filled barrel at the gas port. The length of the barrel beyond the gas port has to be of sufficient length to keep the gas pressure high enough and long enough for sufficient pressured gas to be vented through the gas port to function the system. This can be accomplished by increasing or decreasing the gas port size, by using an adjustable gas port, by moving the gas port, by shortening or lengthening the barrel.

If the system is under-gassed it doesn't have enough 'ooomph!' to cycle and can fail in several ways - not extracting fully, not ejecting as a result of this, failing to pick up the next round because the bolt head doesn't come far enough to the rear, and failing to lock back on the last round. There is more, but you get the idea.

If the system is over-gassed it tries to cycle too fast. There can be all kinds of problems as a result, but a primary problem is that the bolt tries to extract the round BEFORE the elastic case material - mentioned in the first paragraph - has contracted enough to allow the case to be extracted. As a result case rims can tear-off (which you haven't experienced), the extractor can lose it's grip on the stuck case and leave it in the chamber, or extraction can be impeded enough to cause a failure to eject.

A weak extractor spring, or a damaged extractor can cause problems in any rifle, but perhaps is most evident in properly gassed and over-gassed systems. This is why, even in a piston system, ensuring the extractor is functioning properly is a first step.

The pictures you have provided seem to indicate that the fired cases was loose in the upper, further evidence of an extraction problem.

You seem focused on using ejection pattern to diagnose, and while can be usefull, it is not an exact science. For instance, on my service rifle I clip the ejector spring to alter ejection pattern to aid in retrieving brass and to keep from plunking folks I am squadded with, you might think I'm overgassed, but that isn't the case.

Get a new extractor spring installed.

JM $.02, someone will be along to correct any glaring misconceptions I've put forth.

[MegademiC]

No, I've not replaced the extractor. I keep thinking that something is either moving too fast or too slow and sometimes forcing the new round out of the magazine at some odd angle and ramming it in canted. The big scratch marks indicate it has come into contact with possibly the feed ramps in a bad way - fast, slow?

Thats not how it typically works. I’ve never seen it. Its nearly inconceivable with good magazines.

The only time Ive seen this malfunction- both in real life and online- was extractor or extractor spring related. Replace both.

What is likely happening is that the case pops out if the bolt head, bounces around the action and knocks a round out of the magazine. Then the bolt pushes the round wherever because its not being fed from the mag.

Edit- a grossly overgassed gun could cause this, but the extractor should still hold, so that would be a combo of things going wrong (overgassed + weak extractor)

[tehpwnag3]

The insert is conical and should only go in one way, to match the shape of the spring. Take a normal pair of pliers and put some tape on the jaws (electrical or masking). This will help protect the finish. Use the pliers to press the large end of the spring into your extractor. A drop of oil will help with this. Once that is snapped in place, you may need to use same pliers (shifted to wide) to re-install the extractor into the bolt. Gently squeeze on the rear portion of the extractor to align the pin holes; insert pin, flush on both sides.

If you still have malfs, replace the extractor with a Colt or BCM. Install the new spring and insert from above. You can remove it by pressing on the side of the spring with your thumb, prying it out. Do not squeeze or scratch the spring with a hard tool.

[masterdrago]

Okay, so I'll order the extractor today. LMT from Primary Arms.

[georgeib]

Okay, so I'll order the extractor today. LMT from Primary Arms.

Excellent.

[MistWolf]

If the problem persists after getting the extractor sorted out, the next thing to address is the ejector spring and ejector.

[masterdrago]

I had a chance to experiment this morning with the original factory buffer spring and the H3 buffer. Also installed the new extractor and put the extractor spring in correctly (wide end in the extractor hole). Seemed to run better with pattern 1:30-2:00 in suppressed gas setting. The problem was that when inserting a new magazine after dropping the empty, the weaker original spring just did not have to oomph to drive the fresh round all the way in. I had to pull the bolt all the way back for the spring to have enough power driving the H3 buffer all the way to battery. Put the "blue" Sprinco spring back in w/H3. Pattern changed a bit - near 3:00 w/XM193 and 4:30 w/Hornady TAP SBR 75gr. Had a few failures to load new round in very rapid fire but okay otherwise. Guess I need to slow down.

Took a close look at brass and feed ramp... see pix... There is a small sharp spot on the ramps that appears to be shaving some brass. I think that sometimes the contact will deflect the round just enough to feed it at a slightly "wrong" angle. Then it will jam and bend and not seat the bolt.



I did a video of one round being fired, although the phone is just too slow to get what I was wanting to share (maybe with a lot better lighting - real cloudy). Maybe someone might see something I cannot. I'll make an attempt to capture a longer string of shots with a bit better lighting if I can get DW and I to sync better. She starts the camera rolling and I might be off a bit.

[masterdrago]

Sorry, forgot the blue arrow which points to the sharp high point with brass shavings

[Dr. Bullseye]

I had a chance to experiment this morning with the original factory buffer spring and the H3 buffer. Also installed the new extractor and put the extractor spring in correctly (wide end in the extractor hole). Seemed to run better with pattern 1:30-2:00 in suppressed gas setting. The problem was that when inserting a new magazine after dropping the empty, the weaker original spring just did not have to oomph to drive the fresh round all the way in. I had to pull the bolt all the way back for the spring to have enough power driving the H3 buffer all the way to battery. Put the "blue" Sprinco spring back in w/H3. Pattern changed a bit - near 3:00 w/XM193 and 4:30 w/Hornady TAP SBR 75gr. Had a few failures to load new round in very rapid fire but okay otherwise. Guess I need to slow down.

Took a close look at brass and feed ramp... see pix... There is a small sharp spot on the ramps that appears to be shaving some brass. I think that sometimes the contact will deflect the round just enough to feed it at a slightly "wrong" angle. Then it will jam and bend and not seat the bolt.



I did a video of one round being fired, although the phone is just too slow to get what I was wanting to share (maybe with a lot better lighting - real cloudy). Maybe someone might see something I cannot. I'll make an attempt to capture a longer string of shots with a bit better lighting if I can get DW and I to sync better. She starts the camera rolling and I might be off a bit.

Why do you have an H3 buffer? You have a stiffer buffer spring in the blue spring but shouldn't you be running an H1 or H2 buffer???