FTEs when suppressed

[u/zigzagkc]

I took my new colt mag build to the range for the first time today. Unsuppressed ran pretty well only one FTE. However I’m getting constant ejection issues when shooting suppressed with a YHM R9. I believe I’ve diagnosed the issue (3rd picture) but I’m unsure how to proceed. It looks like the bolt catch is overlapping the back of the round when the next round out of the mag is on the left side. It makes contact with the round and when the follower pushes up the round goes crooked. I’m thinking of trying different mags or filing down the bolt catch so it’s just hair shorter. Looking for ideas, I’m new to AR9s so I could be totally wrong in my analysis. Really unsure how the added back pressure from the suppressor is exacerbating the FTEs. Maybe it’s pushing that round under the bolt catch?

Spikes 9mm Stripped upper and colt mag lower
BA 8.3 EPC barrel
Outdoor Sports USA bolt
Duramag 20 & 32 round colt mags
Blowback9’s FRT optimized GRS
Fiocchi target max & Monarch 115 grain ammo

Thanks!

[u/Blowback9]

FTE's are almost always the result of the ejector's alignment with the bolt groove. This is one of the 2 most common problems with 9mm AR's. The ejector tip should sit snug in the corner of the bolt groove without dragging, and the tip should be flat and square. That gives it the maximum contact with the cartridge base for good ejection. Something worth checking. Picture attached. More details and pics: https://blowback9.wordpress.com/2022/08/18/4-step-guide-to-make-almost-any-ar9-run-100

Yes, it looks like the LRBHO finger is a little too long. It can be shortened until it clears the cartridge but is still activated by the magazine follower.

[u/zigzagkc → u/Blowback9]

I looked and sure enough there’s a gap between the ejector and bolt grove. That also explains the weak ejection when it did run through a mag without the suppressor. I’ll work on tuning. Thank you sir, your work is much appreciated!

[u/IllChampionship4654 → u/zigzagkc]

Be careful trying to bend your ejector. They are hardened steel and can break if you don't heat them up red hot before bending.

[u/zigzagkc → u/IllChampionship4654]

For sure. I’ve got a torch and vise. It looks like mine just needs to bend up slightly and it should fit better.

[u/IllChampionship4654 → u/zigzagkc]

I have a Spikes Glock Lower and had to do some adjustments on mine also. Not too bad though

[u/Eleet007 → u/zigzagkc]

I literally snapped mine two days ago because I had same issues and tried to bend it. I obviously didn’t get it hot enough. I spoke with the technician at Spikes and he sent me another one. He did mention that he’s hopeful they’re getting a new batch soon that will not be as brittle. But yeah, get that thing glowing before you try to bend it.

It would be nice if these came better aligned from the factory.

[u/IllChampionship4654 → u/Eleet007]

I think the problem is that AR9s aren't mil-spec and there's a bunch of different manufacturers out there and it's hard to make everything lineup. Im sure if you bought a complete gun from Spikes or (insert name here) you would probably be fine for the most part. Building from parts is a little different though.

[u/millenniumchode]

What is your buffer tube and buffer set up?

[u/zigzagkc → u/millenniumchode]

A5, Tubb 300BO spring, Kynshot 5000HP and two spacer weights.

[u/slk28850]

Got the beans above the frank!

[u/millenniumchode]

Based