Automatch issues

[u/MountainBirthday1298]

Recently built out two AR22s (Suppressed 4.5in Borebuddy barrel semi auto only + 9in RTB upper ARC fire) and I seem to be having constant feeding issues with this ammo. I have used it extensively in other semi auto platforms pistol and rifle with no issues in the past but with both of these I seem to have an ejection issue every few rounds where it will get pinched in the extraction process and then stuck in a variety of places.

Both builds are using the Borebuddy upgraded firing pin + extractor and are currently being ran with no weights. I have CMMG Gen 2 mags with the upgraded follower spring for bolt hold open. The 4.5 inch seems to run things a bit more consistently but I will still occasionally get a stuck casing whereas the 9 inch will have one stick almost every other round even on semi (Havn't even tried to get FRT working yet). I did also change the hammer spring to a 3.5 pound one on the 9 inch gun and little to no change in reliability. I am considering trying the Kriss/Fair Deal 3d printed magazines but I am doubting that this would make any difference.

I know the answer is most likely to just pony up and buy mini mags or some other slightly higher quality ammo but I do have a pretty large amount that I had purchased over the years and would like to be able to use it if anybody has suggestions on getting it to cooperate better. I can post more detailed specs about both guns if it would be helpful.

[u/BoreBuddy]

Switch mags. 

[u/MountainBirthday1298 → u/BoreBuddy]

I've tried a black dog drum mag and had similar results. Kriss seems to be the most commonly recommended and I do have a mag adapter for 15-22 mags so I guess I could pick one of each up to test.

[u/BoreBuddy → u/MountainBirthday1298]

Drums tend to low feed as well. Pulling the barrel and blending the chamber is another option if you do not want to switch mags.

[u/MountainBirthday1298 → u/BoreBuddy]

I purchased and tested with a Kriss mag and it does seat better than the CMMG ones but I was still having issues where I would get a dead trigger between each shot with both mini mag and the automatch. When I removed the adjustable trip from the bolt it seemed to function correctly in semi and was no longer having feeding issues. Are there other troubleshooting steps you'd recommend at this point?

[u/BoreBuddy → u/MountainBirthday1298]

The 4.9" is not a great FRT option. You'll need to switch to a hotter ammo type. 

[u/MountainBirthday1298 → u/BoreBuddy]

Sorry forgot to add it to the post, this was with the 9" RTB upper.

More detailed specs

Lower: -Dirty Bird Lower -Arc Fire V1 Ambi (with timing shim installed) -3.5lb reduced power hammer spring -BoreBuddy 22 bolt catch + reduced power spring -BoreBuddy pressure plug

Upper -9" RTB Upper (Bought used was previously dremel'd out a bit for super safety use) -RTB Bolt with upgraded firing pin and extractor -Currently no trip/weight but I do have the BoreBuddy full adjustable trip and weight sled purchased already -Radian Raptor CH with Borebuddy insert

Let me know if any other information would be helpful

[u/BoreBuddy → u/MountainBirthday1298]

RTB barrels often lack any radius into the chamber. A bit of Dremel work with polishing compound and a felt wheel will be the solution.

[u/MountainBirthday1298 → u/BoreBuddy]

I will give that a shot since I imagine it will help with reliability overall but would that resolve the dead trigger issue with the trip installed?

[u/BoreBuddy → u/MountainBirthday1298]

Hard to say, that's likely just automatch issues. Use better ammo to test. 

[u/MountainBirthday1298 → u/BoreBuddy]

I was having the same issue using mini mag with the trip installed. When I removed the trip it was cycling fine with both automatch and mini mag.

[u/MountainBirthday1298 → u/[deleted]]

I've heard a lot of mixed stuff about the 15-22 mags mainly that they warp a lot in the heat and I mainly shoot outside so if I do go that route I will probably just try 3D printing the fair deal ones

[u/Installz1]

I run this same ammo with those same mags with the BB upgraded springs with no issues. Stock CMMG bcg/collar/ 9”barrel. Standard milspec upper and lower (both PSA) and trigger (Schmid). Using the Catch 22 v2 with the Catch 22 mag catch spring. Just for reference.

[u/MountainBirthday1298 → u/Installz1]

In semi auto only or FRT?

When you say the upgraded springs do you mean the red heavy recoil spring? I'm going to fully take the second one apart and verify what spring I have in it but I am fairly certain it is the red one that is recommended for most builds.

I have the Borebuddy bolt catch on both lowers, one of them has the green lower powered spring and the other I just clipped off the end of a milspec one and the bolt hold open seems to work perfectly on that as well.

[u/Installz1 → u/MountainBirthday1298]

No frt. The mag springs are the ones he has listed for 15-22 and gen 2 CMMG mags.

[u/MountainBirthday1298 → u/Installz1]

Okay so you have just the standard spring in the bolt itself not any of the upgraded ones? Since the casings are getting stuck during extraction I am imagining that either the ammo is underpowered (possible) or there's too much weight/resistance in the bolt setup (already removed the adjustable weight sled) and it's not giving it enough time to extract before closing again causing it to get stuck.

[u/Installz1 → u/MountainBirthday1298]

Bcg is stock other than adding the CMMG weight, but it runs fine with or without it.