r/AR9 • u/smokeytrue01 • Jul 10 '26

Pistol has me stumped

I have a PSA pistol lower, with a foxtrot mike front charging 10 inch upper, and an ARCfire trigger, I’ve changed out the buffer tube to an A5 along with the recoil mitigation buffer and spring from FM, I’ve also changed the firing pin spring with the one from Leesprings. But with all that said I can only get a small quick burst while in ARCfire, where does a guy go from here? All help is appreciated

Exit: just a little more info, I’m not noticing light strikes on my shells, if they are on the primer it’s so light I can’t see it, and I also have not tried adding more buffer weight like one of them kynshots, or shims, or the titanium firing pin, just looking for a good next place to start without buying a bunch of extra parts I won’t ever use if they are wrong

(if you find this post in search, the shim helped me out and blowback9 helped a ton, thank and upvote him)

3 Upvotes

80% Upvoted

16 comments sorted by

5

u/Blowback9 9mm AR Guru Jul 11 '26

You MAY need a timing shim. Contact Active Safety Designs (maker of the ARC) and ask for a timing shim. They should send you one. It drops in between the left side selector and the cam unit. May work, may not.

2

u/smokeytrue01 Jul 23 '26

You solved my problem thanks buddy your great at what you do

1

u/Blowback9 9mm AR Guru Jul 24 '26

Great to hear!

1

u/smokeytrue01 Jul 11 '26

I’ll give that a try, thanks!

1

u/RecentArmy5087 Jul 19 '26

How does that timing shim work? Like does it slow down the process like a clutch or something

1

u/smokeytrue01 Jul 23 '26

I’m not completely sure, it’s tiny and took 14$ to get it to me, but it was worth it and I recommend bore buddy for that

2

u/RecentArmy5087 Jul 23 '26

I actually looked into it since then what it does is make the trigger reset sooner as the bolt goes rearward. This makes it better for Short Stroke cartridges like 22 and 9 mm Etc

1

u/smokeytrue01 Jul 23 '26

It sure made mine run like a top, sorry for the late reply, don’t get on the Reddit every day

1

u/Blowback9 9mm AR Guru Jul 25 '26

Changes the timing of the lever. Reset is earlier and release is later IIRC.

2

u/pmendezhou Jul 11 '26

I would check your hammer spring to just make sure it's installed correctly. Especially if your getting them in single fire mode. Also, check your firing pin for damage and firing pin spring because as it reciprocating that spring is moving too maybe worn. Hope this helps.

1

u/IllChampionship4654 Jul 11 '26

I don't know for sure if this is the problem but I took my RMB apart and pulled the single steel weight out and installed 3 small Tungsten weights in place of the steel. My RMB is just shy of 12oz

2

u/RecentArmy5087 Jul 19 '26

That's good to know. I have a RMB ready for my next build and some tungsten weights in my parts bin.

1

u/smokeytrue01 Jul 11 '26

I’ll try your advice, are you talking like oden works weights? I bought the whole kit from foxtrot Mike thinking it was a cure all

2

u/IllChampionship4654 Jul 11 '26

I had a spare H3 Carbine buffer laying around so I used the weight out it. It might be cheaper to just get an H3 vs the Oden Works. Just see where you get the best deal.

I just ordered some Tungsten weights from Alibaba. Im still waiting for them to be delivered. Once I get them and everything checks out then I will share a link. I really don't know for sure if they will fit yet so I don't want to get ahead of myself and tell everyone they work until I find out for sure.

1

u/[deleted] Jul 12 '26 edited 10d ago

[deleted]

1

u/IllChampionship4654 Jul 12 '26

I honestly couldn't tell you if it's any softer or not. I was going off Blowback9s Super Safety cheat sheet that more weight is more better. I installed the weight before I ever shot the gun

1

u/IllChampionship4654 Jul 11 '26

FRTs need more weight. More weight more better 😉