RRA 9mm not running right
I bought a rra 9mm to shoot uspsa matches with. Well its not cycling, it will shoot 2 or 3 rounds then a fresh round will be chambered but the hammer will not
be cocked back and will follow and new unspent round foward. I ordered a wolf reduced power main spring and that didnt work. I cut a bunch of coils off it helped a little but it still messes up if you dont hold it perfect. I am running subsonic rounds 160gr at 830fps. What shoud I try next? drill out the buffer to lighten it? lighten the bolt?
I really could use some help. Thanks
ps. the reason im running the ammo at that speed, is because that is what works best in my xdm and I dont want to load 2 different types of ammo.
For 9mm ARs, the ejector HAS to ride as high as possible in the bolt.
Use a cresent wrench to gently bend the ejector up so it completely fills the slot in the bolt.
Your ammo selection may not reliably cycle a blowback rifle without a lot of mods.
Get the action too light and you will have extraction too soon, which can be dangerous.
Originally Posted By Desert_AIP:
For 9mm ARs, the ejector HAS to ride as high as possible in the bolt.
Use a cresent wrench to gently bend the ejector up so it completely fills the slot in the bolt.
Your ammo selection may not reliably cycle a blowback rifle without a lot of mods.
Get the action too light and you will have extraction too soon, which can be dangerous.
the gun is extracting and feeding perfectly the only problem is the hammer is not always locking back
I misread "not cycling".
Check that you do not have the trigger spring installed upside down.
The legs should point forward and wrap around from the bottom rear of the trigger.
Are you sure you have the disconnector spring installed correctly?
If the trigger and disconnector springs are installed correctly, it sounds like it's short cycling, probably due to the low power ammo.
[quote]Originally Posted By Desert_AIP:
I misread "not cycling".
Check that you do not have the trigger spring installed upside down.
The legs should point forward and wrap around from the bottom rear of the trigger.
Are you sure you have the disconnector spring installed correctly?
If the trigger and disconnector springs are installed correctly, it sounds like it's short cycling, probably due to the low power ammo.
Yes I think its short cycling too. And I also think its because of the ammo what can I do to make it work?
This week end im going to try and shoot some real hot ammo through it and see what happpens.
I am not a 9mm AR expert, but I do own and shoot two of them that I built. Weak ammo might cycle but not fully cock the FCG. Double check all your parts are installed properly and then try some full power ammo to see what happens.
BGW, I reload all my 9mm ammo and I shoot it in a Beretta PX-4, a CZ75, a CX-4 carbine, a KelTec Sub2k, a Marlin 9mm Camp carbine, a HighPoint TS995, as well as my two 9mm AR's and the same ammo will work fine in all of them. I load a mild, but not weak, load of 95-124 grain bullets, sometimes 147's. With about 5 grains of Unique or similar loads they all love it.
Originally Posted By qqqq33:
Yes I think its short cycling too. And I also think its because of the ammo what can I do to make it work?
This week end im going to try and shoot some real hot ammo through it and see what happpens.
Still check the springs before you go mucking with the internals.
If the ammo is appreciably less powerful, you'll need to lighten things up.
Start with the buffer. Try a CAR buffer.
You already cut the spring.
With the short cartrige the necessary recoil cycle is really short anyway.
If the ammo is too weak to cycle the short distance, it's really not moving the bolt much at all, which surprises me it is feeding ok, which makes me think it is the trigger spring.
Originally Posted By Desert_AIP:
Originally Posted By qqqq33:
Yes I think its short cycling too. And I also think its because of the ammo what can I do to make it work?
This week end im going to try and shoot some real hot ammo through it and see what happpens.
Still check the springs before you go mucking with the internals.
If the ammo is appreciably less powerful, you'll need to lighten things up.
Start with the buffer. Try a CAR buffer.
You already cut the spring.
With the short cartrige the necessary recoil cycle is really short anyway.
If the ammo is too weak to cycle the short distance, it's really not moving the bolt much at all, which surprises me it is feeding ok, which makes me think it is the trigger spring.
well next weekend ill run some +p in it and see what happens. If the same thing happens ill know its the hammer spring or disconector.
Im really looking for a way to get the gun to run with really low power ammo I thought one of the nfa guys would be a pool of knowledge. With a standard 16" barrel this gun is quiet.
Trigger spring, not hammer spring.
If the trigger spring is installed upside down, the reset force on the trigger is in the wrong direction and the disconnecteor doesn't release the hammer, so the trigger hammer and dsicooector move as a single unit and the trigger and hammer sears are not engaged, so the trigger can't release the hammer.
If the hammer spring is installed backwards, the symptom is the trigger pin walks out because there is not enough downward force on it from the hammer spring.
Originally Posted By Desert_AIP:
Trigger spring, not hammer spring.
If the trigger spring is installed upside down, the reset force on the trigger is in the wrong direction and the disconnecteor doesn't release the hammer, so the trigger hammer and dsicooector move as a single unit and the trigger and hammer sears are not engaged, so the trigger can't release the hammer.
If the hammer spring is installed backwards, the symptom is the trigger pin walks out because there is not enough downward force on it from the hammer spring.
If the spring is instaled upside down will the gun shoot at all? I ask this because The gun will shoot several shots then stop shooting because of what I said earlier
Does it pass a function check? If not, remove and re-install your LPK correctly and/or replace any parts that are damaged/defective. A mis-timed disconnector is sometimes the culprit and not many people do proper function checks to catch this stuff before they load the gun up and start firing it.
What does it do if you load a single round and fire it? Does the hammer reset and the bolt lock back? What if you load and fire 2? 3? 4? full mag? Could be a mag/s that are dragging on the bolt and slowing it down at times.
I would recommend not cutting action springs. Just get a std. car action spring and leave it alone. Focus on the LPK, buffer weight, mags and ammo primarily and it shouldn't take long to get it sorted.
Originally Posted By qqqq33:
Originally Posted By Desert_AIP:
Trigger spring, not hammer spring.
If the trigger spring is installed upside down, the reset force on the trigger is in the wrong direction and the disconnecteor doesn't release the hammer, so the trigger hammer and dsicooector move as a single unit and the trigger and hammer sears are not engaged, so the trigger can't release the hammer.
If the hammer spring is installed backwards, the symptom is the trigger pin walks out because there is not enough downward force on it from the hammer spring.
If the spring is instaled upside down will the gun shoot at all? I ask this because The gun will shoot several shots then stop shooting because of what I said earlier
Yes it can.
Depending on when you release th trigger in teh recoil cycle the trigger itself can capture the hammer instead of the disconnector.
The vibrations can also move trigger forward enough that it appears to operate as normal.
This is whay a complete, static, non-firing function check is so important.
