I have an LPR with about 100 rounds through it. I took it to the range the other day and it had several failure to feeds. Didn't count exactly, but somewhere in the neighborhood of 10 out of 50 rounds had a failure to feed. Sometimes the round would get caught halfway out of the magazine and into the chamber. Other times it would short stroke the round and I would drop the hammer on an empty chamber. I was using a brand new 20 round pmag. I have also replaced the factory collapsible stock with a PRS (full length buffer, tube, and spring as well). The rifle seemed to be a little more reliable suppressed, but I did experience the same issue once while it was suppressed. I was getting an average muzzle velocity of 2,770 without the can. All shooting was done with Black Hills 77gr. I have previously shot it with 55s and 62s and didn't have any issues. Any advice of possible fixes would be appreciated. I'd like to shoot 77s out of it, but right now it's not liking them.
KAC LPR Feeding Issues
- Thread starter WeaselWalker
- Start date
Have you checked the gas key on the bolt carrier? I've had short stroking issues once before, not on a KAC gun, and it turned out the key was loose.
WW -
A) Did you buy it new?
B) Upper only or full gun?
C) Haven't tried to do any shade tree gunsmithing on it?
D) Did you shoot it prior to swapping out the buttstock / buffer / spring?
E) Have you shot it with a different mag?
F) Where are the spent cases ejecting un-supressed and suppressed?
G) Esp if running suppressed - how dry was the gun?
While it may be possible that you have a rifle that has an issue with a gas block, I believe your issue is likely centered around swapping out the rear end or the mag. I don't see any reason why it shouldn't run in that configuration but keep in mind that it comes with a collapsible stock, a carbine weight buffer, and a shorter spring. Sounds like you have introduced a buffer that is @ 2.2 oz heavier and spring that is @ 1/3 of an inch longer when compressed - all of which may or may not translate into the type of issues you are experiencing.
If I were you - I'd clean and lube the BCG, reassemble the gun as it came from the factory and confirm that it shoots. Then I'd isolate the variables - starting with the mag. Next I'd focus on the spring length, and if all of that didn't do it look to lighten the buffer (which I don't think your going to have to do).
Once you get it dialed in, I guarantee it will become your favorite rifle (of all of your rifles).
Good luck
A) Did you buy it new?
B) Upper only or full gun?
C) Haven't tried to do any shade tree gunsmithing on it?
D) Did you shoot it prior to swapping out the buttstock / buffer / spring?
E) Have you shot it with a different mag?
F) Where are the spent cases ejecting un-supressed and suppressed?
G) Esp if running suppressed - how dry was the gun?
While it may be possible that you have a rifle that has an issue with a gas block, I believe your issue is likely centered around swapping out the rear end or the mag. I don't see any reason why it shouldn't run in that configuration but keep in mind that it comes with a collapsible stock, a carbine weight buffer, and a shorter spring. Sounds like you have introduced a buffer that is @ 2.2 oz heavier and spring that is @ 1/3 of an inch longer when compressed - all of which may or may not translate into the type of issues you are experiencing.
If I were you - I'd clean and lube the BCG, reassemble the gun as it came from the factory and confirm that it shoots. Then I'd isolate the variables - starting with the mag. Next I'd focus on the spring length, and if all of that didn't do it look to lighten the buffer (which I don't think your going to have to do).
Once you get it dialed in, I guarantee it will become your favorite rifle (of all of your rifles).
Good luck
Last edited:
I was short on time yesterday when this issue occurred so I didn't have a lot of time to diagnosis the issue. I'll be going back to the range tomorrow if all goes well. To answer a few questions: I bought it new. No gunsmithing done other than a Geissele Hi-Speed National Match trigger installed and a Surefire brake. Never shot it without the PRS, but I have a Mod 1 and I'll be swapping to test that lower out on it. I haven't contacted KAC, but will be this afternoon. I only used the one magazine yesterday. I'm not sure if it was the same magazine as when I shot it with the 55s and 62s.
How dirty / dry was the BCG when all of the fun took place?
BTW 77s are all I have shot - 23.8 TAC / LC cases / 77 CC or 77 SMK
BTW 77s are all I have shot - 23.8 TAC / LC cases / 77 CC or 77 SMK
Last edited:
It's in your stock and buffer setup. The KAC parts are engineered to run together and make a soft shooting platform, any time you mess with that you're going to have issues. Put the factory parts back on it and treat it like a sore dick, don't fuck with it. If you want to keep the rifle length setup then you're going to have to figure it out, KAC is going to tell you to kick rocks and rightfully so.
KAC's recommendation was to swap the rifle length buffer for the stock carbine length buffer. No recommendations for rock kicking.
How heavy of a buffer is it, just a standard rifle? With my Lpr and a suppressor I was able to go to a 7 oz mgi buffer while maintaining 100 percent reliability with same spring. So Im guessing the spring is stiffer then the factory setup.
Yep,
Sounds like you need the Carbine length spring. You could try purchasing a Tubb performance spring and cut the coils until it works.
Tubb Precision AR-15 SS Buffer Spring (Fits both Carbine and Standard length stocks)
Sounds like you need the Carbine length spring. You could try purchasing a Tubb performance spring and cut the coils until it works.
Tubb Precision AR-15 SS Buffer Spring (Fits both Carbine and Standard length stocks)
Changed out the rifle length buffer for the carbine length buffer and it shoots lights out. Thanks for the recommendation KAC.
OP, I think he meant since you changed their tuned setup you would have to fix it on your dime. Of course they would make "recommendations" on how to fix it. KAC is the best
Last edited:
