PCC Doubling - Causes and Cures?

[CaliPCC]

I just built a PCC with QC10 receiver, Hiperfire Reflex trigger and Taccom short stroked 3 stage buffer with JP 308 rifle spring and experienced doubling and tripling at the range today. Recently added KNS pins to the hiperfire.

 

Testing with Taccom supplied rifle spring proved reliable, however muzzle rise was not acceptable to me as this will be a competition gun I need it to shoot flatter.

 

Testing with Taccom 308 carbine spring the gun shot flatter but shook enough to drop the magazine after every shot or two.

 

I'm using different types of factory ammo, not chrono'd from 16" barrel- aguila 124, blazer 124, Speer 147, federal 124 & 147, Winchester 115 & 124. Planning on trying some subsonic ammo.

 

Wondering if anyone has some feedback on what I can do to make it shoot flat and reliable. I'll order another spring Eric suggested, perhaps it will solve all my issues.

 

Many thanks.

[HoMiE]

32 minutes ago, CaliPCC said:

I just built a PCC with QC10 receiver, Hiperfire Reflex trigger and Taccom short stroked 3 stage buffer with JP 308 rifle spring and experienced doubling and tripling at the range today. Recently added KNS pins to the hiperfire.

 

Testing with Taccom supplied rifle spring proved reliable, however muzzle rise was not acceptable to me as this will be a competition gun I need it to shoot flatter.

 

Testing with Taccom 308 carbine spring the gun shot flatter but shook enough to drop the magazine after every shot or two.

 

I'm using different types of factory ammo, not chrono'd from 16" barrel- aguila 124, blazer 124, Speer 147, federal 124 & 147, Winchester 115 & 124. Planning on trying some subsonic ammo.

 

Wondering if anyone has some feedback on what I can do to make it shoot flat and reliable. I'll order another spring Eric suggested, perhaps it will solve all my issues.

 

Many thanks.

Make sure if using the kns  pins that the hammer and trigger rotate freely. If they stick, it can probably allow the hammer sear to barely engage.