DPMS style 6.5cm problems.

[jscb1b]

Good morning all!  I have a PSA-10 lower with a Davidson Defense upper in 6.5cm.  With one round in the magazine and the bolt locked back when hitting the bolt release the bolt will strip the round and fully chamber the round and lock the bolt. Upon firing the rifle, the bolt will extract and eject the case.  The bolt locks back too.

When trying to fire multiple rounds the bolt will strip the next round but the bullet gets jammed between the bolt and barrel extension.   This happens with either the left or right side of the magazine. 

The rifle did cycle and feed the next round 4 times.  After looking at the cases that cycled, 2 had split and 2 had pierced primers.

The rounds that split the case are seller and bellot 140gn FMJ.  The ones with the pierced primers are reloads.  Hornady brass 140gn ELD-M 43.8gn staball 6.5 powder.   

Am I over gassed and/or over pressure?

The barrel is 24" with a .093" gas port and a 15.5" gas tube.  The gas tube extends 3/4 of the way into the cam cut out. There is 10.75" of dwell. 

The bolt firing pin hole is .084" the firing pin is .065" and has .046" protrusion. 

The buffer weighs 3.8oz and is 2.503" long.  The extension is 7.135" deep.  The spring is 11.5" long and has 30 coils.

I am ordering a heavybuffer and spring.  2 quarters are going into the reciever extension.  An adjustable gas block is on order too.  

I loaded 5 rounds of staball 6.5 and 140gn Sierra boat tail lead tips at 37.5, 38, 38.5, 39, 39.5, 40, 40.5, 41, 41.5, and 42gn to test. 

Have I missed anything?  Thank you everyone for your time and help!  Scott. 

[jscb1b]

Headspace was checked with go no go gauges. 

[shooterrex]

Your buffer is too light. But you already figured that out.

Just change 1 thing as a time.

The 140gr Hornady American Gunner runs great in both my Creedmoors.

It also groups well.

Davidson doesn't have the best reputation for quality parts.

I would wait on changing the gas block till you try the heavier buffer and spring.

[jscb1b]

I went out and shot my reloads to day.  40gn of staball 6.5 ran the best.  41gn and above pierced one primer out of 15 rounds.  The rifle still will not feed from the right side of the magazine.  I'm going to polish the ejector.  

[Albroswift]

I am surprised the firing pin is so much smaller then the hole. You have the correct  0.065 firing pin, I don't have a HP bolt laying around to measure but 0.083 sounds like the bolt for a standard pressure pin. Big hole will cause problems. What do the primers look like after firing?

[shooterrex]

https://kakindustry.com/lr-308-bolt-carrier-group-ejector

 

This is what I put in my Creedmoor bolt.

Edited Monday at 05:31 AM by shooterrex

[Albroswift]

Those are just fine, always have a couple spares laying around. I also just radius the square ones and polish.