Pressure signs at 31.5gr of Varget in Alpha 6 Dasher.

[jroberts1968]

6 dasher, PVA prefit in a TL3, 32.5gr Varget, 450, Alpha brass, bumped .002 and a 108btt Berger about .020 off gives me 2940 @ 5200’ elevation and 45 degrees out. Shoots high teens and low 2’s. Slight primer cratering and a little bit of bolt lift stiffness that I can barely feel, but it’s there. So I am right on the edge.

 

[boltfluter]

So last night I decided to measure my brass. I had sized my once fired cases using a +4 Redding competition shell holder and a Redding Type S FL bushing die. I measured the shoulder on 5 fired cases and 5 resized cases. Looks like my brass is still 5-6 thousandths short when using a +4 shell holder. I confirmed this by adding a piece of making tape to the back of a sized case which adds 4-5 thou and was still able to close the bolt on this although it felt kind of snug. I decided to double check my head space so I took out the extractor (no ejector on a TL3) and it does not close on my PTG no-go gage which is good. I guess not I am going to have to use the +8 shell holder. I wonder if my die is a bit small or something. Have never had to use a +8 before.

Sounds like you are bumping shoulders back way too much. All you need is .002 max. Imo. With .005 to .006 most likely the case is being driven forward and then gets a run at the bolt face, leading to what seems to be high pressure. Personally I would reduce the load a little and jam the bullet. 030 into the lands and basically fire form them again. Then measure to make sure they are .002 or under for chamber fit. Then, return to normal seating depth and gradually increase powder till it shoots little groups. Sneak up on sizing so as to not oversize the cases. If they are tight with .002 hs you may need a tighter die for the body. Hopefully this helps you out.
Paul

 

[Mike Hightower]

Sounds like you are bumping shoulders back way too much. All you need is .002 max. Imo. With .005 to .006 most likely the case is being driven forward and then gets a run at the bolt face, leading to what seems to be high pressure. Personally I would reduce the load a little and jam the bullet. 030 into the lands and basically fire form them again. Then measure to make sure they are .002 or under for chamber fit. Then, return to normal seating depth and gradually increase powder till it shoots little groups. Sneak up on sizing so as to not oversize the cases. If they are tight with .002 hs you may need a tighter die for the body. Hopefully this helps you out.
Paul

This is excellent advise.

 

[boltman13]

Kreger 1:8at 28". Alpha brass, Varget 31.5 gr, CCI 450, 0.010" jump, altitude 4,700', MV=2,919 fps. I use a Widden FL Click Adjustable Bushing Die and bump the shoulder 0.002". No pressure signs in my rifle.

 

[SS GO DEVIL]

Defiance Deviant Single shot cone
Mullerworks barrel .236 bore 4 groove 28”
6 Dasher .104 freebore
Alpha OCD .002 bump
CCI BR4
Berger 105 vld .012 in lands
31.6 Varget
Averages 2980 ish
SD 5-10