6dasher- sizing die

[mgdietrich]

First dasher barrel, Stolle panda with ejector, over 1000 rounds and it shoots well. Lapua brass long freebore 0.178.
32gr n135, 3rd time firing brass 2980fps 107 Sierra. I get some heavy bolt lift and pressure, clean barrel. Harrels “3” sizing die. Wondering if I should get next smaller base sizing? Could I be getting pressure because I am not sizing the base enough?

The gun shoots good, but I want my brass to last and have easy bolt lift.

 

[Ray123]

First dasher barrel, Stolle panda with ejector, over 1000 rounds and it shoots well. Lapua brass long freebore 0.178.
32gr n135, 3rd time firing brass 2980fps 107 Sierra. I get some heavy bolt lift and pressure, clean barrel. Harrels “3” sizing die. Wondering if I should get next smaller base sizing? Could I be getting pressure because I am not sizing the base enough?

The gun shoots good, but I want my brass to last and have easy bolt lift.

Not much help, cause I don't use that powder, but if you are going to continue using that powder, for your safety I'd drop it down a full grain, and investigate. You have plenty of freebore,.. but what about neck clearance? Some chambers are tight chambered in the neck diameter so ya have to turn necks. Will a 107 MK fall through the fired case neck with ease or is there drag or resistance. ...I use Wilson FL bushing die, and Alpha Munitions brass, and it all works great for me. I chambered the barrel to the Alpha brass, no neck turn, and the go gauge.
Change powders, and work with a few known powders that work well, and are with in the operating pressure for the 6 dasher...and see if things improve.
RL 15 with 33.0 gr works good for me, accurate, low S/D 4.1 and 3029 fps, with a 28" barrel.

 

[mgdietrich]

No neck issue, this is a no neck turn reamer. N135 and h4895 are essentially same burn rate. Plenty of people use h4895.
I used n140 for first 8-900 rounds, it would do the same thing as to sticky bolt even with speeds in the 2940 region using a 30” barrel. N135 has better SD and groups are good. Had a 200-18@600 today on NRA target sling/prone with the load.

 

[JMayo]

Cleaning chamber after cleaning barrel?

 

[mgdietrich]

Cleaning chamber after cleaning barrel?

Yah, I do think my mop had some sizing lube on it. I have since cleaned the mop better with brake clean. But I am getting pressure later in string. That is the annoying part.

 

[Dave M.]

Not much help, cause I don't use that powder, but if you are going to continue using that powder, for your safety I'd drop it down a full grain, and investigate. You have plenty of freebore,.. but what about neck clearance? Some chambers are tight chambered in the neck diameter so ya have to turn necks. Will a 107 MK fall through the fired case neck with ease or is there drag or resistance. ...I use Wilson FL bushing die, and Alpha Munitions brass, and it all works great for me. I chambered the barrel to the Alpha brass, no neck turn, and the go gauge.
Change powders, and work with a few known powders that work well, and are with in the operating pressure for the 6 dasher...and see if things improve.
RL 15 with 33.0 gr works good for me, accurate, low S/D 4.1 and 3029 fps, with a 28" barrel.

I shoot 33.1g of RL-15 with Berger 105g hybrids and my girlfriend is shooting 33.3g with Berger 109 hybrids. Both extremely accurate.

 

[Dusty Stevens]

If your primer isnt too flat then try a smaller base die

 

[Jager]

QuickLoad defaults have your load, at 2980 fps, slightly over pressure. Heavy bolt lift suggests you're probably running actual pressures somewhat higher.

You could refine the QuickLoad print with actual case capacity, COAL, and barrel length numbers. But the bottom line is you're likely running a mildly hot load. If long-lived brass is one of your goals, you might want to revisit your load.

 

[mgdietrich]

QuickLoad defaults have your load, at 2980 fps, slightly over pressure. Heavy bolt lift suggests you're probably running actual pressures somewhat higher.

You could refine the QuickLoad print with actual case capacity, COAL, and barrel length numbers. But the bottom line is you're likely running a mildly hot load. If long-lived brass is one of your goals, you might want to revisit your load.

View attachment 1370944

2.395” is my COAL what does that do in quick load?
Barrel length 30”

 

[mgdietrich]

If your primer isnt too flat then try a smaller base die

I send some more cases to Harrels- I am guessing going to a 2.5 or 3 die should help me. We will see what they recommend.

 

[Jager]

2.395” is my COAL what does that do in quick load?
Barrel length 30”

That actually makes a pretty big difference, bringing your pressure down a couple thousand psi under spec'd max (63K vs a max of 65K).

Do you have your case capacity? That's probably the most critical measurement.

 

[mgdietrich]

That actually makes a pretty big difference, bringing your pressure down a couple thousand psi under spec'd max (63K vs a max of 65K).

Do you have your case capacity? That's probably the most critical measurement.

I will try to way a fired case this am with h20. Lapua 6br case fireformed.

 

[mgdietrich]

I will try to way a fired case this am with h20. Lapua 6br case fireformed.

40.86 grains for capacity H20

 

[dgeesaman]

Yah, I do think my mop had some sizing lube on it. I have since cleaned the mop better with brake clean. But I am getting pressure later in string. That is the annoying part.

How long are your rounds stewing in the chamber with the bolt closed?

David

 

[mgdietrich]

Not long normally, 22 shots in about 10minutes roughly

 

[Jager]

40.86 grains for capacity H20

Very good... that's very close to the QL default. With your updated numbers for COAL, barrel length, and case capacity here's your refined print. Chamber pressure right around 63K. So your load, on paper, seems entirely fine.

I wouldn't expect a new sizing die to fix a pressure issue.

Have you trimmed your brass? I'd double-check case length.

And do you have a bore scope? A carbon ring can cause inconsistent pressure issues.

 

[mgdietrich]

Yep, no carbon ring. Thanks for running the numbers. I believe it is a sizing the case base not enough. We shall see.