Dasher primer cratering

[gambleone]

I have a new dasher that will crater about 25% of cases under a light load.
Powder is rl-15 at 31.6gr. cci-450 & have tried wolf with the same results.
This is a bat bolt with a Krieger 1-8tw barrel using berger 108, 105vld, & 105
hybrid. used hornady 105 hpbt with same results. The craters are not all the
same, some are just barely cratered while others are a little more & some
not at all. No stiff bolt lift or pressure signs. Freebore is 0.114. Would like to go
up on the load but have larger craters & more of them using 32.5gr.
Not sure where to go from here?

 

[Terry Altom]

What is your neck clearance? You may have a carbon buildup in the neck/freebore area.

 

[gambleone]

neck is .2705. I turned my necks to .2675.
Have only about 500 shots through barrel.
Also had firing pin spring changed, which
didn't help.

 

[swd]

For pressure signs I watch for ejector marks more than primer cratering unless the cratering looks like it's close to piercing.

 

[Pappy42]

Any pressure required to chamber your loads.

 

[gambleone]

no ejector marks, not close to piercing & no pressure to chamber load. no flattened primers.
Has a 237 bore also. Should i not worry about this cratering & just keep an eye on it?

 

[swd]

no ejector marks, not close to piercing & no pressure to chamber load. no flattened primers.
Has a 237 bore also. Should i not worry about this cratering & just keep an eye on it?

Yep, that's what I would do. Might want to consider having the pin turned to .062" and the bolt bushed if it's not already. That will probably cure the cratering. Pour some more powder in...

 

[dmoran]

Post a picture of a few cases, so we can see the extent of the cratering.
What model Bat?
What is the firing-pin diameter?

Donovan

 

[gambleone]

Didn't think they needed to bush bats. I did send a remington to Greg Tannel
to be bushed & that cured it. Model is 1.35 round sv584, 3 screw. not sure what
the diameter pin is. Dave Bruno put an after market spring in it but I'm pretty sure
the pin was not changed. Came stock with bolt. I'll try to get a pic up
tomorrow. Gotta go to work soon.

 

[luckyshot52]

Freebore needs lengthed. IMO.

 

[LRPV]

Firing pin may be bouncing but a stiffer spring is supposed to cure that. My SV would just do it every now and then but not all the time. It was better with 450's than anything else.

 

[gambleone]

Finally able to get a good pic up.
This is the worst one out of about 40.
What do you guys think?

 

[ridgeway]

Ignition maybe. Get a new spring and/or heavier.

 

[dkhunt14]

How short are the cases on headspace? Matt

 

[gambleone]

Dave Bruno put an aftermarket spring in. Didn't change
anything. The shoulders were bumped about 4 thou. I wondered
if that was too far. After i bumped the first couple, i saw i went
further than i wanted, but didn't want to change the setting so i
could keep them all the same.

 

[ridgeway]

How long ago was it replaced?

 

[gambleone]

spring was replaced last summer. Has about 80 firings on it.

 

[johara1]

.004 seems excessive .0015 to .002 is where you want to be. Do you have the weight and a spring change? did you check the weight of the spring your self?

 

[ridgeway]

spring was replaced last summer. Has about 80 firings on it.

Get a new one and give it a try...

 

[gambleone]

I don't know the spring wt & don't have a way
to check it.