Pressure problem???

[jackinfl]

This is my reloads. 44 gr Varget, 168 amax., 2.8 COAL

Is this "flattening" of the primers?
Thanks. If it is what do I do to correct it. By the way I wa trying to duplicate Factory Hornady TAP 168 AMAX ammo. Over the Chrono, my 44.0 gr of Varget was only 40fps faster than factory. Dimensionally all else is the same.
Jack

 

[doc76251]

Re: Pressure problem???

That is a loose chamber or you have bumped the shoulder back too far. The edges of the primer are still round but the face is flat w/ a firing pin dimple from being slammed back against the bolt face.

Let the brass grow a bit and don't push the shoulder back so far (let the brass grow till it won't chamber, then re set your dies so they just chamber smooth).

Cheers,

Doc

 

[buffybuster]

Re: Pressure problem???

Looks like slight primer flattening. Nothing really to worry about, but I won't go much higher. If this is a stock M700, the primer cratering is normal and nothing to worry about.

As for trying to duplicate a "factory load"...... IMO it's a waste of time. Factories have access to powders that we do not, so you're flying blind. Better off trying to develop the best load for your rifle. What velocity were you getting with your load? My guess would be ~2700-2725fps from 24" barrel.

 

[jackinfl]

Re: Pressure problem???

My gun is a 700, Trued and re-barreled by GAP. The barrel is a 22" Bartlein. My average fps over 10 rounds was 2684.9. Factory averaged 2643.

I did bump the FL sizing die down or smaller, as I had a few rounds that would not chamber. So now the bolt closes with little pressure.

 

[BOLTRIPPER]

Re: Pressure problem???

boltripper likes hornaday brass

 

[SnkBit]

Re: Pressure problem???

In the photo it looks as if the case on the left is showing signs of flowing into the ejector hole. That's what it looks like in the picture anyway, right where the "or" is in "hornady". Can you feel anything there with your fingernail?

 

[jackinfl]

Re: Pressure problem???

These are some numbers. Measured with Hornady tools screwed onto my micrometer.
Reloads Factory
Head space: 1.603 1.6055
COAL off ogive: 2.185 2.170


Brass Measurements Shot in my rifle.
My Reloads Factory
Head Space: 1.6105 1.610

Any advice is appreciated

 

[doc76251]

Re: Pressure problem???

You've got a bit of wiggle room in your head space

Reloaded 1.603 Reloaded fired 1.6105 = 0.007" you're only trying to push it back 0.002" or so.

Another question you may wish to investigate is if the fired brass will chamber in your rifle. If it does you need to back the FL die off a bit and let it grow to find out exactly where your chamber head space is. Then load 0.002" off that.

Cheers,

Doc

 

[jackinfl]

Re: Pressure problem???

Thanks Doc!!! I will check and report back.

 

[vman]

Re: Pressure problem???

I second that. Not only is it SAFER but your brass will last longer. I say safer because brass that is over-sized is more likely to see case head separation.

After your done at the range take your brass and try to rechamber the empty brass. If the bolt closes without a problem your still not fully fireformed.

If they feel a slight resistance turning the bolt handle down, then you need to bump the shoulders back 0.001 to 0.002

A common mistake people get is to take brass that isnt fully formed, and bump it back 0.001 with their dies. You are then setting up your die to size a case when it doesnt even need it.

 

[jackinfl]

Re: Pressure problem???

More questions.

I checked my fired brass and I can close the bolt on the fired brass. What should I do?

Jack

 

[SnkBit]

Re: Pressure problem???

Does it have slight felt resistance or does it close nice and smooth?

 

[jackinfl]

Re: Pressure problem???

Minimal resistance when closing bolt

 

[SnkBit]

Re: Pressure problem???

Sounds like your'e right there. The way I do it is cycle twenty fired cases through the action and keep the three that had the most felt resistance to the side. Now measure those and take an average. Use that measurement and bump it back .002".