Excessive head space

[danj]

What problems can happen if I bump the shoulder back more than .003. on a 338 edge using remington brass? I had my die set to bump bertram brass back .003 and ran the remington brass with the same die setting and bumped the remington brass back .006-.007. Had a primmer burn through(black where pin struck primmer) on one of the rounds .Happened on 3rd shot so I stopped . I did just blend 2 lbs of new h-1000 with 3lbs of old h-1000. Load was 90.5 grs 300 smk 2805fps.

 

[Gene]

First, blending powder lots is not a good idea for best accuracy. If it would work well, are you going to blend the next batch?

Headspace answer: probably nothing, cause the brass will go forward until stopped by the chamber shoulder. If your brass was pushed back more than 6-8 thous, it could potentially cause a problem and ruin your day. I would throw those away.

 

[MagnumManiac]

What problems can happen if I bump the shoulder back more than .003. on a 338 edge using remington brass? I had my die set to bump bertram brass back .003 and ran the remington brass with the same die setting and bumped the remington brass back .006-.007. Had a primmer burn through(black where pin struck primmer) on one of the rounds .Happened on 3rd shot so I stopped . I did just blend 2 lbs of new h-1000 with 3lbs of old h-1000. Load was 90.5 grs 300 smk 2805fps.

Even though that primer partially pierced, unless there are other signs of excessive headspace, such as severely flattened primers with normal known loads, then it probably isn't a factor. 6-7 thou isn't excessive, just don't make a habit of working them that much.
A more likely cause is just a primer with a pin hole in it from the factory. It could also be a near max event caused by blending lots of powder, I've had 3gr difference in lots of H1000 over the years.

If your primers look normal when you punch them out and don't have a 'top hat' appearance, then the headspace on your beass is not excessive.

Cheers.
gun)

 

[J E Custom]

Personally , I don't recommend setting the shoulder back at all unless your brass is hard to chamber
and then only enough to close the bolt.

Next - .006 to .007 head space is to much In My Opinion and loads the bolt when the case impacts
the bolt. It also works the brass to much and shortens case life.

Also mixing powders is never a good idea. Some times you get away with it and sometimes you
don't.

To save the rest of your brass, I would pull the bullets, dump the powder. and load with un-mixed
powder in a reduced charge to fire form. (Don't go below the minimum listed charge).

To make a mistake is human, Not to learn from a mistake is dumb.

J E CUSTOM

 

[danj]

Don't think I'll blend anymore . Also going to pull rest of loads and fireform. Thanks for the info!!

Dan

 

[Canadian Bushman]

I gotta plead ignorance here. I don't understand why blending lots of the same powder is a bad idea.

 

[J E Custom]

I gotta plead ignorance here. I don't understand why blending lots of the same powder is a bad idea.

Even though the powder is the same Number it is not unusual for it to have slightly different burn
rates. So you can end up with different powders mixed together.

The age of the powder can also make a difference. The older it gets it changes burn rates naturally.

Sometimes as powder gets older the groups can change because of this. I have had to add a 10th
of a grain or two to a known load the get the performance back as the powder got older.

Normally, if you are shooting max loads and run out of powder and have to buy a new can, you should
lower the powder charge on a few and test them to make sure that you are not going to
load over Max loads. I have also seen new powder lose velocity because the burn rate was
slightly slower.

Sometimes the powders are very close but often they are not. So it is not recommended that you
mix powders with different lot numbers.

J E CUSTOM

 

[Canadian Bushman]

Thanks for the wisdom. Ill heed your advice.