excessive headspace

[TackDriv3r]

Set up your die each loading session. Your brass will be different every time so locking the lock ring is just inviting a mishap like this.

Could you please explain how the brass can be different if its fireformed to the same chamber? I am not an expert, but its good to ask.

 

[Dusty Stevens]

Could you please explain how the brass can be different if its fireformed to the same chamber? I am not an expert, but its good to ask.

Hardened brass springs back different each loading. If you bump it .002 this time it may only be .001 or less next time and that could cause you some issues

 

[TackDriv3r]

Hardened brass springs back different each loading. If you bump it .002 this time it may only be .001 or less next time and that could cause you some issues

I understand, annealing every firing will eliminate that issue?

 

[Dusty Stevens]

I understand, annealing every firing will eliminate that issue?

In theory

 

[AlNyhus]

I understand, annealing every firing will eliminate that issue?

Just set your die up to bump the shoulders .001-.0015 on fired cases. Now, the die is set for your chamber...no need to adjust the die every time. Once the die is set, the brass is the variable that you control, not the die.

Make sure you remove the primers before checking as fired primers can add .002-.003 to your base-to-datum dimension. Check the b-d dimension every firing at first and get a feel for how the brass acts in your particular chamber. After a few firings, if the shoulder won't stay where you bump it, just lightly stress relieve the area and continue on.

Good shootin'. -Al

P.S. It's not head space you're controlling. Head space is the dimension from the front of the bolt face to the datum line in the chamber. It's a fixed, finite, dimension.

What we control with the die is the base-to-datum dimension of the case. This B-D dimension determines the clearance between the case and the chambers datum point.

 

[Ccrider]

I understand, annealing every firing will eliminate that issue?

Not really. Like Dusty said, only in theory. Measure and you will see. Don’t count on it being the same. Measure and adjust accordingly of needed.
If you are really interested, measure each piece after sizing. You will find that some pieces will not jump as much as others at the same setting and some will be more. You can cull those pieces or use them as sighters if they hit a different place on the target.

 

[Ccrider]

Just set your die up to bump the shoulders .001-.0015 on fired cases. Now, the die is set for your chamber...no need to adjust the die every time. Once the die is set, the brass is the

This has not been my experience. Also, .001 to .0015 may not be enough. The only way you will know is by sizing down and checking with your chamber until you get the bolt to close freely or to your liking.

 

[Webster]

Just set your die up to bump the shoulders .001-.0015 on fired cases. Now, the die is set for your chamber...no need to adjust the die every time. Once the die is set, the brass is the variable that you control, not the die.

Make sure you remove the primers before checking as fired primers can add .002-.003 to your base-to-datum dimension. Check the b-d dimension every firing at first and get a feel for how the brass acts in your particular chamber. After a few firings, if the shoulder won't stay where you bump it, just lightly stress relieve the area and continue on.

Good shootin'. -Al

P.S. It's not head space you're controlling. Head space is the dimension from the front of the bolt face to the datum line in the chamber. It's a fixed, finite, dimension.

What we control with the die is the base-to-datum dimension of the case. This B-D dimension determines the clearance between the case and the chambers datum point.

Don't now why people think something really bad will happen if they don't control head space to a few thou with a bump gauge. 10-20 years ago reloaders never heard of a bump gage. I have reloaded 10's of thousands of cases sucessfully before I heard of shouder bump.

 

[AlNyhus]

This has not been my experience. Also, .001 to .0015 may not be enough. The only way you will know is by sizing down and checking with your chamber until you get the bolt to close freely or to your liking.

If a .001-.002 'bump' still gives excessive feel with a stripped bolt, there's other sizing issues going on.

With the BR cases, the sizing at the body/shoulder junction is often the culprit. A bigger and less apparent issue is contact between the shoulder of the case and the die. Very few dies actually contact the entire shoulder along it's entire length. If you take a 30 degree angle and overlay a 28 degree angle, it's easy to see what can happen. Add to that the tolerances of the reamer and the problem can get fairly significant.

A good way to check this is with a case that needs to be bumped...a little Dykem on the shoulder can be pretty revealing.

For what it's worth.... -Al

 

[Ccrider]

If a .001-.002 'bump' still gives excessive feel with a stripped bolt, there's other sizing issues going on.

With the BR cases, the sizing at the body/shoulder junction is often the culprit. A bigger and less apparent issue is contact between the shoulder of the case and the die. Very few dies actually contact the entire shoulder along it's entire length. If you take a 30 degree angle and overlay a 28 degree angle, it's easy to see what can happen. Add to that the tolerances of the reamer and the problem can get fairly significant.

A good way to check this is with a case that needs to be bumped...a little Dykem on the shoulder can be pretty revealing.

For what it's worth.... -Al

Could just be where on the shoulder you are measuring from too.

 

[AlNyhus]

Could just be where on the shoulder you are measuring from too.

Yep. The narrower the area of contact between the gauge and the shoulder, the more higher the chance of error. -Al

 

[DJSBRS]

Excessive heads pace is the first step for potential issues that you will be chasing if you are expecting consistent, quality benchrest reloads. However, if you are just shooting a rifle where you are harvesting an animal that it does not know it was shot a half inch from aim point then it is not as much a big deal in the scheme of things within a couple of firings. Every time you fire that brass it stretches to match the chamber then relaxes to allow extraction. How much it relaxes depend on the metal make up of that particular piece of brass and pressures it withstood to fire the projectile and how often you anneal between firings. Then the best resizing process should be not less .0015 under chamber size. This puts less compress and stretch on your brass and it will last longer.

For what it's worth, I have checked new brass head space often and use the bolt face to the datum line method often and I will tell that I have never found a 100 in the box with the same head space. Even with a stationary die set up for your chamber that resizes your brass for your chamber in your press, you will not get 100 to resize exactly to your head space specs. I have had to re-anneal those culprits that will not hold the resizing specs and put them in the die the second time and hold it down longer to get those "difficult cases" to respond to my die dimension settings. Most will respond accordingly and be just fine after the second annealing and resizing. However, when I get a couple that just do not feel exactly as the others, those few never make it back in my match box. I use them to set my neck turners up for the first cutting or trash them before they accidentally get back in the match batch.

Simply put, some brass metal make up is just out of tolerance specs and does not respond well to die settings. Remember these are very few but will cause your head to hurt if you are looking for perfection.

Fire forming brass thins the side walls and creates more case capacity. Depending on the original factory thickness of the case walls and number of times fired and how much cases are resized, they will split or at the thinnest point eventually. I have a neighbor with over 50 firings on his Lapua 6BR cases by just minimum full length resizing and regular annealing and shooting a moderate load.

Watch your pressures and inspect your brass after every firing. Understand that all brass is not made the same and were not designed originally to be reloaded or to shoot other than what they were originally designed for. Every time you fire, the case it is stretching and flowing forward and getting thinner somewhere.

To stay safe, it helps to be safe.

Just my .02¢ worth.

DJ

DJ's Brass Service
djsbrass.com

 

[searcher]

so locking the lock ring is just inviting a mishap like this.

Most threaded dies will get better results (concentricity-wise) without locking the ring as well.