Consistance in headspace

[nuclear_shooter]

When setting up my FL sizing die, I generally set it to bump the shoulder back about 0.002" to 0.003". However, when using my Hornady headspace tool, I measured some of my pieces getting much larger bumps, some 0.005". Aside from issues involving brass life, how will this effect my end product (accuracy, MV, et cetera)? What causes this/what can I do to prevent this? I'm sort of new to reloading bottlenecked cartridges and its something I just noticed.

Some info about my setup: Reloading 300 win mag, Redding standard FL sizing die, clean Winchester once fired brass (only had a factory load though it so far), RCBS rock chucker press, Imperial sizing wax. When I say headspace, I'm measuring from the head to the datum line on the neck.

 

[elfster1234]

1.) having an even amount of lube....... brass that is more lubed with more imperial case wax will be bumped more.... brass that has less lube with little case wax will be bumped less.

2.) it really is all about getting a consistent pressure on the handle as you raise the ram.... each press will be different, but with my hornady LNL press, I just barely over-cam the action and stop raising the ram JUST as the handle touches "bottoms out"

3.) q-tip with imperial case wax inside the case mouth on the first & ever 20th pc of brass.

 

[SPAK]

I don't think it will affect things very much but you'll have to see how your rifle reacts and what happens on target. The only time I have issues is when my brass doesn't size enough and I have a hard to chamber round. that's my clue I've waited too long to anneal the neck and shoulders. I usually anneal every third firing to mitigate this.

Individual pieces of brass can have different properties when it's sized. As those few pieces of brass that size more than the others is fired and sized repeatedly they will cold harden and the shoulders won't get pushed back as much. Annealing your brass regularly will help keep your batches consistent when sizing, but even that's not a guarantee, but it will help.

Personally I wouldn't get too worked up over the occasional brass that's sized another .002" more than the others... Better than not sizing enough.

 

[FLIGHT762]

My experience has been on par with elfster and Frogman's comments. The type of case lube and the amount will effect brass sizing. It's a good idea to get all of the brass lubed as evenly as possible. The brass can also be affected by the duration or how quickly you raise the ram and the duration/time the case spends in the die. I did some testing and cases sized very quickly in/out of the die will cause inconsistencies.

For precision ammo, I run the case slowly into the die and let the case stay in the die for a two second count. I will sometimes run the case twice through the die, rotating the case 180º after the first time through. Cases will also spring back at a varying rate due to the work hardness of the brass.

This is why some shooters anneal their cases. It keeps the case batch consistent. I tested a couple of cases from the same batch, fired several times. I F/L resized one case and measured the shoulder bump. I then took the case and annealed it, ran it back through the die and the shoulder had been bumped back .003" or so more.

With the batch of brass you have now, I don't think you're going to see a great change in cases bump back slightly more. Take some cases and try what I recommended and see if it helps.

 

[elfster1234]

Thats a good suggestion about letting it sit in the sizer for a couple seconds. Ill try that! Thanks!

As in my epic ar thread, i put a small amount of imperial case wax in my palm, put all brass in a popcorn bowl and spray it with spray lube, work the brass with my hand that has the dab of wax, spray once more, keep working brass in hand, then use imperial wax on the body of the first sized brass with wax on the first and 20th pc inside the neck with qtip

My experience has been on par with elfster and Frogman's comments. The type of case lube and the amount will effect brass sizing. It's a good idea to get all of the brass lubed as evenly as possible. The brass can also be affected by the duration or how quickly you raise the ram and the duration/time the case spends in the die. I did some testing and cases sized very quickly in/out of the die will cause inconsistencies.

For precision ammo, I run the case slowly into the die and let the case stay in the die for a two second count. I will sometimes run the case twice through the die, rotating the case 180º after the first time through. Cases will also spring back at a varying rate due to the work hardness of the brass.

This is why some shooters anneal their cases. It keeps the case batch consistent. I tested a couple of cases from the same batch, fired several times. I F/L resized one case and measured the shoulder bump. I then took the case and annealed it, ran it back through the die and the shoulder had been bumped back .003" or so more.

With the batch of brass you have now, I don't think you're going to see a great change in cases bump back slightly more. Take some cases and try what I recommended and see if it helps.

 

[nuclear_shooter]

My experience has been on par with elfster and Frogman's comments. The type of case lube and the amount will effect brass sizing. It's a good idea to get all of the brass lubed as evenly as possible. The brass can also be affected by the duration or how quickly you raise the ram and the duration/time the case spends in the die. I did some testing and cases sized very quickly in/out of the die will cause inconsistencies.

For precision ammo, I run the case slowly into the die and let the case stay in the die for a two second count. I will sometimes run the case twice through the die, rotating the case 180º after the first time through. Cases will also spring back at a varying rate due to the work hardness of the brass.

This is why some shooters anneal their cases. It keeps the case batch consistent. I tested a couple of cases from the same batch, fired several times. I F/L resized one case and measured the shoulder bump. I then took the case and annealed it, ran it back through the die and the shoulder had been bumped back .003" or so more.

With the batch of brass you have now, I don't think you're going to see a great change in cases bump back slightly more. Take some cases and try what I recommended and see if it helps.

Great advice guys. I have all my brass currently sized, but I'll post later after I fire it all up. I planned to shoot my brass twice before I annealed it, but maybe I should start annealing every time?

 

[nuclear_shooter]

1.) having an even amount of lube....... brass that is more lubed with more imperial case wax will be bumped more.... brass that has less lube with little case wax will be bumped less.

2.) it really is all about getting a consistent pressure on the handle as you raise the ram.... each press will be different, but with my hornady LNL press, I just barely over-cam the action and stop raising the ram JUST as the handle touches "bottoms out"

3.) q-tip with imperial case wax inside the case mouth on the first & ever 20th pc of brass.

Also, how do you do 1? Do you clean your dies often? I use an US cleaner and with the really long 300 win mag cases I'm worried the necks are not getting cleaned very well, which leads to me pushing harder on some pieces of brass than the others. I noticed this when my really 'sticky' pieces of brass seemed to be the ones getting the 'extra' bump.

 

[SPAK]

really the place you want the most lube is on the body and especially at the base near the case head. this tends to get sticky in the dies. You can anneal every firing, but it is time consuming. In my testing, my most accurate firing is the 2nd firing after annealing. The first right after annealing is ok, but the 2nd one has always been the most accurate. The third firing does ok enough, and by the 4-5th I need to anneal again for sure. It might be a head thing, but this is generally why I'll anneal every 2nd firing and definitely by the third.