FL sizing inconsistent

[CovertGunny]

Got some factory amer. Eagle ammo that i fired once to get some brass for. In the process of FL resizing it i notice that i get varying degrees of shoulder bump. I use a rcbs prec mic and check my brass before it goes in and normally am +.002 to +.005. I normally try to take off .004 since its for an ar. Now my knowledge would tell me that fl sizing bump as it is referred to is taking off .00? Per case, not necessarily setting the headspace to .00?. Therefore, is there any good way to get consistent shoulder measurement without sorting brass like .005 is bucket A and .003 is another bucket. That seems very cumbersome if you are doing 000s rounds. Maybe my understanding is flawed to what goes on in the die when fl sizing, but thats is why i ask! My normal process is using a case gauage and if it fits than thats good, simply because i didnt know any better at understanding why every case comes out of sizing die at different bumps

 

[GrocMax]

Might be a 'case' of inconsistent lube vs. heavy resizing. Significant shoulder bump and body sizing takes a lot of force.

Is it a small body die? Makes things even worse.

CMD #3 dissolved in Heptane (brake clean), best spray on heavy sizing lube ever.

 

[37Lincoln1]

Annealing will help. Isn't American Eagle Federal brass? That may be part of the issue.

Also I don't believe the difference between .003 and .005 will matter much in an AR platform.

 

[TimP]

I agree with 37Lincoln1 annealing after every firing of your brass if done correctly will greatly reduce the variance in your shoulder bump. Technique also comes into play. How long do you leave the case in the die or do you just run it in and out. I have found that if I run the case into the die and leave it there for as long as it takes to lube another case with Imperial wax my consistency is better. And as others have said you need to be consistent with your case lube.

In an AR platform trying to achieve .004 bump; .003 - .005 isn't really that bad. IMO

 

[CovertGunny]

Yes it is federal brass, nothing expensive. Its a lee die guessing short body its part of the pacesetter package, doesnt specifically say. What kind would you suggest? I understand it wont make much difference just trying to develop good habits versus doing everything sloppy. But to verify a fl sizer is bumping the shoulder back a specific .00? Not say bumping it back to a flat number. So if one piece of brass starts at .005 other at .003 if even pressure and consistent lube they should still be .002 difference between them after sizing?

Ill have to look into this annealing see if i can good results, i typically use spray lube and i try to have even coating all the way around.

 

[Jet]

Gunny
In addition to the discussion above, make sure you use the same shell holder. I experienced similar issues when I use to keep my shell holders in a container seperate from the dies. It is best to dedicate one specific shell holder to one specific die.

Good Shooting.

Jet

 

[TimP]

Yes it is federal brass, nothing expensive. Its a lee die guessing short body its part of the pacesetter package, doesnt specifically say. What kind would you suggest? I understand it wont make much difference just trying to develop good habits versus doing everything sloppy. But to verify a fl sizer is bumping the shoulder back a specific .00? Not say bumping it back to a flat number. So if one piece of brass starts at .005 other at .003 if even pressure and consistent lube they should still be .002 difference between them after sizing?Ill have to look into this annealing see if i can good results, i typically use spray lube and i try to have even coating all the way around.

Yes and no. It all depends on the state of your brass and how may times they have been fired. Your brass will work harden at at different intervals. Hence the importance to anneal your brass after each firing. But even if annealed perfectly not all of the brass will soften exactly the same amount and you will get small variation in spring back. With my .308 Lapua brass I can hold the majority of that variation to .0005.

 

[amlevin]

My "varying sizing problems" disappeared when I made two changes.

First I anneal at frequent intervals.

Second, I bought a set of Redding Competition Shell Holders. Rather than backing off on the die to get the desired bump I now leave the die tight enough to the shell holder to cause the press to cam over rather firmly. Shoulder bump is then adjusted by using different shell holders, smaller increment by increment, until the sized case chambers with the desired feel. With any "Press Flex" taken out of the equation, as well as brass spring being as even as possible, I rarely see any variation more than .0005" after sizing. Even when I do see variations in measurement it's no more than .001".

 

[bigedp51]

On top of what amlevin said above about Redding Competition Shell Holders, if you pause at the top of the ram stroke for three to four seconds the case will have more uniform cartridge headspace length.

The Redding Competition Shell Holders remove any flex or give in the press by making hard contact with the bottom of the die every time.

Pausing at the top of the ram stroke tells the brass who's the boss and the brass springs back less with more uniform headspace length. Also if you rotate the case 180 degrees and size again using the same pausing technique your cases will have less runout and even better case headspace uniformity.

Another thing to remember is the cheaper .223/5.56 ammo is many times made from cartridge cases that are seconds and not as uniform as standard or higher grade ammunition. Meaning the cheaper ammo has more variations in case body and neck thickness, etc and only good for "blasting" ammo.

I use the "plus 4 thousandths" (+.004) Redding shell holder with my .223/5.56 full length die when sizing my AR15 ammo. "BUT" this will depend on "YOUR" die because we live in a plus and minus manufacturing world and all dies will be a little different in diameter and length.

I also use the Lee die lock nut with a rubber o-ring and only tighten finger tight, this allows the die to float and self center in the presses coarse 7/8-14 threads and produce less runout.

 

[CovertGunny]

This is all very informative advice and techniques. Things i wouldve never considered. Thanks ill have some experimenting to work on

 

[Brians356]

My "varying sizing problems" disappeared when I made two changes.

First I anneal at frequent intervals.

Second, I bought a set of Redding Competition Shell Holders. Rather than backing off on the die to get the desired bump I now leave the die tight enough to the shell holder to cause the press to cam over rather firmly. Shoulder bump is then adjusted by using different shell holders, smaller increment by increment, until the sized case chambers with the desired feel. With any "Press Flex" taken out of the equation, as well as brass spring being as even as possible, I rarely see any variation more than .0005" after sizing. Even when I do see variations in measurement it's no more than .001".

I'm not sure about need for frequent annealing, but if done properly (another whole topic!) it won't hurt.

But +1 on the Redding Comp Shell Holders. And I like to make sure the die cams over firmly, somewhere between 1/8 and 1/4 turn engagement. You shouldn't have to hang from the press handle, but it shouldn't just easily click over, either.

Finally, I believe consistent lubing will help. I use Imperial and just a very thin film. And I skip the case lube every third or fourth case or so, letting it use what's left in the die. If the case bodies are gouged up any or dirty it could cause inconsistency. Are you cleaning the die reasonably often?

Also, only .003" variation is not a huge number, but using a dial caliper and Hornady shoulder comparator, I usually see only .001" variation, but requires careful handling of the caliper - easy to be inconsistent in measuring!

 

[CovertGunny]

I try to clean this out with just some gun scrubber every now and then probably not as often as I should. I went back last night and made sure to get an even coat of lube and leaving the brass up in the press while I measure my round that just went through in my comparator just to check everyone. After doing this I was seeing .002 difference, which I guess maybe is pretty darn good. 1 out of 50 or so I'd one that is just way off like .01 movement, so I usually just tossed it as I blamed bad brass on that one.

 

[SFGUY]

Semper Fi, Gunny;

Try Imperial sizing wax. Just get a little on your fingers and rub the case with it. It is all I use. Even on my Dillons with casefeeders, i just grab a batch of brass and work them up with my fingers. Not too much lube or you will see dents on the shoulders ( which will blow back out when fired).