Crimping rifle rounds with Lee FCD

[TonyAngel]

I recently started loading for .308 and haven't been crimping. Yesterday, I loaded up a couple hundred rounds for this weekend, and noticed that the bullet is a bit harder to seat into some cases than others. I can only assume that this is because the neck tension on some of the cases is higher on some than others.

It is my understanding that some load their rounds to an OAL that allows the bullets to either seat into or be very near the rifling. I can understand the use of this practice to lessen the impact of the "jump" on accuracy, but I can also see how this practice would also serve to improve consistency, or perhaps inconsistency due to variances in neck tension.

Perhaps, using a FCD would serve to do the same thing, in terms of helping with consistency. Have any of you tested this? What were your results? How much crimp did you use?

 

[jcwit]

How would one know for positive that by crimping each round would then have the exact same tension on the crimp?

I shoot benchrest as a casual hobby "no compition". I neck size only and use the same 5 cases over and over. They are all from the same mfg. and from the same run AFAIK, they were selected from 100 cases from that run. They have now been reloaded almost 80 times each.

 

[rcmodel]

Yep, if you have inconsistent neck tension, crimping will not change that.
Seating to the lands won't either for that matter.
If one case is tighter then another one, what you get is what you got, regardless of what else you do to it.

My most accurate varmint rifles & loads do not get a crimp.
Nor do they get seated to the lands.

About the only thing I roll-crimp is revolver and lever-action rifle rounds.

rc

 

[Mags]

Would annealing the case mouth give the OP the desired result? I have never annealed and don't see a reason to for my shooting habits so maybe someone more experienced will pipe up about annealing.

 

[USSR]

It is my understanding that some load their rounds to an OAL that allows the bullets to either seat into or be very near the rifling. I can understand the use of this practice to lessen the impact of the "jump" on accuracy, but I can also see how this practice would also serve to improve consistency, or perhaps inconsistency due to variances in neck tension.

If you intend to seat your bullets long so that they contact the leade, then you want low neck tension so that the bullet is softly seated slightly further in the case as you chamber the cartridge. I also suggest you drop your charge weight back at least 1 full grain if you want the same velocity as a bullet seated short of the leade.

Perhaps, using a FCD would serve to do the same thing, in terms of helping with consistency.

What you are doing is compounding whatever inconsistency you have with your neck tension, with the inconsistency of your crimp. There is a reason benchrest shooters, who are looking for the ultimate in accuracy, don't crimp.

Don

 

[rcmodel]

Would annealing the case mouth give the OP the desired result?

Without knowing more about the cases it's hard to say.

If it's mixed headstamp brass with varying neck thickness, probably not much.

If some of it has been reloaded more then the others, annealing would help.

So would chamfering & deburring the case mouths, if you're not already!

rc

 

[Walkalong]

If you intend to seat your bullets long so that they contact the leade, then you want low neck tension so that the bullet is softly seated slightly further in the case as you chamber the cartridge.

Yep.......

Besides, it's much easier to get less variance with low neck tension than heavy neck tension. Do the math....

 

[TonyAngel]

Thanks guys. The above is what I needed to know. I'm slowly learning. For one, I've quit using lots of mixed lake city brass. I've gone to winchester for better or worse. One thing I am considering is getting some of the lake city brass in .223 from natchez. At least that will all be from the same lot. I've loaded up a mix about 500 rounds of .223 and .308 and didn't crimp any of them. I'm gonna go try them out tomorrow.

One thing I did do was to polish the whatever you call that thing in the sizing die that sizes the neck down to 2/1000ths smaller than the bullets that I use. I got a pretty consistent neck tension just judging by the amount of force that it took to seat the bullets. It "felt" more consistent than it did before. Of course, it could just have been my imagination.