When to use a taper and roll crimp?

[fastfire]

I have been using a roll crimp for 300BLK but was considering one for .308.
Have used LFCD for everything else but like the looks of the roll crimp.
Which to use and why is my question.

[Bohica793]

I can't speak to rifle ammo, but in the pistol world it has been my rule of thumb that if it is an automatic, it is a taper crimp and if it is a revolver AND the bullet in question has a crimp groove, it is a roll crimp. I would extrapolate to the rifle world to be roll crimp if there is a crimp groove and taper crimp otherwise.

[Krumfola]

The only time I've ever crimped rifle bullets is in lever actions. I don't know that it's really necessary to crimp a 308.

[fastfire]

Doing this for SHTF loads

The only time I've ever crimped rifle bullets is in lever actions. I don't know that it's really necessary to crimp a 308.

[DaveInFloweryBranchGA]

It's been my experience with thousands of rounds of .308 and .223 loaded that the Lee Factory Crimp Dies give absolutely ideal crimps for SHTF cartridges. A very light crimp with the FCD has gotten the job done for me every single time.

BTW, while you're crimping those cartridges, you might want to consider sealing them with some water proof lacquer of some sort at the neck and at the primer. Nail polish should get the job done and lots of colors out there, a ridiculously large variety. A little goes a long way.

[fastfire]

YEP, been using Markon bullet and primer sealer.

[W.R.Buchanan]

Fastfire: Using the Lee FCD for rifle brass like you describe is a good way to go and the crimp should be centered in the cannelure of the bullet or towards the top of the cannelure for best results. If it is too low on the bullet it will produce a small bulge in the case neck just below the crimp which may affect chambering of the suspected rounds in an Semi-Automatic firearm..

I do this on all of my 5.56/.223 ammo that I load, and I do this because it is the easiest way to get consistent results over large quantities of production.

Unless all of your brass is trimmed to exactly the same length, the roll crimp will not do this, and the result will be some cases will get a good crimp that folds over the bottom edge of the cannelure, and others will have the roll crimp at various places up or down, or even off the cannelure.

With the Lee Die the crimp tends to be "in the cannelure some place" which is exactly what you are looking for, and this is sufficient.

The other thing that can affect the crimp is bullets that don't have the cannelure in the exact same place. This can be caused by several things but the main one is the bases of the bullets being slightly different and thus the cannelure gets rolled onto the bullet in a slightly different place each time.

Typically the Lee Die absorbs/copes with, these differences better than roll crimping does.

I do use a Roll Crimp on my .308 and .30-06 loads as well as other calibers, however these are all low volume loadings usually, 50-100 rounds and the brass is all trimmed to the same length and resized in a RCBS X Die which establishes the OAL of the case to a specific length after the first trim and subsequent resize. That way my Roll Crimps come out the same everytime.

However, if I was loading these rounds for high volume usage they would get the Lee FCD treatment as well. It simply works better for hi volume production.

I crimp everything! It simply makes for better ammunition.

Randy

[Mike Kerr]

I will cast another vote for the LEE Factory Crimp Die. They are a good tool for rifle rounds as others have said. They are also great for handgun rounds using j word bullets.

[fastfire]

Haven't heard of the RCBS X Die, what is different?

Reviews aren't that good, http://www.midwayusa.com/product/807...on-small-base#

[DougGuy]

I think a crimp is very necessary for .308 unless you are loading for a single shot. My loads that were in the magazine when live rounds were fired have a significant flat spot on the soft point. Enough to move the boolit back into the case some without me knowing it? Even though there is a considerate amount of neck tension? I dunno.. That's what a crimp is for!



I use the Lee collet style crimp on .308 because I seat out long, .020" from the rifling, the cannelure is probably .100" out in front of the case mouth. Works a charm..

[W.R.Buchanan]

Fastfire: the X die requires some small amount of finesse to get to operate as advertised. The instructions are not easy to understand in that they must be read several times thru to fully extract the exact meaning.

This seems to be beyond many users and as a result they will have problems.

It took me several read troughs to get the die to work properly, but it does in fact stop case stretch which occurs mostly as the expander button is extracted from the case. I have trimmed my current batch of .308 brass twice. Once when I started reloading them and two reloads later when I started using the X die. They have not been trimmed for the last 6 reloadings.

Randy

[fastfire]

Well, I might just have to try the x die.
So if the case is trimmed a bit short when the expander die is pulled out will the case eventually stop lengthening after it gets to the recommended length, after several firings?

[tomf52]

For light target revolver loads a taper crimp has proven itself to me to help produce the most accurate ammo. Doesn't apply to heavy revolver loads or semmi auto loads.

[W.R.Buchanan]

FF yes that is what happens.

Randy

[Barnacle Brad]

I am working on some .357 mag loads with a ww cast 158gr tumble lubed bullets and 3.7gr Clays. I taper crimped some test rounds in my sizer die. Is that the method of choice for a taper crimp? The average velocity for the string of ten was 784fps with a SD of 15.

I would like to go to a four die set - I guess I should just up and get it done for all my handgun calibers.

Thanks

[LUBEDUDE]

I am working on some .357 mag loads with a ww cast 158gr tumble lubed bullets and 3.7gr Clays. I taper crimped some test rounds in my sizer die. Is that the method of choice for a taper crimp? The average velocity for the string of ten was 784fps with a SD of 15.

I would like to go to a four die set - I guess I should just up and get it done for all my handgun calibers.

Thanks

It all depends if that works for You.
Generally one would use a roll crimp with a 357. (Exception- lever gun or Coonan Auto) However, you have a light load there. Is your crimp falling into the crimp groove? Big plus if it is.
Are you checking your crimp?- by pressing the nose of the bullet with significant force against the edge of your workbench.
If it is holding, and this works for you, go with it. However, as your loads increase in level, keep testing your crimps and maybe rethink your process with hot loads.

Good Luck

[Barnacle Brad]

I agree. I would normally use a roll crimp for this, but I wanted to check the velocity consistency with the taper crimp. It holds the bullet very good - still I wanted to check for creep when I was at the range and I forgot to bring calipers. I seated the bullet to 1.610 as prescribed for the bullet, which put the case mouth at the base of the top driving band.

I think I will load another set to test that are roll crimped and compare with the taper crimp results. Another excuse to go shoot....

Thanks!

[LUBEDUDE]

I agree. I would normally use a roll crimp for this, but I wanted to check the velocity consistency with the taper crimp. It holds the bullet very good - still I wanted to check for creep when I was at the range and I forgot to bring calipers. I seated the bullet to 1.610 as prescribed for the bullet, which put the case mouth at the base of the top driving band.

I think I will load another set to test that are roll crimped and compare with the taper crimp results. Another excuse to go shoot....

Thanks!

Ah! Testing, I get it.

Not too long ago one of the gun writer's for whom I forget, did a good write up on tight crimps vs. velocity in the 44 Mag. His findings were surprisingly negligible.

I would like to se what you come up with.