Too much crimp?

[Friar Whently]

Hey guys. So I just started reloading and had my first trial run of .38 special. I used a taper crimp die for crimping and I was unsure about how much crimp to use...so I used varying amounts of crimp in the first few bullets I made. In the pics below, I have the "most crimped" on the left and the "least crimped" on the right, and I've included a bullet to show the profile of what I'm working with. Does the bullet on the left have too much crimp? Are they safe to shoot? For what it's worth, the "most crimped" brass was shaved a bit in the die as I crimped it. Assume I used a minimum powder charge for these...

Any wisdom and guidance would be most appreciated.

 

[tightgroup tiger]

I always used a roll crimp on revolver cases. You don't need a lot, just enough to straighten out the flare from the neck sizing die.

The neck tension on the bullet is what really holds it in place, not the crimp.

 

[j1]

Good question, thanks. I always learn something here.

 

[Walkalong]

The one on the left looks good, while the one on the right looks OK. I would use a roll crimp on a lead bullet with a crimp groove, but that will work.

 

[Salmoneye]

To me, it sure looks like taper crimping those bullets is swaging the front driving band to below caliber...

 

[tightgroup tiger]

Unless your trimming your cases to all the same exact length you could run into problems with a heavy crimp if you happened to set your crimp die up on a short case.

When you use that same die on a longer case, it could over crimp and could bell out the top of the case just below the mouth, making the loaded round hard to get in the cylinder.

With the size of the crimp groove on lead bullets you have a lot of room to play with.

Some powders like 2400 require a heavier crimp to help hold back the bullet to build pressure but I doubt your using 2400 in a .38 special.

Lighter loads just don't require it and lighter crimps give you room to come and go if your not trimming.

 

[Friar Whently]

So some of the replies are making me wonder about OAL now...should I crimp at the bullet groove or get closer to the published OAL? You can tell from the pics that the groove is pushed down into the casing, but that was done so that I could get closer to the OAL. The minimum OAL for that load is 1.44 (I think; I'm away from my manuals at the moment) and I seated the bullets somewhere between 1.45 and 1.50. If I had seated the bullet at the crimp groove, the OAL would have been close to 1.60...

 

[Josh45]

For revolver ammo, You crimp in the groove. That is what the groove was intended for.
Also, that is where you will obtain the OAL for your ammo. Handguns are a little more tolerant about the OAL depending on caliber.

Just set em up to roll crimp into the groove and you will be good to go. Obviously start low and work up.

 

[918v]

Yes, the left one has too much crimp. You flowed the case mouth past the crimping shoulder inside the die. You don't need that much. The one on the right is good.

I taper crimp my revolver rounds as well. They haven't made a roll crimp die smooth enough to leave case mouths unmolested. Maybe someday they will make a carbide roll crimp die. I'll be in heaven.

 

[tightgroup tiger]

So some of the replies are making me wonder about OAL now...should I crimp at the bullet groove or get closer to the published OAL?

At the crimp groove.

They should fall in your cylinder and fall right back out again, Then try to close your cylinder on them to see how much clearance you have between the tip of the bullet and frame of the revolver. As long as the they don't hit the frame and the cylinder closes freely, you should be alright.

I've used cast bullets that made my loads over published maximum length before also.

What is the weight of the bullets your using?

What kind of revolver is it.

I don't know why they would be to long as far as OAL goes, your crimping them in the right place, unless you have a short cylinder in your revolver.

If for some reason you do, you will have to trim your cases accordingly or use a different bullet.

 

[blarby]

One on the left looks 'bout perfect.

Save that taper crimp for your semi-autos.

 

[Friar Whently]

What is the weight of the bullets your using?

What kind of revolver is it.

158 grn, S&W 640 Pro (chambered for 357)

 

[Friar Whently]

Save that taper crimp for your semi-autos.

I got the taper crimp die because I ordered some copper plated bullets, and word is to taper crimp them. Picked up the lead bullets at the LGS since my reloading equipment got here before my bullet order and I got impatient .

 

[ljnowell]

The neck tension on the bullet is what really holds it in place, not the crimp.

That would be true on your semi autos regarding setback, etc. On a revolver though, that crimp will be what helps keep the bullet in place sometimes. Magnum loads out of a small frame revolver especially.

 

[Uniquedot]

Too much crimp with a taper crimp die will damage lead bullets and cause leading. If the loads are light enough for a taper crimp die just crimp them enough to hold the bullets under the inertia of firing the gun or use a light roll crimp.

 

[Walkalong]

In the pic you can see the good neck tension, and the roll crimp into the crimp groove. Seat the bullet so the case mouth crimps into the crimp groove, and whatever OAL you get is the right one for that bullet and your case length.


A couple more posts and pics of crimps on lead bullets.

http://www.thehighroad.org/showpost.php?p=5871460&postcount=30

http://www.thehighroad.org/showpost.php?p=5873477&postcount=32

 

[gamestalker]

I deffinitly agree with Tighter Group Toger on this one. Crimping brass that is not all trimmed to same lenghts can and usually wil lead to over/under crimped mouths. If the variance is more than minimal you could buckle case that are longer, and shorter ones will wind up with little to no crimp.

I always keep my revolver brass, or any brass I intend to crimp trimmed to same lengths.

GS