To Crimp Groove not to Crimp Groove

[Haywire Haywood]

I'm putting together a design for a 235gr, .378 GCFP mold from Dan, and the question of crimp grooves is running around my head. I just read in an article that the author never gets crimp grooves in molds for his single shot rifles. What say you? It's for that 375 Winnie NEF barrel I've got in the works.
What's running around my head is this: I've read that some powders like a heavy crimp, H110 comes to mind. Does this apply to any rifle powders that the 375 will likely see? If I dispense with the crimp groove I will increase the lube capacity by almost 50%. I see that as a plus.

Ian

[357maximum]

From some of the playing I have done with the Lee factory crimp dies,,,a crimp groove may not be neccessary or desired. They allowed me to use long nosed boolits in shorter throats. I was very skeptical of it until I tried it, it works.

Michael

[Bass Ackward]

I'm putting together a design for a 235gr, .378 GCFP mold from Dan, and the question of crimp grooves is running around my head. I just read in an article that the author never gets crimp grooves in molds for his single shot rifles. What say you? It's for that 375 Winnie NEF barrel I've got in the works.
What's running around my head is this: I've read that some powders like a heavy crimp, H110 comes to mind. Does this apply to any rifle powders that the 375 will likely see? If I dispense with the crimp groove I will increase the lube capacity by almost 50%. I see that as a plus.

Ian


Ian,

Play around with it.

From my experience, crimp has a dramatic effect up to 25,000 psi. Moderate to 30k and minimal above that level tapering to nothing at about 50k. So it depends on your use for the bullet, what powder speed you intend to run, which determines the pressure level range.

But you can go for a long crimp groove and fill it with lube if you are running higher pressures where you need extra lube and crimp has minimal effect. I cheat like that all the time because the farther up a bullet you can get lube, the less of it you will ultimately need. If you drop down in pressure where crimp helps more, then crimp in the proper location for a good fold and you shouldn't need all the lube at those levels unless you have a long barrel.

[PatMarlin]

From some of the playing I have done with the Lee factory crimp dies,,,a crimp groove may not be neccessary or desired. They allowed me to use long nosed boolits in shorter throats. I was very skeptical of it until I tried it, it works.

Michael

Ditto.. :Fire: :drinks:

[David R]

It seems to me OAL is a real important factor to get accuracy with any kind of boolit in a rifle. It also seems the crimp groove doesn't line up when I find best OAL by expermenting. I never crimp. Even with my magazine fen 1917 enfield or Savage 110 308. This is all with cast.

David

[Haywire Haywood]

Done... no crimp groove. Factory crimp die in the shopping cart.

thanks for the input,
Ian

[PatMarlin]

There was a fairly extensive interesting study on the net of crimp vs no crimp and I have a remote signal in my brain the says it possibly was on the accurate reloading website.

Anyway the test showed there was no increase in accuracy by not crimping, and many times the crimped cartridge out performed the non crimp.

I always crimp with Lee factory crimps for most every caliber and a light crimp for bolt action rifle cartridges... :drinks:

[357maximum]

There was a fairly extensive interesting study on the net of crimp vs no crimp and I have a remote signal in my brain the says it possibly was on the accurate reloading website.

Anyway the test showed there was no increase in accuracy by not crimping, and many times the crimped cartridge out performed the non crimp.

I always crimp with Lee factory crimps for most every caliber and a light crimp for bolt action rifle cartridges... :drinks:


I concur, except I would add almost in front of always...:drinks:

[Buckshot]

...............There is a thought that possibly the act of crimping may help to straighten the boolit in the casemouth, and THAT's the benefit derived by the operation?

...............Buckshot

[357maximum]

I believe crimping does have some alignment qualities, that being said I utilize a crimp in my single shots for the main reason of consistant ignition. It becomes quite apparrent when crimping for powders like H110.

Straight walled pistol rounds:

Lately I have been "letting" my lee factory crimp die do some of my boolit sizing right through the neck. I simply pan lube then seat the boolit "as cast" then final crimp with the lee die. You need to expand/flare the case mouth sufficiently to allow this, but not too much or the lee die will do interesting things to your brass. It is a simple way to load and best of all in most loads it has shrank group size. I haven't used my lubesizers for strauight walled rounds in quite awhile now. I simply

cast
panlube with cookie cutter method
seat boolit
final crimp with lfc die

tah dah it works, purdy damn good in fact for most my short irons...If you require a "HUGE" boolit or a tiny boolit this may not be so good, but for average bores and boolits it is almost a failsafe method...


The final boolit if pulled come out harder than normal, so adjust load data appropriately as if you were starting a whole new load workup...it will/may increase pressure espesially with faster pistol powders.

Michael

[Haywire Haywood]

I was just thinking that I would hone out (or rather have honed out) the sizing ring in my 357 crimp die so it didn't squeeze my already sized boolits down. I size to 358, and after crimping and pulling the boolit, they now measure 357. This is for my 357 Maxi NEF. I'm also thinking that I will have to do that for the crimp die I'm getting for the 375 winnie.

Ian

[357maximum]

It takes awhile to "HONE" one of them out with a split dowel and wet/dry emery paper, but is well worth your effort. You may find some of your irons will actually need different dies, I did.