Please explain profile crimp

[southerncomforthemi]

Hi..I have started reloading and can produce .45 acp and .38 special semi wadcutter that work ok...but want to improve case accuracy.

I am using Redding taper profile dies.

I do have a problem in knowing if I am using the right amount of crimp.

What is the secret to this?

What should the finished case measurement be for .45 acp and for .38 special?

Thanks.

[Mk42gunner]

For the .45 ACP I use a taper crimp, just enough to straighten the bell of the case against the bullet. For the .38 there should be a crimp groove in the bullet that you can turn the brass into, it really shouldn't take much crimp for a .38.

Whatever you do, don't apply a crimp that is heavy enough that you bulge the case below the crimp.

Robert

[Buckshot]

...............Profile crimp is another name for taper crimp. The 45 ACP is supposed to headspace on the casemouth, but unless you've had it custom made (the barrel) or they've changed things in the past several years, I seriously doubt that it does. Most likely like 100% of them I've checked out over the years, the case really headspaces off the extractor.

Maybe 10 years ago (or there abouts) that was a topic of discussion amongst the Burrito Shooters. Several had pistols chambered 45 ACP. One guy named Freeman had one of the first Kimber 1911's, and true to form no 45 ACP cases truly headspaced off the casemouth. They were simply too short. He bought fifty 45 Winchester Mag cases and trimmed them back to where they really did in fact headspace off the casemouth. In all his testing they performed no better or worse then the run of the mill short 45 ACP cases.

If I was you I'd apply as much crimp as you want, so long as it leaves a visible edge of the casemouth showing around the boolit. That is looked straight down on the boolit's nose you should see some of the outside edge of the casemouth. You could probably use a full roll crimp if the boolit design had a crimp groove.

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

[armyrat1970]

Case length for the 45ACP should be, according to SAMMI specs, .898. This may vary a little with different pistols. Case length for the 38, according to SAMMI specs, 1.155. I suggest you get a good loading manual like the Lee Modern Reloading Second Edition and read through it. The manuals are your best source of information and have a wealth of info in them. Don't reload without a couple of good manuals to cross reference data.

[243winxb]

For a proper crimp, seat bullet to correct COL. Put round in ram/shell holder, raise fully to top of stroke. Now screw crimp die down by hand, make tight as possible with hand pressure. If the round will not chamber, turn die down another 1/8 turn when using a taper crimp till round chambers. All done. The neck tension between bullet and brass case is what holds the bullet for the most part. Roll crimp for Revolvers, Taper crimp for autos. Profile Crimp Die - These handgun cartridge crimp dies were designed for those who want the best possible crimp. Profile crimp dies provide a tighter, more uniform roll type crimp, and requires the bullet to be seated to the correct depth in a previous operation. These dies are not for cartridges that headspace on the case mouth. Basic use is to roll crimp in a separate operation . http://www.redding-reloading.com/pages/crimpdies.html Lee Dies taper first then roll crimp in the same die, they were modified in 1986. :coffeecom
What is the secret to this? The secret with revolvers is have your brass trimmed to the exact same length so the roll crimp does Not crush the case. Taper crimp of the 45acp brass does not need to be trimmed. This is because the angle of the taper is not as sharp as the roll crimp.
What should the finished case measurement be for .45 acp and for .38 special? The case mouth of the 45acp should be around .470" to .472", this will vari because of case wall thickness. No idea on the 38, just as said above.

[mike in co]

Taper crimp of the 45acp brass does not need to be trimmed. This is because the angle of the taper is not as sharp as the roll crimp.


sorry but i will disagree with this statement.
any crimp is more consistant with the brass all trimmed to a uniform length.

and i have only once seen 45acp brass anywhere near the spec'd length. most of mine is shorter by .010 or more....making a trim to length a number i pick for my brass.

roll crimp for revolvers, taper crimp for autos.
in an auto all one really needs is to take the belling out of the brass and sould finish at about one thou or less than the seated boolit/case dia.
in revolver crimp is very helpful in getting a proper initial burn, consistant ignition...uniform down range performance.

mike in co

[243winxb]

Buckshot
.Profile crimp is another name for taper crimp. I think this is Not correct. Tho i must admit that i have never used the Redding die. Please see Redding link in my above post. :bigsmyl2:

[243winxb]

mike in co. If your using 45 acp brass of the same lot/brand/type, brass never needs trimming. If you have range brass/scrap, the taper crimp/brass length would be an issue. IMO

[runfiverun]

case length is always an issue, even with brand new from the bag or even factory once fired brass.
i am in agreement with buckshot , and mike.
i use the minimum amount of crimp i can get away with at all times,whether roll or taper.
i use a taper crimp on my 38 target rounds b.t.w.

[felix]

Crimp according to feel and all case length issues fade away. Crimp as light as possible. Increase boolit compression when necessary for powder burn and/or boolit movement during recoil. ... felix

[Edubya]

How about if you crimp an empty brass in your press and it crimps to several thousandths smaller less than your bbl size? I think that we all know what happens if your boolit is 0.002 undersized. You can also verify this by pulling some of your loaded boolits and measuring them. This is what I've found with softer alloy in 9mm, and .44. That's why I'm currently trying 15+ BHN in these two calibers now. I've not had any leading in my .38, even with 8 BHN.
EW

[mike in co]

How about if you crimp an empty brass in your press and it crimps to several thousandths smaller less than your bbl size? I think that we all know what happens if your boolit is 0.002 undersized. You can also verify this by pulling some of your loaded boolits and measuring them. This is what I've found with softer alloy in 9mm, and .44. That's why I'm currently trying 15+ BHN in these two calibers now. I've not had any leading in my .38, even with 8 BHN.
EW

you control the crimp....well unless you do not control the case length.

crimp by feel is not an option when using modern progressive presses. my high volume loading of 9mm, 40 s&w,45acp all go thru dillon 550's.....feel is the end of the stroke.....

your issue was not the bullet..it was your lack of crimp control.

soft boolit, lite load ? little crimp..
and in a 9mm 2 thou is excessive crimp...my 9x21 with a case full of powder doing 1300 fps with a 135 grn boolit only has a .001 taper crimp and then don't move in the case.

mike in co

[felix]

Crimp by feel implies PID controls for seperated operations. Impossible with single cam progressives like you say, Mike. ... felix

[Char-Gar]

The Redding Profile Crimp die is neither fish nor fowl, it is both. With this die you get both a taper and a roll crimp. In use, I just set it to be a moderate roll crimp and let the taper portion take care of itself. I am talking sixguns here.

For auto-pistols I use a straight taper crimp.

With the Redding Profile Crimp die, you will gain nothing and might loose something if your case mouths are not square and of uniform length. This means trimming.

[Le Loup Solitaire]

Just about all 45ACP cases are shorter than they should be. And firng them makes them shorter. Dean Grennell in his ABC's of Reloading series devoted a chapter to dealing with the issue. He cut down a batch of 308 Winchester cases to make ACP's of the proper length, using a homemade jig on the table saw. His writeup is complete with pics and results. Worthwhile reading. LLS

[deltaenterprizes]

I taper crimp all my target loads auto or revolver , taper crimp works the case mouth less .

[southerncomforthemi]

I have no feed problems.......the gun is a Clark 1911 wad gun..that bit is not the issue.

I put the question badly.

What amount of crimp after the bullet has been sized in thousandths of an inch should I use on .45 acp and ,.38 spl revolver, to get the best accuracy.

Have I asked the right question still new to this.

[Edubya]

I have no feed problems.......the gun is a Clark 1911 wad gun..that bit is not the issue.

I put the question badly.

What amount of crimp after the bullet has been sized in thousandths of an inch should I use on .45 acp and ,.38 spl revolver, to get the best accuracy.

Have I asked the right question still new to this.
Measure the wall of the brass and doouble that thickness measurement; add the diameter of the boolit and you will have the end diameter that you're looking for.
EW

[Edubya]

BTW, measure the COL then place the nose of the boolit against the side of your loading bench and with your thumb against the back push as hard as your thumb can stand to see if you can compress the length any. Upon remeasuring the COL, if you find that it has shortened any you will want to tighten your crimp a smidgen at a time.
This is called "the thumb press" and it is done to insure that your crimp will hold the boolit in place while being subjected to recoil and the action of the automatic.
EW

[44man]

I don't know if I am correct in my thinking but it seems the profile crimp die will be smaller below the crimp shoulder to support the brass. The portion the bullet enters is also smaller.
This will allow you to start the roll crimp, then force the edge into an ironed out section into a cannelure. (Spelling?) You can actually size down about 1/16" of the case mouth into the bullet without bulging the brass below the crimp.
You can see a perfect example of this on factory loaded .454 rounds.
I don't do that, I just roll crimp with the dies and it works perfect on jacketed and cast that is small enough. But if you need a larger boolit, the dies are death to accuracy because they will size down the brass and the boolit. They try to "profile" the whole round.
With larger boolits I only use the crimp from the seat die.
You have to choose the right crimp die for your boolit just like you do the expander.
I posted this picture before of a Redding profile die and my RD boolit that will not enter the die. This is what it looks like.
Then a picture of a loaded round that will not enter from the bottom either. The boolit is .432".
Do you REALLY want to do this to a proper fitting boolit?

[armyrat1970]

sorry but i will disagree with this statement.
any crimp is more consistant with the brass all trimmed to a uniform length.

and i have only once seen 45acp brass anywhere near the spec'd length. most of mine is shorter by .010 or more....making a trim to length a number i pick for my brass.

roll crimp for revolvers, taper crimp for autos.
in an auto all one really needs is to take the belling out of the brass and sould finish at about one thou or less than the seated boolit/case dia.
in revolver crimp is very helpful in getting a proper initial burn, consistant ignition...uniform down range performance.

mike in co

Yeah. I just went through some once fired remington cases for the 45ACP that I fired and all were shorter than specs by as much .006 to .010. None were at the SAMMI spec of .898 and the majority fell around .892. I never crimp for the 45 and only set my die to remove the case mouth flare that I use to seat the boolit. I rely on case neck tension for the 45. Will crimp for a magnum revolver load to keep the boolit from jumping forward in the case from recoil and for loads in a tube feed weapon to keep the boolit from being pushed back into the case.