Ken Waters, Pet Loads, Taper Crimping

[cabezaverde]

I was thumbing through my well worn copy of Pet Loads tonight, looking at the update on 38 special with cast bullets.

He mentions that he taper crimped all of his lead bullet loads to prevent distortion. I got the impression this was his general practice with cast.

Any thoughts on this?

I always am concerned about taper crimps in revolvers due to the possibility of tying up the cylinder.

[FAsmus]

cabezaverde;

I have not read Ken's remarks about taper-crimping so this will be my insight only.

I have found that certain types of loads must be crimped in order for the powder to burn properly. That is, the same load un-crimped would not have enough resistance to get the powder burning with enough pressure to do the job in some exotic pistol loads I have fired.

But! That kind of thing is quite rare. In almost all rifle shooting the crimp is not needed. Revolvers and semi-auto pistols will need crimp to retain bullets in their cases under normal operating conditions.

Lots of rifle shooters (myself included) figure that the less interference fit of bullet into case the better. Less chance for the bullet to be deformed you see and that is just for the amount of sizing the case gets before the new bullet is pressed into the neck of the case.

As for me, I cannot remember if I have ever crimped a rifle bullet into its case. Certainly I do not ever do so today.

Good evening,
Forrest

[Guesser]

I taper crimp my 38 Special HBWC ammunition; fast powder, small charges, more uniform velocity for all my Colt OM's.

[94Doug]

This was also mentioned in a recent Handloader Mag article about 38 specials. They too stated that accuracy is generally better with a taper crimp in cast loads. News to me.

Doug

[fecmech]

I have always taper crimped my .38 and .357 loads. My standard .357 load is the 173 gr Lyman 358429 at 1300 fps and I get no bullet movement in recoil. I use a light taper crimp that just gets rid of the bell on the case and leaves a light mark on the front driving band of the bullet(my oal requires the crimp groove be just inside the case). I'm away from home now and don't have access to my notes but I chronographed a taper crimped and roll crimped load of I believe 13.5/2400/173 gr bullet. I did a 10 shot string with each load and the results were the same. Average velocity, es and sd were all within a couple FPS. The .44 mag and stiff loads in the .45 colt may need the heavy roll crimp but .38/.357 does just fine with taper crimp.

[35remington]

The ability of a taper crimp to hold a bullet in the case against bullet pull in a revolver isn't much. In fact, it's difficult to see how it would help in any way. In most instances the taper crimp removes the flaring of the case mouth and that's it.

If the bullet is being held fast, it is due to bullet/case friction, not the taper crimp.

Take a case and bullet with a loose fit. Taper crimp, even savagely. It's still loose.

[9.3X62AL]

I'm not a fan of taper-crimping in general, for the reason that the process by its very nature runs the risk of deforming (usually down-sizing) boolits if even slightly overdone. FOR SURE, I dislike taper-crimping of cast boolits during the bullet seating operation--your are BEGGING for distortion by case wall compression at the same time the boolit is sliding home. If I taper crimp at all, it gets done as a seperate die step. I far prefer the older RCBS autopistol seater dies with roll crimp shoulders--these can be set to just "kiss" the case mouth flare to straighten them out as the bullet seated in place.

[cabezaverde]

So just to continue the discussion..........

Mr. Waters was not talking about low pressure target loads, he was talking about full loads with a variety of bullet types.

And I think the article 94Doug referenced had some plus P data.

[cptinjeff]

I think it depends on boolit and load.

If loading a boolit without a crimp grove or COL that doesn't match the crimp grove a roll crimp can deform a softer lead boolit (like a HBWC). With a fast powder and light load (normal for the HBWC) a taper crimp is just the ticket.

If loading a boolit with a crimp grove with a slower powder and stiffer load....the roll crimp is a no brainer. My $.02.

[35remington]

Full or heavy loads in revolvers, the taper crimp is almost valueless in holding the bullet fast. All it really does is turn in the flare.

A taper crimp shouldn't be applied with the thought that it will help hold the bullet in place under recoil forces. It won't.

And yes, I agree that taper crimping while seating the bullet at the same time is a bad idea if any significant mouth reduction is being done, as it tends to plow up lead in front of the case mouth. This distorts the bullet and in automatic pistol cartridges, potentially lets lead build up against the chamber stop shoulder.

[fecmech]

The ability of a taper crimp to hold a bullet in the case against bullet pull in a revolver isn't much. In fact, it's difficult to see how it would help in any way. In most instances the taper crimp removes the flaring of the case mouth and that's it.

If the bullet is being held fast, it is due to bullet/case friction, not the taper crimp.

Take a case and bullet with a loose fit. Taper crimp, even savagely. It's still loose.

The taper crimp is not holding the bullet, the sized case is holding the bullet and that is determined by your sizer and the diameter of your expander plug. Also take a case and bullet with a loose fit and "savagely" roll crimp it , it's still loose. The primer will still blow the bullet out of the case with no powder. I personally feel the crimping thing be it roll or taper means next to nothing ballistically, bullet pull as determined by sizer/expander is what matters.

[44man]

Ken was a wonder that I shall always miss. He was the epitome of gun writers with every caliber.
What he found was case tension was best with only enough crimp to hold boolits under recoil. A nice roll crimp does good too if not over done. A profile crimp works with some bullets but can ruin over size boolits.
It is still up to you to find the right combination.
I have taper crimp dies that do nothing but a nice roll crimp with revolver brass, nothing like what is needed for a .45 auto.
Do not do damage to cast boolits and change crimp dies to fit.

[35remington]

fecmech, agreed, it's still loose with a roll crimp too, but the roll crimp at least provides somewhat increased resistance to the bullet moving forward, even if you can spin it in the case. The case mouth needs to be physically straightened if the crimp is good.

And yes, bullet friction is very easily most what holds a bullet in place, but I can pop a bullet out of the case that has a roll crimp and good friction fit with a primer only as well. When that primer lights, something's gonna move.

I'd rather have good friction fit and a mediocre roll crimp than poor friction fit and a good roll crimp. Ideally, in a revolver, I'd have both.

Taper crimps really don't do it for me. I'd doubt I'd be able to tell the difference in accuracy, but I'm not willing to give up any cartridge integrity in the hard kicking revolver calibers.

[sniper]

I tried the Lee collet crimping die, with reduced accuracy, so I set my rifle dies to just
"bump" the case mouth to remove the last bit of flare, making it fit the bullet closer, and reduce the chances of a hang-up; both cast and jacketed. So far, so good, but it's still early!

The same with my .38-.357 handgun dies. My pro crimp die does both a taper and roll crimp, so I adjust it for a slight roll, and have not had a problem with recoil induced bullet pulling...but, I like mild magnum loads. Having said that, it will probably raise its ugly head the very next trip to the range.:lol:

[9.3X62AL]

Having said that, it will probably raise its ugly head the very next trip to the range.:lol:

I call that "The Karma Running Over My Dogma Effect".

[fecmech]

I call that "The Karma Running Over My Dogma Effect".

I like that Al!

[sniper]

I call that "The Karma Running Over My Dogma Effect".

Izzat something like Murphy's law?:mrgreen:

[steg]

I'm not familliar with the term taper crimping, just what is it?..............steg

[cbrick]

Here is the result of crimp tests I did a few years ago. Crimp it seems is nothing more than insurance against bullet creep under heavy recoil, any more crimp than needed for this will only distort the boolit. Case tension is what does the holding of the boolit until the powder starts to burn, proper boolit tension from the cartridge case is mandatory.

All of these tests were with H-110, once fired brass was carbide die sized, virgin brass in one test was not sized or crimped. All tests were fired for groups scoped from the bench @ 150 meters with no noticeable difference in groups. The last (5th) round was removed and measured for OAL before being fired, no bullets in these tests pulled under recoil. The FA is a five shot cylinder and all five cylinders were used in every test.

All five tests were fired on the same day during the same session without cleaning.

This is a heavy load and should be used in FA revolvers ONLY.

Rick

FA Model 83 357 Mag 9”
RCBS 180 GC Silhouette @ 192 gr. (WW 3% tin HT @ 18 BHN)
16.0 gr. H-110
Winchester brass
CCI 550 primer
Temp 70 Humidity 38%

All chrono tests 10 shots

1> My normal profile crimp, second firing of WW brass, Carbide die sized
E.S. 30
A.V. 1518
S.D. 9

2> Roll crimp, second firing of WW brass, Carbide die sized
E.S. 30
A.V. 1520
S.D. 9

3> No crimp, second firing of WW brass, Carbide die sized, very slight bell only
E.S. 30
A.V. 1528
S.D. 9

4> Light profile crimp, virgin WW brass, not sized, not expanded, slight bell only
E.S. 26
A.V. 1532
S.D. 8

5> My normal profile crimp, virgin WW brass, not sized, not expanded, slight bell only
E.S. 26
A.V. 1536
S.D. 8