.357 magnum crimp

[rojo]

hi guys , require input for aproject starting New Years day so we have time for a chat.I will start reloading .357 magnum to test firing in a Ransom rest. I will be using Lyman 357446 & 357429.
test revolvers will be 3 Vintage Colt .357 magnums
how much a crimp shall I use ?? I plan on testing the bullets at 25, 50 & 100 yards , well if they group at 25 yards.
how much of a crimp should I use ??
If you gentleman will assist me , what brass you are using?
the overall case length ?
and cartridge brass manufacturer
and a micrometer mesure at the top of the cartridge case
after crimpimg ,this should be a great start.

many thanks,
happy holidays rojo

[bhn22]

What powder will you be using?

[rojo]

howdy , I am planning on using 2400

[gray wolf]

Bullet ? cases ? expander Diameter ? powder ? primer ?
Just as an aside: whatever powder you choose be enlightened that someplace in between max and Minimum load will probably be the best accuracy load, and that could get better or worse with a different powder. Unless you get lucky with a known standard load you may have to go up and down the load scale for a particular powder to find the most accurate, and then the bullet speed may not be what you want and it's game over, start again. Also all three pistols may show different results as to pressure related findings and accuracy. A different crimp may be required for different powders and sometimes the primer is different also. The amount of crimp will be dependent on the load you are shooting.
a target load will get along with a less aggressive crimp than a full house speed ball load.
What is your end goal here ? you sound like your in uncharted waters as to knowledge related to hand loading.

[rojo]

hi gray wolf , hoping to save some time , in the past I have had to screw in the crimp die for Remington / peters brass compared to Winchester or federal, brass.
trying get a load that will shooting within the 5X on Colt Silhouette target at 100 yards.
wondering how much of crimp you all use ???

[bhn22]

Use a full roll crimp with 2400, I use a Redding Profile Crimp die. I always seat bullets at one station, and crimp at the next station.

[brasshog]

You mention a ransom rest so let me ask "Are you testing the load in the three pistols or are you testing the three pistols against one another for accuracy ?" The reason I ask is because that determines if you need a crimp and how much. For example.. are you firing numbered cylinders in each firearm in order to find the most "true" cylinder to bore alignment for accuracy and hunting purposes which may not require a crimp ? I always crimp as a separate step and unless it's a particularly long boolit or max load I'll just give it a medium crimp.

[rojo]

hi brass hog , I will find a load with the 6 inch .357 and try it in the other two

[rojo]

hi bhn22, I also use a two stage seat and then crimop.
can you tell me whose brass you are reloading ?
also what is the diameter of the case at the top of the round [ the crimp] ??
many thanks, rojo

[bhn22]

I mainly use WW unplated brass for accuracy testing. I have never measured a roll crimp on a revolver case, I simply make certain everything has an identical crimp. Here is a two part article on accuracy loading the 357 magnum. You might enjoy it:
http://www.lasc.us/RangingShotFreedomArms357CastBullet.htm
http://www.lasc.us/RangingShotFreedomArms357CastBulletPT2.htm

[gray wolf]

Here is a two part article on accuracy loading the 357 magnum. You might enjoy it:
Thank you for the article, very informative.
I asked so many questions purely in an effort to help. I didn't mean to confuse anything.

Sam

[detox]

Starline brass is very consistant and in most cases trimming is unnecessary. Neck tension is also pretty tight so use a harder alloy to prevent sqeezing down bullet diameter or expand case larger. My Starline case thickness @ neck measures .009-.010".

Good luck in finding the ellusive most accurate load. You will own more moulds before it is overwith.

[bhn22]

I should mention that I use WW brass because I have so much of it. The "std" accuracy test usually involves new Starline brass.

[44man]

ONLY enough to fold brass to the bottom of the crimp groove and NO MORE. Each boolit will have a different depth groove. You depend on case tension for accuracy and the crimp is only needed to keep boolits in the brass under recoil.
Crimp has zero affect on accuracy unless it does not open fully from soft boolits that get sized going through.
The crimp is the same from a shot of Bullseye to a max load of 296.

[detox]

Usually jacketed bullets are more accurate than cast. So i would first test with jacketed before moving to cast just to get a baseline of what to expect.

I wish i owned a 357 Freedom Arms revolver with shorter 6" barrel. These guns will shoot most anything accurately.

[mdi]

Usually jacketed bullets are more accurate than cast. So i would first test with jacketed before moving to cast just to get a baseline of what to expect.

I wish i owned a 357 Freedom Arms revolver with shorter 6" barrel. These guns will shoot most anything accurately.

OOOOOOH! Jacketed bullets more accurate than cast? Wow, yer in for it now...:popcorn:

[cbrick]

Usually jacketed bullets are more accurate than cast. So i would first test with jacketed before moving to cast just to get a baseline of what to expect.

Nonsense!

Rick

[felix]

Yes, they can be more accurate when the gun is seriously out of tune for any number of reasons. And, they can be more accurate when shooting projectiles above 2400 fps with a barrel having a faster twist than necessary for the boolit being used/contemplated. Otherwise, NONSENSE as mentioned by Rick. ... felix

[gray wolf]

Usually jacketed bullets are more accurate than cast.
Lets see ? 44 mag, 30 yards .650" 6 shot groups 250 grain Keith style gas checked bullet cast from ACWW
19 grains of 2400 mixed brass WSPP .432 bullets, nothing done to the brass cept size and De-cap, prime, expand and seat the bullet. sand bagged.
Now exactly how much more accurate are those condom bullets ?

Short answer = Nonsense!

[cbrick]

I have shot a 41 mag revolver from the bench with cast and shot honest two inch groups at 150 meters.

I have competed with cast in NRA state championship long range revolver against some of the very best long range revolver shooters in the country, every single one of which was using jacketed . . . And I won!

Nonsense doesn't even come close to describing that comment. Perhaps he read that on the internet and felt he should pass on that bit of "wisdom".

Rick

[cbrick]

44man answered the OP perfectly. Here are the results of crimp testing that I did with the 357.

Crimp Tests
FA 357 Mag 9”
RCBS 180 GC Silhouette @ 192 gr. (WW 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
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

As 44man said, crimp helps keep the boolit from moving under recoil and has little to do with combustion consistency, that is a function of boolit pull, boolit weight and powder burn rate.

Rick

[Bullshop Junior]

Usually jacketed bullets are more accurate than cast. So i would first test with jacketed before moving to cast just to get a baseline of what to expect.

I wish i owned a 357 Freedom Arms revolver with shorter 6" barrel. These guns will shoot most anything accurately.


This will start a war....

[44man]

This will start a war....
Oh yes, but I won't touch it! :mrgreen:

[44man]

OOOOOOH! Jacketed bullets more accurate than cast? Wow, yer in for it now...:popcorn:
Sure is for a fact. Too many here out shoot those funny bullets that cost money.

[bhn22]

ONLY enough to fold brass to the bottom of the crimp groove and NO MORE. Each boolit will have a different depth groove. You depend on case tension for accuracy and the crimp is only needed to keep boolits in the brass under recoil.
Crimp has zero affect on accuracy unless it does not open fully from soft boolits that get sized going through.
The crimp is the same from a shot of Bullseye to a max load of 296.

I said "full roll crimp" to remove any potential notion of using a taper crimp, which some find fashionable.

[44man]

I said "full roll crimp" to remove any potential notion of using a taper crimp, which some find fashionable.
Yes, roll. Taper is for auto guns that head space on the front. But there is full profile too, way too much.

[seaboltm]

I prefer Lee FCD, one full turn of crimp for heavy loads, 1/2 turn for light loads.

[Qc pistolero]

Lot of work in there Cbrick and very informative!

Qc Pistolero

[bhn22]

Taper crimps are designed to help prevent the bullet being pushed into the case while the cartridge is being cycled through a semi-auto. Roll crimps are designed primarily to prevent the bullet creeping forward under recoil in the magazine or cylinder in heavy recoiling firearms. There's a lot of crossover of course, and I know a number of bullseye shooters who insist on using a taper crimp on their light wadcutter loads for what they feel is greater consistency. Different strokes for different folks...

[mdi]

Taper crimps are designed to help prevent the bullet being pushed into the case while the cartridge is being cycled through a semi-auto. Roll crimps are designed primarily to prevent the bullet creeping forward under recoil in the magazine or cylinder in heavy recoiling firearms. There's a lot of crossover of course, and I know a number of bullseye shooters who insist on using a taper crimp on their light wadcutter loads for what they feel is greater consistency. Different strokes for different folks...

I would disagree, but I'm not an expert on reloading for semi-autos, as I only load for 4 (2, 9mm and 2, 45 ACP) and only for mebbe 17 years. I never crimp semi-auto rounds. I only use a taper crimp die to remove any flare in the case mouth and return the case to spec. to enable consistent chambering. The neck tension from properly sized brass and bullets holds the bullets in place during cycling.

[Echo]

Use a full roll crimp with 2400, I use a Redding Profile Crimp die. I always seat bullets at one station, and crimp at the next station.

+1, although I use an RCBS seating die to crimp separately.

[MtGun44]

Consistent trim length, then a consistent, fairly tight crimp into the
crimp groove but not over crimped, and crimping as a separate operation
can be necessary with many designs. The Keith designs work fine
crimping while seating due to the large, angled crimp grooves.

I would suggest that you ensure your sizing diam is the same as the
throat diam, measured with a .0001 reading micrometer, NOT a caliper.

Hornady dies have a floating sleeve that will ensure straight seating in
the case, critical to accy. Everybody else charges double or triple
for their "benchrest dies" to give you this capability. I strongly prefer
Hornady New Dimension die sets for this and several other reasons.

I am unconvinced on GCs for any pistol loads, but I do not normally
shoot beyond 50 yds for groups, so all I can say is that I find no
gains whatsoever going super hard alloy or GCs out to 50 yds. Beyond
that, I have no great body of experience, so I will refrain from comment.

Here is a visual aid - although it is .44 Mag, the crimp should look the
same.
http://castboolits.gunloads.com/attachment.php?attachmentid=50454&d=1245298989

Soft boolits (8 BHN) can work just fine, even at high velocities in .357 & .44
Mag. Again, perhaps at 200 meters hardness starts to make a significant
difference, but at shorter ranges, I cannot find it and it has seemed to cause
worse grouping at 50 yds in .44 Mag the times that I have tested it. Others
report opposite results, all I can say is what I have found.

http://castboolits.gunloads.com/attachment.php?attachmentid=50446&d=1244513448

Bill