Roll crimp vs Taper Crimp for Revolver Loads

[Claude Clay]

I must learn how to work the Macro on my didgital 35mm, it's on my rather lengthy do to list.

or move the lens back further and use your zoom

no zoom... still move back, up the pixel setting and later crop

if you want to use the cameras flash, moving back also takes the harsh out of the light

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for crimping I take a finished round and with both hands hold it and push the bullets nose against the edge of my wooden desk leaning with about 100 pounds of myself against it. if it does not move I consider it a good to fire round. except for magnum loads I seldom have to trash brass cause of it being reloaded too many times.

 

[ljnowell]

I must learn how to work the Macro on my didgital 35mm, it's on my rather lengthy do to list.



or move the lens back further and use your zoom



no zoom... still move back, up the pixel setting and later crop



if you want to use the cameras flash, moving back also takes the harsh out of the light



-----------

for crimping I take a finished round and with both hands hold it and push the bullets nose against the edge of my wooden desk leaning with about 100 pounds of myself against it. if it does not move I consider it a good to fire round. except for magnum loads I seldom have to trash brass cause of it being reloaded too many times.

IMO cases have been reloaded too many times when they split.

I will make a confession also. Note to any new reloaders, I don't advise this to you , at least not yet. If a case cracks on resizing or seating and the crack is half the bullet length(on a SWC or similar, not a DEWC or HBWCs) or shorter I load it anyway then call it scrap after the next firing.

Not something everyone would do, but for practice ammo, I ain't skeered.

 

[Driftwood Johnson]

Howdy

Perhaps the reason for the difference between taper crimps and roll crimps should be explained. Walkalong's photos demonstrate the difference beautifully.

Most semi-autos headspace at the front of the case. Notice on the taper crimped 357 Mag that the case mouth stands slightly proud of the bullet. That is what is needed with most semi-auto rounds so the case mouth can headspace against the square shoulder in the chamber. With a good taper crimp, the case mouth will dig slightly into the bullet, but leave enough of the brass standing proud so it can butt up against the square shoulder in the chamber.

Most revolver cartridges headspace on the rim. Most revolver chambers do not have a square shoulder, in the chamber, most have a slightly tapering section where the chamber necks down to bullet diameter. So there is no necessity for a square shouldered crimp. The roll crimp 'rolls over' into the crimp groove. Most revolver bullets do have a crimp groove (cannelure) where the crimp rolls over. Varying the amount the crimp rolls over into the groove varies the amount of mechanical strength the crimp has, which in turn can help prevent bullets from backing out of the groove from heavy recoil.

 

[chiltech500]

So here's my 1st 38sp 148 gr DEWC, the crimp die has not been dialed in yet so this is un-crimped at .381. The end of the forward driving band at the taper is exposed. My plan is to crimp just enough to smooth out the bell when using a fast powder like VV N310. I'm not sure to what extent to crimp when using the slower VV N320?

 

[rcmodel]

IMO: Seated just slightly too deep before crimping.

If anything, the bullet should be seated just past the back edge of the crimp groove.

Then the crimp will end up in full contact with the rear edge of the groove so no foreword movement is possible.

rc

 

[ljnowell]

IMO: Seated just slightly too deep before crimping.

If anything, the bullet should be seated just past the back edge of the crimp groove.

Then the crimp will end up in full contact with the rear edge of the groove so no foreword movement is possible.

rc

I actually like them seated like that. I have never had a bullet pull from the case on a light DEWC load.

I do believe I would put just a super light touch of more crimp on it. Not much more, just a little bit.

Edit: the more I look at it I think you do have the case straightened out. Give them a shot and see what you get.

 

[chiltech500]

Thanks for the replies fellas.

I did not crimp the round pictured - width is .381. LJ I was going with your ideas of very little crimp with a light VV310 load. I'm thinking a 2.7 gr VV310 which is a bit faster than Bullseye.

RC, I would use your idea of seating at the crimp groove to benefit from a slight crimp were I using a slower powder or a hotter load.

I believe somewhere, maybe the Bullseye forums, that some seat so the wadcutter top is flush with the case! Others say just a minimum showing to make loading the round easier.

 

[chiltech500]

My first effort will be VV N320 3.0 gr, which VV says is the starting load for the 148 LWC - their OAL is shorter at 1.180, mine is 1.210 so I expect the charge to be weak.

I engaged more of a crimp than just smoothing the bell - .381 uncrimped and my crimp is about .376 pictured below.

Opinions on the crimp?

 

[ljnowell]

My first effort will be VV N320 3.0 gr, which VV says is the starting load for the 148 LWC - their OAL is shorter at 1.180, mine is 1.210 so I expect the charge to be weak.



I engaged more of a crimp than just smoothing the bell - .381 uncrimped and my crimp is about .376 pictured below.



Opinions on the crimp?

I don't think you have over crimped by any means. Usually the proof is on paper. I was astounded when I shot groups with roll crimped into the groove rounds and neat uncrimped and seated slightly deeper.

On the depth your round looks just like mine.

I also use AA#2 for my wadcutters and SWC bullseye comp loads.

 

[gamestalker]

I don't think 38 spl. seating dies are available with a taper crimp function, unless you have them custom made anyway.

So just as RC said, die adjustment will produce the desired amount of crimp from either the rimless AL cartridge seating die, or a rimmed wheel gun seating die. In other words, you can attain a taper type crimp if you adjust a 38 spl. seating die light enough to do that. And you can also adjust a rimless 9mm, 45 acp or what ever seating die down far enough to produce a deeper crimp, similar to that of a roll crimp. It's all in the adjustment process.

GS

 

[ljnowell]

I don't think 38 spl. seating dies are available with a taper crimp function, unless you have them custom made anyway.



So just as RC said, die adjustment will produce the desired amount of crimp from either the rimless AL cartridge seating die, or a rimmed wheel gun seating die. In other words, you can attain a taper type crimp if you adjust a 38 spl. seating die light enough to do that. And you can also adjust a rimless 9mm, 45 acp or what ever seating die down far enough to produce a deeper crimp, similar to that of a roll crimp. It's all in the adjustment process.



GS

You can most definitely buy off the shelf taper crimp dies for 38 special and most other revolver cartridges.

In this case we are talking about, as you mentioned, adjusting a roll crimp die to where it just irons out the case mouth or applies just a very slight touch of crimp.

 

[chiltech500]

I was astounded when I shot groups with roll crimped into the groove rounds and neat uncrimped and seated slightly deeper.

lj, do I understand you to mean : that the uncrimped and deeper rounds were more accurate than the rounds where the bullet set higher and crimped into the groove made for the crimp?

I'm feeling I need to try some less crimped than the .376 pictured all the way out to uncrimped to ultimately look for the best.

 

[ljnowell]

lj, do I understand you to mean : that the uncrimped and deeper rounds were more accurate than the rounds where the bullet set higher and crimped into the groove made for the crimp?

I'm feeling I need to try some less crimped than the .376 pictured all the way out to uncrimped to ultimately look for the best.

Absolutely they were. Where a firm roll crimp is needed with a full house load it most certainly is not needed in a light target load.

I load for bullseye shooting where accuracy is absolute king. I have tried everything from deep seating, shallow seating, heavy crimp, light crimp, no crimp, different primers, etc.

The biggest improvement I found was not roll crimping and just barely, if any, crimp at all. Seating the entire crimp groove and half the forward driving band in the case gives you the full diameter bullet to close the case mouth against.

I only came to these conclusions after extensive testing and load work up. Shooting over 10k+ of these a year and striving to come up with the most accurate. When an idea would pop on my mind I would work it up and load a minimum of 50-100. I would then shoot them in 10 shot groups measuring them and scoring them, all at 25 yards. Then I average them together to get an idea of the big picture. This method of seating and crimping showed the most potential.

I will see if I get the time today to take a few pictures today.

 

[chiltech500]

Sounds like when looking at my photo your wadcutter projected a bit more out of the case? Looking my first photo above, before the crimp was applied, I'm not sure if some of the taper wasn't lower than the case rim. I can visualize your concept of that last flat portion of the bullet closing the case mouth, thus mine may have been to low inside the case.

lj I am trying to make my way into Bullseye accuracy with centerfire. I have only shot the 22 at a Bullseye league, which is a conversion on a 1911 frame. Best score was low 80's, so I don't have big expectations for myself given that I'm almost 60.

That said, I would like to know that the scoring is me not the ammo! So I will gladly take all the advise you have to give.

 

[340PD]

I load only plated bullets in .45acp, 9mm, and light loads in .357 cases using only very light taper crimp. I do check chambered, loaded rounds from time to time to insure there is no bullet setback or forward movement of the bullet. Zero problems to date.

 

[MCgunner]

A good roll crimp on heavy revolver loads stops bullet pulling under recoil. I would have less confidence in taper crimps on heavy bullet magnum loads. I don't load "light" magnum loads. I load 'em to kill things. .38s work for "light" loads in my .357s. I still roll crimp 'em, though.

 

[340PD]

I understand, but I only use .357 brass because it makes cleaning much easier and I have 10,000 empty .357 cases.

 

[Saleen322]

I starting putting a bit of a roll crimp in my 38 special wad cutters because it aids in feeding with my 52 Smith. The seating depth is with the bullet completely in the case. I now shoot the same rounds from my revolvers, especially my model 14. After doing a bunch of testing at 50 yards, the roll crimp rounds consistently produce the best groups for me. I am guessing but it must have something to do with more consistent bullet pull on ignition. It works for me. YMMV

 

[Jaymo]

I loaded a bunch of .38 Hornady 140 grain cowboys with 5.6 grains of CFE Pistol yesterday.
There was one round that I couldn't remember whether I'd "powdered" or not.
After dropping/checking powder and seating/crimping boolit, I shake each one and listen for the rattle of powder.
Couldn't hear that one rattle like a baby's rattle.
Time for the green hammer.
Pulled the boolit and, whaddya know?
No friggin powder.
Weighed all of the rounds to be sure I didn't miss any more.

I hate when I screw up a round. It makes me second guess all the other rounds.

 

[ljnowell]

A good roll crimp on heavy revolver loads stops bullet pulling under recoil. I would have less confidence in taper crimps on heavy bullet magnum loads. I don't load "light" magnum loads. I load 'em to kill things. .38s work for "light" loads in my .357s. I still roll crimp 'em, though.

We are talking about really light loads here. We are also looking for Bullseye comp accuracy. A heavy crimp is detrimental to that.

 

[mcappys]

lite loads, lite crimp usually works, but I can use the 357 & 45 Colt in my Rifles,
so the get a pretty good crimp, not in favor of some compressed loads

 

[ku4hx]

Substantial recoil (357 & 44 Mag; 454 Casull) get heavy roll crimp at or near full power. All the rest generally get no crimp, just remove the flaring. For peak accuracy I've always favored no crimp. And since peak accuracy loads are, for me, always mid-range loads (or sometimes lighter) the case backing away from the bullet has never been a problem.

 

[ljnowell]

Substantial recoil (357 & 44 Mag; 454 Casull) get heavy roll crimp at or near full power. All the rest generally get no crimp, just remove the flaring. For peak accuracy I've always favored no crimp. And since peak accuracy loads are, for me, always mid-range loads (or sometimes lighter) the case backing away from the bullet has never been a problem.

Exactly. I shoot in a few bullseye leagues and none if us roll crimp a revolver load. Nor do you see much of a tight taper crimp either. It's just not conductive to maximum accuracy using fast powder.

 

[Old Guy]

In loading for my classes in Toronto, Canada, for 23 years. My problem was in getting locally made plated bullets, to be kept in spec, re size.
Had to have plated bullets, to cut down on lead exposure.

My Star Progressive had a roll crimp. The 160g projectiles had a canalure, as all reloading was done with Safariland speed loaders, the roll crimp into it, aided smooth reloads. I think the 700X powder I used (cheap, able to purchase in 12lb kegs) was used in 3.5g lots, per round!

Quite accurate from S&W model 65s, furthest range, 15m. Recoil close to factory 158g Semi Wadcutters.

 

[ljnowell]

In loading for my classes in Toronto, Canada, for 23 years. My problem was in getting locally made plated bullets, to be kept in spec, re size.

Had to have plated bullets, to cut down on lead exposure.



My Star Progressive had a roll crimp. The 160g projectiles had a canalure, as all reloading was done with Safariland speed loaders, the roll crimp into it, aided smooth reloads. I think the 700X powder I used (cheap, able to purchase in 12lb kegs) was used in 3.5g lots, per round!



Quite accurate from S&W model 65s, furthest range, 15m. Recoil close to factory 158g Semi Wadcutters.

Accuracy is a varying degree. I have doubt the loads you describe were quite accurate. However, being accurate and being bullseye competition accurate are different things. When we laid bullseye ammo we treat it like match rifle ammo. All cases trimmed to exact length, matching headstamp and preferably lot of brass, same lot of primers, exact powder charge, even weighing bullets.

Many people will claim that doing this for 25 yard or 50 yard shooting is excessive or a waste of time. It isn't.

In doing that kind if loading I have come to the conclusion that roll crimping is detrimental to accuracy in these super light loads. I have been posting that for some time.

Edit: 700x is a fantastic powder for accurate 38s I have to agree with you there, I have certainly burned up lots if it in 38, 45 acp, and 45 colt loads.