I have a set of rcbs dies on the way with a taper crimp die. My question is can this be used to crimp the case for medium/heavy loads in a revolver or could bullet set back in case upon firing?

I use a roll crimp for .357 mag. I believe the taper crimp is mostly for semi auto pistol rounds.

Sure you can use it, and I suspect it will work fine. You won’t have setback problems in a revolver. You’ll have bullet-pull problems. Unless you are using a lightweight revolver, I doubt that will be a factor. Keeping your brass trimmed to the proper, uniform length is essential to getting good crimps. I believe that’s the case no matter what tool you use, whether roll, taper, or factory-crimp die type. If you’re gun is a 340PD, or something similar, you might be heading for a little experimenting.

My first reaction is why would you order a taper crimp for the 357 mag cartridge?
Set back would be a real possibility for heavy rounds - IMO.

I use 38 caliber blue bullets and they have no cannelure. Therefor I need a little taper crimp to bring the case mouth in line. I use the RCBS 9mm die on my 4th stage, remove the seater and set the crimp to just the right amount.

It all depends on what BULLET you are using. If it is plated bullet with no cannelure then yes, a taper is good. But that said I don't use those "things" in revolvers. I prefer coated lead or Jacketed with a cannelure.

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Still Running Against the Wind

Taper crimp die works extremely well. No concern about case length being exactly the same. Taper crimp does not depend on turning the mouth of the case into a crimping groove on the bullet. Ideal for jacketed and swaged bullets. For really heavy loads, it is conceivable that a bullet might creep out a smidgen, but the likelihood of a bullet setting back into the case as with a semi-auto pistol is at best slight. In a light weight revolver using heavy loads where a couple of rounds remain in the cylinder after multiple cycles of shooting several shots then reloading, then the possibility of bullet creep increases. This would be true regardless of the type of crimp used. Sincerely. bruce.
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The revolver I will be using is the S&W 686 5" barrel 3-5-7 model

For 357 Magnum, I use a collet crimp.

Lee makes what they call the Factory Crimp Die, but there are 2 styles for the 357 Magnum. This is not the standard FCD.

This started out as a custom order die, but they always seem to have them in stock these days

357 Magnum Custom Collet Style Crimp Die - Lee Precision

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"Acta non verba"

I've been taper crimping a cast lead 124 gr. TC bullet ,with no crimp groove , it's the NOE #358-124-TC-GC designed for 9mm Luger .
The bullet drops at .3575 and when run through a .358 sizing die, to lube , they work just fine in 38 special / 357 magnum (size them .357 and I use in 9mm ) .
No crimp groove . The gas check lets me use it in 357 magnum at 1000 to 1200 fps , taper crimped with my 9mm crimp die .
Put quite a few stout loads through a Ruger Blackhawk and so far no bullets have crept forward ... that I could notice . 38 special loads hold tight ...no problems at all .
Give the taper crimp die a shot..(excuse bad pun) .. my 9mm taper crimp die works just fine on 357 magnum .
I do use the roll crimp for bullets with a proper crimp groove or cannelure .
Test the crimp by pressing on the seated and taper crimped bullet with your thumb ...if it will resist a good hard press it should hold...
final test is shoot 5 and examine the 6th .
In revolvers the bullets want to creep forward...just the opposite of sem-auto's bullets getting shoved back into the case .
Gary

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In revolvers the bullets creep forward under repeated recoil so bullet setback in the case wont be a problem at all .

I use a 9mm Luger taper crimp die to crimp 357 magnum loads with smooth sided bullets designed for 9mm semi-auto's , a cast 124 grain truncated cone gas check design (it has no crimp groove) loaded to 1000 to 1200 fps , taper crimped in a 357 magnum case . These bullets have held , showing no creeping forward in 6 shots in a Ruger Blackhawk .
Taper crimp should hold , test it with firm thumb pressure on a loaded round ... put enough crimp so it will resist the thumb force then range test.
Gary

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On super hard recoiling loads in my 357 and 44 Contenders, I roll crimp then push that further with a taper crimp. This makes a High chamber pressure round into a SUPER High Pressure round, but the velocity is extremely consistent. This will be fine in Super Blackhawks but I wouldn't use it in my S&W's!

Ivan

There are some powders, 296 & 2400 come to mind, that require a heavy crimp for optimum powder burn. This usually translates to a roll crimp. I guess some experimentation is in order. If you see lots of unburned powder in the barrel, you need a firmer crimp.

I've got a couple taper crimp dies in revolver calibers to use on moderate loads with plated bullets. Seems to work OK, but I'm not using the slow burning powders. If you swap bullet types with any regularity (cannelured/non cannelured) or powder types it might pay to spring for a roll crimp die. FWIW, I found the hassle of changing taper crimp adjustments for the different bullets in a specific rifle caliber so much a pain, I bought a second taper crimp die to eliminate the need to fuss with the adjustment.

And, the bullets don't set back in a revolver, they do pull forward in recoil if the crimp isn't enough and the recoil is enough.

Exceptions abound and there are really no firm rules on any of this. It's worth experimenting with different degrees of taper crimp. Probably the lightest taper crimp that will prevent bullet movement from recoil will be the most accurate and should be sufficient for proper ignition and complete burning of slow powders. But, you'll have to try it with your gun and components to know for sure what works best. Benchrest your gun and fire groups at 25 yards.

That is not the issue


What BULLET are you using??

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Still Running Against the Wind

I use a taper crimp with light loads and plated bullets. With heavy loads, I use a cast or jacketed bullet and a roll crimp.

I have found the taper crimp works better with a 38 sa if you need it. Over the years I have found a roll crimp works better in a 357 and more accurate also. If you have a four die set you don't need a taper crimp. The roll crimp is very adjustable in stage #4- 0 to smash. Also on my hbwc dewc and bnwc 38s a slight or no crimp works perfect for me. 38 or 357. Like others have said the bullet goes forward under recoil and will lock the cylinder without the proper crimp. A 9mm is about all I taper crimp.

Thinking of 125 gn plated without cannular (sp?)

That will work. Measure the bullet <should be 357 OD.> Seat it until it measures about .354 OD <starts to taper>at the mouth end of the brass and crimp. <not heavy> I do .357s from Armscor like that with no problem. <I use a roll crimp now with plated of jacketed without the crimp groove but I used taper in the past> If the overall length is to short back off on the powder.

If you crimp too hard with a smooth plated bullet you can break through the plating.

They make plated bullets with a cannelure that allows you to give the bullet more crimp, meaning a light roll crimp.

38- 125 HP



Again I use a taper crimp on light to lower medium loads in .357, .44 Special and .44 magnum. And once the load goes up with slower burning powders I use a roll crimp.

And my point being with thin-skinned plated bullets you do not want to break through the plating. Some reloaders get by with just roll crimping but this means trimming the cases to the same length and applying a light roll crimp.

There is really no point to using a taper crimp die on a rimmed cartridge. They are designed to crimp semi auto cartridges that headspace on their mouths, such as the 9mm Luger or 45 ACP. If you use the roll crimp, I suggest that you seat the bullet first and do the crimp as a separate operation. I can tell you that once you use a Lee collet crimp die, you will never go back.

I use taper crimp on plated bullets in 357. Handles 158 grain bullets at 1000 fps in a full size revolver. Above that, don't know, never been there with a taper crimp.
My favorite crimp die for 357 is the Redding profile crimp. Adjusts from a light taper crimp to a collet style crimp.

I know a collet works differently, but both the collet and the profile crimp lay the case mouth parallel to the bullet, a roll crimp drives the case mouth into the side of the bullet on longer cases.

Actually a Collet crimp drives the case mouth into the cannelure as well

If I were at home I could probably pull out some rounds to photograph

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"Acta non verba"

I bought a Lee 357 magnum collet crimp die for use with plated bullets with no crimp groove and that die produced some of the tightest crimps I've ever seen in any 357 round and with no damage to the copper plating either. The dummy rounds I made up were quite difficult to knock down with the plastic hammer taking multiple hard hits before they released. This die doesn't just crimp at the mouth of the case like a taper crimp but produces a smooth crimp down the flanks of the case. I haven't fired any of the rounds I loaded with it yet but I believe it's going to be the real deal for heavy loads in a j frame.

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"I gots to know"

I always taper crimp all handgun ammo because I think it makes small to moderate variations in case length less of a problem.
With a roll crimp, small inconsistencies in case length cause a quite noticeable variation in the effort required for the crimping operation from one cartridge to the next.

But full disclosure here; I don't load magnum loads in revolvers.
I load .38 Special up to +P, and .44 Special, 9mm, and .45 ACP at standard pressures.

Has anyone ever seen proof that a roll crimp will cut through the plating and cause issues in copper plated bullets?

I've bought some 158gr RNFP bullets that were pulled from demilled factory ammo. They had no cannelure, but they had very noticeable rings from a roll crimp and close inspection under magnification showed no indication that the plating was cut or cracked.

Since the plating is deposited through electrolysis it seems to me that it would take some pretty severe distortion/damage to make it crack and separate from the lead. Also, if roll crimping were likely to damage the plating and cause a problem, what factory would use a roll crimp with plated bullets? Doesn't make sense to me.

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Send lawyers, guns & money...

I've been looking at their collet crimp dies myself. Need to pick 1 up and do some head to head testing with:
roll crimp vs taper crimp vs collet crimp
Should prove interesting.

Myself I don't use/shoot plated bullets, never had any desire to and never will.

That should work , I do it with 124 grain cast lead truncated cone bullets that are sized .357 or .358 .
I have had poor results with some bullets , plated and cast that were sized .355 and .356 , they were too small for my Ruger Blackhawk's throats ...small bullets = not great accuracy .

technically the correct spelling is cannelure but we knew what you were saying .
Gary

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I tested some 357 (158 gr) bullets from RMR (Rocky Mt Reloading)


I crimped the snot out of them and also gave them the bench vise and hammer test!


The plating did not crack at all. Other brands may vary!

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Still Running Against the Wind

That is what I would expect.
So far I've never seen any proof that the plating can be cracked or damaged by crimping.
I have to wonder if it isn't just theoretical.
Kind of a reloading urban myth maybe?

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Send lawyers, guns & money...

OUCH !!

Bad day at the office, Bunky ??

You sure put the hurt on those bullets.

It's all about the "research"

I think some of the early plated bullest may have had issues.

To me, the RMR bullets are as good or better than name brand FMJ bullets

After-all, technically speaking Speer Gold Dot bullets are "plated"
Super duper, high tech molecular bonded to the metal plating

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Still Running Against the Wind

I find that when using taper crimps in 38 Spl +P with 158 gr lead swc in my Airweight 642 that there is some bullet creep. I prefer a firm roll crimp in this application.

I have used taper crimps using Hornady swaged bullets in 357 Magnum cases in my Ruger 4 5/8 Blackhawk at approx 1,000 FPS (I coat the bullets with Lee Alox) without any creep, and they are very accurate.