Taper crimp in a revolver?

F

FoghornLeghorn

New member
I took my S&W 25-2 to the range today with some 45 ACP handloads using a taper crimp. 5.5 grains Unique. CCI standard primer.

The cylinder wouldn't turn after about 50 rounds and there was a lot of unburned flakes of powder in the barrel. After I cleaned the gun (pulled cylinder, copious amounts of Hoppes, etc) it functioned just fine.

I used the same crimp die (Dillon Square Deal press) that I use for my 1911s.

Am I going to have to start using a roll crimp for the revolver or is it some other issue? I haven't had this problem with my 357 magnum or 44 magnum revolvers even though I also use Unique in them.
 
That's a pretty light load (assuming you are shooting 230grn bullets.) It's quite possible the cylinder gap contributed to a poorly burning light load.
 
With a four inch barrel M25 and .45AR brass, I roll crimp rather soundly. That works rather nicely for me. I use just under what you do for a charge with a 230 grain bullet for both ACP and Rimmed. The Rimmed likes a 255 grain .45 Colt SWC and a above middle charge of Power Pistol better. Again with firm crimp.

For that matter, the .45 ACP gets a good crimp, but the taper sort.
 
Ok, you stated your load data and the gun they are shot in.

The gun stopped functioning at 50 rounds according to your post.

You cleaned the gun, and it started working fine.

How does that play into the crimp when cleaning got everything working again??

Unique is a good powder for the 45 ACP, but it is dirtier than others.

WW231/HP38 is much cleaner, VV N340 is even cleaner....from my experiences.
 
^^^^^^

If the crimp is insufficient to keep the bullet in the case long enough for the powder to burn, then there's going to be unspent powder in front of the cylinder, the breech, barrel, etc. That could clog up a cylinder's rotation, yes?
 
If the crimp is insufficient to keep the bullet in the case long enough for the powder to burn, then there's going to be unspent powder in front of the cylinder, the breech, barrel, etc. That could clog up a cylinder's rotation, yes?
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Yes.

Thing is, I use a taper crimp on almost every handgun cartridge I load for, and some rifle cartridge/bullet combos, to include the .45ACP. I've never had Unique foul so badly that it tied up one of my revolvers.
 
Did you use the "moon clips"?

if yes, well, there you go, that's your problem, sort of...:rolleyes:

seriously though its actually part of the problem. Moon (half moon etc) clips make rimless cases behave like rimmed cases. In a revolver, rimmed cases are held at the rear, by the rim, so recoil tries to pull the case off the bullet. The direction of force is opposite the hammer type kinetic bullet pullers, but the effect is the same. We call it "jumping the crimp".

How great this effect is, varies with the size & weight of the bullet and the size and weight of the gun. with a heavy bullet in a light gun, the effect is greatest.

What I believe you have is not so much a failure of the type of crimp (roll vs. taper) but more likely a failure of the amount of crimp needed for the specific gun & load you shot.

It's easy enogh to check, with another shooting session using the same gun and ammo. Measure the length of the rounds, before starting. Shoot 4 or 5, and measure the length of the unfired rounds. Repeat this a few time, checking each time. If you are getting increased length of the unfired rounds due to recoil pulling their bullets. If you do, there's your answer. What was enough crimp in your other guns isn't enough in that one.

Load ammo with more crimp, and try again. You should find a point where you are applying enough crimp to hold your bullets in place in that gun.

That being said, a taper crimp is better for holding the bullets in place from being pushed in, than from being pulled out. If the stars line up in just the right way, you may find you can't get enough taper crimp to do the job in a revolver. Doesn't happen often but its not impossible, if just the right factors are involved.

IF that happens, you will have to try a roll crimp for loads used in that gun.

The .45ACP is a pretty short round, and its not impossible for bullets in the cylinder to move forward enough so not only the powder space is enlarged, but the case grip on the bullet is lessened, considerably. This can result in incomplete ignition of the powder, leaving a lot of unburned or partially burned powder left to gunk things up. This could happen without the bullets moving far forward enough to jam the cylinder.

Good luck, and let us know what you find out!
 
I've shot thousands of rounds in a 625 loaded with Dillon dies. No problems. But, I shoot WST powder which burns cleaner. Pet load is 4.3 WST, Fed primer, 200 gr cast SWC. Had to load 4.9 WST to meet minimum power factor for IDPA. I ran into a problem loading Green Dot in a .38 Special. Flakes of unburned powder would get under the extractor and lock the gun up. WST works fine. I still brush under the extractor between strings.
 
"...going to have to start using a roll crimp..." Absolutely not. The ACP requires a taper crimp only because it headspaces on the case mouth regardless of the firearm. "Moon clips" do not change that.
"...200 grain SWC plated..." 5.5 of Unique is .1 above the current MAX for a 200 grain plated(they use cast bullet data.) bullet according to Alliant's site. Not enough to cause any grief though(differences in manuals will cover that much), but you MUST work up the load from the start load. Not just pick one and hope. Start load is 4.9 of Unique.
 
"...going to have to start using a roll crimp..." Absolutely not. The ACP requires a taper crimp only because it headspaces on the case mouth regardless of the firearm. "Moon clips" do not change that.
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44amp thoroughly explained what MAY be the problem with this statement...

a taper crimp is better for holding the bullets in place from being pushed in, than from being pulled out.
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Quickly followed by this statement...

The .45ACP is a pretty short round, and its not impossible for bullets in the cylinder to move forward enough so not only the powder space is enlarged, but the case grip on the bullet is lessened, considerably. This can result in incomplete ignition of the powder, leaving a lot of unburned or partially burned powder left to gunk things up. This could happen without the bullets moving far forward enough to jam the cylinder.
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This may not necessarily be what the OP is experiencing, but I suspect it probably is. It would be similar to my observations with HS6 in low pressure .38spl... the SAAMI max pressure in .38spl just isn't high enough for HS6 to act right. Add to that a fairly large case capacity and a fairly dense powder, and I had unburnt powder all in my revolver after trying it.
 
Strange, I don't see anything for Unique and a 200 gr cast .45 ACP on Alliant www
But they show a Maximum of 7.3 gr for a 200 gr Gold Dot, which is really plated.
That would lead to a 90% starting load of 6.6.
5.5 gr of Unique is way soft, poor burnup to be expected.
 
T. O'Heir said:
The ACP requires a taper crimp only because it headspaces on the case mouth regardless of the firearm. "Moon clips" do not change that.
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You can drop a .45 ACP round into a 25-2 cylinder and it will headspace on the step in the chamber profile, as Mr. O'Heir suggests. The drawback is it won't eject, as there is no rim for the ejector to push against. That's the problem solved by using moon and half-moon clips or .45 Auto Rim brass. Without them, you need to keep a pencil or a short length of dowel rod with you to eject your spent cases.

4.5 to 5.5 grains of Unique would be a target load range with a 200-grain bullet in the 1911 or another pistol. The 25-2, however, has a cylinder length that adds roughly half an inch of freebore the pistol chamber doesn't have, so it takes more powder to reach the same peak pressure in it. The fact Unique is leaving a lot of unburned flakes strongly suggests your ammunition is not reaching the same peak pressure in the revolver it would in a pistol. You could try a magnum primer, as one possible way to improve ignition. Another possibility is to roll crimp, but you need to be sure your clips or rims are stopping on the cylinder and ejector before the cartridge case mouths reach the headspacing step in the chamber to do this. A roll crimp expanding inside that step could produce very high pressure by jamming release of the bullet. If you want to use a roll crimp it would be safest to use Auto Rim cases and make sure they are short enough to prevent that happening. However, increasing the charge weight a little should solve the problem. Using a cleaner burning powder will solve the problem.

A number of old-time bull's eye competition shooters would roll crimp .45 Auto, but they did this with the bullet was sticking out far enough to headspace the cartridge on the throat of the barrel or they had an extractor tight enough to be the headspace stopping surface. The 25-2 cylinder won't let you do that, which is why the length precaution is necessary.
 
"...going to have to start using a roll crimp..." Absolutely not. The ACP requires a taper crimp only because it headspaces on the case mouth regardless of the firearm. "Moon clips" do not change that.
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While this is the prevailing wisdom, I do not find it to be 100% accurate. There are exceptions.

The first one, and the one most people will possibly encounter is the .45acp case that is simply too short to reach the headspace ledge at the front of the chamber. it happens more than people realize, I think. Anyone who has reloaded .45ACP brass for a while can tell you that the cases seldom get longer, and often get shorter, and can even be below minimum length specs and still function in certain firearms.

When this happens, depending, of course on tolerances and design, it is possible the too short case will be held in the firing position not by the ledge in the chamber but by the extractor's grip on the case rim, or by the grip of the moon clip. This is more likely with a semi auto using the controlled round feed like the 1911A1, than one where the round is chambered then the extractor snaps over the rim. It can work in DA revolvers using moon/half moon clips. It will not work in an SA revolver, if the case is too short, it will go too far into the chamber before stopping on the headspace ledge. SO, depending on the specific firearm, and stacking tolerances, the .45ACP does not always headspace as intended.

Second example is rare, but some are still out there...The first production run of COLT 1917 revolvers in .45ACP had cylinders that were bored straight through. There is no headspace ledge in the chambers of these guns, and they can only be fired using moon clips (or .45AR cases).

a number of people weren't all that happy with that, especially since S&W put the ledge in their 1917s, so they could at least be fired, without clips. After the initial production batch, Colt put the headspace ledge in the chambers of all following production 1917s.

As UncleNick mentioned, you can, with care and proper preparation use roll crimped .45ACP ammo in certain guns. Not all of them, by any means, but some of them absolutely, if certain steps are taken.

So, the while it is the intended manner, the .45acp does not headspace on the case mouth in 100% of the firearms made in .45ACP.

Moon clips CAN change the heaspacing of the case. They aren't supposed to, but they can, and in some cases, do, depending on their thickness, and other tolerances.
 
My late model 625 JM does not, DOES NOT , head space on the case, it's not bored thru it's either a new design from S&W or a screw op. It head spaces on the moon clip. The older guns I've seen do head/will work without the moon clip. Bought the gun new and I love it but S&W ain't what it used to be.
 
I've read this before. S&W has trouble with .45 ACP cylinders. M25 cylinders were known for oversize throats, M625s have proper throats but some come through with deep chambers.

a number of people weren't all that happy with that, especially since S&W put the ledge in their 1917s, so they could at least be fired, without clips. After the initial production batch, Colt put the headspace ledge in the chambers of all following production 1917s.
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I've read this many times, even on paper, so it must be so. I have not seen or heard reliably bored through Colt cylinders in the latter day surplus/collector market. Did they replace those thousands of cylinders?
 
I shoot almost nothing but plated 230s through my M22, load on the same Dillon dies that I use for my auto pistol rounds, with the same taper crimp.

Bullets do migrate forward while shooting, my only concern has been that the velocity will decrease enough, due to the enlarged internal volume, that my rounds won't "make power factor" for competition.
You could probably get the same velocity with 3.5 grains of Clays that you do with 5.5 of Unique, so why waste the money?

I've seen a revolver tied-up because a bullet had migrated forward of the chamber, blocking cylinder rotation, but would a 230 be clear of the case mouth before it moved forward enough to contact the barrel?
 
I've read this many times, even on paper, so it must be so. I have not seen or heard reliably bored through Colt cylinders in the latter day surplus/collector market. Did they replace those thousands of cylinders?
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On paper one place you can find the information is W.H.B. Smith's Book of Pistols and Revolvers, page 507, under 1917 Colt, it states that the first 50,000 will not discharge unless the cartridges are on clips. Later numbers have shoulders at the front of the chamber to prevent cartridges going in too far for the firing pin to strike them when singly inserted.

As to why these guns don't seem to be in the surplus/collector's market, I can't say for sure, but its not impossible that after WW I, when all the 1917s were taken in for "restoration" prior to being placed in storage, that first batch might have had the cylinders replaced with ones that have the ACP headspace ledge. I have nothing to prove that, but I think its possible.

A friend suggested a possible reason the first batch was "bored straight through" could be that Colt simply took some New Service .45 Colt cylinders and machined them for half moon clips, creating the 1917 from the New Service. A .45 colt chamber wouldn't have the ACP headspace ledge, and would fire ACP ammo headspaced on clips.

The .45 Colt chamber is oversize for the acp case, but headspaced on a clip, it absolutely will fire acp ammo. and remember the priority was neither match accuracy, nor reuse of the brass, so I think its quite possible that's what happened, though there is no real proof we can find.

Headpaced on a clip, either a taper or a roll crimp will work just fine, provided it is strong enough to hold the bullet in place. GI ball ammo, taper crimped (and with bullets sealed in the cases) seems to work in those guns, just fine (as long as you have the clips ;))
 
RickB said:
…but would a 230 be clear of the case mouth before it moved forward enough to contact the barrel?
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Yes. The cylinder on my 25-2 is 1.540" long, exactly. Cartridges headspacing on the chamber mouths stick out about 0.085" from the chambers, so the combined length is about 1.625". A maximum length cartridge is 1.275", so there is a remaining 0.350" of throat beyond the tip of a bullet loaded to maximum COL. So, any bullet not seated more than 0.350" into the case will fall out.

In dropping pin gauges into empty brass, I've found 0.350" to be about the maximum depth you find before the case wall starts to thicken inward. So that limits seating depth if you don't want the sides of the case to bulge out and prevent chambering. Military hardball bullets, with their long elliptical nose profile and slightly heavy (234 grains max with minus 3 grains tolerance) are longer than most 230 grain ball bullets, at 0.68", and even they are only 0.3" into a typical new case length of 0.895" when the bullet is seated to the 1.275" maximum COL. So, yes indeed, they would fall out.

I suspect that was an intentional design feature to allow a pulled bullet to be dumped out on the ground to clear the weapon.
 
I mainly load .357Mag for my Marlin Rifle and prefer doing a light taper crimp and then a final crimp with the Lee Factory Crimp Die. The Factory Crimp Die just smooths things up for easy feeding and works perfect for my application.
 
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