Reloading 45ACP for revolvers--can I load to higher pressures?

[ExMachina]

Am I wrong in thinking that for a given 45ACP loading, the pressure of that load in a revolver (same absolute bbl length) will be slightly LESS than in an auto because of the b-c gap? If so, can I then load 45ACPs slightly hotter in a revolver and still stay w/in pressure specs?

 

[ExMachina]

So to clarify, I'm not meaning to ask opinions on how high is too high. I'm not looking for load advice. I'm really wanting to know if there are any weird dynamics that I'm not thinking about when I'm thinking about the pressure relief provided by the barrel/cylinder gap?--the pressure situation in a revolver always has to be lower, relative to the pressure curve in an autoloader, right?

 

[Steve C]

I would think that the chamber pressure is the same for a solid barrel like you have in a semi auto and a revolvers chamber. IF there's a slight difference because of the cylinder gap it's likely so slight that without very involved testing with a strain gauge set up you don't know how much heavier you could go on your charge. IMO its a colossal waste of time for minimal potential increase in velocity. The ACP case is smaller capacity than the old Colt case and the only real way to increase velocities is to use slower powders. The smaller case capacity negates some of the benefit of slower powders.

 

[ExMachina]

So am I wrong in recalling that revolver's consistently deliver lower velocities using the same load?--I cannot cite any data now so could very well be mistaken...

 

[ArchAngelCD]

Velocities aren't the problem with loading any caliber hot, pressure is. You do lose some velocity because of the gap in a revolver BUT, by the time the bullet reaches that gap the pressure is already starting to drop. For the most part peak pressure is reached before the bullet moves an inch. You should never load a caliber over SAAMI pressure limits, even if you are shooting a semi-auto round in a revolver.

 

[Clark]

Clark Custom guns [no relation] does a modification service on S&W 25-2 revolvers to convert them to 460 Rowland for $100.

They also show 460 reloading data at 40,000 c.u.p.

This has been on their web site for the better part of 10 years.

A 460 Rowland is a 45acp with the same OAL but a different case length.

I am not going to run MY S&W 25-2 at 40,000 c.u.p. because I have measured the chamber wall thickness, and I have blown up lots of revolvers in experimental destructive work ups. I have something like $360 + FFL in 2002 into this revolver.

CAUTION: The following post includes loading data beyond currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The High Road, nor the staff of THR assume any liability for any damage or injury resulting from use of this information.
I am running 28,000 psi in my S&W 25-2
I have been called crazy and dangerous on the internet for doing that.
It may seem that way if you run yours at 21,000 psi SAAMI max average with 30,450 max SAAMI proof pressure.
But it does not look so crazy and dangerous when you see what has been going on at Clark Custom Guns.

In the meantime, I am doing what I am doing because of the chamber inside diameter and the chamber wall thickness, not based on SAAMI or what someone else does.

 

[highlander 5]

Cylinder walls on a S&W are thin,plus the bolt cuts are at the chamber walls which makes me a little leary about any hot loads for a 45 acp revolver. If you were talking a Ruger Blackhawk I'd say yes on slightly hotter loads but as the previous gentlemen have said don't do it. You came into the world with 2 eyes and ten fingers and I'm sure you wish to leave it the same way.

 

[MrBorland]

can I then load 45ACPs slightly hotter in a revolver and still stay w/in pressure specs?

Pressure specs of the cartridge or the gun? Just to be clear, though, you're really asking whether the same load will have different velocities when shot from a revolver vs semi-auto?

Cylinder walls on a S&W are thin,plus the bolt cuts are at the chamber walls which makes me a little leary about any hot loads for a 45 acp revolver.

If it's a S&W N-frame, it's the same platform as their .44mag, which runs at considerably higher pressure. Some USPSA gamers use .45GAP in their 625, which roughly generates .45 ACP +P pressure.

 

[ExMachina]

Pressure specs of the cartridge or the gun? Just to be clear, though, you're really asking whether the same load will have different velocities when shot from a revolver vs semi-auto?

yes, i titled this thread poorly. i'm not interested in hot-rodding the 45ACP.

basically i wanted to know if i could/should increase the powder charge of published data by 0.1 grains (or whatever) to duplicate published velocities--this, under the assumption that reloading data for 45 ACP is geared strictly to auto-loaders.

the solution would be to use a chrony but i don't currently have access to one

 

[RidgwayCO]

As unsatisfying as the answer is... it depends.

A 4" revolver barrel is actually 4" from the forcing cone to the muzzle, whereas a 4" semiauto barrel includes the length of the chamber. I believe the pressure generated when the cartridge fires is the same, but you might get slightly lower velocities from the revolver due to the barrel-cylinder gap.

As an example, when testing a 125gr LRN load in 9mm Luger, I got higher velocity from a 3" revolver (S&W M547) than from a 3.6" semi-auto (Beretta 8000F). Conversely, I also got lower velocity from a 4" revolver (another M547) than from a 4.9" semi-auto (Beretta 92FS).

The bottom line is, it's impossible to "know" the velocity of a cartridge without testing it over a chronograph.

 

[sourdough44]

Not saying you couldn't do it, with due consideration. I just wonder how one would know those rounds don't end up in a semi-auto 5-10 years down the road?

 

[Claude Clay]

^-----------or your at the range with friends and ammo gets shared.....

 

[rcmodel]

S&W N-Frame .45 ACP revolvers are rated for any .45 ACP ammo, including +P.

But they in fact are not as strong as the same gun in .44 Magnum.

As highlander 5 already stated, .457" .44 chambers don't remove as much metal as .476" .45 chambers.

The weak link in the chain is how close the bolt cuts in the cylinder are getting to the chamber walls in a .45 Cal N-Frame.

It was designed from the getgo as a .44 cal revolver, and making it a .45 is pushing the design as far as it can be pushed.

rc

 

[ExMachina]

I just wonder how one would know those rounds don't end up in a semi-auto 5-10 years down the road?

that's a concern with all reloaded ammo, and in fact with all factory ammo that is loaded to +P pressures. ultimately, it's up to the shooter to know what he's shooting and to come up with labeling/boxing habits that are designed to prevent accidents from happening.

but in my case, i was only interested in knowing how much velocity loss i could expect form the barrel-cylinder gap and whether i could make up that loss with slightly more powder--those "hotter" rounds would still not be pushing the limits of the pressure envelope.

 

[P-32]

I would not worry about it. No body is going to know your bullet could have been going 25 fps faster.

 

[sourdough44]

O.K. guys, yeah I load the 45 Colt to several different levels,low up to 'Ruger only' levels. Back to the question at hand, we have higher pressures and then we have HIGHER PRESSURES. So I guess a lot of it depends on specifics. For the most part though I stay within common data,just makes things easier.

 

[Funshooter45]

Sure, if you're still within the safe published range, and as long as you're moving up very gradually, like 0.1 grain as you suggested, it's fine to play with a bit more powder. Maybe it will help, maybe not so much.

Just take a look at those cylinder walls in a .45 though for perspective and it will make you a bit cautious. The first revolver I ever loaded for was a Blackhawk in .357. The cylinder walls are what they are and I didn't give it any thought. Next was for a couple .44 mags. The Blackhawk had somewhat thicker cylinder walls than the S&W 629, but not anything I really gave any thought to. Then came my .454 Casull in the BFR platform. This is only a 5-shooter so the cylinder walls are massively thick. I hot-rodded .45 Colt rounds in it just for fun. Finally though I got a Colt clone in .45 Colt. I knew better just from reading than to try to put the super-hot .45's I had made for the BFR into that revolver. But when I first looked at the cylinder on that revolver I thought my eyes were playing tricks on me! YIKES! The chamber walls on a "normal" .45 caliber revolver look paper thin compared to what I had been used to. I assume it's the same way on your revolver as well. Just looking at those chamber walls relieved me of any temptation I ever had to play at the high end of the pressure range for that gun.

 

[murf]

peak pressure is reached before the bullet gets out of the chamber. if you increase the powder charge you increase the pressure regardless of the type of weapon.

murf