I just got a JM625 45acp Smith and Wesson, and revolvers are far less picky with Overal Length than Automatics. so Im wondering how to determine ideal bullet seating, aka OAL.

With my rifles, its a process of loading a dummy round where I mark the projectile with a black marker and observe where the projectile is scratched after chambering it, then measure with a micrometer to dial in the exact OAL where the bullet just seats under the ogive...., chambering it, an ideal point where the bullet wont vibrate any more than necessary as it leaves the chamber.

Revolvers are not like autos where the OAL needs to cater to the confines of magazine feed and feed ramp.

So, whats the method of setting OAL for a revolver?

I seat revolver bullets to the cannelure or crimping groove for lead rounds.
Crimp, if necessary, in that groove.


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What he says about typical rimmed revolver cartridges. Anything less than cylinder length is OK.

I don't load .45 ACP for a revolver, but my take on it would be to load to published overall length. That is most likely the length at which the data was developed. If no length was published, I'd load them to SAAMI max for safety purposes.

The method you use for rifle cartridges will give inconsistent results for a number of reasons. I suggest buying the Hornady Lock N Load overall length gauge. It's a precision instrument that will give consistent results with each lot of bullets. One of the reasons we get excellent groups with one load and then patterns with the next batch is varying distances off the lands with different ogive shapes, even with a different lot of the same bullet. The overall length gauge will allow you to seat the bullet to the same distance off the lands with each batch of loads.

For what it's worth, I've occasionally gotten excellent accuracy with bullets seated as much as 1/8" off the lands. A short jump may not always give you the best groups.

Same here, those cannelures and grooves are there for a reason, but with the 45 ACP, using bullets designed for that caliber, there are no such things. My only experience with a 45 ACP revolver was with a Colt M1917. The cylinder was long enough for 45 Colt rounds and it is not at all practical to load 45 ACP rounds to such OAL's. For 45 ACP in a revolver, I would seat them to the recommended OAL for 45 ACP as found in your reloading manuals.

For 45 ACP just load using the same process as an auto-loader.

You can go longer or shorter(if you account for the less case capacity), but for the most part it's not going to make a difference.

With a 25 and decendants you are not limited to rounds designed to feed reliably in semiautos. I load lead .38 bullets in 9 cases for my 940 crimping them into the groove. There are lots of .45 bullets that would do fine in a sixgun.

__________________
Certified Curmudgeon

I tried extra long OAL in my 38 and 357 with lead wc and RN bullets
to see if it would help out accuracy in my light target loads?

NOT !!

I did not mess around with any jacketed bullets at medium or high speeds
since a major "Bo-Bo" might be in the making and I don't load these low vel.

The "Ideal OAL" is pre-determined by the bullet design. Seat the bullet to the canalure or crimp groove. The bullet designers took into consideration what guns the bullet would be used in and how much of the bullet will enter the case. Basically as long as the cartridge isn't too long for the cylinder, it's OK...

I too tried experimenting with different seating depths/OAL in my revolvers, but found not enough difference to be of any benefit...

for my 25-2 I seat cast SWC almost to it's shoulder so when I put a light taper crimp, it will not deform the bullet, there will be a little air showing between the crimp and the curving shoulder. Meaning I seat them low. I also like to seat and crimp in 2 steps. If you seat high and even with a FMJ and regular taper crimp...go try a bullet puller and pull one, likely there will be a noticeable ring...avoid that as it will totally kill accuracy.

With a 45 acp revolver, loading for function is the main thing. Some semi-wadcutters will hang up on the cylinder throats if seated too long. Some bullets may not have enough case tension to prevent pulling under recoil if not seated deep enough. Within a range of proper functioning, I've not found much accuracy difference from reasonable seating depth variations. Depending on the dies used, it can be a problem getting enough case tension with lighter .451" bullets. An undersize sizer is nice to have when loading .45 auto for revolvers.

Like everyone else said, your wibbles & wobbles with a handgun are going to be more than any imaginary benefit from playing with OAL. To get near the rifling in a revolver you'd need a round longer than the cylinder.

You might get some benefit from the use of a Kieth style bullet with a full diameter portion of the body close to the nose of the bullet.