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Old December 1, 2012, 01:45 PM   #1
rrruger
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Revolver bullet seating depth?

I am quite new to the sport of shooting and I have a question about revolver hand loads.
I read in the latest issue of 'Shooting Times' that the “bulletseating depth respective to bore leade can be a significant factor in accuracy”. The article was in reference to rifle rounds, and the resulting difference in group size was remarkable. My question is in the amount of difference one would experience in different seating depths for handgun rounds in a revolver.
Given the fact that a revolver round has to jump from the cylinder to the forcing cone to the barrel should you expect any significant change in group size, all other factors being the same?
I am aware that the same gun will shoot different loads with different degrees of accuracy and that two identical models will shoot the same load differently. I am curious to know if seating an identical bullet higher or lower in the case will change accuracy to any measurable degree in a revolver.
I look forward to your feedback.
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Old December 1, 2012, 02:11 PM   #2
Pond, James Pond
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I sure there will be way more detailed and informative posts to come, but the first thing that springs to mind is that big differences in seat depth will make differences in pressure which could ultimately affect accuracy and possibly safety too...
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Old December 1, 2012, 02:25 PM   #3
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FWIW; for the last 30 years I've been seating revolver bullets to the cannalure or crimp groove, disregarding OAL measurements. With one exception; a 357" cast SWC that has two crimp grooves and if seated out the bullet may not fit some cylinders (can't rmember the Lyman mold number off hand). I suppose a smaller jump from case to rifling may have some effect on accuracy, but in my experience it is very little (if noticable at all). I automatically think of .38 and .44 Specials shot in Magnum guns and producing very good accuracy. I prefer to try for consistancy in other areas for most consistant accuracy (but as I age, my shootin' ain't gettin' no better...).
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Old December 1, 2012, 07:29 PM   #4
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I started reloading for shotgun, rifle, pistol and revolver in '65. Few data sources even suggested an OAL, those that did only listed the SAAMI normal magazine and minimum chamber leads designed for heavy round nose bullets. In all the years since I haven't looked at a book OAL, I find what feeds, chambers and shoots best for the load I'm developing.

Seating/OAL often matters a good bit in rifles, not so much in handguns.
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Old December 1, 2012, 08:24 PM   #5
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Seating bullets to different depths in revolvers usually doesn't matter to accuracy EXCEPT

(1) when using wadcutters,

and

(2) when there are more than one case length that can be fired in the same gun, for example: .38 Special and .357 Magnum; .44 Special and .44 Magnum; etc.

The concept is not related to "jump to the rifling" but rather the jump to the bullet-diameter section of the chamber/throat.

When a full-diameter section of the bullet is not placed into the same diameter throat section of a revolver cylinder, gravity makes the cartridge sit slightly out-of-alignment with the axis of the chamber. When fired, this slightly deforms the bullet as it is forced out of the case and into alignment. That deformation makes a slight difference in accuracy in a gun/load combinaton that is potentially very accurate.

That is why I always seat my full wadcutters out of their cases far enough to have them enter the chamber throats, and one of the reasons I shoot Special-level loads from Magnum cases instead of Special cases.

Testing has shown me that this makes a difference in several of my guns with my best loads, when shooting from a rest at ranges like 25 or 50 yards.

But it is probably not much of an issue with the way that most people shoot off-hand.

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Old December 2, 2012, 10:49 AM   #6
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Good post, SL1. Well put...

I've used the canelure as a depth gage as well...and for those bullets without a canelure, I allow about .050" of clearance between the bullet's nose and the front of the cylinder to keep the gun from tying up if they slip forward in recoil. The amount of "free bore" in a revolver is a moot point, when you consider the forcing cone and rifling lead in. Without taking a measurement, I'd say that most run about 1/2". Best Regards, Rod
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Old December 2, 2012, 11:34 AM   #7
Crankgrinder
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My shootings accuracy is about the same across the board much as ive been shooting, but i have also been seating the bullets out real long for more gunpowder for a long time.
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Old December 2, 2012, 01:09 PM   #8
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You really don't have much choice in the OAL of revolver loads. Most bullets made for revolver calibers have cannelure rings made for crimping those bullets to prevent inertia from pulling those bullets from the cases. The gun fires, the bullets tend to stay put while the gun recoils backward, result; the bullet moves forward out of the case.

Yeah, I know all about case neck tension is more important that a crimp. That's the answer for MOST other applications in reloading/shooting, like rifle and semi-auto handguns. Most rifle rounds need no crimp,(the exception is the leverguns). Semi auto handgun need only to have the crimp cancel the case mouth belling.

Magnum handguns need a good hard roll crimp to prevent bullet creep. That means the OAL is pre-set by where the crimp groove/cannelure is, live with it!
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Old December 4, 2012, 02:46 AM   #9
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Thank you for the feedback, you guys are a wealth of info.
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Old December 6, 2012, 11:55 AM   #10
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For what it's worth,
I reload .454Casull and the manual lists COL 1.765" and I have trouble loading them in my Freedom arms Revolver. I set my COL to 1.760 and then they drop right in. And I do not shoot .45Colt in the .454 cylinder. I have both cylinders if need be.
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Old December 7, 2012, 01:07 AM   #11
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my two cents:

Cent 1) Some loads/powders do better if they are packed tightly. I know that my blackhawk is in lust with 15 grains of 2400 under a 158JSP. It will cloverleaf all day, if I could stand to shoot them that long, and would not be surprised if some of that was because it fills the case in a great way. It's not compressed, but if I were to double-charge, it would overflow the case. In a round-about way, seating the bullet deeper in the case would allow less dead-space, or maybe even compress the powder. I personally wouldn't do that, and certainly not with that load, because that load is up there in pressure already.

cent 2) FWIW, I've anecdotally noticed that my accuracy is more dependent on how hard I roll the crimp (which may be related to cent 1, or maybe not). I know rifle rounds don't work that way, and conversely, I know slow powders in the .357 need that hard crimp to let the round build up pressure properly, above needing it to keep the bullet from wandering. I'm not smart enough to break it down without down off the top of my head. Unless you want to ignore the channelature, the COAL is kind of dictated, but the crimp's not.
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