Hi,

I am just starting to reload the 357 magnum for a Rossi 92, using a Lee Progressive Loader, and am having problems keeping my COAL consistent between rounds. It varies by as much as .005" from cartridge to cartridge, doing everything the same. The dies are Lee 38/357, using a 158 FMJ, Rem nickle brass. Is this acceptable deviation in cartridge length?

Thanks, Jimmy

The variation could well be a result of an inconsistent nose shape for the bullet you are using. Is your seating die stem and body lock rings fixed firmly?

Another option is that YOU may not be operating the press in a consistent manner and causing this slight variance. If you can't trace it to anything else it could be your press. I wouldn't sweat it just so long as your rounds are being crimped in the cannelure, but you'll get differing opinions on that matter.

Jimmy,

Lee Precision (http://www.leeprecision.com) has a pretty good FAQ's but you can't use a URL to link the individual pages. I've copied and pasted the following topic... hope they don't mind.

Seating depth variations

There are a number of possible causes for overall length variation. One is the way it is measured. If you measure overall length from the tip of the bullet to the base of the case, remember to subtract the variation due to bullet length tolerance. The bullets will vary in length due to manufacturing tolerances (bullets with exposed lead noses are the worst in this regard) and this will add to the overall cartridge length variation. Remember that the bullet seater plug does not (or shouldn't) contact the tip of the bullet when seating, but contacts farther down the ogive. For a more accurate seating depth measurement, take the seater plug out of the bullet seating die, place it on top of the cartridge and measure from the base of the case to the top of the seater plug.

Another possible cause for bullet seating depth variation is seating and crimping at the same time when trying to apply a firm crimp to untrimmed cases. Variation in case length also causes variation in the amount of crimp applied. Long cases get a heavier crimp than short ones. When seating and crimping at the same time, the crimp is formed as the bullet is seated into the case. The crimp will form sooner on a long case, and therefore the bullet will not be seated as deeply. The solution is to seat and crimp in a separate step (the Lee Factory Crimp die is good for this) and/or trim cases to a uniform length.

The amount of force required to cycle a progressive press varies with the number of cases in the shell plate. When the shell plate is full, it is harder to lower the lever than when there are one or two cases present. This can lead to variation in cartridge overall length because there are different loads placed on the working parts of the press. When the shell plate is full, seating depth will be slightly long, because the load is higher and all of the clearances are taken up. With the shell plate nearly empty, the load is not great enough to squeeze out these clearances, and the seating depth is short.

A potential solution for this on progressive presses is to turn the sizing die in far enough so that the carrier is stopping on the bottom of the die. This removes clearance problems when no sizing but yet seating / crimping is occurring. Take special care not to turn the die in further than to just touch the shell plate and possibly just a tad more. About 1/4th of turn more is all you want to go, turning the sizing die in too far causes other problems.

0.005" isn't necessarily all that bad - if the crimp groove in the bullet is lining up with the case mouth, I wouldn't worry about it.

If you are seating and crimping in the same step, I'd be surprised if you got much better than that. I never seem to be able to unless I do each step separately.

Are all the cases trimmed to the same length to start with?

Lastly..... having used a bit of Lee equipment, I'd say it may well be some tolerances in the press. Their stuff tends to start out 'loose' and doesn't get tighter over time.

For blasting ammo, I probably would not worry a lot about it.