rawhide: Thank you for listing that information. The caveats you have taken from the Lyman reloading manual are good sound advice that I hope all would follow to avoid pressure problems, and these are caveats that apply to all reloaded cartridges whether revolver or pistol, and reloaders should pay heed.
I agree with Ron Reed that the 10mm is pretty easy to reload (for me, as it is a straight case). When proper seating and crimping procedures are used the bullets should not re-seat more deeply under recoil nor should you experience pressure spikes. Actually, I wonder if those problems you have seen as a result of pressure spikes due to deeper seated bullets may not have been caused when the slide striped the loaded round from the magazine and slamed it into the chamber, especially if the nose of the slug takes a wallop on the way in. I think that slugs that seat more deeply under recoil, while in a magazine, aren't properly crimped and the problem may be compounded if the slug seats more deeply under slide battery. This just means the reloader needs to pay attention to the caveats you listed and to the advice given by Ron Reed that reloading is a very precise action and MUST be done properly.
I have had my own difficulties with slugs 'walking' out of the case under recoil with the heavier magnum rounds I did not crimp tightly enough and have seen semi-auto slugs seat more deeply in the case under slide battery when the crimp was not tight enough but fortunately (knock on wood) nothing untoward has happened.
I have always felt the 10mm would benefit more from a good solid semi-wadcutter slug than a jacketed slug and I like the Keith 40170 (RCBS???) (or 40183 Lyman) slug he designed for the 38-40, if that slug would function properly in a semi-auto and I would like to see other cast slugs for the 10mm to wear a crimping groove. The 10mm can be loaded to the lower ranges of the 41 magnum which makes it a fairly effective contender nearing the magnum category.
To get back to the topic, I have 'some experience' with 10mm cartridges, including my own wildcat and have seen my own hardcast slugs penetrate through the ribcage of whitetail out to 100m. I have also seen my own cast slugs bust through the on-side shoulder and penetrate the chest cavity to be found just under the hide on the off-side. I believe a 200 gn 10mm round loaded to 1200'/sec (original load for the Bren 10) will perform the same or better and should be every bit as capable in the hands of a good shooter at reasonable distances (now for me only out to about 50-75m with a very clear sight picture). I consider the 180 grain weight slug in the 10mm to be about optimal but a 200 gn slug should be heavy enough for the bore so as to add significant penetrability out to effective ranges. Again, as in my earlier post, a 10mm loaded with a 200 gn slug to 1200'/sec, or even a 180 to the same velocity, places the 10mm squarely in the range of performance for the older 38-40 from a carbine or rifle and that load was taking whitetail, black bear and hog long before the 44 magnum was developed. Hope this helps. Mikey.
