Probably something under 1000 fps, but you would have to provide a number of other details to allow a really useful reply. The bullet hardness and the gun's internal bore and throat diameters would be relevant. The real player is the lube.I'm prepping the brass for some 240gr non-gas check SWC bullets. I'm using Bulls Eye powder. What's the best load without lead fouling?
One would have to observe that at lower velocities leading will occur and is relieved by adequate lubrication.Leading is the result of Gas cutting. Just make sure the bullets are at least .001"+ to your throat diameter. The bullet should drop freely through the chamber.
Gas cutting occurs when the hot gases pass around the bullet. This allows droplets of hot lead to adhere to you guns bore. Gas checks are rarely needed in handguns. They are expensive and offer very little for velocities below 1,500 fps.
I wonder about any lube on bullets that old. On bullets I purchased, I have been using tumble lube in alox as a supplement to wax lube in lube grooves, when elimination of leading is otherwise elusive.I'm shooting my SW Model 29 and my late fathers SW "Smith & Wesson .44 Special CTG." Those are the only makings on it. He competed with
it back in the '50's. It's had a LOT of lead run through it. My M29 will be my primary. I picked up the SWC's at a gunshow about 15 years ago. There
are no markings on the box. They mic at .429
No name SWC's, and first name in revolvers.