Recently loaded 38 Special Xtreme 158 gr. SWC plated bullets I bought several months back. Normal bullet was 158 gr lead SWC, 3.1 gr. Winchester 231, which I chronographed at 640-650 for 6 rounds a couple weeks back. Was very pleased with the round, but had 2,500 plated bullets and no lead bullets.

Loaded up a test batch of 50 plated bullets and couldn't hit the paper at 25 yards, much less the target. I have my Model 67 sighted for a 6:00 hold, and with the lead, can do 2-2 1/2 " from sandbags. With the plated bullets, I have to hold center of target, and the point of impact is about 6 inches low, 3 inches right. So what gives? Thinking it's me, I switch back to the lead, back to 6:00, center of target. Plated, no such luck.

Things I have noticed:

Plated bullet is shorter (.665 vs. .725 for lead according to my calipers).
Both lead and plated mic at .358.
Both weight 158 gr, +- a bit.
Crimp is the same (very light)
OAL is the same

I think there is some sort of pressure difference causing this, but not sure why changing bullets would cause such a dramatic change.

Things I've thought about:

Changing crimp-seat bullet to cannelure and taper to hold (mild recoil so bullet shouldn't move)
Seat a tad deeper
Increase powder to about 3.5 gr. 231
Switch to 3.6 Titegroup (my old load) and see what it does
Dump remaining 2,450 plated bullets and replace with lead (offers to ship to you should include some form of compensation plus shipping if you are more than 50 miles away from the Sacramento area in the People's Republic).

Can anyone think of anything else to try, or know what's so different?

Thanks.

Bill