Anyone have experience with M&P 45 and .453 ?

[Papa Duck]

I recently bought a box of "45 ACP" 230 grain round nose cast bullets and am preparing to load them for my new M&P 45. I was wondering if anyone has any experience or knowledge about the M&P and this size bullet.

I can do a chamber/barrel cast if I have to... but I thought I would ask if anyone has loaded this size and had any issues.

My plan is to go with Win 231 4.8grn and c.o.a.l of 1.2 to start with. If you have suggestions or warnings before I put a couple dozen of these together and head to the range I would really appreciate your feedback.

THANKS!

[bumpo628]

Commercial cast bullets are usually .452".

I have an M&P45 and I have run plenty of 230grn LRN through it. I also use W231 (4.7 grn @ 1.250 OAL) and it is very accurate.

[Echo]

My guess is that they were cast from the Lyman 452374, or a clone. That is a fairly standard profile for 45 RN cast boolits, matching the profile of the jacketed HB round. Have you put a mike on them, to find the true OD? The Lyman Pistol & Revolver Handbook lists 4.0 grs of 231 as a starting load, 5.5 max, and OAL of 1.265. The gentle slope of it's ogive allows this OAL - the Lee 230 gr has a more abrupt ogive that seems to like to be deeper seated.

In any case, standard practice is to dismount the bbl of your M&P and drop a loaded round into the chamber. Conventional wisdom says that the cartridge base should NOT be proud of the rear of the bbl. If your loaded round does stand proud - if it is only 20-30 thousandths, try some on the range and see if you have a problem chambering or feeding. I like a little interference fit between the ogive and the origin of the rifling. It holds end-play to a minimum (like zero!) and seems to improve accuracy.

If, on the other hand, you have issues chambering or feeding , then you will have to seat the boolits some deeper, until the chambering/feeding problem goes away. Professor Gun will tell you what he wants...

[Papa Duck]

Thanks for the responses!

These were in an old box I picked up for 20 bucks for 500 so I thought they would be worth the effort of trying. They are labeled as "45 ACP" but they actually measure .453 for the most part... (some at .4528... etc...)

I will do as you suggest and see how they fit in the bbl and adjust the OAL based on that. My initial set up for length was 1.240. When a round is chambered and then I try to eject it things got sticky... In fact, I had to pull so hard on the slide that the bullet detached from the case and I disassembled the weapon to remove the bullet with a cleaning rod.

I was sort of glad that I didn't fire it since I was unsure if the .453 would have created an over-pressure situation.

If a shorter length doesn't solve the problem I will likely run 'em all through a .452 resizer.

Thanks again !