M&P leading

[bryonbush]

any one shoot lead in their M&P pistols? once again, im getting leading in a new pistol. my last SW worked great with cast. then got the XD and that sucks for lead, now the M&P.

[historicfirearms]

Which M&P do you have? I've got an M&P 340 (J frame 357 revolver) that shoots lead just great. From day one it has never leaded with anything I have shot in it.

[bryonbush]

its the M&P VTAC .40. maybe the revolver is using a different barrel. seems to me that these new guns are using some type of coating inside the barrels that are making it hard to shoot lead in. i had a talk about a year ago with with springfield, and they stated that they are using a coating like glock does that does not take to lead very well.

[garym1a2]

i load for by brothers xdm 5.25 9mm no problem.

[geargnasher]

The brass is swaging the boolits undersized, resulting in gas leaks around the boolit when it's fired. The dust abraded from the boolits sticks to the barrel metal and accumulates.

Make certain all traces of copper fouling are removed from the barrel before shooting cast.

Make sure there's no sharp edge in the throat that can shave lead.

Throw your .40 caliber Lee Factory Crimp die in the garbage.

Use real lube, don't try to tumble lube for that one.

That should cover it for the M&P .40 caliber leading.

Gear

[bryonbush]

im sizing them to .401 with the star using 50/50 beez/Alox mix. works great in the .45.

[geargnasher]

And you still don't know why it leads. Study post #5 some more.

Gear

[lawboy]

any one shoot lead in their M&P pistols? once again, im getting leading in a new pistol. my last SW worked great with cast. then got the XD and that sucks for lead, now the M&P.

Shot plenty of cast boolits in my XD Tac9. No leading problems. What powder are you using?

[MtGun44]

+1 on post #5.

Bill

[bryonbush]

using win 231 at 4.5 gr. ive only shot cast in it from day one so no copper in the barrel. looking at it now and no burrs of any kind that i see and dont use FCD.

[bryonbush]

update: i switched lubes from the beeswax/LLA combo to a stick of randyrats TAC1 lube. got some mixed results. good news is the leading issue that i get is usally in the middle & towards the end of the barrel. bad news is that i got really bad leading right in the first part of it just past the chamber. from what ive read, its a case of not enough pressure building up so gasses are passing over thr bullet. aka, too light of charge for too hard of bullet. sound right?

[MtGun44]

What are the throat dimensions and boolit dimension? What alloy are you using?
What boolit design?

Bill

[Plinkster]

I've had two .40s now and the smallest groove dimension of either was .401, plus I had the case swaging the boolit down when seating. I shoot Lee's 175gr TC and it drops at .403-.402 so I shoot em unsized, I had to turn a new expander plug that works like an "M" die but floats and does powder thru. After I got that plug my leading went away, before that I had leading in the same area as you. Measure a boolit before seating then pull it and measure I bet it's smaller. As Gear made reference to .40 brass is tough and it will swage a boolit pretty well. That's my .02

[bryonbush]

I'm running the NOE .403 180 gr sized to .402 using a wheel weight alloy that is water dropped. I did change my charge from 5 grains of win 231 to about 4.2 to see if I was running them too fast. I have yet to slug this barrel but the location of the leading was not where it usually is. I'm not using any crimp, just the bullet seating die that removes the belling of the case.

[akraven]

Throw your .40 caliber Lee Factory Crimp die in the garbage.

Is there a general dislike of all Lee Factory crimp dies or specifically the .40?

[RetAFSF]

The only problem I ever had with leading the barrel was back in the 70's, the factory lead was soft even when shooting light loads. I use cast lead in my M&P 40 and dont have leading issues, but don't use max spec loads and replaced the Orginal spring with a lighter one.

[475/480]

I am surprised .402" works . ALL 3 of my 10MM's like cast boolits sized - .401" .


Sean

[Plinkster]

General dislike of all Lee pistol factory crimp dies, the post sizing carbide ring inside can swage down the boolit through the case and cause undersized boolits. Most consider it a solution looking for a problem as I do. On the other hand Lee's rifle factory crimp dies that use a collet the crimp the case are excellent and I wish were made in all firearm calibers. In fact I think we should campaign Lee to add Ranchdog's lineup to their catalog.

[akraven]

Any advantage to the RCBS or other brands of taper crimp dies or don't bother with any of them? I am thinking of bullet setback in hotter loads if you don't have some for of crimp.

[Plinkster]

The .40 headspaces on the case mouth and therefore does not allow for a heavy crimp like a revolver would. If it gets crimped too much there is no rim to stop forward progress and the round will move too far forward for reliable primer strikes and could cause dangerous high pressure situations. With the .40 as with the .45 a slight taper crimp is all that's needed and the cartridge relies on neck tension to combat setback. This is another reason to make sure that your case is not swaging down the boolit as this will reduce your case tension and could contribute to setback problems. As far as the brand die pretty much all taper crimp dies are created equally and it comes down to budget and preference as to what you want to use. Lee added some extra horse biscuit to their pistol factory crimp die in the form of an extra ring that sizes the outside of the case after the boolit has been seated and this is what can cause issues. Lee's regular taper crimp die is fine though. Hope I shed some light.