My M&P .40 can chamber ANY OAL! (?) Reloader weird stuff.

[TommyH]

Hi everyone, new here. Ive had my M&P for about 6 months now. Ran a few thousand thought it flawlessly. Ran into an issue recently. Well, sort of an issue.

I can chamber and shoot ANY OAL. I reload and noticed that no matter what, the rounds load and shoot. I stick to 1.125, but ive done some 1.135's just to see. They all ran fine.

I found this curious so I loaded some deprimed (but sized) bullets to 1.28x inch. These are so huge they wont fit in mags. However, they'll drop right in perfectly into the barrel.

I loaded one up live to about 1.18. Slid smoothly into the barrel and it shot fine. This is beyond out of spec and should cause interference, and the slide should not close... correct?

Ive read a ton about reloading, and im seeing people with very marginal OAL differences have major problems. A bit over and the bullet hits the lands and wont chamber. Mine will unconditionally chamber!

My father reloads 9 in a glock (aftermarket barrel) and had to fine tune his OAL to get them to run properly. Not mine.

Is my barrel out of spec? It shoots fine. Great actually (I shoot 2 inch targets at 7 or 10 yards weekly, 9/10 hits).

Curious what other reloaders have seen with factory barrels in terms of OAL.

 

[robkarrob]

My hollow point 40 ammo is 1.105 LOA and my target FMJ ammo is 1.130, and both run perfect. I don't hand load, so I can't control LOA, but have never had an issue in my Shield 40. Your getting a 1.280 in seems surprising. That close to 3/16 inch extra clearance, from short OAL cartridges, at the end of the chamber. I would think that could cause accuracy issues.

Bob

 

[x10x10]

If you were using a bullet with a lot of taper it sure will give you plenty of room, if you were shooting a Semi Wad cutter you may find your self jamming rounds into the throaght pretty quick, I don't have the dimensions but most firearms now are made with plenty of "freebore" or bullet jump depends on you nomiclature.

Too deep and you could run into pressure problems and loading the bullet to the right depth will give your taper crimp dies good purchase on the side of the bullet for a good strong round that won't push the bullet back when something does go wrong

 

[OKFC05]

the slide should not close... correct?

Not really.
The cartridge headspaces off the mouth of the case.
Depending on the ogive (taper) of the bullet, you can extend it out until it touches the rifling, which can be quire a way with a secant ogive (long skinny nosed) bullet.
Using something blunt like a SWC is more likely to drive the bullet into the rifling before it locks closed.
You should see the long-throated barrels on a competition .40 STI.

 

[TommyH]

^ I agree... but so many people hit that length before hitting the max length of 1.135. I can load bullets until they're falling out of the brass and they chamber! Ive seen people talk about reloading below 1.125 because it hits the rifiling. Mine loads them like nothing.

Im using missouri 180gr TC's. Its not really a narrow bullet by any means. Also, when seated to a more proper 1.125, the taper of the bullet is pretty close to the brass. When loaded to a silly 1.28, the taper starts pretty far out! Its a lot of flat straight lead from the brass. If you've loaded lead, this means the wax ring is outside of the brass.