smith and wesson m&p 45acp barrel issue

[Strtspdlx]

i dont know if I should call it an issue just yet, ive been trying to load for my M&P for awhile. for some reason it seems as though all the published load data ends up being too long in oal and I usually have to shorten the oal by between .035-.050. Has anyone had this issue before? ive been getting some very knowledgable help from another member here I was just curious to see if anyone had run into this before. I did notice where the rifling starts there is almost no free bore. There may be about .010 before it starts a tapered ramp into the rifling which may be .030-.040 long until it hits full height. cases sized to .473 after a bullet is seated rotate fine in the chamber so I don't believe its a chamber issue but more rifling.

[35remington]

Very common. I have it in some of my pistols. Actually, "had" is a more correct term. If the gun doesn't tolerate any length of full caliber bearing surface outside the case I consider it something of a flaw.

If the gun shoots well, does not lead and is reliable, then you don't have a problem. If it doesn't, you do.

Due to greater seating depth versus manual specs you should reduce your loads slightly. Fifty thou is a lot....in that case, you need to reduce your load by more than slightly.

[gnostic]

If your handloads work in the magazine and drop into the chamber, why does it matter? There's always some fine tuning involved with getting it just right...

[DougGuy]

You would be much better served by having that barrel throated, then you don't have to compromise published load data which btw, is a poor workaround to the original problem. Auto pistol barrels respond very well to a lengthened freebore and a gentle leade in to the rifling instead of the non existent throat from the factory, and they shoot lights out after throating.

[Strtspdlx]

So what are my options. Send the barrel out and have someone machine it. Or can I buy a barrel that is already setup correctly from an aftermarket manufacturer. I really wish I still had my lathe right about now.

[w5pv]

Doug Guy knows his business send it to him

[DougGuy]

You can buy an aftermarket barrel, I think Lone Wolf will throat it for you but unless you get it throated for .452" cast boolits and at LEAST .100" or more .4525" freebore, you are back where you are now. I usually give .200" or more freebore so you can seat out long as you want. Longer throats work great with autoloaders.

Here is a Sprinigfield .45 ACP barrel stock unmodified on left, after throating on right. It will plunk anything that will cycle through the magazine.

http://i1202.photobucket.com/albums/bb374/DougGuy/Cylinder%20Services/Both1_zps194dd462.jpg (http://s1202.photobucket.com/user/DougGuy/media/Cylinder%20Services/Both1_zps194dd462.jpg.html)

Something like this is what you will need for shooting cast, even if you get an aftermarket barrel most still need throat work for best results with .452" boolits.

The M&P barrel is salt bath hardened and believe me it's tough. Cannot be throated or machined with HSS tooling. I had some coated carbide reamers made to my own specs for these hardened barrels. VERY expensive tooling required for these.

[35remington]

Let it be said....there is no point in planning for an overall length for your cartridge of over 1.275" as that is the maximum that will fit in the magazine box. So there is a limit on how far out you can seat a bullet or your gun won't feed automatically......and that is the point, isn't it?

Even short SWC's can't be altered greatly from standard OAL's as that changes the way they feed from the magazine. Which means the gun starts to jam instead of working correctly. Don't get carried away on OAL's just because you've been on the short side, as long OAL's are just as bad, if not worse.

[DougGuy]

Don't get carried away on OAL's just because you've been on the short side, as long OAL's are just as bad, if not worse.

Not necessarily so. Some of the Glock guys send their KKM barrels with dummies seated well out of the case mouth as this is the COA they want to seat out long and then load to .45 Super ballistics and it works pretty good. I also have one guy that sent both his .40 and 10mm Lone Wolf barrels and asked me to throat the .40 barrel so he could use .40 brass but load to 10mm COA and his worked out pretty good.

[35remington]

DG, I have yet to see an autoloader that could feed a round that did not fit in the magazine. The admonition not to get carried away with OAL as it has its limits is quite factual when we're talking about a 45 ACP, as here. 1.275" is it.

It's not a 40/10mm issue. The 45 Super has the same max OAL is the 45 ACP, so that's not relevant either. Converting a magazine that is limited to 1.275" to any longer OAL ain't gonna happen.

[DougGuy]

DG, I have yet to see an autoloader that could feed a round that did not fit in the magazine. The admonition not to get carried away with OAL as it has its limits is quite factual when we're talking about a 45 ACP, as here. 1.275" is it.

It's not a 40/10mm issue. The 45 Super has the same max OAL is the 45 ACP, so that's not relevant either. Converting a magazine that is limited to 1.275" to any longer OAL ain't gonna happen.


Agreed.. I went back and looked at the dummies the customer sent with that KKM barrel, and they were 1.260" I thought they were longer.

Still, there is a LOT of boolit sticking out in front of the case mouth...

http://i1202.photobucket.com/albums/bb374/DougGuy/Cylinder%20Services/Glock%20Throating/KKM%20Glock%2021%20for%2045%20Super/DSC03645smaller_zpsh9zvodwz.jpg (http://s1202.photobucket.com/user/DougGuy/media/Cylinder%20Services/Glock%20Throating/KKM%20Glock%2021%20for%2045%20Super/DSC03645smaller_zpsh9zvodwz.jpg.html)

[35remington]

Yep, sure is, compared to how it is normally seated, which is more in the 1.200-1.220" vicinity.

[gwpercle]

Forget OAL dimensions , the bullet has to be seated deep enough to chamber in your gun.
Short throated chambers mean you might not get to a published OAL before the boolit hits the rifling. Three ways to cure this, 1.) seat the bullet deeper or , 2.) ream the barrel to have more throat . or 3.) change the bullet to a different profile. The Lyman 452460 200 grain design works well for short throats.
Always more than one way to skin the short throated cat !
Gary

[zomby woof]

My M&P 45 likes the LEE TC230. Loves WST. Mine is very accurate. Do the plunk test.