Has anyone cut their chamber (leade/throat) longer?

[twodownzero]

My M&P has a pretty short chamber and will only accept ammo loaded in the 1.120" range. Has anyone had their barrel reamed out to take slightly longer ammo?

Edited December 26, 2010 by twodownzero

[Pat Miles]

Don't know about reaming the M&P chamber deeper but you might see what OAL round will fit in the magazine. That may be the controlling factor.

Pat

[twodownzero]

Don't know about reaming the M&P chamber deeper but you might see what OAL round will fit in the magazine. That may be the controlling factor.

Pat

No, by far the controlling factor is the rifling, which my 147 FPs will hit if I load longer than about 1.120"

[Joe4d]

Probably easier to find a different bullet.

[twodownzero]

Probably easier to find a different bullet.

I don't disagree with that, but I'm not sure that I have a lot to lose by reaming my chamber a bit deeper. I've been very happy with the way a 147 grain flat point has worked for me for a long time.

I recently got a 9mm 1911 and it won't feed the 147s at 1.120", but it will if loaded longer. Rather than have two loads, I'm trying to consider the possibility that a minor ream job might allow me to use the longer ammo in both guns. They'll definitely fit in the mag (SAAMI max for 9mm is 1.169").

Edited December 26, 2010 by twodownzero

[mike cyrwus]

the chamber and throat on M&Ps are deep enough to take most anything that can operate in the mags.

[twodownzero]

the chamber and throat on M&Ps are deep enough to take most anything that can operate in the mags.

Mine isn't, and that's why I'm wondering if mine is an outlier, or if this is common with the M&P 9.

[kend]

Most of the time it's just nitpicking but in this particular case terminology means everything. If you cut the chamber deeper you will create headaches and wind up with a gun that won't fire due to excessive headspace, to use longer ammo you need to deepen the THROAT and not the chamber.

[Joe4d]

I reamed my singlestack .40 for the same reason, so all my .40s could use the same ammo, it's pretty simple operation, all you need is a small vice to hold the barrel and a hand reamer,,as kend pointed out you are looking for a THROAT reamer not a chamber reamer, I rented my reamer if it is gonna pretty much gonna be a one time deal, I used 4d products (no relation) but there websight is down, check all the easy stuff first, make sure the chamber and throat are clean, you may only need a minor polish job.

[twodownzero]

I reamed my singlestack .40 for the same reason, so all my .40s could use the same ammo, it's pretty simple operation, all you need is a small vice to hold the barrel and a hand reamer,,as kend pointed out you are looking for a THROAT reamer not a chamber reamer, I rented my reamer if it is gonna pretty much gonna be a one time deal, I used 4d products (no relation) but there websight is down, check all the easy stuff first, make sure the chamber and throat are clean, you may only need a minor polish job.

Yes I was aware that a chamber reamer would cut the shoulder forward (which I don't want to do). Rental would be great!

I started this thread in the M&P forum wondering if anyone else's "throat" is as short as mine. I'm not even sure that "throat" is the correct term--I've always called it the "leade" but that may be incorrect also. Either way, we're talking about the space forward of the chamber shoulder where the rifling begins...same thing.

I do have one local friend who shoots an M&P 9L and a 9mm 2011. He uses longer ammo in his 2011 and he agrees with me that it sucks to have two loads for the same caliber.

Edited December 26, 2010 by twodownzero

[tunakilla]

Throat or leade should be cut to run the bullet profile you want.

[kend]

I'm not even sure that "throat" is the correct term--I've always called it the "leade" but that may be incorrect also. Either way, we're talking about the space forward of the chamber shoulder where the rifling begins...same thing.

You are correct, it is the same thing. I would recommend 4-D as well, good folks to deal with.

[twodownzero]

I do wonder if the rest of you out there in M&P land also have barrels with such a short leade. I know the 147 FP is pretty big/long, but I'd imagine that a 125 grain JHP loaded to 1.160" would smack the rifling, too.

It seems unnecessary for a pistol's leade/throat to be that short.

G-manbart is checking his factory barrel for me to see how long it will accept. I know mine is pretty darn short. In fact, the M&P is the only gun I've ever owned that will fit ammo in the magazine that won't fit in the chamber. My STI .40 will chamber ammo even longer than its magazine.

[kend]

My L has run 95, 115, 124, 125 and 147 with no problems, I didn't check to see how long I could load it but the limiting factor was the magazine.

[eisenhow]

the chamber and throat on M&Ps are deep enough to take most anything that can operate in the mags.

Mine isn't, and that's why I'm wondering if mine is an outlier, or if this is common with the M&P 9.

I've had issues with 125gr truncated cone precision bullets. At "normal" lengths they engage the rifling. If I load them short they work fine. I was contemplating a single stack STI 9mm and was wondering if I would have the same issues that you are experiencing. The thought of having my M&P reamed has crossed my mind.

[twodownzero]

the chamber and throat on M&Ps are deep enough to take most anything that can operate in the mags.

Mine isn't, and that's why I'm wondering if mine is an outlier, or if this is common with the M&P 9.

I've had issues with 125gr truncated cone precision bullets. At "normal" lengths they engage the rifling. If I load them short they work fine. I was contemplating a single stack STI 9mm and was wondering if I would have the same issues that you are experiencing. The thought of having my M&P reamed has crossed my mind.

A round nose bullet will probably feed at any length, but the flat points nose dive at 1.120" and crash into the ramp and stop. at 1.150", though, they appear to hit the ramp higher and go straight in (on the 1911). I don't have any round nose bullets to try, but my gun will hand feed 125 Zero JHPs at 1.140". I could try shortening them and see if anything changes.

The M&P will feed anything, it just can't chamber ammo that is longer than about the length I'm loading them at now. I had a bunch hit the rifling at 1.135" and shortened them back to 1.120" about two years ago and have had no problems since.

Edited December 26, 2010 by twodownzero

[CocoBolo]

I just opened the throat on one of my Major 9 guns. I have 3 but #3 wouldn't take the ammo I load for the other two, so it got deep throated. I just ordered up a throating reamer from Manson chucked it into a vise and then took the barrel in vise grips set it down on the reamer and gave it a couple turns checked it with a drop in round and after a couple times it was all good. For 9 mm the reamer is a .35 and costs $40 from Manson. Brownells has the clymer for $35.00.

[G-ManBart]

My factory M&P Pro barrel would chamber dummy rounds set at 1.70" with Montana Gold 147gr CMJ, Precision Delta 147gr FMJ/TC, and Zero 147gr JHPs (those were actually 1.180"). They all dropped right in, and it was obvious the bullet wasn't making contact with anything. R,

[twodownzero]

My factory M&P Pro barrel would chamber dummy rounds set at 1.70" with Montana Gold 147gr CMJ, Precision Delta 147gr FMJ/TC, and Zero 147gr JHPs (those were actually 1.180"). They all dropped right in, and it was obvious the bullet wasn't making contact with anything. R,

Thanks G-man.

That really makes me wonder why mine is so short. It could be the bullet profile I'm using, though. I don't have any MG 147s to compare, but I figured they might be sufficiently similar to get in the ballpark.

Edited December 27, 2010 by twodownzero

[G-ManBart]

Just checked some Zero 125gr JHPs and they make light contact at 1.170". At 1.165" they drop in just fine.

Hard to say why the difference...wear on the finish reamer, different production runs...who knows. R,

[twodownzero]

Just checked some Zero 125gr JHPs and they make light contact at 1.170". At 1.165" they drop in just fine.

Hard to say why the difference...wear on the finish reamer, different production runs...who knows. R,

I just wanted to make sure that my barrel was atypical.

.050" is quite a bit.

[jar]

It's all about the bullet profile. Mine won't take 147FPs (precision) longer than 1.125ish IIRC. My notes are at home and I'm at the parents for the holiday weekend. Round noses out to max mag length are fine.

[G-ManBart]

Just checked some Zero 125gr JHPs and they make light contact at 1.170". At 1.165" they drop in just fine.

Hard to say why the difference...wear on the finish reamer, different production runs...who knows. R,

I just wanted to make sure that my barrel was atypical.

.050" is quite a bit.

The other possibility is that mine is the oddball. I've seen other folks post issues with slightly longer OALs as well (like 1.130+). R,

[BMartens]

I've load 147 grain lead CFP, plated RN, molly FP and MG CMJ all out to 1.170 for my M&P with no problems at all. Box stock barrel in a standard M&P.

I agree with Jar, I think the profile is what's causing your issues.

[Cosmik de Bris]

I had a similar problem with my 9, I loaded some 124 truncated cone bullets as long as they would go in a mag. I then loaded some lead with a slightly different ogive and they jammed in the rifling.