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

[RH45]

Yup, it's the profile. A guy gave me some Sierra's, and I loaded them to the same OAL as I do Zero's, and they wouldn't chamber in my M&P Pro. I just burned them up in my open gun.

[throttleup]

Well, you got me wondering about mine. I load S&S Casting 147 gr. lead FP's to OAL 1.130 to 1.132. I just cycled 8 rounds from the magazine through my M&P 9 Pro and happily there are no rifling marks on any of the bullets. Maybe your bullets have a longer bearing surface or maybe you do have a short chamber. Hope you figure it out because those kinds of things can drive you nuts! Bill

[Kevin G.]

twodownzero, I have been working with the coated 147 Precision FP in my M&P. I've found that anything loaded longer than about 1.125 causes buildup in the chamber shoulder and throat that prevents closing into battery. Rounds loaded 1.14 & longer fail a drop tesst in the chamber, but shorter drop in fine. I can't make sense of the buildup. I can only guess that the shoulder of the bullet is far enough forward that it is hitting the chamber shoulder and scraping off the coating while chambering. The chamber seems loose enough for that to happen, but I can only guess.

All that to suggest; using these bullets loaded long, even after reaming the throat may cause issues resulting from the bullet's profile.

I can't claim any of this is fact. I'm only speaking based on my limited experience and assumptions.

[twodownzero]

Well it remains to be seen if these bullets will run in my Spartan 1911 at all. The ramp has a pretty big ridge between the frame and barrel, which creates the perfect place for the flat point to ram right into it and stop.

[The_Vigilante]

Just curious, have you contacted S&W about your problem yet? What do they say?

[twodownzero]

Just curious, have you contacted S&W about your problem yet? What do they say?

No, I haven't. Before I modify my M&P, I want to make sure that these bullets will run in my 1911 at 1.150" (it appears that they might, but once these are gone, I'm switching to RNs).

[waktasz]

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.

Same exact problem. At the same OAL as my FMJ loads the TC bullets jammed up the gun.