Hey Guys

I called Smith and Wesson Tech support to see if the 2.0 Performance had a match barrel, they told me it is exactly the same dimensions as the standard MP 2.0 compact.

I am using Bayou polymer coated 145gr FMJ and what is strange, the chamber seems shorter than many other pistol brands If I load the OAL, anything longer than a 1.075 will result with the bullet rubbing up against the lands and grooves, thus it causes gun to not go into full battery or if it does go all the way i get light primer strikes.

Now my Sig X5 Legion, you can literally load the OAL to 1.160 and it will not rub against the rifling. I was thinking maybe my Performance barrel is defective but then again my 2.0 Compact version it is exactly the same. Factory loads work perfect never had any issues.

What worries me is the seating depth is so deep, I am wondering if I can be overpressure. your thoughts

I assume they are round nose? Unless you want to measure to the ogive just switch Bullets to a TC vs RN. I have loaded for all sorts of M&p barrels and never had that issue with my blue Bullets or DG Bullets. I load blue 147s RNs to 1.16 OAL with no issue right now for my X5 and M&Ps FWIW.

I am using Round nose 145gr bayou bullets and at 1.160 it spins freely in the ker plunk test in the X5 Legion but for MP 2.0 in both compact and 5" will not work. The load touches the land and grooves

Chamber spec's can be different even if from the same day and lot,
due to die wear and even human error.

One reason that I find the "Safe" minimum and maximum OAL
for any new bullet that I may be using, for any weapon........

before I start to reach for any powder.

Stay safe.

If you just seat deeper a load that works in another pistol - sure it could be over pressure. That's why we have the adage that we do: Start low and work up.

It seems to me if you want to have one load for multiple pistols then the load workup needs to happen using the pistol requiring the shortest OAL. And doing that that load might not work well in all pistols.

I have a PPQ with an incredibly short chamber. I also have a Hi Power that seems to have freebore the size of Texas. It goes on and on and on. What load works optimally in each pistol is not the same load.

The X5 Legion has a very long chamber I guess compared to the others. After seating my polymer 145 round nose at 1.075 OAL(book calls for 1.058 but that is for 147gr), it cycled fine no more issues except the CCI primers are lousy and horrible. Every other round it would be a light primer strike

Apparently your M&Ps have short leades (not chambers) which is why it's always good to do a "plunk test" when your start loading a new bullet & to be aware of differences in your pistols.

All my 3rd Gens have generous leades & 1.160" is what I load my 9mm 125gr JHPs to for Major loads but bullet shape does make a difference. Can't load Speers 125gr TMJ that long because they are RNFPs.

My Colt Mk.IV, Series 70 has a very short leade & I load ammo just for it to a shorter COAL".

Your only choice, short of having the chambers reamed to lengthen their leade, is to seat them deep enough to pass the plunk test, & reduce the load if you have to go too much shorter, or change to a bullet with a different profile.

.

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Waiting for the break of day

Forst, Bayou are NOT fmj. So you load them like a lead bullet.
2nd, OAL is always gun & bullet specific. So you have to match the oal to each gun, regardless of data.
Yes, seating deeper increases pressures but so does jambing the bullet into the rifling. If your loads are midrange or below, not a huge issue, but yes you need to drop powder charge a bit if seating deeper.

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NRA Cert. Inst. IDPA CSO

Lot of different bullet designs out there which can cause problems with the OAL of a load and also the minimum OAL that can cause high pressures with certain bullets.

There is a huge difference in pressures with these two 147 gr bullets due to their over all lengths and designs when loading with different powders

Stay safe.