Unimpressed with the accuracy for this load. Berry's 115 grain, Plated Bullets over 4.4 grains of Titegroup. The OAL is 1.135. CCI primers. Accuracy was worse than 115 grain WWB at 25 yards. The gun is a fairly new M&P9. Any suggestions?

Also, what is the shortest OAL I can get away with the following load? 124 grain Berrys Plated HP, over 4.0 grains of Titegroup? The OAL is 1.095. The bullets contact the rifling, before the round is fully seated.

First thing to do is do a 'plunk' test with your 115gr loads at 1.135". Remove your barrel from the gun. I'm guessing that they will easily fall into the barrrel when you drop them in, they will make a nice plunk sound, and when you turn the barrel over, they will easily fall out. If that doesn't happen, you've got a minot problem with your loading process. I run the 115gr Berry's RN, but run them closer to 1.145" which matches what I've measured for 115gr RN factory rounds from Federal and WWB. Try running your Berry's up at 1.145 if they pass the plunk test in your barrel and feed from your magazine. The shorter distance from the tip of the bullet to the rifling could improve your accuracy. By the way, are you removing the flare that you added to the case during the expansion process? For me, 4.0gr Titegroup worked best with the Berry's 115gr RN.

For your 124gr loads, your barrel is already telling you that 1.095" is too long. Reduce it to 1.075 and see if they chamber properly. If so, consider this the max COL for this bullet in your gun.

__________________
S&W15-22 RIA 1911
CZ75B SR9

I'll seat the next "test" batch of 115 grain, Berry plated bullets, at the longer suggested OAL. Also, the reduced charge of.4.0 grains of Titegroup. I feel pretty good about "removing the flair". But, something is wrong.

The second question about the 124 grain HPs, concerns the increase in pressure when seating the bullet deeper. Just how far can I go?

You can't load the TCHP much longer in most guns, the shoulder hits the rilfing. Are you over crimping? Worst thing to do w/ a plated bullet is over crimp. It breaks the plating & it strips off going down the bore & as it leaves the muzzle, accuracy goes to hell. Pull a bullet, check the dia, it should still be 0.355"-0.356". Are you using the LFCD? I found it devistates accuracy w/ plated bullets by resizing in the case. Toss it, use the crimp ring in the seating die instead.

Measure the length of just the 115 grain bullet. Let's say for discussions sake it measure 0.546". A typical completed 115gr RN round measures 1.150", and a typical piece of 9mm brass is 0.754" long. Based on these dimension, the total amount of bullet actually seated inside the brass is (0.754 - (1.15 - 0.546)) = 0.15"

Now measure your 124gr HP bullet length. I'm guessing that it may be shorter than your 115RN, but maybe not. If you seat your 124HP to the same total cartridge length (COL) as your 115gr rounds, your actual length of bullet inserted in the brass will be equal to or less than the inserted length of the 115gr round. If your 124gr HP is shorter, you can insert to an amount equal to the difference in length, and the amount of the bullet inserted in the case will be the same as the 115gr round. It will not be seated deeper.

So, if you have to seat your 124gr HP deeper than the difference in bullet length because of the plunk test, decrease the powder charge slightly and work up to the velocity (or recail pulse) you're looking for.

Oh, fredj338 is spot on, if you are overcrimping and breaking the plating, your accuracy will be non-existent. Seat and crimp a dummy round based on your current die settings. Remove the bullet from the dummy round and check for bullet indentations where it meets the top of the case. There shouldn't be more than a faint hint of a mark on the bullet. More than this and your crimp is too much. A separate taper crimp die would be preferable to the factory crimp die.

__________________
S&W15-22 RIA 1911
CZ75B SR9