9mm xtreme TMJ RN OAL / bullet deforming

[Seamastersw]

I'm pretty new to reloading 9mm and just started using the xtreme 124gr TMJ rn bullets at an OAL of 1.165". The max OAL my Lyman book says is 1.169" and I saw Brian Enos recommends as longer OAL for reliability on his Lenny McGill video. When I load two rounds in a mag in my Glock 26, and fire one to let the gun chamber the next round, the bullet point gets damaged. It appears during the chamfering process the bullets strikes the bottom edge of the feed ramp, deforms, then gets directed into the chamber. I reduced my OAL to 1.165" and still have the damage occurring although to a lesser extent. My Glock 26 is a new Gen 4 model with a test fire date of March 2015.

My load was:

Mostly Speer lawman brass

Xtreme 124gr TMJ round nose bullet

CCI 500 small pistol primer

5.8 and 6.0 grains of power pistol powder.

What OAL do you guys recommend, powder charge ectera? I'm going to make a batch at 1.145" at 5.2grains of power pistol. And see if that does anything.

[JPetrowski]

I'm running 1.150 out of my glock 34 and it seems to like it. I haven't noticed any issues. I think the 1.145 should run fine.

[noylj]

COL should be as long as possible--given 100% feed and chamber reliability.

In most cases, if the round jams against the feed ramp, the COL is too long.

If the round jumps up and jams at the top of the barrel, the COL is too short.

Per Ramshot:

"SPECIAL NOTE ON CARTRIDGE OVERALL LENGTH “COL”

It is important to note that the SAAMI “COL” values are for the firearms and ammunition manufacturers industry and must be seen as a guideline only.

The individual reloader is free to adjust this dimension to suit their particular firearm-component-weapon combination.

This parameter is determined by various dimensions such as

1) magazine length (space),

2) freebore-lead dimensions of

the barrel,

3) ogive or profile of the projectile and

4) position of cannelure or crimp groove.

• Always begin loading at the minimum "Start Load".

• Increase in 2% increments towards the Maximum Load.

• Watch for signs of excessive pressure.

• Never exceed the Maximum Load."

Your COL (OAL) is determined by your barrel (chamber and throat dimensions) and your gun (feed ramp) and your magazine (COL that fits magazine and when the magazine lips release the round for feeding) and the PARTICULAR bullet you are using. What worked in a pressure barrel or the lab's gun or in my gun has very little to do with what will work best in your gun.

Take the barrel out of the gun. Create two inert dummy rounds (no powder or primer) at max COL and remove enough case mouth flare for rounds to chamber (you can determine this by using an empty sized case, expand and flare, and remove the flare just until the case "plunks" in the barrel).

Drop the inert rounds in and decrease the COL until they chamber completely. This will be your "max" effective COL. I prefer to have the case head flush with the barrel hood.

You can also do this for any chambering problems you have. Remove the barrel and drop rounds in until you find one that won't chamber. Take that round and "paint" the bullet and case black with Magic Marker or other marker. Drop round in barrel (or gage) and rotate it back-and-forth.

Remove and inspect the round:

1) scratches on bullet--COL is too long

2) scratches on edge of the case mouth--insufficient crimp

3) scratches just below the case mouth--too much crimp, you're crushing the case

4) scratches on case at base of bullet--bullet seated crooked due to insufficient case expansion (not case mouth flare) or improper seating stem fit

5) scratches on case just above extractor groove--case bulge not removed during sizing. May need a bulge buster.

[Garmil]

I like to drop a bullet in a fired case then push the case in until it bottoms out and gently pull out and measure then subtract a few thousands for you length. Much less trial and error.

[Hi-Power Jack]

noylj, nice post - new info for me.

[RandyLahey]

yeah I think with 124's which I run BTW you are too long. 1.145 will probably work, but I think I run 1.130-1.135 and my accuracy seems decent, except for an occasional flier, which I don't think is COL related but more just a bad bullet etc....