Best OAL for Montana Gold 9mm 125gr. JHP in Glock

[orygunmike]

Hello.

I've never reloaded JHP before until I recently loaded some MG 125gr. JHP.
I set the OAL at 1.09 and out of 50 rounds had about 6 FTFs ....

Can someone provide info on what you have found to be best OAL for running this bullet in a Glock?

thanks

 

[gamestalker]

There are a couple of areas you want to look at here. Your seating depth sounds like it should be fine, but lets go through this one area at a time.

First, check your primer seating depth to be sure they are all seated below the case head, about .004" is enough and less than .002" may cause FTF's. If all primers are deffinitely seated deep enough you can then move on to the next most likely cause, which is seating depth.

Take the barrel out of your firearm and drop a few of the loaded rounds by hand into the chamber, they should make a solid plunk sound when you drop them into the chamber. Another way to check is to try and spin them in the chamber by hand, they should easily turn with little resistence. Reistence or any indication that the bullets are touching the lands indicates you need to increase seating depth. However, if there is need to seat deeper don't go over board, just seat deep enough to clear the lands or pressures can jump extremely high. But in all honesty I rather doubt seating depth is going to be the culprit here, maybe, but we'll see.

The next possible cause is over crimping of the case mouth. Over crimping creates excessive head space, and being that rimless cartridges head space off the mouth, over crimping allows the the case to chamber too deep to allow for enough firing pin contact. This is one area of reloading that is commonly misconcieved when referring to rimless cartridges, as follows. The crimp used on these type cartridges is only intended to remove the mouth belling produced by the mouth expander die. Crimping more than is necessary to remove the belled mouth will reduce neck tension and creates excessive head space.

The way I've been seating jacketed bullets for 9mm and other rimless cartridges for several decades is, I chamfer the inside of the case mouth evenly and then simply seat the bullet without using any crimp what so ever. It eliminates the need for belling the case mouths, and entirely eliminates the need for crimping, thus eliminating any question about under or over crimping that can only create more grey areas of function.

Take some case mouth measurements to help identify a possible over crimping issue. The outside diameter of the case mouth should measure very close to, if not exactly the same as the bullet shank region of the case containing the seated bullet, or roughly .050" below the mouth.

GS

 

[orygunmike]

thanks you Gamestalker for the thorough post. I realize I was not clear in my OP. I meant to say, theose 6 rounds failed-to-feed .... the gun would not go into full battery.

Again, I would appreciate your thoughts on that

Thank you!

 

[ranger335v]

"Can someone provide info on what you have found to be best OAL for running this bullet in a Glock?"

In "a Glock" isn't the issue, all guns vary a bit so what you really want to know is the best OAL for that bullet in your Glock and, sadly, none of us know that. You're going to have to do what the rest of us do, experiment.

 

[rfwobbly]

9x19 Luger is a strange cartridge. There are generally 3 reasons a 9mm gun fails to go into battery:

• OAL too long for the chamber. With your short OAL (more typical would be 1.125-1.140") and a Glock chamber, I somehow think that is highly doubtful. Now since this whole answer revolves around the Glock chamber, then it could be a factor with a Lone Wolf or other target barrel. Anytime you see the term "target barrel", then you know it's going to be tight fitting chamber and more care is required in reloading.

• Improper taper crimp. On other pistols, say a 40 or 45ACP, if you have the wrong crimp, then the cartridge won't even begin to chamber. But the 9x19, owing to its tapered exterior, makes it half-way into the chamber before the errant taper fouls the chamber walls. By far, the best taper crimps are done in a separate die. Try one of these dies for great results. Click Here. You should set your crimp diameter to the range of .379 to .376 inches. More is not better.

• Expanded cases. Some range brass could have been shot in a "9 major" gun. In such cases, the base of the cartridge, just above the rim, can get blown out to .393" and larger. Since a standard sizing die doesn't re-size all the way to the rim, this error is not corrected and the cartridge will jam half-way into the chamber. This situation is easy to spot because the slight diametrical difference allows the slide to jam the gun to "impossible to fix" levels. In fact it may take the aid of a plastic hammer to remove the round.


Spotting taper crimp and expanded base issues before they enter your chamber is the job of the 'cartridge gauge'. It sounds like you could really benefit from owning one of these gauges Click Here. They really help and will save you hours of disappointment.


Hope this helps.