9mm Montana Gold Bullets Question

[mr-mom]

I have been reloading for my 9mm Sig, H&K and Glock semi-automatics, using Hornady 115 gr. FMJ-RN-ENC bullets (bullet length 0.548”). My pet load is 4.4 gr. of Alliant Bullseye powder with a COL of 1.100”, light taper crimp. Would this be an appropriate powder charge and COL using your 115 gr. CMJ bullets (bullet length 0.568”)?

I would appreciate input from those of you familiar with and using MG bullets.
mr-mom

 

[rfwobbly]

Mom -

The 9x19 is a high pressure cartridge and nothing to be taken lightly. You are right to ask questions.

• While it is generally correct that you can substitute one 115gr jacketed bullet for another 115gr jacketed bullet, in this case the second bullet is almost .020" longer. This means it will seat deeper at the same OAL, thus raising the chamber pressure. Raise by exactly how much is a guess. Thus....

• It is accepted safety practice to start again at the starting load and work your way up to be sure you do not have more chamber pressure than you planned. This is the only true safe way to load with a new bullet.

• However, seeing as how it's the position of the bullet's base that has one of the largest affects on pressure, if you were sure that the stated load was very far down the load range (sorry I'm not looking at a book to confirm) then you might simply try seating the bullet with +.020" on the OAL (iow 1.120" in place of 1.100"). But they would need to be tested for proper chambering using some "test cartridges" built-up using no powder and no primer.



The above graphic explains why you want to think in terms of seating depth, and not OAL. I think you intuitively sensed that, and that's very astute of you. Of course, seating depth cannot be directly measured, so we simply throw around the term "OAL" like it was magic. However, you have the opposite issue shown in the graphic. Your new bullet will be deeper than your previous reloading efforts.

In "all things reloading" try to err toward safety.

 

[918v]

Somebody could QuickLoad that combo for you to estimate the difference in pressure. Unfortunately, my copy won't load into Windows 7

 

[GLOOB]

That seems short for an FMJ/RN bullet, anyways. Assuming both bullets are flat base, why not seat the MG FMJ a couple hundredths longer (the difference in bullet length) and see if it feeds?

I use the MG 124gr HP. They have a sharp shoulder, so I have to seat them a bit shorter to feed. But the FMJ will probably feed in your listed guns all the way out to 1.169".

 

[larryf1952]

That seems short for an FMJ/RN bullet, anyways. Assuming both bullets are flat base, why not seat the MG FMJ a couple hundredths longer (the difference in bullet length) and see if it feeds?

I use the MG 124gr HP. They have a sharp shoulder, so I have to seat them a bit shorter to feed. But the FMJ will probably feed in your listed guns all the way out to 1.169".

This is the way that I normally handle bullets of varying lengths. I've long since established my safe operating loads and COL's, so if I run into a bullet that is a different length than one I've previously used, I measure it and adjust the OAL of the cartridge accordingly.

For instance, if I use Brand X bullet, and it is .005" longer than my normal Brand Y bullet, I add .005" to the COL, thus giving me the same seating depth and case volume as the Brand Y bullet. Conversely, if it is shorter by that amount, I make the COL .005" shorter than the Brand Y bullet. As long as my COL falls within spec for the cartridge, I try it in my guns and see if it'll feed and function OK. By doing things this way, I can be assured that my pressure levels and velocities will remain constant with bullets of the same weight.

So far, so good.

BTW...RFWobbly, that is an EXCELLENT illustration! Very well done!

 

[918v]

.568" is not short for a 115gr FMJ.

 

[GLOOB]

I was referring to the OAL of 1.10". I've never used factory luger FMJ seated that short.

 

[mr-mom]

Thanks for sharing your thoughts fellows. I added 0.020"
to the OAL. They seem to feed and shoot OK, very similar
to my Hornady loads. By the way, the COL of 1.100" using
115 gr Hornady FMJ's is directly from Hornady's 7th edition
manual.
Stay safe, shoot straight and have fun!
mr-mom

 

[rfwobbly]

By the way, the COL of 1.100" using 115 gr Hornady FMJ's is directly from Hornady's 7th edition manual.

What that means then is that you can safely use any OAL between 1.100" and the longest the barrel will accept. They are simply reporting what they used in their test. They are in no way suggesting that 1.100" OAL contains some kind of magic, or must be strictly adhered to at all costs.

It's like when the diaper box says "up to 16 pounds". You can go ahead and change the diaper after the first poop. You don't need to wait until the diaper weighs 16 pounds.

All the best!