Working up a 9mm load

B

BondoBob

New member
I made my first batch of 9mm rounds and test fired the starting load yesterday. They seemed to work ok. Cycled the gun ok, one FTE out of 50 rounds. But I noticed the slide did not lock back as usual when the mag was empty. I figure this is too light a load.

Hodgdon and Speer data I'm using is 124gr FMJ, universal powder 3.8 - 4.4 gr (33,500PSI), 904-1045 FPS. Given the starting load is a bit weak. I've worked up loads 1/10th gr apart to 4.4

My question is, should I just stop firing as soon as the slide starts locking back? Or, should I continue and fire all of them, just to see what happens? Being a bit new, I don't want to push things unnecessarily. I think the MP Shield 2 9 is not rated for +P so not as much cushion.
 
Lacking a chronograph, I would standardize when I got to reliable slide stop operation.
But the maximum load is not going to hurt your gun, no reason not to use them up.
 
Well, you always want to keep an eye peeled for pressure signs as you work up, but the lackluster performance of the first round is probably a good clue that the maximum will not be an issue. Most of the short barrel guns have relatively stiff recoil springs. It is not uncommon for them to fail to function with reduced loads, so I would weigh the charges and work up a couple of steps above the first properly functioning round. Otherwise, normal powder measure throw variation may cause a reliability issue. But test it to see.

If your gun has less than 500 full-power loads through it, it may not yet be broken in, reliability-wise.
 
The other thing to consider is that grip can affect lock back in some guns. When I was working up loads for my boys G17, loads would lock back good for me with less powder than for him.

Stopping right at the first load that locks back during your initial testing may run into failure to lock back in different situations. Going a little past first lock back (as has previously been mentioned) is a good idea.
 
Here is how I work up a handgun load. I will use your info as an example.

5-3.8
5-4.0
5-4.2
5-4.4

Start at 3.8. shoot 1, check ejection, flattened primes, if it looks ok, shoot the next 4. It should eject cleanly and lock back.
repeat until you get done with max, or you see pressure signs you don't like (flattened primers, throwing casing an 10ft for example)

Once I have worked up to max and know it is safe I can play around below that to shoot the way I want.

For example. I am currently using Power Pistol with 125g cast lead for 9mm. I ran from 6-6.6 as recommended by lee. at 6.6 I got 1 flattened primer and I was throwing casings and extra 2ft. 6.4 was ok and I use that as my personal max for the load. 1233fps average. I also worked down further to 5.4, and found that 5.4 was consistently subsonic with an average of 1105fps with clean ejection.

Also unless a book says its +P its not. Your fine to load to max, its personal preference on how you want your loads to be. +p would be above the max in the book.

On a side note, I would check 2 things. How old are your mags, are you keeping your finger off the slide stop. I have had issues with a new gun where I keep hitting the slide stop and it will drop on the last shot, or lock open during firing. If the mag spring is worn it may not be pushing the rounds up fast enough.

How far are the cases ejecting? I tried a new powder the other day, at the starting load it dropped the casing as my feet, but it did lock open. I went up 0.4g total until it started ejecting normally and was fine all the way up to max, although I was about 100fps lower that I was hoping for.
 
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