Verifying COAL 9mm PX4 Storm

[Toy4Rick]

Hey gang. I have loaded and shot 4-5k rounds through this handgun with just OK results. Seem to get the occasional flyer and not sure if it's the load, the gun or me. Most groups at 10 yds are 3-4" with one out of 10 that might be 6-7"

Same load from a 92 FS gives me tighter groups with fewer flyers

Looking for good target loads with good accuracy, no chrono, no competitions...

Std PX4 storm 9mm
MG 124 gr RN
3.9-4.2 grns Titegroup (tried 3.6 up to 4.4 with no better results)
OAL 1.132-1.142
Tulammo SPP
Mixes brass

As I start to consider a new load using MG 124 grn JHP I wanted to verify my OAL and this is where I'm stuck

Take the barrel out of the storm. Drop in an empty sized case and it does not bottom out. You can imagine what happens when I setup a dummy round. Stops short by another 1/16th of an inch and gets stuck pretty easily when I snug it in to try and set the depth.

What is the best way to check OAL in my Storm?
Originally I used an average of data that I could find and the OAL from some Federal loads on hand. Maybe 2 FTE over this many rounds, never a failure to close battery... So in general this thing runs great

What thoughts or suggestions do you have

Thanks in advance
Rick

[Jon Road King]

Quick and dirty: take a spent, sized, cleaned, unprimed case and make a cut down the center with a dremmel (then clean up any burs on the outside of the case with a small file). Then slip a bullet in the now loose case, but leave it long. Now press the case/bullet into the barrel. The lands will force the bullet into the case till the case bottoms out. Do it easy and light, don't force, then repeat 5-6 times taking measurements of the bullet/case each time.

The measurement will probably be a bit long so take .02 to .04 off then check that length and make sure it fits in the magazine. Then a light work up in 0.01 increments from the shortest measurement.

Or get a Hornady OAL gauge and do the same thing for $40

(Oh and I have that gun - love it ) (PS. My 92 always shoots tighter than my storm too - shorter barrel, so accept it, heh)

[J-cat]

I think you missed the part where the OP said his empty sized case does NOT bottom out in his chamber.

That means he is not sizing his cases correctly.

He needs to make sure the sizer die is bottoming out against the shell holder during sizing. Otherwise everything that follows is a waste.

[Jon Road King]

I think he meant it doesnt bottom out to the rim like a 45acp does. The storm hangs out like a glock.

[J-cat]

OP,

Can you feel the case mouth bottom out against the end of the chamber?

[Toy4Rick]

Hi everyone

Thanks for the replies, The slit in the case helps a lot, thanks for the tip.

Yes, I can feel the mouth of the case bottom out now. Maybe I wasn't using a sized case the first time. Doh

I tested it with a bullet and bottomed out the case, measured it 10 times and they were all between 1.202 and 1.203. Evenly split so the average was 1.2025

That seems way long doesn't it?

Jon Road King. What did you mean by your comment to "Then a light work up in 0.01 increments from the shortest measurement". Not sure I am following

Thanks again
Rick

[Jon Road King]

Jon Road King. What did you mean by your comment to "Then a light work up in 0.01 increments from the shortest measurement". Not sure I am following

Thanks again
Rick

Load up a dummy round at 1.205 (your measured length), then make sure it fits in the magazine. If it doesn't fit, then back off .01 and keep trying till it fits. Then do 5 round strings at your pet load in the different OAL's...

(If the dummy round doesn't fit, then start at the length that does and back off .04 then work up, but if it fits, then do loads below)

1.175
1.185
1.195
1.205

Shoot 5 round groups at each OAL and see which one works best. Look for signs of pressure as usual, and feed/eject issues. (if the bullet is pressed into the lands, you will increase pressure)

Don't expect the world though. After all, it is a pistol I didn't even bother checking OAL on my pistols. If I shoot 3" at 25', I am lethal, and the only thing I care about more than that is my pistols eat every single round If you start playing with OAL, you could run into feed issues, and that's something I do not want. So find that balance of OAL and reliable feed.

Good luck!

[J-cat]

MG 124JHP cannot be loaded to 1.200" for a 9mm magazine. It's a truncated cone bullet whose nose will drag against the magazine wall if loaded too long. The correct OAL for this bullet is the same as Hornady XTP- 1.060"+ but the longest that will reliably feed is 1.140" or so.

[Toy4Rick]

So now that I have a better idea of what's going on and my brother and I reload for his 92fs as well, not to mention my son is looking to get a 9mm of his own, it will take some to to see if we can dial in a single load that will work with decent results

I also know 1.200 will not load into the mag so need to play a bit more

Question, is accuracy affected that much by COAL or just PF, speed and maybe a couple other things... Since I don't have a chrono and going longer will only reduce pressure with the same load, grouping is about all I have to go on

Thanks everyone for the help
Rick

[J-cat]

OAL affects accuracy because it affects pressure and velocity. These variables are all interrelated.

Here is a good thread about this bullet:

http://www.brianenos.com/forums/index.php?showtopic=121676