G34 recoil problems

[Boolit_Head]

Open guns have to be tuned to the load. You find a load you want to run then get the gun to run it by changing comps or recoil spring rates to get the gun to shoot flat. If you change the load you have to do it all over again.

In this case for the load there is to much comp, in that situation it will be very hard to get it to run at all. Up the powder charge to +P levels before you try to adjust the recoil spring rate or you will find the slide coming back to fast and a host of other problems.

[Boolit_Head]

Come to think of it some of the open 2011 38 super guns are probably running in the 7 to 8 pound range with much hotter loads.

[Chapo]

Thanks all. Appreciate all he feedback. Made a ladder of test loads ranging from 6-7.4grs and bought a 10lbs spring a kit with other internal trigger springs. Will post results....

[Chapo]

Well, went to the range and had catastrophic results. I started with the 11lbs spring, 5.7gr of auto comp and the cast 124gr boolit. Also installed the competition trigger spring kit. The OAL was 1.065. From 5.7-6.6gr all cases were showing signs of pressure, although I did not notice. By 6.7grs the explosion occurred. The force expelled the mag and gave me a big scare. Me, being stupid, had to confirm, and replicated the issue by firing a second round and the same happened. This time, not only the mag was expelled, but the magazine release busted out and broke in two.

This pic is the incremental signs of pressure....
Attachment 176017
View of primers...

Attachment 176018

Busted mag...

Attachment 176019

Next, I will replace the part, change the recoil spring to a 10lbs and will probably create loads in the 5-5.6gr range. Then shoot again.

Thoughts?

I figure, other people shoot much more hotter loads from g34; I'm just wondering what Im doing wrong.

[Boolit_Head]

Did you go look on Brian Enos? Several of them are probably running lighter bullets and probably using different primers. Read with caution because some of these are highly tuned 2011's and may be loaded longer than your glock. But these are the people who are running those loads all day.

http://forums.brianenos.com/index.ph...omment-2625301

[Chapo]

Yeah. Great source. Maybe I should try the small rifle primers.

[Mytmousemalibu]

Oh wow! Yikes! Unless you made a typo, that OAL is wayyyyy too short. In fact with a 124gr boolit with that big of a charge of Autocomp, that's gotta be getting into compressed load territory with OAL that short. I would not be at all surprised if that was the cause. I know larger charges of Autocomp have been burned off in 9mm's without case ruptures. Also, is your 124gr boolit of proper size per slugging the barrel?
My 147gr load had me seating all the way out to 1.180 and I can seat all the way out to 1.200 in my M&P. You won't have that kind of room in a Glock because of the thickness of the mags will probably limit your OAL before your chamber will.

[Chapo]

Thanks Chris. Will increase OAL.

[Mytmousemalibu]

Yeah, seating that short will send your chamber pressures through the roof. I just looked at your primer pictures and there is some very defined flattening of the primers in the ones in the right of the picture and heavy cratering with the primer cup flowing into the rectangular firing pin hole. It's pretty common for 9mm Major loads to exhibit some signs of pressure. My primers are flattened somewhat and I do get some cup flow into my firing pin hole but it's not to an extreme degree like some in the right of your picture. I would load up a dummy round, just a piece of sized brass and seat a bullet in it way long, like say 1.220 should do. Little by little, seat the bullet deeper and deeper checking it in your mags to see when it will fit and freely travel in the mag with out dragging the bullet and wedging in the mag body. Too long/not enough clearance will result in feeding issues. When you establish a maximum magazine OAL, see if that will chamber in barrel fully. You may find the ogive on that cast 124gr'er and the throat length of your barrel don't mesh. That is a pro to the 124gr plated RN bullets, the ogive they often have allow for seating long. The throat measurement will vary with each bullet design too so keep track of that. There is a fine balance between OAL, charge weight, powder type, bullet, etc. It can be tricky finding this balance. Adding in the issue of tuning the load to work the comp, run the gun and maintain accuracy, etc, etc is another story. You might have to go with another powder besides Autocomp to get where you need to go. I would certainly pick brains of the gang at Brian Enos to get your loading back on track. That might save you a lot of headache trying to fully tune a load from scratch and just have to do a little fine tuning. Those case head ruptures are no joke, that's an easy way to get hurt. A good friend of mine had an XDm 9mm open gun that had a case head rupture but instead of blowing the mag out, it popped the frame on the right side and beat his hand up a little bit. Lucky judging on what the optic mount looked like. Be careful, gotta be on your tippy toes with 9mm having to be as hot as it does in some of these race guns.

[Chapo]

Thanks again. I played a bit with the OAL and from the longest, it started chambering at 1.085". So I loaded a few of these from 5.7 to 6.4gr and also changed the recoil spring to 10lbs. We'll see what happens tomorrow. Chamber pressure should be less.

[Chapo]

Went to the range again and tested those loads although I only shot 5.7-6.0grs. Noticed the sweet spot is 5.9grs with the 13lbs recoil spring. No issues afterwards.

[Mytmousemalibu]

Glad to hear you are getting it sorted out!