Jonesjohnm

Steel open gun bouncy

20 posts in this topic

I've been shooting an STI Trubor 9mm for a few months and have been doing very well. As much as I love my Trubor I've been lusting after an STI Steelmaster 9mm for Steel Challenge. I finally found one and got it in yesterday. I brought 100 rounds of my standard 9mm minor loads to the range.

 

I was SO DISSAPPOINTED.

 

The gun feels super soft, but it's very very bouncy. The only solution I can think of is to go with a heavier charge to generate more gas for the comp. my Trubor shoots so flat it's not even funny, but this Steel Master dot is up and down like my pregnant wife's mood swings. HELP!!!!

 

 

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The 9 minor may be the issue.
Was it factory ammo? May Not have enough gas for the comp. Try your trubor loads and see if it flattens out?

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Really analyze the movement as well. Is it up and down, or is it down, up, and down.  If it's down, then up, then down, that could be too strong a load that is first pushing the muzzle down from too much pressure through the comp, then up from a hard hit on the rearward travel of the slide, then down from a hard hit on the forward travel of the slide with too strong of a spring.  Honestly I don't know if that's the issue but if you're using your "normal" minor load that shoots flat in a "normal" USPSA gun, it probably won't work as well in a specialized steel gun which is going to be tuned for a very light load-- likely even a sub 125pf load.   Play with the loads and analyze the exact movements, which can tell you how it needs to be tuned.  

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The gun is specifically made for minor loads, that's why I chose it. I'm pretty sure I would destroy that gun if I put major loads in it without replace the recoil system.

My load is
124 grn bayou bullets lrn
W231 4.4 grn
Roughly 1.110" I believe

My local supply suggested using a 115 grn bullet to need more powder to create more gas.

Ooooh good question Jkrispies.. I didn't pay attention to the exact pulse. I believe it was just up and down. I believe it's roughly the same movement as my Limited 9mm minor, I think I'm just spoiled with a stupid flat perfect matched load in my Trubor. In my mind that's my expectation of how an open gun should shoot, so I guess I think it's so "bad" because my Trubor load is so "good"


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I will load 25 rnds of 124 grn @

 

4.2 grn

4.4 grn

4.6 grn

4.8 grn

 

Take notes on dot movement and accuracy and report back tomorrow with pics

 

 

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Try a diff recoil spring if it has the recoil master still in it.  Also a slower powder. 

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What do you think echotang? 7lb? I keep plenty of autocomp laying around too. I can give that a shot

 

 

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1 hour ago, Jonesjohnm said:

The gun is specifically made for minor loads, that's why I chose it. I'm pretty sure I would destroy that gun if I put major loads in it without replace the recoil system.

My load is
124 grn bayou bullets lrn
W231 4.4 grn
Roughly 1.110" I believe

My local supply suggested using a 115 grn bullet to need more powder to create more gas.

Ooooh good question Jkrispies.. I didn't pay attention to the exact pulse. I believe it was just up and down. I believe it's roughly the same movement as my Limited 9mm minor, I think I'm just spoiled with a stupid flat perfect matched load in my Trubor. In my mind that's my expectation of how an open gun should shoot, so I guess I think it's so "bad" because my Trubor load is so "good"


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Remember that bounce isn't necessarily bad if the sights return to the same spot after the cycle.  Your Trubor moves too-- it's just doing it too fast to notice.  

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I ran a 7# with a 130pf round. It didn't like much lower than that. 

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I got my dedicated single stack steel gun to run with a 5 1/2 pound recoil spring and 16 pound mainspring with a generous FP radius, but only if the mags were about 1/2 full.  (yeah I know what good is that!!) :rolleyes: 

 

It is a balance between low recoil spring weight and enough spring weight to reliably strip rounds off the mag and feed them into the chamber crisply.  I ended up using a 6. 3/4 - 7 pound recoil spring (measured poundage on gauge) and 115 - 124 gr bullets loaded to about the 950 fps range using faster powders.  Seems to yield a consistent dot and it shoots soft.  I tried 95 grain bullets and they work great but to simplify inventory I use 124/115 jacketed. 

 

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I'd lose the 231 and go to something like Silhouette, WAC or HS-6 to get more gas.  There is nothing wrong with 124.  However, the lighter you go in bullets, the more powder you need and the more gas generated.  Many people find they have to go to 145-155PF to get the gun to shoot flat.

 

I can get my gun to shoot almost flat with HS-6, but I don't like the dot movement.  With Silhouette or WAC i get more dot movement, but it tracks straight up and down and returns to the same spot.

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Try a large charge (8gr+) of a slow powder like 3n38 under a 95gr bullet for maximum fun ;)

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Hello: You are shooting steel so one shot on each and then you move to the next piece of steel. You don't need it to double tap in the same spot. A steel gun is a different animal than a open USPSA pistol. Try some HS-6 and 115's at about 140-150PF. Thanks, Eric

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It must be broken. Send it to me and I'll make sure its destroyed

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As mentioned the load should be tweaked as well as the recoil spring. When using a fast powder the comp is almost not even part of the equation. Fast powders have less volume and muzzle pressure to work the comp to any great degree as compared to slower powders a comp thrives on. So with fast powders it's all recoil spring doing the work and to therefore tune to change the feel. Slower powders will work the comp and then change how the gun tracks. But even with a slower powder the recoil spring should be experimented with to fine tune. Either way the recoil spring weight matters; Too light of a spring will unlock too soon giving you more perceived muzzle jump, to heavy of a spring will give you a muzzle dip. So you got some experimenting to do. Personally I've found a stiff minor load 145-150 pf of slower powders and a 8 lb spring is a good starting point. The theory of ultra light bullets and fast powder in an open style pistol for steel is useless...needs to light of a spring and gets to damn sluggish and clunky. I think you said it was a 9mm? If so HS-6 at 6 grains will make a good load to start with and work it from there.

 

 

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Update: I loaded and shot 50

124 grn
5.8 grn Autocomp

Sweet giblets that's a stout load. I'm glad I put the 8 lb recoil spring back in. More "felt" recoil in that load than my 9 major load.

I'm going to load 50 more at:

115 grn
5.8 grn autocomp

And

124 grn
5.4 grn autocomp




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If it was 'harder' than your Major load, you have too much gas jetting out the front of the comp.

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nice load for the steelmaster 

124gr xtreme rn

5.2gr power pistol

oal 1.145

pf 130

shoots very flat and fun

 

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