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Slow barrel. Harder on gun?


Shmella
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I have a really slow barrel in my current open gun. Schuemann 9mm shorty with 3 small poppel holes. The same load that made 170pf of my sv imm with two large holes in the barrel makes like 160pf or less out of this gun. My question is would this correlate to being harder on the gun to run a much hotter load to make the same pf? The load was aa7 10.5gr with a 115 Bullet. I can’t use 115 grain with this gun because I would have to get up to like 11+ grains to make major now. So I’ve tried a 125gr and at 10 grains it makes on average 163pf with a coated Bullet. I’ll have to go up to like 10.2 or more with a 124 jacketed Bullet to make 165+pf. I’m also curious if a “slower barrel” makes the same pf load feel harsher. 

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How hard it is on the gun will be determined by what recoil spring you end up using.  If you are whacking the vertical impact surface, you are stressing the gun.

 

As for adding more powder, it depends.  Startling low, adding powder makes the gun softer.  With poppels it also make the gun flatter, but hit your hand harder.  That continues right up until the point were a lot of gas starts exiting the front of the comp.  From then on, adding powder makes it feel a lot harsher.  Slide action is more violent and you need a stiffer recoil spring.

 

If you are loading long, like 1.165", your pressures will be relatively low (for 9mm major), so I would not be afraid to go to 10.2 under a 124.  This BTW is the exact reason I did not go with a shorty.

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I just find it strange with this gun to be so much slower than my sv was. They are identical length. Just a much slower barrel. From what I remember reading all schuemann barrels are notoriously slow. It just worries me that the same pf load will beat this gun up quicker.  

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7 hours ago, 36873687 said:

Have u tried 125 .356  size Bullet. It dropped my charge .5 an srp. With aa7

That is a good thought...i have about 15,000 coated at .355 though to burn through though.

 

 

I will try some .356 though. Sometimes i overlook the easiest solutions. If that works I could save the bullets i have for my production and steel loads.

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Have you slugged the barrel? Are the outside of the fired cases very sooty? You may not be getting a good case seal, with an over sized bore, & losing pressure. Be surprised if the .356 bullets don’t help. I remember reading Schueman recommended even a .357 bullet. 

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Just now, OPENB said:

Have you slugged the barrel? Are the outside of the fired cases very sooty? You may not be getting a good case seal, with an over sized bore, & losing pressure. Be surprised if the .356 bullets don’t help. I remember reading Schueman recommended even a .357 bullet. 

You're right, schuemann recommends .001 - .002 larger than the grove diameter which is .3550  and that is for jacketed. so either a .356 or .357.

For lead (and Im assuming Coated) recommend going up to .002 - .003 larger.

 

ill try a .356 and see what happens.

My problem is I really like RMR Bullets JHP profile and price $ but theyre .355-.3556 :(

Edited by Shmella
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3 hours ago, Shmella said:

 

That is a good thought...i have about 15,000 coated at .355 though to burn through though.

 

 

I will try some .356 though. Sometimes i overlook the easiest solutions. If that works I could save the bullets i have for my production and steel loads.

Try the tc profile I’m amazed with accuracy also. 

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