6.5 SHERMAN SHORTS WITH 156 BERGER

I had a similar issue with a savage in the 6.5 Norma. It always pressures out sooner than normal. I never had the gun looked at but one of the smiths at the range told me a loose chamber will pressure out sooner than a correct cut chamber. I'm not exactly sure what it means but I suspect it has something to do with how much the case has to expand in relation to the chamber or the actually size of the chamber. Any ways I just shot it and it still produced good accuracy but never reached any blistering speed of it. It ran the 140 around 2880. I still never understood how a loose chamber would do this. Anyway need to re-barrel it now.

Could this be because of virgin brass expanding more in the chamber when shooting closer to max loads? I am showing pressure sign around 3058 w/140 hybrid in a 24" barreled 6.5SST. 3048 would be max with a new barrel and virgin brass. I am thinking once I have 1x / 2x shot brass and the barrel broken in I should be able to hit close to 3100 w/N565.
 
Could this be because of virgin brass expanding more in the chamber when shooting closer to max loads? I am showing pressure sign around 3058 w/140 hybrid in a 24" barreled 6.5SST. 3048 would be max with a new barrel and virgin brass. I am thinking once I have 1x / 2x shot brass and the barrel broken in I should be able to hit close to 3100 w/N565.
What barrel do you have? My 26" Bartlein gets 3100' with a 156 and brass lives??
 
I'm doing a comfortable 3000 with 147's and 56gr of H1000 in 26". Very accurate with this speed and bullet. I could do upper 3000+ but it is hot.
 

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I'm doing a comfortable 3000 with 147's and 56gr of H1000 in 26". Very accurate with this speed and bullet. I could do upper 3000+ but it is hot.
Yep! N565 loads at the same charge rate as H1000 but has more energy and is very temp stable. Thats what Im using in 140-156 now.
 
Yep! N565 loads at the same charge rate as H1000 but has more energy and is very temp stable. Thats what Im using in 140-156 now.
I am going to test for accuracy next with N565. I just was able to throw a load together to hunt with and a few rounds to test speed. I did heart shot a scrub buck at 200 yards. The 140 hybrid blew right through and destroyed the heart and one lung. Deer only went a few steps. I will say I have a 6.5 SAUM shooting 140 hybrids at 61 grains of H1000 out of a 24" and only getting 2958fps. I am really liking this 6.5SST :)
 
What barrel do you have? My 26" Bartlein gets 3100' with a 156 and brass lives??
it is a 24" Bartlein. I am shooting suppressed so I am not sure if that makes a difference pressure wise. I am also way down south.
6.5SST
N565
140 hybrids
60.3 - 3002fps
60.5 - 3000fps
60.8 - 3046fps
61.1 - 3056fps shiny ejector stiff bolt
 
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Those are some good numbers with 156 in a 24" pipe I want to run a 22-23" pipe on a 6.5 Sherman max that should keep me up well over 3K if this is what you guys are getting with the SS. I'm hoping that N570or 565 will work for me too.
 
it is a 24" Bartlein. I am shooting suppressed so I am not sure if that makes a difference pressure wise. I am also way down south.
6.5SST
N565
140 hybrids
60.3 - 3002fps
60.5 - 3000fps
60.8 - 3046fps
61.1 - 3056fps shiny ejector stiff bolt
If this is the first firing on the brass, that could be why. It moves around a lot more in the chamber than fully formed!
 
If this is the first firing on the brass, that could be why. It moves around a lot more in the chamber than fully formed!
This is what I am thinking as well. I plan on switching to the 156's after I have a decent load of 140's to finish out the season. I will post my results when that happens. I would like to keep this thread going because of the great info!
 
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