Savage 12 F Class 6mm br
- Thread starter malcarjeb
- Start date
From what I can tell the neck is .272. My loaded rounds are .269-270 unturned and everything is going good.
The gun shoots the SMK 107 in the .3s at 100 yards. I tried 30.8 grs. of Varget, the same load i use in my other 6mm br, and was piercing primers. I backed it down to 30.5 and the primers have flow craters but not piercing. Velocity with the 30.8 was 2800 and 30.5 is 2730. I have no trouble at all with my other gun with faster velocitys, not sure why it is building so much pressure,or the signs of pressure).
I had some IMR 4007 ssc that I have never tried. I thought maybe a slower powder might do better with the velocity. I loaded up 31.5 and got 5 shot average of 3720 fps. The primers have a little less flow but still more than I like. The accurcy has been outstanding with the IMR 4007ssc, CCI 400 primers, Lapua brass, and SMK 107. It is shooting constant high .2s and low .3s!!
If anyone has any Idea what might be going on with the primers, let me know.
Other than the slower speeds, I'm well pleased with how the gun shots and the accurcy. The barrel also cleans very easy with little copper and powder fowling.
The gun shoots the SMK 107 in the .3s at 100 yards. I tried 30.8 grs. of Varget, the same load i use in my other 6mm br, and was piercing primers. I backed it down to 30.5 and the primers have flow craters but not piercing. Velocity with the 30.8 was 2800 and 30.5 is 2730. I have no trouble at all with my other gun with faster velocitys, not sure why it is building so much pressure,or the signs of pressure).
I had some IMR 4007 ssc that I have never tried. I thought maybe a slower powder might do better with the velocity. I loaded up 31.5 and got 5 shot average of 3720 fps. The primers have a little less flow but still more than I like. The accurcy has been outstanding with the IMR 4007ssc, CCI 400 primers, Lapua brass, and SMK 107. It is shooting constant high .2s and low .3s!!
If anyone has any Idea what might be going on with the primers, let me know.
Other than the slower speeds, I'm well pleased with how the gun shots and the accurcy. The barrel also cleans very easy with little copper and powder fowling.
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Malcarjeb,
Terry Brady is testing one of the new 6mmBR Savages. His fired casenecks are about 0.271, from which we figure the chamber neck diameter is .272, assuming some springback.
Re your cratered primers--the Savages are known to have a lot of clearance around the firing pin. This means you can get some rather serious cratering even at pressures lower than the cases can handle in a nice tight chamber. Greg Tannel will bush the firing pin for about $60 with a fast turn-around. After bushing the pin you'll probably find you can hot up the load.
Re pressure--every barrel is different. My hand-lapped 27" 6BR Pac-nor 3-groove is running 2900+ fps with 30.5 Varget. Other barrels may be closer to 2800 fps with the same load.
Nominal bore dimension may be slightly tight on the Savage barrels and they're going to have more tooling marks inside which can increase friction,and pressure).
Re Speed--I would also borrow another chronograph. I am VERY surprised that speed would drop 70 fps from 2800 to 2730 fps with a reduction of just 0.3 grains Varget. I would expect the change to be 30-40 fps max.
Terry Brady is testing one of the new 6mmBR Savages. His fired casenecks are about 0.271, from which we figure the chamber neck diameter is .272, assuming some springback.
Re your cratered primers--the Savages are known to have a lot of clearance around the firing pin. This means you can get some rather serious cratering even at pressures lower than the cases can handle in a nice tight chamber. Greg Tannel will bush the firing pin for about $60 with a fast turn-around. After bushing the pin you'll probably find you can hot up the load.
Re pressure--every barrel is different. My hand-lapped 27" 6BR Pac-nor 3-groove is running 2900+ fps with 30.5 Varget. Other barrels may be closer to 2800 fps with the same load.
Nominal bore dimension may be slightly tight on the Savage barrels and they're going to have more tooling marks inside which can increase friction,and pressure).
Re Speed--I would also borrow another chronograph. I am VERY surprised that speed would drop 70 fps from 2800 to 2730 fps with a reduction of just 0.3 grains Varget. I would expect the change to be 30-40 fps max.
Has anyone ever tried H4350 with the 107 SMK? I tried it today and my velocity picked up about 50fps and the groups shrunk. My thinking in trying this slow powder was the long 30" barrel on these Savages. I was hoping to build up pressure a little slower and maybe get some more velocity.I was only shooting 3 shot groups and it put all 3 in the high .1s and low,low .2s every time. Hope to have a little more time tomorrow to try some 5 shot groups at 300 yards.
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