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270 Sherman Short Mag

F215M and 60.7 H4350 with a 225 ttsx going just under 2700 with my 22" barrel. I stopped chasing velocity and narrowed down powder choices to non temp sensitive. Varget pressured up too quick in my particular barrel, RL17 gave better velocity but not as accurate as H4350. I fought with mine for a long time and decided to stop and get using it.
Probably smart. I did get up to 2800 FPS with 64 grains of H4350 but there were slight pressure signs and I am wanting to get good life out of the brass. Probably should go back down to the 2725 load and go out and hunt rather than spend the life of the barrel chasing something that might not be attainable.
 
I wish I would have gone back to this post and saved myself some powder and bullets yesterday. I started lower than I would have had I remembered this data. I am playing with the 145 eldx and started with h4831sc and cci 250 in my 19" barrel. Pretty similar results it seems.

55.4 2730
56.0 2761
56.6. 2806
57.2. 2801
57.8. 2841
58.4. 2871
59.0. 2898
59.6. 2913
60.2. 2948. First shadow of extractor mark
60.8. 2975. Same. Stopped here
It looks like I'm going to give 59.3 a try for groups now. After this I'm going to start with RL23 and see how it does then maybe circle back to h4350 after seeing your results.
 
I wish I would have gone back to this post and saved myself some powder and bullets yesterday. I started lower than I would have had I remembered this data. I am playing with the 145 eldx and started with h4831sc and cci 250 in my 19" barrel. Pretty similar results it seems.

55.4 2730
56.0 2761
56.6. 2806
57.2. 2801
57.8. 2841
58.4. 2871
59.0. 2898
59.6. 2913
60.2. 2948. First shadow of extractor mark
60.8. 2975. Same. Stopped here
It looks like I'm going to give 59.3 a try for groups now. After this I'm going to start with RL23 and see how it does then maybe circle back to h4350 after seeing your results.
I bet you'll have good speeds with the R23. I have 20+ pounds of H4350 so it's typically something I try first on everything from 6.5 Creed to 338 SS. For some reason I didn't with this rifle.
 
I wish I would have gone back to this post and saved myself some powder and bullets yesterday. I started lower than I would have had I remembered this data. I am playing with the 145 eldx and started with h4831sc and cci 250 in my 19" barrel. Pretty similar results it seems.

55.4 2730
56.0 2761
56.6. 2806
57.2. 2801
57.8. 2841
58.4. 2871
59.0. 2898
59.6. 2913
60.2. 2948. First shadow of extractor mark
60.8. 2975. Same. Stopped here
It looks like I'm going to give 59.3 a try for groups now. After this I'm going to start with RL23 and see how it does then maybe circle back to h4350 after seeing your results.
I wish I would have gone back to this post and saved myself some powder and bullets yesterday. I started lower than I would have had I remembered this data. I am playing with the 145 eldx and started with h4831sc and cci 250 in my 19" barrel. Pretty similar results it seems.

55.4 2730
56.0 2761
56.6. 2806
57.2. 2801
57.8. 2841
58.4. 2871
59.0. 2898
59.6. 2913
60.2. 2948. First shadow of extractor mark
60.8. 2975. Same. Stopped here
It looks like I'm going to give 59.3 a try for groups now. After this I'm going to start with RL23 and see how it does then maybe circle back to h4350 after seeing your results.
This is why I started this thread. Love the 270 and didn't find many results or postings on the 270 SS.
 
This is why I started this thread. Love the 270 and didn't find many results or postings on the 270 SS.
I did the testing on the first one and I'm sure it's a hard thread to find at this point. This is my second barrel on it now. I hear you on trying the powders you have the biggest supply of... I've been starting with 26 and 23 since i have 30+ pounds of each. 23 did give me more speed but I made the mistake of shooting a 4 shot group, at 118 yards, where I saw a flat spot in velocity with H4831sc. This is just with a 3-15 vx5hd with the windplex. I should throw on another scope with more magnification and see how it does.
20220706_175622.jpg


I ran the same charges with rl 23 as I did with H4831sc. My last charge of 23 had roughly the same pressure signs as I had with my 60.8 load with H4831sc. Here's the pressure test with 23.

58.4. 2928
59.0. 2960
59.6. 2987
60.2. 3007
60.8. 3014
61.4. 3055

Looking at this I can run almost 100 fps more where I see a flat spot than with H4831sc.
 
I did the testing on the first one and I'm sure it's a hard thread to find at this point. This is my second barrel on it now. I hear you on trying the powders you have the biggest supply of... I've been starting with 26 and 23 since i have 30+ pounds of each. 23 did give me more speed but I made the mistake of shooting a 4 shot group, at 118 yards, where I saw a flat spot in velocity with H4831sc. This is just with a 3-15 vx5hd with the windplex. I should throw on another scope with more magnification and see how it does.
View attachment 377079

I ran the same charges with rl 23 as I did with H4831sc. My last charge of 23 had roughly the same pressure signs as I had with my 60.8 load with H4831sc. Here's the pressure test with 23.

58.4. 2928
59.0. 2960
59.6. 2987
60.2. 3007
60.8. 3014
61.4. 3055

Looking at this I can run almost 100 fps more where I see a flat spot than with H4831sc.
Any particular reason you do load development in .6 grain increments? Just curious if there is a scientific reason behind it or if it's just something you like to do.
 
Haha well to be honest I haven't played with H4831sc more than once or twice ever and I forgot your post so I originally was going to do .3 grain increments. I loaded the lowest charge and shot before I seated more bullets to get a speed (perks of shooting from home). I knew enough of the powder and the speed I had with that lowest charge that I had a long ways to go so I doubled what I originally planned and still worked out to find an area to test further.
 
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