300 Sherman Shortmag (SS)

[ruby76]

What throat length do you have? I keep threatening to rebarrel mine and make it a hunting rifle. It's also on a short action. I do happen to have another Med length action laying around too that I haven't decided what I'll do with yet.

Mine started out with the original reamer, which would now be considered the short one. I did end up getting another .120 added later so not exactly sure what the throat length would be now. The last thing I am going to do is add dbm bottom metal and use the accurate wsm mag I have. That will allow extra room for different bullets if I choose, plus give me 3 round capacity.

 

[elkaholic]

Mine started out with the original reamer, which would now be considered the short one. I did end up getting another .120 added later so not exactly sure what the throat length would be now. The last thing I am going to do is add dbm bottom metal and use the accurate wsm mag I have. That will allow extra room for different bullets if I choose, plus give me 3 round capacity.

the original reamer was .027" FB

 

[Tidesloe]

I got out and shot a ladder at 580 yds with H100V yesterday. I had that and N550 loaded up. I didn't shoot the N550, and possibly won't. I did shoot 2 N550 loads at 1 gr below where I started seeing ejector marks the other day, just to get on paper. They gave me pronounced ejector marks, heavy bolt lift and 3080 fps. It was 30 degrees warmer yesterday and this told me N550 is very temp sensitive. H100V didn't show that and seemed to be fairly stable. I'm liking what I'm seeing with H100V.
I shot 2 4 shot groups starting at 60.2 to 61.6 in .2 gr increments. I had 1 flyer in each at the same elevation but 4" right of the group. Don't know what happened on either one of them, but kicking those shots out put the other 3 in each group at 2.7". Not bad, but hoping to shrink it down a little. Puts those groups at .4 moa at 580 yds.
60.2 - 2980
60.4 - 2966
60.6 - no velocity
60.8 - 2988
61.0 - no velocity
61.2 - 3017
61.4 - 3037
61.6 - 3034
Started seeing slight ejector marks at 61.6.
It was in the 90's vs mid 60's the other day. I think the H100V is showing promise, and what I'll continue with. N550 was clearly too temp sensitive. Higher velocities, but temp sensitive and it comes at more cost to throat. I'm liking what I'm seeing with H100V, and thinking I'll probably work on the 2980 to 3000 fps range, and see what I come up with.

 

[Idaho Trecker]

I've seen a couple charts on temps sensitivities of powders and I think they showed 100v in the .7fps/degree change which is about middle of the pack. I've done my own testing and basically came up with the exact same at .65.

You seem to be on the right track and the 2980 looks like a good place to start testing other factors if the half moa isn't good enough. Did you know which shot in your string was the flier? Same shot each time?

 

[Tidesloe]

I don't know which shots were the flyers, and didn't realize I had fliers until I went to the target and looked. I have a camera system that I'll set up on my target next time.

 

[Tidesloe]

Here is a pic of the groups showing the fliers to the right of each.

 

[Tidesloe]

One thing that could have contributed to the fliers possibly, is this is with new, necked up never fired brass. I had concentricity problems, and ended up frustrated when seating bullets. I had a few that were way out, and most were outside of what I normally consider acceptable. I didn't track any of that, but it'll be much better with subsequent loadings.

 

[elkaholic]

I got out and shot a ladder at 580 yds with H100V yesterday. I had that and N550 loaded up. I didn't shoot the N550, and possibly won't. I did shoot 2 N550 loads at 1 gr below where I started seeing ejector marks the other day, just to get on paper. They gave me pronounced ejector marks, heavy bolt lift and 3080 fps. It was 30 degrees warmer yesterday and this told me N550 is very temp sensitive. H100V didn't show that and seemed to be fairly stable. I'm liking what I'm seeing with H100V.
I shot 2 4 shot groups starting at 60.2 to 61.6 in .2 gr increments. I had 1 flyer in each at the same elevation but 4" right of the group. Don't know what happened on either one of them, but kicking those shots out put the other 3 in each group at 2.7". Not bad, but hoping to shrink it down a little. Puts those groups at .4 moa at 580 yds.
60.2 - 2980
60.4 - 2966
60.6 - no velocity
60.8 - 2988
61.0 - no velocity
61.2 - 3017
61.4 - 3037
61.6 - 3034
Started seeing slight ejector marks at 61.6.
It was in the 90's vs mid 60's the other day. I think the H100V is showing promise, and what I'll continue with. N550 was clearly too temp sensitive. Higher velocities, but temp sensitive and it comes at more cost to throat. I'm liking what I'm seeing with H100V, and thinking I'll probably work on the 2980 to 3000 fps range, and see what I come up with.

Thats good to know! Ive gotten mixed messages on the Vihtavouri powders, and especially 550. Ive tested 570 and its VERY stable but have not personally tested 550.

 

[Tidesloe]

Thats good to know! Ive gotten mixed messages on the Vihtavouri powders, and especially 550. Ive tested 570 and its VERY stable but have not personally tested 550.

In the end I'm getting not much less velocity with H100V than I was with N550 when I started seeing pressure. As of now H100V will clearly be my go to with this bullet choice. Next up will be 215 gr Bergers, and I might start out on that pretty soon. I'm thinking maybe H100V, RL-26, and maybe N160. That's probably the only powders that I've got that may work. Maybe H4831 SC also? Might even see if I get more of the same with N550 with that bullet also

 

[Idaho Trecker]

Once again I'd concentrate on 100v and then 26 with the 215. Rl 22 was great for speed and with the high density it worked well and was very accurate. It is very bad for temp stability.

 

[Tidesloe]

Once again I'd concentrate on 100v and then 26 with the 215. Rl 22 was great for speed and with the high density it worked well and was very accurate. It is very bad for temp stability.

How is RL-26 on temp stability?

 

[Idaho Trecker]

I've tested it at .35 fps/degree BUT that usually only holds true until 80 degrees then after that it does not follow that and spikes a lot. I personally don't shoot in temps like that or have hunts that are open in those temps.

Just opened up my revic app and it shows rl 26 at .38 so my personal testing I did quite a few years back must have been pretty good.

 

[Tidesloe]

I've tested it at .35 fps/degree BUT that usually only holds true until 80 degrees then after that it does not follow that and spikes a lot. I personally don't shoot in temps like that or have hunts that are open in those temps.

Just opened up my revic app and it shows rl 26 at .38 so my personal testing I did quite a few years back must have been pretty good.

I don't either usually, unless I have to. Right now I have to, in preparation for a hunt starting Oct 1.

 

[elkaholic]

In the end I'm getting not much less velocity with H100V than I was with N550 when I started seeing pressure. As of now H100V will clearly be my go to with this bullet choice. Next up will be 215 gr Bergers, and I might start out on that pretty soon. I'm thinking maybe H100V, RL-26, and maybe N160. That's probably the only powders that I've got that may work. Maybe H4831 SC also? Might even see if I get more of the same with N550 with that bullet also

RL26 will likely run the 215 the fastest, but again, not temp stable above 80 degrees. RL23 would work too