300 Sherman Shortmag (SS)

Idaho Trecker

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Apr 19, 2013
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North Idaho
I know there have been a few mentions/suggestions of a 300 SS being built and the first one will be delivered to me on Tuesday. After alot of talks with Rich (elkaholic) and Rhian (bigngreen) I was given the opportunity to have the first one cut to do some initial testing.

Rich sure has some great designs and I am grateful to be able to help out in some testing. Rhian has also been first class to work with and is very fast and helpful with any questions I have had on his end. Thanks Rich and Rhian!!!

Here are my build components:

Tikka T3 action
B&C M40 stock
28" 1:10 Brux, Rem Varmint contour (turned down by Rhian to mate up to Tikka)
topped with Talley ringmounts holding a Zeiss Conquest 4.5-14x50
I may have Rhian put a 3 port Mini-Mag Muscle brake on it at a later date

Rich had the reamer made to accommodate a 215 Berger at 3.035". He also has a new twist with a special throater.

To start off we decided to cut a standard throat to get some baseline numbers. Once that is done I'll send it back to Rhian to cut the new throat in it (unless it shoots so incredible that I dont want to have it done). Rich is anticipating being able to push the 215 around 2900-3000 fps.

To start with I'll be shooting some 215 Bergers, 208 A-Max, 208 ELD-M, and 200 ELD-X. Some powders we are thinking about using will include RL 26, RL 23, RL 17, and possibly some IMR 4451.

I'll get some pictures up once I get it.
 
I'm stoked to get this rifle setup and see what it can do. It sure will be impressive if it will push a 215 around 3000 fps with such a small amount of powder compared to a 300 WM.

Mudrunner... I do have some 7977 on hand but not 7828. I've got to agree with a few others here that 7977 is basically h1000 with a copper remover additive and with my 270 SS I couldnt get near the speed with h1000 as RL 26. I realize the difference in bore size will affect it but it should mean that faster powders will be better in this round. I'll find out soon....:)
 
I'm stoked to get this rifle setup and see what it can do. It sure will be impressive if it will push a 215 around 3000 fps with such a small amount of powder compared to a 300 WM.

Mudrunner... I do have some 7977 on hand but not 7828. I've got to agree with a few others here that 7977 is basically h1000 with a copper remover additive and with my 270 SS I couldnt get near the speed with h1000 as RL 26. I realize the difference in bore size will affect it but it should mean that faster powders will be better in this round. I'll find out soon....:)

If that's the case, then 7828 SSC might be a better option. It's directly above RL25 on the burn chart, and I know RL25 and Rl26 are supposed to be about the same (although some say 26 is actually slightly faster than 25), and that 26 is supposed to be more temp stable than the 25. Might be worth looking into?

I know I get great velocities with 7828 SSC in smaller cases such as much my .25-06 AI and .30-06 AI.
 
I'm stoked to get this rifle setup and see what it can do. It sure will be impressive if it will push a 215 around 3000 fps with such a small amount of powder compared to a 300 WM.

Mudrunner... I do have some 7977 on hand but not 7828. I've got to agree with a few others here that 7977 is basically h1000 with a copper remover additive and with my 270 SS I couldnt get near the speed with h1000 as RL 26. I realize the difference in bore size will affect it but it should mean that faster powders will be better in this round. I'll find out soon....:)

I believe RL26 is supposed to have de-coppering agents also.
 
Will this rifle be a repeater or single shot?

The long answer is both :D
For now it will be single shot unless the bullets like alot of jump. I had this built on a tikka t3 300 WSM action which only allows 2.885" in the WSM magazine. Rhian milled the bolt stop back so all I have to do now is get a "long" action magazine for the tikka and it should be able to run around 3.370". I believe the tikka has one action length but the bolt stop and magazine are the only difference as to what cartridge they originally chamber them in.
 
Yeah, the T3 is a long action with different length bolt stops based on cartridge. Sounds like the 300SS so far is the only one that can't be mag fed in a 2.950" magazine... Yet. Time will tell
 
Can't wait to see this one in action. I am expecting GREAT things with it, but time will tell. I think 2950' is doable with the 215's, and maybe more? I could see this thing being a great carry rifle, or a long range hunting (or target) rifle with very good barrel life! Show us what ya got Ryan!:D......Rich
 
Very curious as well. I had a 300 saum build this year and it shoots awesome. When you are done some testing ill share some of my loads for comparison if you like.
 
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