300 Sherman Shortmag (SS)

[elkaholic]

Good guess Rich haha I might let him pull the trigger on it a time or two this fall!!!

Charge him by the shot. It's cheaper than a build!

 

[Idaho Trecker]

Very true Rich!

I received the barreled action back this afternoon and it looks great!!!

Thanks Rhian!

Unfortunately with the 90+ degree temps I couldnt be talked into touching any rounds off yet. I'll get out before work tomorrow and shoot 2 that I have loaded up with a mild load over the magnetospeed. Each brass is a different neck thickness so I can determine if the bushings I originally ordered are going to work. I may have to order another one or two.

The barreled action dropped right into the M40 stock other than one high spot above the rear of the two front swivel studs. I sanded that down and its now free floated. The low talley rings I ordered were to low and wouldnt work. Mediums are on the way and should be here Friday.

 

[Idaho Trecker]

I'll get some better pictures up later in the week.

 

[wilkup]

Awesome looking rifle! I hope it shoots as well as all the Sherman options I've seen =) What's the weight of the rig all geared up and ready to go?

 

[Wind Gypsy]

The long answer is both
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.

Has anyone gotten the short mags to feed well from long action tikka mags? I'd love to do a 300wsm throated for 215s in that format in a lighter rifle.

 

[Idaho Trecker]

Awesome looking rifle! I hope it shoots as well as all the Sherman options I've seen =) What's the weight of the rig all geared up and ready to go?

I'm thinking it will be about 10.5 pounds when I get the scope and rings on it. I'll get a weight on it put together when I get the rings saturday. I'm sure its going to be a shooter!

 

[Idaho Trecker]

Made it out before work this morning to run 2 shots over the magneto with a mild fire forming load of 56 grains of rl 26 under a 215 berger. First shot got 2436 and second shot 2462. This is a mild load but it does show that rl 26 will be to slow for this cartridge. I'm going to be trying rl 23, rl 17, and hybrid 100v once I get the scope mounted and some more brass formed.

 

[Wind Gypsy]

I'm not overly familiar with your case but that sounds like a low charge of rl26, I would have figured you could easily get into the low 60s safely based on time with 300wsm and 6.5 saums.

 

[bigngreen]

Starting low for the first one chambered out of the gate is a wise choice, much easier and funner to work up than find out you need to back of at the first shot!!

 

[MudRunner2005]

Rich, what powder charge weights are y'all anticipating for slower powders, like Rl25/RL26, compared to the other SS cartridges? I know the larger the bore diameter, the lower the pressures, so the 300 SS should be a few more grains of powder at the same pressures as the other calibers.

Have you ran any QL sims to get an idea? Sorry, I am not meaning this to be a guide for anyone to load by, simply because each rifle will react differently, I was just curious if you had ran the numbers yet.

 

[elkaholic]

We have known all along that if RL26 was to reach max pressure, it would certainly be a compressed load. It appears to me that it would likely take around 65 grains to do that and I think we can only pack 63 and change into the case. I am not sure that RL23 will work either because it is far less dense than 26 and the case will only hold 60-61 grains. I have always thought that RL 17 might be a good choice, but we will see? Ryan has had some good results in other cartridges with Hybrid 100 and will try that as well. I am guessing that RL26 will likely reach no more than 2850, but will be a mild load. Even though the sectional density is there, the larger bore is just a little too much to use the same powder as in the other SS bores......Rich

 

[MudRunner2005]

We have known all along that if RL26 was to reach max pressure, it would certainly be a compressed load. It appears to me that it would likely take around 65 grains to do that and I think we can only pack 63 and change into the case. I am not sure that RL23 will work either because it is far less dense than 26 and the case will only hold 60-61 grains. I have always thought that RL 17 might be a good choice, but we will see? Ryan has had some good results in other cartridges with Hybrid 100 and will try that as well. I am guessing that RL26 will likely reach no more than 2850, but will be a mild load. Even though the sectional density is there, the larger bore is just a little too much to use the same powder as in the other SS bores......Rich

That new RL23 sounds like it might be the ticket for getting a nearly full charge and good velocity. I will be interested in the results.

 

[elkaholic]

That new RL23 sounds like it might be the ticket for getting a nearly full charge and good velocity. I will be interested in the results.

We will see on the 23? It might work but I think being less dense could cause the same issue with holding enough to max out pressure. It is fairly new, and I have not shot that much of it so I really don't have a good feel for what to expect?

 

[Idaho Trecker]

Threw the rifle on the kitchen food scale last night and as is w/o scope or rings it weighs 9 pounds 4 ounces so will probably finish right at 10.5 pounds.

Headed out here shortly to do some more barrel break-in. I loaded 2 up with 56 grains of RL 23 to see how it compares grain for grain with 26 on fireforming. I'm sure this will also be a mild load which is perfect for the fireforming and still gives me an idea how RL 23 will act. Also loaded 1 with 59 grains of RL 23.