My 338 Sherman Shortmag

[elkaholic]

I'm a 375 as well and there's a big difference from the 375 to the 420.
If I use the 375 I end up with tight brass issues as it sits right where neck and shoulder meet. If I use 420 I sit on shoulder.
Whidden gives me a 1.605 shot brass
Hornady gives me a 1.574. Shot brass
This next round I'll try the hornady see if I get a better fit with brass as Jeff Z did.
Shot first round tonight 250 berg @56 -58.5 of Varget at 10 thou off no pressure at all. 58gr shot 1" group at 200 yards 58.5 was 1.25.
I'll run now till I hit pressure then see what speed is. My 53 gr load was almost 2600 so I'm guessing I have to be close to [email protected]
I'm hoping to get north of 60 get these 250s in the mid 2900 Mark.

Very nice! That has to make you smile a little bit!

 

[ruby76]

Hi everybody. I'm new to the site and this is my first post. I also have a 338 ss. My reloading experience is only about a year and a half, so I hope this contributes. I had the same issue with mine until I bought a hornady shoulder gauge. The gauge that came with the whidden dies fits snug to the neck and when I knocked it back what I thought was .002 ( according to the whidden gauge), it was still very tight in the chamber. All I was doing was moving the the little radius back at the shoulder neck junction. My neighbor lend me his hornady 338 shoulder gauge. It measures .420 and actually sits on the shoulder. When I measured a sized piece (which I thought was bumped .002) and a fired piece, both with the hornady gauge there was no bump in the shoulder area at all. So after adjusting to get the actual shoulder to back .002 with the hornady gauge, they cycled just fine. If this sound wrong, please correct me

Thanks for this. I got my hands on a hornady .420 gauge and confirmed that the shoulder was not actually being pushed back like I thought it was when using my whidden .375 gauge. Using the hornady gauge I'm now at 3 thou back, comparing the two same pieces of brass with the whidden gauge it says I'm 10 thou back.

 

[elkaholic]

Thanks for this. I got my hands on a hornady .420 gauge and confirmed that the shoulder was not actually being pushed back like I thought it was when using my whidden .375 gauge. Using the hornady gauge I'm now at 3 thou back, comparing the two same pieces of brass with the whidden gauge it says I'm 10 thou back.

Thanks for that! We can all learn something

 

[KMG]

Thanks for this. I got my hands on a hornady .420 gauge and confirmed that the shoulder was not actually being pushed back like I thought it was when using my whidden .375 gauge. Using the hornady gauge I'm now at 3 thou back, comparing the two same pieces of brass with the whidden gauge it says I'm 10 thou back.

I've got a .375 guage now I know what to look for in my bump.

 

[ramrod79]

So I ran up to 60.5 gr of Varget with the 250 Berger still no pressure. My 60 gr load shows enough promise to run over chrono early but I will run to pressure to see what I get. My 58,58.5,59 show some promise but not like this. That's .80 at 200yards a little seating depth adjustment and it's a one hole load.

 

[elkaholic]

So I ran up to 60.5 gr of Varget with the 250 Berger still no pressure. My 60 gr load shows enough promise to run over chrono early but I will run to pressure to see what I get. My 58,58.5,59 show some promise but not like this. That's .80 at 200yards a little seating depth adjustment and it's a one hole load.

View attachment 131909

Looking mighty good! Primers look fine too

 

[ramrod79]

Looking mighty good! Primers look fine too

It's promising the twins are 60.5 single is 56.5 not any noticeable difference.

 

[slv hunter]

Glad you got things worked out. Great to have some help sometimes. Keep us posted
Thanks for sharing

 

[tdot]

So I ran up to 60.5 gr of Varget with the 250 Berger still no pressure. My 60 gr load shows enough promise to run over chrono early but I will run to pressure to see what I get. My 58,58.5,59 show some promise but not like this. That's .80 at 200yards a little seating depth adjustment and it's a one hole load.

View attachment 131909

What's your Max COAL with that load?

Were you able to keep it to the 2.945" that you loaded awhile ago?

 

[ramrod79]

Todd 2.945 was my 65 Sherman load.
My current with Berger 250 is 2.19 that's 10 off for me. Once I get home I'll do some chrono work get some numbers. I'll also run to pressure see where I end off.

 

[tdot]

Thanks. I've been trying to decide between a short action and the medium length action. I think that settles it for me. I'll go with the slightly longer medium action and be able to load to a moax COAL of 3.2".

 

[ruby76]

Thanks. I've been trying to decide between a short action and the medium length action. I think that settles it for me. I'll go with the slightly longer medium action and be able to load to a moax COAL of 3.2".

With the standard reamer and 250 Berger I'm at 2.9 COAL (.020 off). you would gain some fps with the longer throated version.

 

[ruby76]

Well lately I've been starting over with my testing once I got the ADG SS brass. I was discouraged at first because I was hitting pressure at basically the same loads as my RP brass. The recent issue with the shoulder bump and using a .420 gauge to accurately measure the bump made me rethink my cartridge overall length and where I may be with distance to lands. I admit I made some assumptions with the coal and by setting what I thought was .020 off by reducing the max coal number by .020. Wrong, I know. Why. Becasue I didn't have the proper tools to accurately measure the CBTO. Well, I do now.

Once I measured the CBTO with the 250 Berger, compared to where I was actually loading, I found out I was actually jamming into the lands. Dugh, there's the source of my over pressure at fairly mild loads. I re-tested the same loads over again with the new CBTO of 2.039, and whattya know, significant reduction in pressure. I'm now at a COAL of 2.900 (.020 off), give or take a few thou for differences in the bullets. With RL17 it looks like my goal of 2800 fps and the 250 Berger is achievable. Lesson learned, use the right tools for the job.

On a side but related note. I started by using the 250 Berger elite hunter, and now am using the 250 Berger hybrid OTM. I measured a difference of .005 in the bullet base to ogive between the two bullets. Something to keep in mind if you are using one or the other in your loading.

 

[slv hunter]

Thanks. I've been trying to decide between a short action and the medium length action. I think that settles it for me. I'll go with the slightly longer medium action and be able to load to a moax COAL of 3.2".

I'm saving up for the Defiance Deviant Hunter XM action and bottom metal, is there a better choice for the 3.2 mag length