My 338 Sherman Shortmag

tdot said:

I need some help/advice from the collective!

Rifle details: 338ss, in a Ti medium length action. 22" barrel. Lands are at 2.100". I have room for 3.200" COAL. 150 rounds down the barrel. ADG brass.

Right from fireforming, I have had pressure signs in this rifle a few grains earlier then other people have reported. Now that I have fully formed brass with 2 firings on it, I'm running some final pressure tests and seem to be a bit slower then I'd expect.

I will get an ejector mark, with only the tiniest flattening of the shoulder of the primer (Fed 215M) as the first sign of pressure. It will typically take 2 grains more powder before I see a substantial flattening of the primer and an increase in the bolt lift.

The gun is going back to the gun Smith to fix a mistake he made on the stock. While it's there, I'm thinking about having him increase the throat by .050" to .100" .

It seems I can get an additional 2.5 to 3 grains of powder in the case, before I hear about the same level of Varget crunch, if I seat it 0.100" further out. Of course this is somewhat meaningless, but thought I'd try.

I do have one load that I'm happy with. It is a Hammer Hunter 213, running about 2850. Loaded .010" off the lands. I cant load this bullet any longer, so if I increase the throat, I will have to jump this bullet further.

But I was hoping to run heavier bullets in the 225 to 250 class.

The pressure tests I've run to-date are, first signs of pressure showed 1 grain above these loads. I've run faster and slower powders, all with similarly or slower results.

235 Hammer Hunter @ 2.090" BTO, w/58.0g Varget, 2670fps

250 Berger Hunter @ 2.090"BTO, w/58.0g Varget, 2600fps


Thoughts on increasing the throat by 0.050" to 0.100"? Any guess on what increase in velocity I might see?

Click to expand...

tim_w said:

What is the COAL of your current loads and those of bullets you might want to use to touch the lands?

Whatever the difference between the longest coal of those and your mags max coal is what you have to play with in increased freebore.

Click to expand...

tdot said:

I need some help/advice from the collective!

Rifle details: 338ss, in a Ti medium length action. 22" barrel. Lands are at 2.100". I have room for 3.200" COAL. 150 rounds down the barrel. ADG brass.

Right from fireforming, I have had pressure signs in this rifle a few grains earlier then other people have reported. Now that I have fully formed brass with 2 firings on it, I'm running some final pressure tests and seem to be a bit slower then I'd expect.

I will get an ejector mark, with only the tiniest flattening of the shoulder of the primer (Fed 215M) as the first sign of pressure. It will typically take 2 grains more powder before I see a substantial flattening of the primer and an increase in the bolt lift.

The gun is going back to the gun Smith to fix a mistake he made on the stock. While it's there, I'm thinking about having him increase the throat by .050" to .100" .

It seems I can get an additional 2.5 to 3 grains of powder in the case, before I hear about the same level of Varget crunch, if I seat it 0.100" further out. Of course this is somewhat meaningless, but thought I'd try.

I do have one load that I'm happy with. It is a Hammer Hunter 213, running about 2850. Loaded .010" off the lands. I cant load this bullet any longer, so if I increase the throat, I will have to jump this bullet further.

But I was hoping to run heavier bullets in the 225 to 250 class.
i

The pressure tests I've run to-date are, first signs of pressure showed 1 grain above these loads. I've run faster and slower powders, all with similarly or slower results.

235 Hammer Hunter @ 2.090" BTO, w/58.0g Varget, 2670fps

250 Berger Hunter @ 2.090"BTO, w/58.0g Varget, 2600fps


Thoughts on increasing the throat by 0.050" to 0.100"? Any guess on what increase in velocity I might see?

Click to expand...

ruby76 said:

My original shorter throat with a 250 berger touched at 2.045 bto, coal to The lands at 2.900. I'm adding .100 throating right now. I'm aiming to also reduce pressure signs and will next be loading 230 Eldx. I also confirmed switching to fed 210M primers from 215's reduced pressure. I have abandoned varget and found H4350 reduced pressure signs, next I want to try H1000 once I get my rifle back.

Click to expand...

ramrod79 said:

Hey Tdot what is your neck bushing size to much tension will also give you pressure. I went 0.0100 past design I run 250 Berger in the lands at 3.20 a 265 AB was 3.39 I run the 230ELDX @ 50 tho off 3.15.
I think more throating if you have mag room.

Click to expand...

tdot said:

What was your max powder/velocity from the 250, before you saw pressure signs?

I tried H4350, but didnt get above 2400fps with the 250, didnt hit pressure. But didnt play any further as I figured it was just too slow of a powder for the 22" barrel and this cartridge. Maybe I need to revisit it.

Interesting about the 210 primer. I hadnt thought of that. Did you see improvements in your fastest loads?

Click to expand...

tdot said:

I use a mandrel to resize my necks. It's .002 under sized. I have one of the Redding dies that doesnt have a neck bushing. It leaves the necks really tight, something like .010" of neck tension, so changed that with a mandrel before firing a shot.

What was your max Varget under the 250?

Did you use the 338ss for your sheep hunt this year? Success?

Click to expand...

ramrod79 said:

61.7 is my max with Varget and 250 that is .5 from extractor marks. I did use it for all my hunting this year only took a WT buck no sheep or late season elk but was a good season have a new hunting partner that likes shooting the 338SS

would be interesting to see if you hit pressure with that load using bushing dies set @ 1to 1.5 NT. Do you want me to send you a couple to try? I'll size to my gun you may have to push shoulders back slightly.

Click to expand...

ruby76 said:

With my 25" barrel I hit around 2700 with 61.5 grains of H4350 and the 250 berger. With a couple different faster powders about the same velocity at a lower charge.

With my primer testing I was very close in speed between 210 and 215, but for sure less pressure with the 210's.

Click to expand...

ramrod79 said:

I know this is along thread that I have read numerous times so I apologize if this was covered. Did anyone ever try N140 in their SS burn rates very close to varget and almost identical to RL15 but faster and cleaner than 15 from what I read. Just looking for another option that may produce a bit more speed than Varget.

Click to expand...