300 Sherman Shortmag (SS)

[elkaholic]

So it's too slow? On the burn rate chart its a little faster than a lot of the powders used in your cartridges and in mine, but I guess it acts differently in different cartridges.

I don't think its too slow. You'll be at top pressure with a case full though which is why it works in that case!

 

[Tidesloe]

Its not uncommon for 550 to outperform other powders neat the same burn rate. H100 is a little slower, as you have discovered, and may get close to the same velocity if you reach the same pressure. I try to stay below extractors marks of any kind with my final load, but its good to know where they start to occur. The extractor mark, in and of itself, does not affect accuracy, but normally accuracy will be less at high pressure. (not always) I would go with the one that shoots the best in a ladder test if I were you.

Thanks! I actually thought 100 V was faster until I did the pressure test. I'll continue with it to see if I can even get it to pressure out or not. I know where I'm at pressure wise with the 550, and I do intend to end up somewhere just short of ejector marks. I'd rather better brass life and accuracy than soaking the last bit of speed possible out of it. Based on what I've seen an accuracy load of 3000 may be possible without beating the brass up. Wouldn't be disappointed if it's not that high either. It's still smoking performance out of that little cartridge. Pretty darn amazing!

 

[Tidesloe]

I don't think its too slow. You'll be at top pressure with a case full though which is why it works in that case!

I did see pressure at 60.5 but not 61. It was my first shot after cleaning and probably had a little something left behind in the chamber even though I mopped it out with a little bit dirty mop.

 

[Tidesloe]

In my original 300ss I was at 59 3 grains of 100v with a 208 eldm. I'd think you would be right on the edge of pressure now... at least within 2 or less grians. Looking at your numbers I like the way the 100v is flattening out more on your last. 5 grain increment.

Yes and that's a good sign. It could end up being the better of the 2. The 550 hasn't really flattened out like that, and 100V seems to be getting flatter over the last couple of grains. Might be a wider and more forgiving accuracy node in there. I'll know where I get pressure this weekend and then just see where ladders take it.

 

[Tidesloe]

You have a swing in temps there. Be better to stay with H4350 than other. Not much change in velocity in 100 dregee swing. It also depend on how far you are shooting.

That is good info to have. I've never seen this but I knew I'd be more affected than the Extreme powders. I think for the most part it in hunting scenarios it shouldn't have a big effect and something I might actually test through the year to see for myself. I'm hands on. It would be interesting to see for sure, and I like to shoot at extended ranges.

 

[Mike Matteson]

That is good info to have. I've never seen this but I knew I'd be more affected than the Extreme powders. I think for the most part it in hunting scenarios it shouldn't have a big effect and something I might actually test through the year to see for myself. I'm hands on. It would be interesting to see for sure, and I like to shoot at extended ranges.

I know I have used H4350 in weather from over 100dr to -20, At yardage of out to 500yds. No noted different in impact either. Long before that I was using IMR powders. Weather only change 50dr at most, and below a primer out of the case.
I will say I do load hot. In my belted mag generally 5+ grains over manual call out. I stop at creator primes or just before that on my loads. No ejector marks either. I do a run up of powder in starting out with a new rifle. Increasing at the rate of about .5gr each time in a string of loads. I start out at low loads called out in the manuals and go up from there. I am very careful on adding addtional powder as I go. Not all want to cross the mark, and that fine by me.
Generally I have objective to hit with veloicty in the load I develp. I like most of my rifle to in the 3200 to 3300fps area. That way I don't have to think about my hold. Because they are all about the same drop per yard.

 

[ruby76]

Didn't see if you are using large rifle or magnum primers. I would suggest moving up with H4350, I'm at 63.5 grains and a F210M in my 338ss, 210 grain bullet. Shot it in cool and warm temps safely, great accuracy and at 2850. No drop tube, full case.

 

[Tidesloe]

Didn't see if you are using large rifle or magnum primers. I would suggest moving up with H4350, I'm at 63.5 grains and a F210M in my 338ss, 210 grain bullet. Shot it in cool and warm temps safely, great accuracy and at 2850. No drop tube, full case.

2850 is pretty good velocity. I've also got a 338 SS, but it's an 18 lb rifle set up for target shooting and I haven't done much with it since load development. I think I was getting 2813 fps with Varget, 250 gn Berger. I don't remember what my charge weight is on it. My 300 SS I'm using Fed 210. You might have convinced me to see what I can end up getting out of 4350. This 182 gn HHT I'm working up isn't what I plan on shooting, but what I'm working up for 1 hunt in October, then I'll be working on 215 gn Berger. I remember your testing notes on your 338 SS. Did you end up where you want to be on it?

 

[ruby76]

I remember your testing notes on your 338 SS. Did you end up where you want to be on it?

Super happy with it now. 8 3/4 pounds, no brake, and cartridge fits in a factory Rem 700 short action mag box with a 210 Barnes. Shoots bug holes

 

[Tidesloe]

Super happy with it now. 8 3/4 pounds, no brake, and cartridge fits in a factory Rem 700 short action mag box with a 210 Barnes. Shoots big holesView attachment 488316View attachment 488317

Very nice!! Not much way to beat that. I think if mine were configured for hunting, I'd still be shooting it, and I keep saying I'm gonna rebarrel and restock it. At some point I will

 

[ruby76]

Very nice!! Not much way to beat that. I think if mine were configured for hunting, I'd still be shooting it, and I keep saying I'm gonna rebarrel and restock it. At some point I will

I had the barrel chopped to 22" and turned down, compact LTR stock and Leupold 4.5-14. Took over 3 pounds off the previous configuration. Well worth it.

 

[Mike Matteson]

Didn't see if you are using large rifle or magnum primers. I would suggest moving up with H4350, I'm at 63.5 grains and a F210M in my 338ss, 210 grain bullet. Shot it in cool and warm temps safely, great accuracy and at 2850. No drop tube, full case.

No I don't use mag primers. I feel it's only needed if using the 80+ area. I generally use barrels that are 26"+. I use Fed 210's primers. I was using a 308 NM with 165gr Nosler BT or AB bullets. I use 200grs Noslers BT or AB in my 338 WM. Having a 338 WM with a 28" barrel being built presently. I might get this year. . I have to grin and bear it. It's only 7 years in trying to have that rilfe built. So you can laugh with me or at me

 

[ruby76]

No I don't use mag primers. I feel it's only needed if using the 80+ area. I generally use barrels that are 26"+. I use Fed 210's primers. I was using a 308 NM with 165gr Nosler BT or AB bullets. I use 200grs Noslers BT or AB in my 338 WM. Having a 338 WM with a 28" barrel being built presently. I might get this year. . I have to grin and bear it. It's only 7 years in trying to have that rilfe built. So you can laugh with me or at me

Sorry, my comment was meant for Tidesloe

 

[Tidesloe]

Super happy with it now. 8 3/4 pounds, no brake, and cartridge fits in a factory Rem 700 short action mag box with a 210 Barnes. Shoots bug holesView attachment 488316View attachment 488317

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.