300 Sherman Shortmag (SS)

[elkaholic]

I will be beginning initial testing with my 300 SS this coming weekend. I've got the .180 freebore and intend to shoot Berger 212's. However I'm hunting Elk in the timber in Oct, so I think I'm gonna give some 182 gr Hammer Hunter Tipped a try for this hunt. I sure might loose a little case capacity with this bullet but it really doesn't matter with this load and mostly close range shots. Of the powders I have on hand, I'm thinking I'll do pressure tests starting at 53 gr of H4350, H100V, and N550. Is this a reasonable start?
As far as burn rates go, does the longer bearing surface and harder material in copper bullets affect the go to burn rates in powder selection? I will get back to Bergers after this hunt in Oct, but I've never tested copper bullets and unsure of the theory behind a change to copper bullets. Thanks for any advice or direction you guys might have to give.

I would use 300 saum data and you'll be fine. 53 would be ok. The baring surface and alloy can affect pressure but Hammer bullets with the grooves reduce the baring surface considerably and sometimes run even faster than cup and cores.

 

[Tidesloe]

I would use 300 saum data and you'll be fine. 53 would be ok. The baring surface and alloy can affect pressure but Hammer bullets with the grooves reduce the baring surface considerably and sometimes run even faster than cup and cores.

Thank you Rich!

 

[Tidesloe]

I got out today for some initial pressure and velocity testing, with 3 different powders. I only got through the loads I had for 2 of the 3, before it started getting too late. I'm shooting 182 gn HHT, just for a timber elk hunt in Oct and then I'm going back to what I intend to mostly shoot in this rifle.
I loaded rounds of H4350, H100V, and N550 starting at 55gn to 60 gn. I didn't get to the N550, but the 4350 100V I did. I got no pressure sign of any kind in either, and I'm starting to wonder if I can even get enough in the case to hit pressure. Maybe I can, I'll just have to see on the next go round.
These are my results so far.
H4350
55 gn no velo. Forgot to plug in Magneto speed
56 gn 2738
57 gn 2750
58 gn 2810
59 gn 2856
60 gn 2901

H 100V
55 gn 2713
56 gn 2744
57 gn 2770
58 gn 2848 Big velocity jump.
59 gn 2880
60 gn 2913

With no signs of pressure at all obviously I need to keep going, and I'm expecting about the same from N550. I'm questioning if the powders are a little too slow for this light of a bullet and 24" barrel. Another thing to add, I'm at .001 neck tension. I'm going to .002 maybe even .003 next time. I'm assuming this may help build pressure??

Any recommendations, suggestions and advice is sure welcomed.

 

[elkaholic]

I got out today for some initial pressure and velocity testing, with 3 different powders. I only got through the loads I had for 2 of the 3, before it started getting too late. I'm shooting 182 gn HHT, just for a timber elk hunt in Oct and then I'm going back to what I intend to mostly shoot in this rifle.
I loaded rounds of H4350, H100V, and N550 starting at 55gn to 60 gn. I didn't get to the N550, but the 4350 100V I did. I got no pressure sign of any kind in either, and I'm starting to wonder if I can even get enough in the case to hit pressure. Maybe I can, I'll just have to see on the next go round.
These are my results so far.
H4350
55 gn no velo. Forgot to plug in Magneto speed
56 gn 2738
57 gn 2750
58 gn 2810
59 gn 2856
60 gn 2901

H 100V
55 gn 2713
56 gn 2744
57 gn 2770
58 gn 2848 Big velocity jump.
59 gn 2880
60 gn 2913

With no signs of pressure at all obviously I need to keep going, and I'm expecting about the same from N550. I'm questioning if the powders are a little too slow for this light of a bullet and 24" barrel. Another thing to add, I'm at .001 neck tension. I'm going to .002 maybe even .003 next time. I'm assuming this may help build pressure??

Any recommendations, suggestions and advice is sure welcomed.

Unless the bullet is taking up case capacity, you should make pressure. N550 is more dense and has more energy than the other two. I suspect you may hit 3000 with it. If not try H414 or even Varget.
RL15 may work too?

 

[Tidesloe]

Unless the bullet is taking up case capacity, you should make pressure. N550 is more dense and has more energy than the other two. I suspect you may hit 3000 with it. If not try H414 or even Varget.
RL15 may work too?

Ok thanks! Maybe N550 is gonna work. Heck I suppose they might all work. The H4350 is gonna be low on velocity either way and probably won't test that any farther. If not I've got Varget and will try it. I've also got a little N540? N550 is what I'm hoping works with 215 gr Berger. I've got a lot of it, and I came up with a jug of that magic ferry dust after 3-4 yrs of trying to get, that I'll also try with 215's.

 

[Idaho Trecker]

I've been a big fan of 100v in the 300ss. It has worked well from the 180 to 225 grain bullets I've shot. I'd definitely continue on that path and see where you get.
I've had the itch lately to form some more brass and scope up my original 300ss. Maybe after hunting season I'll get around to it.

 

[Tidesloe]

I've been a big fan of 100v in the 300ss. It has worked well from the 180 to 225 grain bullets I've shot. I'd definitely continue on that path and see where you get.
I've had the itch lately to form some more brass and scope up my original 300ss. Maybe after hunting season I'll get around to it.

I'll certainly test on out with it. It shot better than 4350. I'll continue on with 100V and N550 in the next day or two. That 182 gr HHT actually works pretty well in it and isn't taking up case space.

 

[Tidesloe]

I got back out yesterday evening. My questioning wether I'd hit pressure or not were put to rest.
Here are the results comparing H100V and N550.
H100V. N550
55 gn - 2713 2774
56 gn - 2744. 2823
57 gn - 2770. 2869
58 gn - 2848. 2934
59 gn - 2880. 2982
60 gn - 2913. 3044 Max load
60.5. - 2944. 3070
61 gn - 2952. Still no pressure
I have a couple of questions here. I didn't expect so much more velocity with N550. Is this normal?
At 61 gn H100V I'm still seeing no pressure signs. N550 60 gn is about max without beating brass up too bad. Potentially I'm guessing I may get a better case fill with H100V and possibly near 3000 before I see pressure, and would that be more desirable?
My last question is with ejector marks, does primer pockets loosening typically go along with that and does ejector marks affect accuracy at all? I never hear talk of that, but it seems to me that it could?
N550 was the most accurate. Last 4 loads at 2.5 gn spread went into just slightly over .5"

 

[Hudge76]

I've used 100V in .338 WM and .300WSM and a couple more cartridges. I've yet to have any pressure signs from it. I ran out of case room first.

 

[elkaholic]

I got back out yesterday evening. My questioning wether I'd hit pressure or not were put to rest.
Here are the results comparing H100V and N550.
H100V. N550
55 gn - 2713 2774
56 gn - 2744. 2823
57 gn - 2770. 2869
58 gn - 2848. 2934
59 gn - 2880. 2982
60 gn - 2913. 3044 Max load
60.5. - 2944. 3070
61 gn - 2952. Still no pressure
I have a couple of questions here. I didn't expect so much more velocity with N550. Is this normal?
At 61 gn H100V I'm still seeing no pressure signs. N550 60 gn is about max without beating brass up too bad. Potentially I'm guessing I may get a better case fill with H100V and possibly near 3000 before I see pressure, and would that be more desirable?
My last question is with ejector marks, does primer pockets loosening typically go along with that and does ejector marks affect accuracy at all? I never hear talk of that, but it seems to me that it could?
N550 was the most accurate. Last 4 loads at 2.5 gn spread went into just slightly over .5"

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.

 

[Tidesloe]

I've used 100V in .338 WM and .300WSM and a couple more cartridges. I've yet to have any pressure signs from it. I ran out of case room first.

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.

 

[Mike Matteson]

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.

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.

 

[Hudge76]

I wouldn't say it's too slow, but it depends on the application it's being used. On my .338, I think it's my brass I'm using, but I could be wrong. I'm compressed at 3 grains under the Barnes online load data.

 

[Idaho Trecker]

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.