FINALLY Got to Shoot My 338 Ultra Mag.

[LongBomber]

My edge AI just does not like the 250AB, I went through a box with never finding a group under 1moa, from a rifle that groups berger hybrids into 0.3-0.4 moa for 5 shots. I picked up a box of barnes 225ttsx to try last weeked. I ran them 0.050" off the lands, in nosler brass, cci 250 primer with retumbo, running from 91 - 95gr in one grain steps. I had no problem getting them into half moa at 200. I settled on 93gr which was the max load for the 338rum in the Barnes manual.

I would swap bullets, either the 225 AB or ttsx. You could burn two pounds of powder trying loads and never find a accurate load with the 250.

 

[Good]

I know this is apples and oranges, but after all the hype of R17 and 208 AMAXs, I tried it in my '06. My gun hated it. Most of my load development is 200yds or further depending on weather conditions. Going up near max load had the 208s moving at 2730ish out of my factory 22.5" sporter. Again, the gun hated it to the tune of 4" vertical dispersion at 200yds as the best group confirmed over and over.

I changed powders to h4831 and I'm not getting the velocity with the 208s, but the accuracy is back down under MOA. For me, vertical needed less powder, not more...

I think you're still too hot and judging from your chrono numbers, I'd look around 88.5. If you don't want to drop that far, looking at your pictures, 94.5 might be a node as there isn't much vertical, just a bunch of horizontal.

But before all that with no offense intended, focus on "you". Make sure you're doing everything right. Proper weld, not torquing, pulling straight back with hand, pulling trigger straight back, etc. Dry fire or shoot a 22 a bunch while practicing all that.

 

[Outlaw6.0]

Have any of you guys tried the sierra match kings in 300 gr? I have heard of it being used in the 338 edge but I haven't heard of anyone trying it in a 338 Rum. I am jsut getting started and needing some info. Sierra's website shows the ballistic coefficient on it at .760 at 2300 fps and above, so that sparked my interest.

thanks for the info guys, happy shooting

I am using the 300grn SMK in my RUM, IMR-7828 produced av velicity of 2812 & 1/3 MOA at 100. But primer pockets only last 2 loadings.... dang Rem brass... anywho, Kirby Allen was stating that the actual BC of the SMK is closer to .800... I haven't had the chance to stretch mine out yet... I'm playin with Retumbo now.

 

[Good]

I am using the 300grn SMK in my RUM, IMR-7828 produced av velicity of 2812 & 1/3 MOA at 100. But primer pockets only last 2 loadings.... dang Rem brass... anywho, Kirby Allen was stating that the actual BC of the SMK is closer to .800... I haven't had the chance to stretch mine out yet... I'm playin with Retumbo now.

I plan to try Retumbo first when I get the cashola to get my barrel threaded on.