Help with 300 ultra groups....

[Lefty7mmstw]

I rebarreled a customers 300 RUM with a 26" #4 Rock Creek Sporter, 1:10, 5R, with a Harrel's Muzzle brake. The rounds are being loaded with 180 Nosler Balistic Tips or 180 Swift Scirocco II. The throat has been opened to 3.315" Thus giving the bullets a .200" jump. I shot 5 shot groups with Reloader 22, H-1000, Retumbo, H-4831SC, IMR 7828. The brass was Remington, Primers were Federal 215 GMM. I full length sized, trimmed, chamfered, anealed, and cleaned primer pockets, between reloadings. My loads with H-4831SC were sub .5moa. and the loads with Retumbo were sub 1. moa. I shot velocities between 3,150 and 3,300fps. Quite a round. I shot over 100 rounds today.

One thing I noticed with the H-4831SC was I shoot 78.5grains with 180 Scirocco in my 300 Win Mag to get 3,1150 fps. With the 300RUM I was shooting 86. grains to get basically the same velocity.

With the 300 RUM it will be nice to be able to shoot 150 grain bullets at 3,400- 3500 fps.
Nat Lambeth

Hell, if I can get the 180's I use to 3300+ fps with rl25 in my rum you can take a 150 to 3600 fps. You are using rather fast powders in your 30 rum for full speed ahead though, especially for 180 grain + bullets. You should nearly be using 50bmg powders. I use rl50 with 225 hornady hpbt's and imr 5010 and wc872 also with both doing very well at modest pressures. It really sucks that my i 5010 went bad as I had a 180 doing 3320 with it at 5 grains below top load tried. I didn't chrono the run-up though so I can't tell you what max was. I need to get some 5010 again but it's very hard to fing good 5010 lately. WC 872 will get you to 3300 fps with a 180 at about full tilt, but I like rl25 better.

 

[snowpro440]

Looks really good with the 91.5 of Retumbo . I would push it a little more., looks to be accuracy between 91.5 and 92 gr,

 

[royinidaho]

Dan,

Took 'nother look at those groups. R U measuring talking edge 2 edge or center-to-center measurement?

The 91.5 load looks 3/4 edge to edge.

 

[IdahoRedneck]

Yes I measured edge to edge......... Is center to center the norm..... oops haha.

 

[IdahoRedneck]

Just measured the 91.5 group center to center...... .48. I was thinkin when you measured a group size it was edge to edge. The 92 grain group center to center went just shy of .75 so I think we'll be able to find somethin right through there somewhere.. Lookin forward to shootin with ya Roy. Dan

 

[royinidaho]

Sheeeesh . . . greenies. . .

Quit lookin' and go to shootin' gun)

 

[cornbread]

Here is a load I load just for target shooting
Hornady A-Max 168 gr.
H-1000 96 gr.
Federal Match primers 215
Factory length and they shoot 1" groups at 300 yardsgun)

 

[royinidaho]

Let's see if IdahoRedneck will post a pic of his big grin after this afternoon's tip to the hills.

One thing for sure, his 300 RUM Sendero is a pretty solid 1/2 MOA in a 26 MPH gusty canyon wind out towards 1200 yds. gun)

 

[IdahoRedneck]

Still grinin.... Couldnt be more happy...that wind was crazy and im still floored I drilled it twice. Most fun ive had in awhile. Ill work on my tinkeritis haha but not with this gun anymore. This one is done other than trueing my drops. Thanks again for takin me up there roy. Dan

 

[royinidaho]

My pleasure.

It was a fun afternoon. The wind taught us some stuff.