.300 Ultra Mag & 7 RUM Reloading Questions....

[sakoshooter]

Hello All,

I am currently taking a break from reloading my competition rifles and I am now currently working on load developement for a couple of hunting rifes, but I'm having some troubles and wondered if anyone could help me out?

The .300 Remington Ultra Magnum belongs to a buddy of mine and he's wanting to run 180 gr. projectiles. I believe the twist rate is 1-in-10. I've been trying IMR-7828, and it's getting close to what I want to group at 100 yards, but I just can't seem to get the load over the last little hurdle. Any ideas on different powders and powders charges??

The 7mm Remington Ultra Magnum belongs to my wife. I'm not sure about barrel twist rate in this gun. My wife like's shooting both the 140 and 150 grain projectiles, but prefers the 140's. I tried running some Retumbo through it, according to reloading specs, but the gun hates it. It's currently pulling 4-inch shot groups at 100 yards.

I'm thinking about trying some Reloader 19 in the .300 and maybe some H-1000 in the 7mm. Anyway, any advice and ideas on some new loads for both of these hunting rifle would be great. I sure would appreciate it guys. Thanks for your time.

Until next time; Keep you powder dry.

Sakoshooter.

 

[jrpilot]

Re: .300 Ultra Mag & 7 RUM Reloading Questions....

Does the 7mm ultra shoot other loads well. With 4in groups, I would think there is something loose or something wrong with the rifle. 4in is spraying bullets.

Try H-1000 in both guns. Great powder. I think there are more people shooting RL-25 in the ultras than RL-19. Dont quote me on that, but that is what comes to mind.

 

[bjohnson_7]

Re: .300 Ultra Mag & 7 RUM Reloading Questions....

I run Retumbo in my .300 RUM and it works great so far. I shoot a 180 Accubond with 101.5 gr under it.

 

[MitchAlsup]

Re: .300 Ultra Mag & 7 RUM Reloading Questions....

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sakoshooter</div><div class="ubbcode-body">The 7mm Remington Ultra Magnum belongs to my wife. I'm not sure about barrel twist rate in this gun. My wife like's shooting both the 140 and 150 grain projectiles, but prefers the 140's. I tried running some Retumbo through it, according to reloading specs, but the gun hates it. It's currently pulling 4-inch shot groups at 100 yards. </div></div>

There is a good chance you are at an anti-accuracy node.

 

[brand692]

Re: .300 Ultra Mag & 7 RUM Reloading Questions....

Retumbo, H1000, or RL 25 in the 300RUM.

People often complain of accuracy problems with Retumbo, but I've had decent luck with it. H1000 and RL25 tend to do better in the accuracy department, but they are a lot further from 100% case capacity. Mine is a 12 twist and shoots anything up to the 180s. Have shot the Nosler 180s at 3200 easily with RL25.

Don't have a 7mm, but considering the chambrage is on the 7mm, that you will have to use something real slow, ie H1000 or Retumbo. But again, I don't have a 7RUM.

 

[bohem]

Re: .300 Ultra Mag & 7 RUM Reloading Questions....

Just to note on Retumbo, I run it in a 6.5-06

I noticed about 0.5gr of a window where the groups were tight little knots at 100yd. Then they started to open up quickly.

They did improve in both ES/SD and accuracy as I got the case towards 100%+ filled, currently QL says I'm putting 113% in the case and it's printing under 2" at 600yd.

Just some food for thought when using Retumbo.

 

[jyd]

Re: .300 Ultra Mag & 7 RUM Reloading Questions....

I just worked up a load for a 7mm RUM. 85 grs. of Reloader 22 with 168 gr. Berger VLD hunting. I seated them so they would just fit in the mag.. The groups were a little under a 1 MOA. at 100 yards and have a speed of 3177 FPS. This is from a off the shelf type rifle with some trigger work and a muzzle brake. Hope it helps.

 

[sakoshooter]

Re: .300 Ultra Mag & 7 RUM Reloading Questions....

Thanks for the help guys. I really appreciate it. I'll definitely be looking into each and every different thing that all of you guys mentioned. If there's anything else that you can think of, please don't hesitate to post again.

 

[GMR]

Re: .300 Ultra Mag & 7 RUM Reloading Questions....

I no longer have my 300 rum in fact I bumped it to a 300 tomahawk. But for loads ( 300 RUM) I love the 178 AMAX and use ramshot big boy ( now magnum!!!) and run 93.5 grns. Tack driver


300 Remington Ultra Magnum (RUM)
Barrel: 24" &#9632; Twist: 1-10" &#9632; Primer: FED 215 &#9632; Bullet Diameter .308"
Magnum 150 BAR X 92.1 3,108 102.3 3,453 62,630 3.600
Magnum 150 HDY SST INTK 91.4 3,076 101.5 3,418 59,580 3.585
Magnum 150 SIE SBT 91.8 3,094 102.0 3,438 61,120 3.500
Magnum 165 NOS PART 90.0 2,967 100.0 3,297 59,880 3.600
Magnum 168 HDY A-MAX 90.3 2,991 100.3 3,323 63,710 3.590
Magnum 168 SIE HPBT 92.5 3,120 102.8 3,467 62,180 3.535
Magnum 180 BAR X 85.3 2,835 94.8 3,150 62,300 3.600
Magnum 180 HDY BTSP INTK 87.8 2,903 97.5 3,226 62,480 3.565
Magnum 180 NOS PART 86.4 2,894 96.0 3,216 62,400 3.575
Magnum 200 SIE SBT 85.7 2,732 95.2 3,035 62,910 3.600
Magnum 220 SIE HPBT 81.9 2,583 91.0 2,870 62,940 3.600


I like the powder has been very temp stable, ball so it drops with no issues. Clean burning. For the real long range load

220 grn MK with 88.7 grns has been the best out of my gun. My gun though loves to jump the bullet into the lands. I am running .060 off the lands.

Maybe this is of some help. Good luck

 

[yoterunner]

Re: .300 Ultra Mag & 7 RUM Reloading Questions....

I'm having a great time working up my 300 RUM with Retumbo. Currently loading 210 Berger VLD's with 92grn of the Retumbo. Much different bullet then OP is shooting, but I had read a lot of RUM shooters using Retumbo and having good luck with it, so I went that way.

 

[89t295k]

Re: .300 Ultra Mag & 7 RUM Reloading Questions....

7mm Sendero RUM here, I have not gone over 86G(max) of retumbo yet but, the groups are improving as I fill the case more. .6 and .5's so far @ 3020fps with 180's. not seeing any pressure signs so i may just see what a little more does bit by bit.

 

[Enios]

Re: .300 Ultra Mag & 7 RUM Reloading Questions....

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 89t295k</div><div class="ubbcode-body">7mm Sendero RUM here, I have not gone over 86G(max) of retumbo yet but, the groups are improving as I fill the case more. .6 and .5's so far @ 3020fps with 180's. not seeing any pressure signs so i may just see what a little more does bit by bit. </div></div>
Same rifle several years old now, but running 92 to 92.5 with old Barnes 140 XLC, 140 fail safes, and 160 AccuBonds. All with excellent accuracy and running over 3200 fps, nearer 3300 with the 140's.

 

[Big Jedd]

Re: .300 Ultra Mag & 7 RUM Reloading Questions....

Sakoshooter,
Im using a powder from the Thunderbird Cartridge Company, T870. Meters really really good. I'm told it's exactly like the old H870. I use a 100 grns behind a Berger 168 vld. Really fast and no pressure signs. C.O.L. 3.70.

 

[Ghogs Nightmare]

Re: .300 Ultra Mag & 7 RUM Reloading Questions....

I like 4831SC and Retumbo in my 300RUM
.
Used the following in Africa:
200gr Nosler AB
94.7grs Retumbo
Win LR Mag
ave vel: 3140fps
oal: 3.60
.
Also like 190SMK
88.5 H4831SC
Win LR Mag
not chrono'd

 

[rschneider]

Re: .300 Ultra Mag & 7 RUM Reloading Questions....

I use R-22 start at 91 and the best group was 92.5 .435 in @ 165 yrds.

 

[rschneider]

Re: .300 Ultra Mag & 7 RUM Reloading Questions....

Try using reloader 22 start @ 91.2 and the best I got with 180gr bullets .432 group at 165 rds.

r 22 works well in 7 rum also starting at 89 grs with 140 bullets