At whitts end with .Sendero .338 RUM load development.

[Speedygoss]

Set up:
Remington 700 Sendero Chambered in .338 RUM. Factory 1:10 twist barrel.
Timney trigger
Vias Brake
Bedded in factory HS Precision stock.
Seekins 4/6 rings on bedded seekins 30MOA base.
Vortex Viper 6-24x50 PST FFP Scope.

This riffle has been giving me fits trying to find a great load for it.
Really only interested in hunting bullets. I have tried 250g and 300gr. Bergers and 300gr. Nosler accubond in every configuration and seating depths using H1000, RE-22 and Retumbo. Best 3 shot group to date is the 250 Berger Elite Hunters with 79.4gr. of RE-22. doing a 10 shot average of 2665fps. .850" group at 100yds. ten shot a 10 shot group to zero at 200 yards. (See Pic.) Set the gong up at 600 yards and its running about a 12" group. Ugh!!! So far all the 300 gr. bullets are completely out. It hates them. 2 1/2" groups at 100yds.

 

[Daveinjax]

It could be a lot of things but I would suspect the factory nature of your barrel and action or your loading techniques or combinations. It can be much harder to find a load for a factory barrel and untrued action. My factory 700 in 7mm-08 was never good for more than 1" 100 yard groups on a good day until after four years and dozens of combinations I happened on a 140gr berger and h4350 load that suddenly was consistent 1/2" and less at 100 yards and good for less than an 1" at 225 yards which is as long of a range as I have access to. The savings in powder and bullets would often pay for a custom rig from the start I believe and I've decided to go the custom route for all my future rifles. It will not absolutely guarantee I'll get a good shooting rifle thats easy to load for but it sure will make it more likely.

 

[Speedygoss]

It could be a lot of things but I would suspect the factory nature of your barrel and action or your loading techniques or combinations. It can be much harder to find a load for a factory barrel and untrued action. My factory 700 in 7mm-08 was never good for more than 1" 100 yard groups on a good day until after four years and dozens of combinations I happened on a 140gr berger and h4350 load that suddenly was consistent 1/2" and less at 100 yards and good for less than an 1" at 225 yards which is as long of a range as I have access to. The savings in powder and bullets would often pay for a custom rig from the start I believe and I've decided to go the custom route for all my future rifles. It will not absolutely guarantee I'll get a good shooting rifle thats easy to load for but it sure will make it more likely.

Good points, Thank you your your input. Whats the average cost of a blueprint job and aftermarket barrel?

 

[300 ultra]

I had the same issues with mine. I finally found that RL22 and a 225 gr Barnes TTSX was the answer. I dont have the charge off hand as Im at work but the gun shoots 1/2 inch all day. Mine is a Remington LSS with factory barrel, Vias brake and a Timney trigger.

 

[Canadian Bushman]

Ever try tuning the barrel?

 

[highridge1]

I had great luck with 338 rum's with 90 gr of RL25 pushing a 300 gr SMK with fed 215 primer. 2750 fps in a 26 inch barrel.Also try torquing both action screws to 45 inch lbs thats where mine shot the best.If not helping go up 5 inch lbs at a time but no more than 65 inch lbs

 

[mrultramag]

I don't load for 338 rum but do for 7,300, and 375 rum. I would second a vote to try RL25 and IMR 7828.... also, I have had some good luck switching to rem 9.5 mag primers when a load is not cooperating with fed 215. Also run your overall length at maximum magazine length if you plan on using the gun as a repeater and not having to single load the cartridges. This is usually somewhere around 3.670 on the rums I own. Make sure your reloads are concentric. Maybe check the crown of your barrel. Run your loads on up towards max. Rums can shoot well right up around max charge. This would probably be somewhere in the neighborhood of 3000 fps with 250 gr bullet. Check manuals to be sure. Hope you get it figured out. Nothing sucks worse than a new toy that doesn't perform.