Home Forums Reloading Big Game Rifles Need help with my ruger mk ll .260

Does anyone have one of these rifles that can help me with a load for it? I shot it today for the first time using a couple different loads starting with 39.5 grains of h4350 working my way up to 42 grains of h4350 both using 140 grain Sierra BTSP. It wouldn't shoot any better than 2.5-3" 3 shot group.
Sent some Remington 140 gr ammo down the tube and the was about 1.5" 3 shot group. Any suggestions?

Make sure all of the action/mounting screws are tight. Make sure that the stock is free-floated. Possible scope problems? After that, you might try some 129 Interlocks. If it does not shoot those, then you have something going on with the rifle.

I found that H4831 and Ramshot Hunter worked better for me, check your twist too, you may be using to heavy of a bullet 1-8 is good for 140gr but if you have 1-9 you might want to try lighter, I think it took 10 different bullets for me to find the 1 that outshoots all others

Try some flat base bullets. Some rifles don't like boat tails.

I have both a Ruger M77 Mk. II and a M77 Hawkeye (neither in .260 though). It's not uncommon for a Ruger M77 to have a magazine box that is binding. Open the floor plate and attempt to wiggle the magazine box. It's should have a very small amount of play. If not, it's a 5 minute fix with a small file. Go slowly and start by removing 0.005" to 0.010" from the magazine box where it contacts the action. It can make a fair difference in the performance of the rifle.

When reassembling, pay attention to how tight you make the action screws.

When I've asked Ruger what their torque specs are for the M77 Mk. II & Hawkeye they recommended:
Front action screw: 95 in/lbs (i.e. "Farmer tight")
Rear action screw & middle screw: Hand tight and then backed off 1/8” of a turn

I don't follow that advice exactly. I have the less expensive Wheeler FAT torque wrench that only goes up to 65 in/lbs, so that's that I set the front-action screw. The rear I give 15 in/lbs and the middle I set to finger tight and backed out 1/8". Those settings have worked best on my two Rugers.

Double check the base & ring screws. IIRC, Ruger recommends the bases at ~30 in/lbs and the ring screws around 18 in/lbs. Don't over torque them and bind up the scope.

I would try that before switching powders or bullets. And a 1:9" twist is more than adequate for the bullet you are shooting.

Good luck.

I am just getting into reloading for my 260 Remington and have read this same thing in multiple threads. Depending on your barrel twist, you might not be able to shoot the heavier grain bullets.

This old thread on here says it should be 1:8
https://www.24hourcampfire.com/ubbthreads/ubbthreads.php/topics/2575711

Since it shot okay, if not stellar with the factory load, my guess is that it doesn't like your handloads for whatever reason. By all means check the screws and mag box, but in my experience with a couple Hawkeyes, that provided an incremental improvement, but nothing major, as did floating the barrels back to the receiver ring; mostly just rounding out the groups a bit. I think the flat-base bullet suggestion is a good one too, along with maybe dropping the weight a bit. Is it a 1-9" twist?

Having two, they are one in 8 twists...

I run 140s fueled by 44 grains of IMR 4350...MV 2750 fps.

If the rifle don't shoot less than 1/2 an inch at 100 yds,
then somethings loose or the shooter ( Seafire) is jerking the
trigger...

Dave in WV. probably gave you the best advice of all. Try some flat base bullets

You might want to try and mimick your factory ammo as far as COL and seat 5-10 thousands on either side of it. Just a thought. powdr

Try a 129 Hornady over H380

If you're set on a 140 try 45gr of RL19.

I had a MkII Ruger in 260 for a while, and now have a Tikka in 260. I don’t have the answer to your specific question, but i’ll share what I have. Both rifles really shot well with a near max load of imr4064 behind Nosler 100 gr BTs and a warm load of R17 behind the Nosler 120 gr BTs.

Thanks guys. I'll give it a try!!!