Loading for a 7X57 Ruger M-77

[Bob C]

I've been trying different loads for four months in a M-77 Ruger in 7x57. My rifle is an older one, made in the early '80's. Some loads did badly, and some have done reasonably well most of the time.

By reasonably well, I mean I've gotten three or four groups around or under 1.5" with a load, and then for no apparent reason I get a group around 2.5" with the same load.

The bedding was not even in the barrel channel, so I've free floated the barrel. That seemed to help some what.

Also, using a Stoney Point gauge I've found that my rifle has an exceptionally throat, almost a free bore in the chamber. My next loads to try will have the bullets seated about .2" over the recommended length shown in the reloading manuals.

Any other ideas, or any comments are welcome.

 

[cma g21]

You might try heavier (160 - 175 grain) bullets.
If this doesn’t work, you might consider rechambering to .280 Remington.

 

[Jim Watson]

A friend of mine had the same rifle with the same behavior. Tried the same things, plus a trip back to Ruger. Didn't do much for it.
He ended up having it rebarreled to .280; the 7x57 chamber neck was so large and the throat so long that a .280 reamer would not have cleaned it up. It now shoots like a champ, accurate and velocity so close to 7mm Rem Mag as to make no difference. But it was not cheap.

I'd try the heavy bullets loaded as long as the magazine would take and see if I could get reasonable accuracy.

 

[Bob C]

Thanks for all of the suggestions. I had a long range session today, trying different loads with the bullets seated out as far as the magazine would allow. Powder charges were all at or very close to maximum in the Sierra or Hornady manuals. All groups were three shots and all were at 100 yards. For 18 groups, I got two at 2.1",one at 2.0", and everything else I tried was under 2". Even better, I found one load that stays just under MOA at 100 yards.

First was a 154 SST with RL-19. Groups weren't great, but were more consistent with one group at 1.7" and two at 2.1".

I then tried the Sierra 160 BTHP Gameking with RL-19, and things improved. Groups were 1.6", 1.3", and 1.7".

Next were four powders, all with the 175 Hornady Round Nose bullet. These did very well, with two of the loads giving very satisfactory results.

With RL-22, I got 2.0", 1.8", and 1.2".

With H-4831 SC, I got 1.2" , 1.6" and 1.7"

Then things really turned for the better:

With IMR 4350, I got 1.0" .9", and .7".

With RL-19, I got 1.3", 1.2", and 1.3"