Over the last year, I've been running a bunch of rounds through my 7mm RM hunting rifle trying to find a load that will shoot better than off the shelf Remington 140gr Cor-Lok rounds, but I still am having no luck. The gun is a Ruger M77 Mark II All-Weather with a 24" SS barrel with 1:9.5 twist. I've been using Hornady 139gr. SST bullets seated deep enough to be just slightly off the lands and they will still fit in the magazine. I'm using H-4831SC powder ranging from 63gr up to 67gr with no luck. The best groups I've been able to get are around 1.5" at 100yds using 64gr of powder. I guess that's not too bad for an off the shelf hunting rifle, but the groups are not very consistent. I seem to get a bunch of strays that are sometimes up to 2" out of the group. At 50yds the groups are actually bigger than at 100yds. I've been reading a lot lately about certain bullets not wanting to stabilize very well if the barrel does not have the correct amount of twist to it. Or taking longer distances to stabilize. Could that be my problem? Are the 139gr boat tailed, ballistic tipped SST bullets a bad choice? Would I get more consistent & tighter groups farther out (200-300yds)? Thanks for the help.

Perhaps try seating them deeper. As an example, one of my .308 Win rifles prefers the 150 SST seated 0.050" off the lands. It shoots groups with that load which are 1/2 the size of groups seated 0.020" off the lands. So go figure?



On another note, I wouldn't get too excited about the accuracy potential of any Ruger M-77. Most Rugers M-77s I have owned (about 9 in various calibres), don't do better than 1.25 - 1.50" consistently. And that is for 3 shot groups at 100 yards. While some on this forum report 1 MOA or better accuracy, I feel they are kidding themselves and reporting the fluke best ever group. Rugers are not known for high-quality barrels. What do you expect for that price?

Don't worry about poor groups with Hornady SST'S, they don't group well in any rifle I own either. I have tried them in 25, 26, 27, 28 cals. With no luck.

If you can't get a Sierra, or Nosler Ballistic tips to shoot better groups, maybe you better check the barrel etc. But in my experience, limited to the cals above, SST'S don't group as well as just about any other bullet.

Jerry

I am on my 3rd 7mag-Have used the same load in all three guns. Hornady Vol#2. Max was 71.4- 3400fps and 69.8-3300 which I got 3250av.fps. I have always used H4831 and a 139gr Hornady. 1st one was a savage 110-flat base bullet 1in grp.--2nd was a ruger-flat base 1in grp.-3rd is a Wby VGX and only the Wby would shoot the 139gr boat tail's and flat base bullets in a circled quarter. htt://stevespages.com/page8a.htm has the same Load Data. Had a Ruger 300Win mag half bull barrel, even a flat base bullet in any grain 150--192gr and 5 different powder's would only get a 2in grp at 100yrds. It would not shoot boat tails either in a decent group. Traded it in on the Wby 7mag. You're groups at 100 yrds would be off a ways, may be 5-6 in at 300yrds per say if you are getting 1-1/2 and a 2in flier at 100 yrds. I always seated mine around the crimping grove or cannelure. Try a 139gr or a 154gr hornady interlock flat base bullet, or a 160gr bullet. Mine all had a 9 1/2 twist and 24in barrels.

Have you tried other powders?

I ordered some heavier ones to try myself.

As for Rugers accuracy, I have had as good from them as anyone and my biggest dissapointment ever was a Rem 700 BDL in .22-250! I do have a .338WM in a M77 that will print MOA all day with Sierra Gamekings and close to that with Partitions.

My seven is a production Model 70 Super Grade and it shoots well with 140 gr. Sierras but does much better with 150-162gr. bullets. The 175gr. seem to shoot like the 140's for accuracy. I seat the bullets at the groove if it has one(Hornady) or at least .010" deeper than touching. You should try some other powders. I'm using slightly over"max" of RL19 with Win mag primers with the 140gr. Gamekings for deer.

I believe I'd try another bullet before I spent a lot of money and bench time with different powders and charge weights. The 7mm Rem Mag is a wonderful cartridge, but muzzle velocity is really too high for best results with 139gr SST's. I'd start with a controlled expansion bullet, or a little heavier bullet to insure the kind of results you'd really want on game. I always shoot 140-150gr Partitions in my 7mm Rem Mag. Accuracy is phenomenal in my rifle and terminal performance is exactly what I expect. You've got plenty of horsepower to handle heavier bullets without sacrificing range or trajectory. That would make for a better starting point for you, IMHO.

I have an all weather 7RM Mk ll 77 with the boat paddle stock. With SC 4831, WLR primers and 140 NP (factory seconds)= 3300 fps and 3/4" or better three shot groups - all I care about. Unlike my other rifles I have not done anything to the bedding - I did modify the trigger myself to lighten the pull. Also added a Pachmyr pad to lenghten the pull and soften the butt. My other M77 is a 338 WM with tang safety. Will also shoot 3/4" 3 shot groups with 210 NP - I did bed the action and forend of the barrel.