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M77 giving me fits
jaytee
Member Posts: 62 ✭✭
Shot my .260 Ruger M77 today and man what a chitty session of shooting. I shot 3 different loads and none were very good. The first one was a load of 34grs. varget, fed match primers and 129gr.hornady interloks. It measured 3.75 inch and was roughly two and a half inches low and two inches right. The next load was 35 gr. varget, fed match primers and 129 gr. Hornady interloks. This group measured 1.75 inches and it too was an inch and a half low and two inches right. The last 3 shot group was with factory Remington Premier with 120 gr.Nosler Ballistic Tips. This group was just shy of 3 inches and it was about 2 inches high and an inch and a half right. Any ideas as to why the wide range of impact points? How finicky are M77's when it comes to action screw tightness? I've never had the gun apart but maybe its time to check for bedding issues. Any ideas as to what I can do to get this gun to shoot tighter groups? I've also read on a few occasions that in the grand scheme of things, powder charges have a lesser affect on accuracy then most people think. With that being said, what factors have more effect on accuracy; primers, overall length, case length, case weight uniformity? Any ideas would be greatly appreciated!!
Comments
Good luck.
p.s. When I tried to "un-stock" my .257 I was afraid I wouldn't be able to loosen the screws without buggering them. Like they'd been put in with an impact driver. Damnded thing.
When reading about the Browning BOSS, I learned that the Browning factory would often take a rifle that had been returned as imprecise and cut an inch of the barrel, taking the chance that it was an instance where it would help. They did this because it often cured the rifle's problems with no other work, and the customer usually never knew what happened. That experience is what led to the invention of the BOSS.
My synthetic stocked .308 MkII shot to a barely acceptable level (like 2-3" groups depending on ammo) until I had the barrel cut down to 19" and a front sight with long ramp installed. I also floated the barrel just for GP, easy to do with the synthetic stock. The areas where the action bedded looked like they were being clamped evenly so I left them alone. Groups got tiny to the point that I stopped telling people how it shot because they never believed me. I just lucked out, but you might want to try lopping off an inch to see what happens.
Nothing to do with harmonics, just enough to clean up a possibly off kilter crown.
Don't harmonics change with bullet weight and style, powder charge, etc?
Of course installing a BOSS would always be an option, but I'd tackle the least expensive and easiest options first; i.e. remove the stock, check for obvious bedding problems, snug down the actions screws in the proper order, play around with a little "up pressure" at the forend tip, make sure scope mounts are secure and scope is good.
Good luck.
Now, load up 5 rounds at the powder charge(s) that gave the smallest group(s) and re-shoot them (eliminating fluke groups).
Than, using the powder charge that grouped the best from above, vary your seating depth in .010 incriments (both longer and shorter) and shoot another 3 shot test. Finaly re-shoot the best of those groups in a 5 shot test.
If your still not satisified, than it's time to start over with another bullet type (weight or brand or style) or another powder type.
The above is all assuming that their isn't a loose nut behind the trigger [:D]. How does it group with a known quality shooter behind the butt?
1; Check scope ring and mount screws for proper tightness.and perhaps switching scopes may cure the problem.
2; Examine muzzle...be very sure there are no dings at crown.
3; Check bedding screws for proper torque.
4; Clean barrel THOROUGHLY
5: check..(slide a piece of paper down barrel channel) for barrel touching wood.
6; All the above check out ? Then remove action from stock and look carefully at the bedding. You will see where action imprinted wood. Be sure it touched at the front of the receiver, and at the tang area.
As mentioned..at this point, don't worry too much about different loads printing different areas.although this COULD be an indication of poor bedding.
took off the wood and replaced with boyds synthetic, loaded with 150 rn nose grand slams and would shoot the eye out of a deer at 299 yrds. like a dummy I sold it. the wood stock was mis-inletted 1/2 inch to the left
Lots of good information there on troubleshooting your Ruger. I have owned two, and still own one of them. I sold the first for the very same reason you are having problems. It was an original (tang safety) M77. It could group 1"...at 25 yds. My second is a MkII in .257 and the best I can get it to shoot is 1" @ 100 yds. I have just come to accept the fact that without some work that I'm not willing to pay for it isn't going to shoot any better.
With that said I will always take and do all the things I can to a rifle to get it to shoot better. Check the bedding, check the barrel free float. While checking the bedding make sure there isn't any metal underneath that didn't get finished out. Make sure when you tighten the lug screws that they torque correctly. Ruger's are a little different with the forward screw being angled. When I tightened mine back up I started front and rear with the action seated and brought the rear screw to 'just firm' then backed off 1/4 turn. I then tightened the front down to 120 in lbs.(10 ft. lbs) I then tightened the rear to the same. The reason I do it that way is to get it all seated then have the rear in place and loose enough to slide while the front gets fully brought back and tightened.
I think the bullet choice is the first thing to look at when looking for groups as well. My .257 does best with 100 gr. bullets for accuracy. But I get the best velocities for bullet weights with Nosler 110 Accubonds. Not too shabby on the groups either. 1.25-1.5" on the groups. But, the 110's are moving at 2940. That is 100 fps better than best factory out of my short little barrel. Powder choice in my short barrel is limited to faster burning powders as the slower ones won't burn all the way in it. However, slow powders in some long barrels give it a harmonic that freaks it out. I have with a couple of my long barreled rifles moved to a faster powder and the groups tighten up. They did that with most powders. Just a certain speed of burn rate works better. It can be a slower powder with a heavier bullet or it may need to be a slightly faster powder for any lighter bullets.
Lastly, I helped a friend work up a load in his rifle and that was 36.2 gr. of H4895(extreme) behind a 125 gr. partition. His was a Remington, but it ended up shooting consistent inch groups with that load. anyhow, those are just some thoughts. -good luck
EDIT NOTE: Sorry, couldn't read my own writing. It was 36.2 gr. not 38.2 gr. of H4895 Extreme.
Do NOT put any shims 'between' the front action screw and the rear screw..the contact should be right around the screws.
Putting a shim between the screws will actually 'bend' the action, if you tighten the rear screw up very much. accuracy goes right out the window...
Cut some heavy paper about the size of the front bedding area, and punch a hole in it for the front action screw. Several layers will build it enough to try.
This will not give best accuracy...but improvement will tell you that you are on the right track...
Generally, the front screw is tightened to about 50 inch pounds...and the rear about 25-30...in wood.
I kind of look at it this way. You can send the gun back to ruger and they will try to make it more accurate for you. Or for a little time with some sandpaper over the proper sized dowel, you can free float it yourself- the gun doesn't shoot well now so take a chance and free float the barrel. If not you can always put something back in the channel (fiberglass or wood putty-type stuff) to put pressure back on the barrel. Worst case scenario-you totally trash the stock and buy a replacement or aftermarket. It is up to you and what you are willing to risk. If you have no clue what you are doing, I would probably send it back to ruger first. If you have an idea or know someone that does, I would probably take the chance and sand out the barrel channel in the stock.
Glad to see you got it shooting good. Keep us posted.
Glad to hear it's shooting well. For the torque on the screws I will have to correct myself and go with what Highball said...which it appears you did. I tightened mine without any specs to go on other that what the screw can hold by SAE standards. I may just go back today and re-torque mine a little lighter. Might be a one hole rifle after all.
i checked everything, bedding, floated the barrel but the biggest improvement came when i started Crimping my reloads with a lee factory crimp die