M77 MkII "Tuning"

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mr surveyor

Blackhawk
Joined
Apr 4, 2008
Messages
597
Location
Texas
Recently I picked up a like new stainless M77 Mk II .243 with Boyd's laminate stock, with an inexpensive Nikon ProStaff 3-9 scope. Very nice looking, and made with the normal Ruger "built like a tank" construction. The first range trip was a bit disappointing with "remanufactured" 100 grain from Wisconson Cartriges Co, Winchester 80 gr, and Rem CoreLockt 100 grain. I knew the gun was better than 3 inch groups at 100 yards off sand bags, but three more range trips, including Fusion 95 grain rounds didn't prove much better. So....I ran the archives here the other night and found a thread from quite some time ago that settled my problem perfectly. The simple answer was in fact what was buried in that thread....proper torque on the action screws. A couple of days ago I decided to check the three screws for basic tightness, then run out to the gunshop and check with a torque driver. The front trigger guard screw wasn't even snugged up, so I hand tightened with a screwdriver, and lo and behold the floor plate wouldn't lock in. I scratched my head for the last two days trying to think of how to correct the problem, thinking the Boyd's stock must have been a bit out of spec. after a hundred rounds of ammunition downrange, and a bit of disappointment, a tiny shim made from a plastic coffee can lid, between the front base of the trigger guard and the wood made the necessary difference. A quick range trip proved successful. I shot several varieties of 80 to 100 grain ammo again, and my last to three round groups were amazing. The Fusion 95 grainers shot two 3 round groups (seperate targets) that could be covered with a nickle, and the with two targets overlayed the 6 rounds could have been covered with a quarter. NJow I can confidently start the quest for the "perfect load".

A big thanks to this forum and the archived information.


surv :D
 

langenc

Single-Sixer
Joined
Aug 22, 2007
Messages
471
Location
Lewiston, MI USA
So would you care to put a number on the correct torque for the screws.

I have a 77-223 that I am having problems with. I read some things on theis site last week. I cleaned the bore, removed the stock, replaced and tightened what I feel is adequate. I dont tighten stock screws nearly as tight as a few years ago.

Somewhere I read that a business card (or maybe 2) under the stock foreend helps w/ groups. It didnt this one.

I have targets w/ nice groups from a couple years ago. I dont know???
 

MADISON

Single-Sixer
Joined
Jan 4, 2000
Messages
175
Location
Roanoke, Virginia, 24017
I had the same problem with my Ruger MK-II in .223 Remmington.
It shot a 3 inch group. The "pencil thin" barrel would get hot and sling rounds everywhere.
I downloaded it until it now shoot dime size groups at 100 yards.
 

Black Frog

Single-Sixer
Joined
Nov 26, 2008
Messages
104
Location
SE Cheeseland
Just keep in mind that those torque settings are only going to be 'ballpark' settings. Since the Rugers have a forearm pressure pad that is applying upward force on the barrel, when you are tightening the recoil lug screw you are actually 'bending' the stock somewhat. That bending of the stock is what is applying the upward pressure on the barrel.

With any manufacturing process there are tolerances. When they machine out the stock- some of those pressure pads are going to be a bit thicker/thinnner than others. The rifle barrels are not all going to be EXACTLY the same either.

So when people are playing with torque settings on that main screw- it is about the same as playing with different shims at the end of the barrel. Both are changing the upward force of the forearm on the barrel.
 

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