Help! Ruger 77, 7mm Remington Mag

[deadeye2]

O. K. guys, first let me say that I do not claim to be a gunsmith, but I have always been able to get all the rifles that I shoot or have worked on to shoot a three shot group at 100 yds that was one inch or under. A friend brought his Ruger 77,  7 mm Remington Mag  to me last fall. He wanted me to work up load for it and tune it as needed. I messed with that Ruger off and on for a LONG month. I could not get it to stop throwing the second or third shot! I was to the point that I wanted to break it over the shooting bench!!! Below you can find listed the things that I have tried. Oh yea, he wants me to try again this fall, I had hoped he would trade it off! I am out of ideas !

1.) Bedding tried: Bedded action floated barrel, then full bedded it. I could see little or no improvement between these two methods.  I then tried a little pressure between the forearm and the barrel. When I did  this  the groups did go wild !

2.) Trigger:  Crisp 32 oz.

3.) Scope and mounts: The bases are tight and loctite was used. The scope is a Redfield  3x9. I wondered if it was the problem so I sent it to OBS and it checked out O.K. I also have tried this rifle using my Leupold  VXIII, 4 1/2X14, the problem was still there using the Leupold. The scope is level to the rifle for sure.

Ammo, I used hand loads only.

1.) Powders tried: H4350, IMR4350, H4831, IMR4831, R22 and  R19.

2.) Primers tried: Winchester WLR, Remington  9 ½, Federal 215, Federal 215 match, and CCI 250.

3.)  Brass tried:  All brass was full length sized and trimmed to 4.490” before loading. Remington, Hornady,  Federal, and Winchester.

4.) Bullets tried: He wanted to shoot 160 gr bullets, so I have not tried any lighter weights. Both  Nosler Ballistic tip, and Partition 160 gr. Hornady Interlock and SST 160 gr. Barnes X 160 gr.

5.)  C.O.L.: I first seated the bullets .10/1000 off the lands. I tried moving the depth of seating  up and back.

I need advice. I must be missing something!!! HELP!

[Omaha-BeenGlockin]

I would try different bullet weights first-----just cause he wants to shoot 160's---doesn't mean the rifle wants to.

Try 150's AND 175's.

[John Traveler]

hey, Deadeye2!

When you fired your three-shot groups for accuracy, how much time did you allow between shots?

Have you tried firing ONE shot, and letting the barrel cool off 15 or 20 minutes before firing another shot?

Probably too early to tell for sure, but once in a long while, you encounter a barrel that has internal stresses that were not relived during the boring/reaming/rifling/contouring machining.

If it's one of THOSE, the barrel will always "remember" it's internal stresses when heated up, and will never group properly.  It can't.

Let us know how it does when fired cold, allowed to cool between shots, and fired again.

John

[gunnut69]

I kind of wonder about the groups going wild when a bit of pressure was applied to the barrel.  Is this an old model 77.  The angled bedding of the gront screw can make a good job difficult.  Usually when when a rifle throws a round or to out of the group I have found one of 2 things.  The action is 'torqued' a bit or the front action screw is bottoming out.  With the rifle going nuts with pressure on the barrel I'd bet on the action not being stress free.  Is there any motion(felt with the fingers) as the action screws are tightened or loosened?  Try the bottom metal also.  If there isn't enough clearance the mag box can bind between the action and the bottom metal.  This stresses the action which can move a bit as the shock of firing is absorbed.  It usually moves from one position to another, hence the 2 groups or the ocassional flier.  A bottomed action screw does something really strange to a rifle.  Usually the rifles reaction is much more erratic than what you describe.  The temporary fix to verify the problem is to shim the action away from the stock until the stress is gone.  then test fire.  I have several rifles but one of my all time favorites is an old M77 in 7mm RemMag that will put 160 Nosler Partitions (3) under an inch all day long.  It's got an old 3X9 Redfield on top and kills quite well.  My best shot was a running coyote at 330+ yards..  First hit a bit to the back, the second applied as he crawled away was on the button...  I love the 7mm clan..  As of now I only have 6 in the vault(mags, 280's, 7X57 etc)..  but the old M77 is a great favorite.

[deadeye2]

Hey Guys thanks for the feed back.

I going to give the Ruger one more try. I have four or five points I want to check again, like the magize and the screws.

I am going try some lighter bullets. I didn't mention that I checked the crown out and found nothing wrong there.

Nor did I mention that I fired both rapid fire groups and cold barrel groups, they were about the same. Bumeeer!!

If the Ruger 77 doesn't group well this round, it is OUT OF HERE! This is the third 77 that I have worked on for friends and I must say I was not impressed with any of them, I think Rugers hate me for some reason!

Be safe, have fun!
deadeye2

[John]

I agree with different bullet weights. I have a ruger that doesn't like 150's but will knock a gnat off a fly's ass at 200 yds. with 165's.

[Omaha-BeenGlockin]

The bullet weight thing is really strange------each rifle is a law unto itself.

Had an A-Bolt .270----130 grainers were a 6 to 8 inch shotgun pattern.

150's would give me 1 to 2 inch groups.

140's OMG!!!  SAME HOLE!!!  first time I shot them---I thought I missed-----esp after how the gun was shooting with the other weights. It wasn't till I walked up to the target and realized what was going on.

Once I found that 140's would work---it put em in the same hole all day long---any timr it was shot---clean or dirty.

Nothing was changed but bullet weight----all were factory loads.


BTW---it was the 140gn Hornady Custom that I always used after that.

[gunnut69]

The rugers are different.  I really like the built in bases..  The old models had adjustable triggers and I've one that's kinda become a friend..  If after all else fails and the rifle still isn't doing what it oughts, try one more thing for me..  Re-cut the crown..  More than once, when at my wits end(a short journey I assure you) I've re-cut the crown and had the accuracy improve remarkably..  I've no certain explanation but it's been suggested to me by a fairly reliable source that the problem may be the button rifled barrels..  The theory is the button rifling process work hardens a thin skin of steel in the bore and the extreme shock of firing causes conchoidal (sp.) at the bore's terminus.  Re-crowning removes the roughness and accuracy returns.  This is just a theory but something you may try.  You may try looking but it is said that 20-30 magnifications are needed to see the fractures.  I've a Remington 223 that doesn't shot as it should and will get looked over as soon as I get the time..  A good friend of mine is a real accuracy fanatic.  He builds some very accurate rifles and his work with barrels and chambering is one of the reasons I've not expanded in that direction..  in any case, he finds the rugers to be great platforms to build from, with one excception.  He dearly hates that angled lug..  He routinely grinds is off and replaces it with a lapped flat washer style lag, a la Remington M700.  It makes an interesting rifle and as all his rifles they tend to shoot bugholes!  Just keep us informed as to your progress!!  Thanks!!

[SingleShotShorty]

Like someone posted just because your friend want to shoot 160 grainer's doesn't make the rifle shoot 160's. I have a Ruger M77MKII Stainless that the only thing that I have done was install a timney trigger, no bedding free floating the rifle is box stock other than the trigger. It shoots 140 Nosler Bt's in the same ragged little hole at 100 yards and shoots Partitions almost as good. You might try 65.5 grains of Reloder 19, Winchester Brass, Federal GM215match primers. This is the load I use for both. I must admit though even with 160's I got under 1" groups with this rifle, I just mainly use it for Deer hunting in open country and the 140 BT's are real Deer Whackers. Hope this helps you out in some way. :-D