Help Please.....Ruger M77

[BigPat]

Here is the story.

A mate has a nice Ruger M77 in .223 with its original drop plate and internal box Mag. It has been an extremely accurate rifle and has been well cared for using only factory ammo and benefiting from a decent cleaning regime and low shot count.

Recently the rifle had a new Wraith NV attached which initially gave no problems. Then without warning the gun starts throwing poor groups. It goes from sub Moa to groups of 8” to 14” with no apparent reason or consistency of inaccuracy.

My mate asks for advice and we tell him to strip the gun, clean, recheck and re-tighten everything. So the gun is totally stripped and every part is cleaned, all mounts, rails, action screws etc are checked and tightened during reassembly.

He takes gun to range and no improvement. Thinking this might be a problem with the Wraith we advise him to go back to the range with his traditional scope fitted and try again.

Gun is still throwing terrible groups.

So, after a lot of head scratching another mate suggests he tries feeding the rounds one at a time straight in without using the internal box Mag.

Now the rifle goes back to shooting sub moa and a further 12 rounds down range prove that hand feeding solves the problem.

An inspection of the rounds fed via the internal Mag vs those being fed directly in doesnt show any obvious difference but we will do a proper comparison and check all the measurements....but my Initial thought process is that any damage to the rounds that is capable of making such a huge difference to accuracy would be fairly obvious upon inspection.

So, my question is whether anyone else has ever come across this problem and what was causing it? Is this a known problem with the Ruger M77?

 

[NP435]

Here is the story.

A mate has a nice Ruger M77 in .223 with its original drop plate and internal box Mag. It has been an extremely accurate rifle and has been well cared for using only factory ammo and benefiting from a decent cleaning regime and low shot count.

Recently the rifle had a new Wraith NV attached which initially gave no problems. Then without warning the gun starts throwing poor groups. It goes from sub Moa to groups of 8” to 14” with no apparent reason or consistency of inaccuracy.

My mate asks for advice and we tell him to strip the gun, clean, recheck and re-tighten everything. So the gun is totally stripped and every part is cleaned, all mounts, rails, action screws etc are checked and tightened during reassembly.

He takes gun to range and no improvement. Thinking this might be a problem with the Wraith we advise him to go back to the range with his traditional scope fitted and try again.

Gun is still throwing terrible groups.

So, after a lot of head scratching another mate suggests he tries feeding the rounds one at a time straight in without using the internal box Mag.

Now the rifle goes back to shooting sub moa and a further 12 rounds down range prove that hand feeding solves the problem.

An inspection of the rounds fed via the internal Mag vs those being fed directly in doesnt show any obvious difference but we will do a proper comparison and check all the measurements....but my Initial thought process is that any damage to the rounds that is capable of making such a huge difference to accuracy would be fairly obvious upon inspection.

So, my question is whether anyone else has ever come across this problem and what was causing it? Is this a known problem with the Ruger M77?

My thought is clean the barrel, seen this before in a Ruger M77MK2 . Go until zero copper remains, zero powder fouling and start over with shooting. A few passes with JB compound before shooting wont hurt a thing, just avoid going full on crazy with it. What of the bedding is there a warp issue?

 

[BigPat]

Will definitely get the barrel cleaned again but it has been cleaned after every outing and given a deep clean while the gun was stripped and reassembled......thing is, why will hand fed ammo shoot sub Moa but Mag fed is all over the place. Same barrel so doesn’t feel like a cleaning issue.

 

[alberta boy]

Here is the story.

A mate has a nice Ruger M77 in .223 with its original drop plate and internal box Mag. It has been an extremely accurate rifle and has been well cared for using only factory ammo and benefiting from a decent cleaning regime and low shot count.

Recently the rifle had a new Wraith NV attached which initially gave no problems. Then without warning the gun starts throwing poor groups. It goes from sub Moa to groups of 8” to 14” with no apparent reason or consistency of inaccuracy.

My mate asks for advice and we tell him to strip the gun, clean, recheck and re-tighten everything. So the gun is totally stripped and every part is cleaned, all mounts, rails, action screws etc are checked and tightened during reassembly.

He takes gun to range and no improvement. Thinking this might be a problem with the Wraith we advise him to go back to the range with his traditional scope fitted and try again.

Gun is still throwing terrible groups.

So, after a lot of head scratching another mate suggests he tries feeding the rounds one at a time straight in without using the internal box Mag.

Now the rifle goes back to shooting sub moa and a further 12 rounds down range prove that hand feeding solves the problem.

An inspection of the rounds fed via the internal Mag vs those being fed directly in doesnt show any obvious difference but we will do a proper comparison and check all the measurements....but my Initial thought process is that any damage to the rounds that is capable of making such a huge difference to accuracy would be fairly obvious upon inspection.

So, my question is whether anyone else has ever come across this problem and what was causing it? Is this a known problem with the Ruger M77?

That is a strange one , and I've never heard of it happening with a 77 , or any other rifle for that matter . I can only think that there was a problem with the factory ammo , as in poor neck tension that allowed the bullets to be pushed into the case during loading , but that's just a guess . Interesting .

AB

 

[User00040]

Has there been in a change in ammo brand/spec due to availability issues?

Check that the rounds are pushed all the way back into the box mag, case head flush with the back of the box.

I've seen factory ammo (which is usually loaded with a shorter than average COAL to accommodate all rifles) feed badly with open tip/hollow point bullets. They were catching the top of the barrel (where it meets the receiver) and scraping the top of the chamber. Ironically this was a result of single feeding on the bench at the range. Issue was resolved when magazine was used correctly.

 

[User00026]

How do you hand feed a bolt with extractor claw?

 

[Yorric]

How do you hand feed a bolt with extractor claw?

Some rifles will allow single feeding ok and some won't. It depends on the profile of the extractor. Ruger 77 usually will, some Parker Hales won't.
Ian

 

[Yorric]

If it is a M77 mk1 V, the barrel will be bedded with a forend pressure pad. This needs to be there supporting the barrel when the bedding screws are torqued down. If the barrel is free floated it probably will throw bad groups.
I had a M77V mk 1 in 308 cal. I was a tack driver. I stripped it to fit a Timney trigger and trying to be a clever sod, I removed the forend support pad to free float the barrel. Groups went from sub moa to four inches! I put a pad of bedding compound onto the front of the forend and cured the problem.
Check the action to stock fit and seating, ensure it isn't free floating.

Ian

 

[andyk]

There’s a known issue with some m77 being bedded against the internal magazine. I believe it’s intentional. I’ve seen this on mk2 Hawkeye’s with the all weather stock, which does he have?

my understanding is that it can cause a pressure point and accuracy problems if everything hasn’t been put back together exactly correctly and everything torqued as it should be (there is a procedure to be followed, front screw quite heavily torqued, rear moderately and middle slightly).

On mine, a .243 and previously a 6.5x55, I bedded them in to boyds stocks. The 55 no longer bedded on the magazine having done this, the .243 did. I used a dremmel to remove material from the mag around the trigger guard and floor plate to stop this. No accuracy problems on that rifles part.

Id suggest he focusses on the internal magazine and the correct bolt torqued (which are somewhere on the internet).

 

[andyk]

I’ve just been thinking about this a little more, specifically why it should shoot when single fed but not when magazine fed.

The 6.5x55 internal magazine, when no longer being bedded against the action, would rattle when unloaded. That would stop with even a cartridge in it. The reason being that putting a cartridge in the magazine would cause it to be pushed upwards as the cartridge, pushed by the follower, would press against the feedlips and so push the magazine against the base of the action.

This never caused any issues for me, but does make me think there could be a slight change in the bedding caused by being loaded or unloaded.

 

[takbok]

I also think it's something to do with the magazine box assembly and screw tightening. Has the stock still got the forend pressure point present?

Lovely rifles but slightly fiddly bottom metal and bedding arrangement.

 

[BigPat]

Thanks for all the ideas guys

I think I will get him to bring the rifle over, do a full strip and clean again and then I can check everything that’s been suggested and reassemble. I’ve never owned a Ruger so this is all a bit of a mystery to me.

I suspect he has reassembled this without knowing the correct torque settings, so I will try to find a listing for them and follow that.

 

[bfltd0]

Load a cartridge from the magazine into the chamber, then unload it without firing it.

Similarly, single load a cartridge into the chamber not using the magazine, then unload it without firing it.

Compare and contrast both rounds for COAL, any damage etc against each other and against an unchambered cartridge.

If there is no quantifiable difference, I'd look at the bedding issues raised above.

 

[BigPat]

Load a cartridge from the magazine into the chamber, then unload it without firing it.

Similarly, single load a cartridge into the chamber not using the magazine, then unload it without firing it.

Compare and contrast both rounds for CAOL, any damage etc against each other and against an unchambered cartridge.

If there is no quantifiable difference, I'd look at the bedding issues raised above.

Yep, done that and no obvious difference. Have not put them in the caliper but they look identical side by side so not expecting to find anything significant.
My mate is going to bring it over and I will strip, clean and reassemble again with a close eye on the bedding.

 

[BigPat]

Update...

Have today, completely stripped the gun down and given it a very deep clean. To be fair it had been kept in good condition but I treated as if it hadn’t. So I can say with complete confidence that there is no build up of copper, gilding metal, lead or carbon in the barrel. The barrel shows no sign of pitting and the rifling is nice and sharp. The crown is spotless as are all parts of the action and bolt. I have inspected the stock pre and post fitting and the only possible issue I found was that due to it being a fairly flexible black plastic stock it was quite easy with minimal pressure to make the barrel touch at the front. So I have opened the end up a bit and now there is more clearance and it stays free floating even under firm pressure.

Unfortunately, my buddy forgot to bring any ammo so I couldn’t check the pre and post cycling dimensions but will do that tomorrow.

In terms of the front support pad that was mentioned earlier, this is a Mk2 M77 so perhaps it doesn’t have one? I certainly couldn’t see any sign of such a pad. The only raised part towards the front of the forend is where the sling stud is fitted......is this where the pad is supposed to be?