Removed & replaced action in stock, went from 0.6 to 2.0 groups. What happened?

[IMtheNRA]

Rem 700 in .300 Win Mag; Remington M40 stock; Remington 26" heavy bull barrel. Bushnell Elite 4200 8-32X scope.

On Friday, this gun was a solid 0.5 to 0.6 shooter. Five rounds at 100 using the stock heavy Remington trigger.

Over the weekend, I installed a Timney trigger and tonight I shot a pair of 2 inch groups at 100. The barrel is not contacting the stock. I used loads from the same batch as Friday's, same bags, same bench, same everything. The scope parallax is set correctly. The scope is not sliding in the rings.

All I can think of is that the scope suddenly failed, or more likely, this rifle is very sensitive to action screw torque. I have no idea what torque the factory used to set the pair of action screws, so when I reinstalled them following the trigger swap, I just screwed them to about the same felt torque as they were when I removed them a few minutes prior.

How do I get my 0.5 inch gun back? Any suggestions?

 

[someguy2800]

Are you sure the recoil lug or part of the trigger isn’t hung up and holding it up out of the stock slightly?

 

[IMtheNRA]

No, I'm not sure of that at all. That's a great suggestion.

 

[Rogue909]

Look into the action screws. Follow good tightening procedures. Bring them all up slowly while alternating.

Per this article they are supposed to be at different torques...

https://loadoutroom.com/thearmsguid...bolt-action-rifle-to-shoot-long-range-part-2/

 

[243winxb]

If the internal magazine is not installed correctly, the action screw will tighten on in. The screw will feel tight, but the action will move on firing. If your M40 is this type?

New trigger changed lock time, Or trigger is making contact with stock? Post #27 https://www.shootersforum.com/gunsmithing/215969-remington-600-mohawk-2.html

The recoil lug should be back , in contact with rhe stock when tighting the front action screw.

Tighten the lug screw first, then the tang screw.

Any screw in the middle (M70) is only lightly tightened.

 

[Mr. Hill]

Try again, you might have just had a bad day at the range, it happens. If same results, then look for a problem with the rifle.

 

[Axis II]

I have the same issue with a savage. 5 shots-one hole with the factory stock and put a Boyds on it and now it wont touch holes. I haven't had time to mess with it so cant help there.

 

[Everready73]

Did you clean the gun when you changed the trigger? Sometimes removing the copper fouling can affect the accuracy

 

[Barny]

Could a new barrel affect harmonics via how the action sits in the new stock? Maybe try a new load or commercially available load?

 

[WelshShooter]

Is the trigger pull different with the new trigger? I find that I shoot heavier triggers (>4lbs) better than lighter triggers (<4lbs).

As the others have said, check that the recoil lug has fully seated into the stock. When you place the action back into the stock, slightly tighten the action screws, then hold your rifle vertically with the muzzle up and bump the rifle down onto the buttstock on a hard surface. The action will move down into the stock due to inertia and therefore recoil lug will seat better into the stock. After this is done, go ahead and tighten up those action screws. Shoot some groups and see if there's any difference.

 

[jmr40]

You didn't put it back together the same. Often aftemarket triggers do require some stock modification, and the magazine box can be installed incorrectly, action screws improperly tightened. There is a certain order that they should be tightened in. Take it apart again and check all of the above.

 

[JDGray]

When assembling rifles, I always finger tighten the action screws, set the rifle on its butt pad, torque screws in vertical position. This may or may not be your problem, but it eliminates a variable. Good luck!!

 

[IMtheNRA]

Someone suggested that the Timney sear may be sticking up too high and it is contacting the bolt or firing pin, causing my vertically stung huge groups. Any opinions on this theory?

Resetting and retorquing the action does not make any difference.

 

[taliv]

it is highly likely your trigger is the problem. either something is wrong with it or you did not properly install it. this is simple to check. put your old trigger back in and see if it shoots well.

my guess reading the first post was that the cocking piece to trigger was the issue.

did you adjust sear engagement on the timney per directions?

 

[IMtheNRA]

Well, I just got back from the range and we figured out the cause of this problem. It is the trigger. The trigger assembly is so wide that the factory Remington trigger guard assembly does not fit it. Specifically, there is a cross pin in the Timney trigger assembly and it is wider than the trigger opening in the trigger guard.

Maybe the rest of the assembly is too wide even without that cross pin, but I won't know for sure until I take some measurements tonight.

The end result was the action was firmly pinched between the stock and trigger guard without actually being seated on the aluminum blocks..

The trigger guard assembly is surprisingly thin around the trigger, and there is no extra material on it that I can mill off without breaking the trigger guard. This is a factory Remington 700 detachable box magazine model, and I guess it is different from the vast majority of other Rem 700 rifles that Timney makes triggers for.

I'll call Timney in the morning to see if they have a solution for this problem, specifically a skinny trigger assembly like the Jewel that I compared this to at the range today.