Harmonics problem....(I think) Ideas??

[Deputy819]

Okay. I checked everything I possibly could. Front action screw does not appear to be touching the bolt (more on the rear action screw further down....wait for it). Both barrel and tang are free floated. Trigger has proper clearance and bolt-handle is not touching stock. I torqued the front action screw to 65" lbs and the rear to 60" lbs, drew reference marks on the stock with a sharpie and fired 3 shots. It printed a 1.5" group (roughly) at 200 yards ....Ignore the smaller .243 holes to the lower left . For a deer rifle and my applications that was good enough for me. I loaded up 3 more of the same recipe for confirmation and shot the lower left diamond and all hell broke loose (quite literally). POI completely shifted and strung out badly.

I immediately checked the action screw position. Front screw was where it should've been and lined up with my reference marks. The rear screw had moved about 1/16th of an inch and was no longer lined up with my reference marks. Think there's part of the culprit. Bedding problem guys????

 

[Barrelnut]

Didn't see where you tried the original stock.
That POI shift might be a badly slipping scope or even a bad scope. Scopes can go bad at the strangest times and have you chasing you tail....

 

[Deputy819]

@Barrelnut ....Was hoping you'd chime in here! Havent switched stocks yet. I wanted to mess with the torque values a little more on the current stock and continue my investigation (it's the cop in me I guess ) The scope is a Leupy VX-L and has served me well for several years. This is the second rifle that has worn it. Unless, like you mentioned, it just all of a sudden went out I dont think thats the culprit. Rings and bases are torqued to factory recommends. I didnt have a chance to shoot anymore today due to rain setting in.....

 

[HARPERC]

https://www.longrangehunting.com/articles/free-floating-barrels-panacea-or-pain-in-the-neck.1220/

At some point you might want to try a little fore end pressure.

 

[Barrelnut]

The rear screw had moved about 1/16th of an inch and was no longer lined up with my reference marks. Think there's part of the culprit. Bedding problem guys????

That doesn't sound good.

 

[xsn10s]

Does your rifle have steel, aluminum or bottom metal? Those torque values are generally for steel floor plate and aluminum block or pillar bed. Neither screw should shift.

 

[Deputy819]

No bottom metal, blind magazine and the stock has pillars. The front screw is staying put. The rear one backed itself right out of 60" lbs of torque. I torqued it back to 60" lbs and quickly loaded up 1 round (it started raining on me), went outside, got comfortable on the bags and fired that shot and it landed a half-inch high center of the diamond-target at 200 yards. I know 1 shot is not enough for a diagnosis after re-torquing, but it would seem that torquing to 60" lbs again indeed would've made the group shift back to center. Wish I could've fired additional rounds. I'll try it again when the rainy weather breaks....

 

[Barrelnut]

The blind mag is usually secured by a thin metal lip. The metal lip is attached to the blind mag. The thin metal lip is secured by, you guessed it, the rear action screw! This mag lip may be what is allowing the the rear of the action to slip. It is between the action and bedding and maybe lifting it just a hair from the bedding. This maybe what allowed the read screw to move in your above post.

 

[Deputy819]

I'll definitely have a look-see at that tomorrow after my shift. That would be a simple fix with a dremel. Well, here's to hoping...