Diagnosis help?

[coop2564]

I have a CA ridgeline 300 wsm that has started shifting zero and groups, I suspect a bedding problem, but wanted some other opinions? Gun shot well first couple of outings but then started shifting zero. it is floated all the way to receiver with plenty of room. Nothing is loose scope rings or mounts checked this, What it is doing it groups in two exact areas high left, low right at 100 yards this shift is about 3" back and forth, at 200 6-7". It may put 2 or three shots touching before the shift. Rarely does it put a shot in-between unless I pull it. Two very distinct groups. 1st couple of outings it grouped ok. last three it started this shifting back and forth. Scope is a sig whiskey 5. I have not checked the guns bedding yet, factory says they spot bed them what ever that means, guessing just around lug area, screws on stock are tight. This sounds like bed or scope issues? Load is worked up before it stated jumping around nosler brass, 175gr edge, H4831sc, cci mag primers. I have not yet tried other ammo as this load was shooting .7 avg MOA before problem started. Thoughts?

 

[gohring3006]

First thing I would do is put a proven scope on. While the scope is off, check mount screws. Check for egg shaped mount holes too.

 

[Tensilon]

Have you figured anything out on your rifle? Gohring is sending you down the right path. If there is no change using a known scope, then I would pull the receiver and barrel out of the stock and start checking the platform itself out... look at all the elements of the stock, the pillars, the bedding, the lug, etc. I've never had a Ridgeline to take apart and look at so I can't speak with authority on it but certainly everything needs to be square to the world. From what I can find it appears that others have had some problems with them throwing random groups......some have had success with getting CA's to fix the issue for them. I do know that certain rifles can only be spot bedded but I do not know what they bed their rifles with or how they do it. I prefer to bed the entire receiver and usually the first part of the barrel if it can be done. At a minimum you need at least 2 solid bedding points to obtain consistency and I also prefer the return to battery method of bedding. As I said I have no idea how they go about bedding their rifles. I would certainly get in touch with CA especially if you do find something amiss. Please let us know what you find...this is certainly interesting and must be quite perplexing for you.
Tens:cool:

 

[Alibiiv]

Have you figured anything out on your rifle? Gohring is sending you down the right path. If there is no change using a known scope, then I would pull the receiver and barrel out of the stock and start checking the platform itself out... look at all the elements of the stock, the pillars, the bedding, the lug, etc. I've never had a Ridgeline to take apart and look at so I can't speak with authority on it but certainly everything needs to be square to the world. From what I can find it appears that others have had some problems with them throwing random groups......some have had success with getting CA's to fix the issue for them. I do know that certain rifles can only be spot bedded but I do not know what they bed their rifles with or how they do it. I prefer to bed the entire receiver and usually the first part of the barrel if it can be done. At a minimum you need at least 2 solid bedding points to obtain consistency and I also prefer the return to battery method of bedding. As I said I have no idea how they go about bedding their rifles. I would certainly get in touch with CA especially if you do find something amiss. Please let us know what you find...this is certainly interesting and must be quite perplexing for you.
Tens:cool:

"I also prefer the return to battery method of bedding" Not familiar with this form of bedding, what does this entail??

From my perspective with shifts such as the OP is experiencing, something has to be loose, a broken screw, or a bottomed out screw before it is tightened up somewhere. I would definitely try shooting the rifle with a known scope, or....two if necessary.

 

[Tensilon]

"I also prefer the return to battery method of bedding" Not familiar with this form of bedding, what does this entail??

Generally there are 2 different ways of bedding a rifle. Rigid bedding or return to battery. Rigid bedding can almost be described as gluing the action to the stock. When a shot is fired the barrel oscillates and vibrates, or whips. If the barrel is unable to whip the same way each time, the bullet will land to a different point of impact. The action is also under stress within the stock. As the shot goes off it produces recoil, and the action is forced backwards and then returns forwards. If the action does not return to the same point with each shot, the rifle will be inaccurate. The point which the action returns to is called battery. The action needs to be able to bounce at a microscopic level, and then return to battery. The movement is so small that it appears nonexistent, but it is there nonetheless. When you bed a rifle the bedding, if done well, is a mirror image of the action. There are points in the bedding that must be relieved to allow the action to recoil without being pinched, not just the recoil lug. But this is one of the reasons that most employ taping the front and the sides of a recoil lug when bedding. If the action gets hung up, or pinched, during this movement it can manifest such annoying things as double grouping, flyers, vertical stringing, or large groups. After bedding my rifles I apply a thin layer of extreme rifle grease to the action and the recoil lug areas to allow it to return to battery. This is a somewhat complicated subject and this is my attempt to explain it to you. I learned about these things from corresponding with a New Zealander named Nathan Foster. He has authored a series of books regarding exactly what all of us in this forum are interested in. I give him credit for my feeble attempt at describing this to you. I would urge you to check out his site ballisticstudies.com. Best money I ever spent on books about long range shooting. I use his information to make my rifles accurate and I have had great success. Hope this makes sense to you.
Tens:cool:

 

[Alibiiv]

Generally there are 2 different ways of bedding a rifle. Rigid bedding or return to battery. Rigid bedding can almost be described as gluing the action to the stock. When a shot is fired the barrel oscillates and vibrates, or whips. If the barrel is unable to whip the same way each time, the bullet will land to a different point of impact. The action is also under stress within the stock. As the shot goes off it produces recoil, and the action is forced backwards and then returns forwards. If the action does not return to the same point with each shot, the rifle will be inaccurate. The point which the action returns to is called battery. The action needs to be able to bounce at a microscopic level, and then return to battery. The movement is so small that it appears nonexistent, but it is there nonetheless. When you bed a rifle the bedding, if done well, is a mirror image of the action. There are points in the bedding that must be relieved to allow the action to recoil without being pinched, not just the recoil lug. But this is one of the reasons that most employ taping the front and the sides of a recoil lug when bedding. If the action gets hung up, or pinched, during this movement it can manifest such annoying things as double grouping, flyers, vertical stringing, or large groups. After bedding my rifles I apply a thin layer of extreme rifle grease to the action and the recoil lug areas to allow it to return to battery. This is a somewhat complicated subject and this is my attempt to explain it to you. I learned about these things from corresponding with a New Zealander named Nathan Foster. He has authored a series of books regarding exactly what all of us in this forum are interested in. I give him credit for my feeble attempt at describing this to you. I would urge you to check out his site ballisticstudies.com. Best money I ever spent on books about long range shooting. I use his information to make my rifles accurate and I have had great success. Hope this makes sense to you.
Tens:cool:

Thank you for this explanation, it is much appreciated as I've never heard or read of this concept. I have seen illustrations where tape will be applied to the front of the recoil lug, I thought it was so the action could be released from the bedding easier. I'll do some research to find some of Forster's books. Thank you again

 

[coop2564]

It turned out to be scope. I sent it back to Sig yesterday. Thanks for the replies.