Gunsmithing Accuracy issues after stock inletting.

[Helter]

I just installed a new bottom metal in my Rem 700, the PTG dbm metal. Prior to this it shot consistently very well. Around .5 moa with FGMM, and smaller with my handloads.

I did the inlet myself for the DBM, and the magazines are feeding 100% reliably. The gun is not shooting as well though. Between yesterday and today I've put about 60 rounds downrange, and it just seems to have lost all of it's consistency. The groups have generally opened up quite a bit, and the zero seems to be shifting. Before if I moved the scope on the rail it would take me about 5 rounds to zero it. Now it seems like I'm adjusting the scope every 7 rounds.

What are some common problems after work like this? Where should I look for the issue? Is it likely a problem with the inletting? Or the amount of torque on the action screws? The scope was off for all of the work, so that shouldn't have been affected I don't think...
Any help would be appreciated. I'm relatively new to precision guns, hoping I can get this sorted shortly.

 

[weber61]

Re: Accuracy issues after stock inletting.

there are several items to check after this type of work is completed at home.
I would start with the actions screws. Are they new with the BDM? correct length? Are they torqued properly when reinstalled?

Next check the barrel float. just validate you have not introduced pressure points whent he inletting and new DBM were compelted.

What stock do you have? SPS plastic, walnut, something aftermarket?? some lend themselves better to changes.

 

[230grRN]

Re: Accuracy issues after stock inletting.

Another thing to check is that the new bottom metal is not making hard contact with the receiver. Also that the mag is not binding between the DBM and the receiver. Did the DBM come with pillars? Generally DBM makers send there bottom metal with pillars cut to the proper length to set these clearances.

 

[Helter]

Re: Accuracy issues after stock inletting.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Weber61</div><div class="ubbcode-body">there are several items to check after this type of work is completed at home.
I would start with the actions screws. Are they new with the BDM? correct length? Are they torqued properly when reinstalled?

Next check the barrel float. just validate you have not introduced pressure points whent he inletting and new DBM were compelted.

What stock do you have? SPS plastic, walnut, something aftermarket?? some lend themselves better to changes. </div></div>

Yes, action screws are new with the DBM, and seem to be the correct length. I don't have an inch/lb torque wrench, so I just tightened them "fairly tight". I guess is will go high up on the "things I might have done wrong" list.

The barrel is still free floated, I can run a dollar bill all the way to the action.

The Stock is a B&C medalist that appeared to have been bedded previously.

 

[Helter]

Re: Accuracy issues after stock inletting.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 230grRN</div><div class="ubbcode-body">Another thing to check is that the new bottom metal is not making hard contact with the receiver. Also that the mag is not binding between the DBM and the receiver. Did the DBM come with pillars? Generally DBM makers send there bottom metal with pillars cut to the proper length to set these clearances. </div></div>

Ok, I'll check that too. How would I tell that the mag isn't binding?

It did come with pillars, but the stock already had them. I milled the pillars in the stock down to as close to what came with it as I could tell.

Thanks, both of you, for the suggestions!

 

[230grRN]

Re: Accuracy issues after stock inletting.

The mag will have some up and down float in it. If its binding it will be basically wedged between the DBM latch and the receiver feed rails.

 

[sawman556]

Re: Accuracy issues after stock inletting.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Helter</div><div class="ubbcode-body">

The Stock is a B&C medalist that appeared to have been bedded previously. </div></div>

Re-bed it to your action using the pillars that came with your DMB. Buy a torque wrench, like the Wheeler Fat Wrench, they're not that expensive and you should have one.

How tight is your DMB? You might want to bed that as well.

 

[Helter]

Re: Accuracy issues after stock inletting.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sawman556</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Helter</div><div class="ubbcode-body">

The Stock is a B&C medalist that appeared to have been bedded previously. </div></div>

Re-bed it to your action using the pillars that came with your DMB. Buy a torque wrench, like the Wheeler Fat Wrench, they're not that expensive and you should have one.

How tight is your DMB? You might want to bed that as well. </div></div>

Yeah, I was already going to fill in around the DMB with some devcon, it's not super tight, but doesn't move once it's all bolted in.

Really I should take out the pillars that came in it? That's That's going to be a pain.

Thanks for the rec. on the torque wrench. I've been trying to limit my spending a bit, I guess this was the wrong area to save money!

 

[sawman556]

Re: Accuracy issues after stock inletting.

Save money? That's funny!!!

If it was mine I would redo the whole thing but I don't know that is what's needed in your case. It's just a suggestion. It's hard to tell what's going on with your rifle from my house. I'm sure the pros will chime in.

 

[Helter]

Re: Accuracy issues after stock inletting.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sawman556</div><div class="ubbcode-body">Save money? That's funny!!!

If it was mine I would redo the whole thing but I don't know that is what's needed in your case. It's just a suggestion. It's hard to tell what's going on with your rifle from my house. I'm sure the pros will chime in. </div></div>

True enough... Looking at the stock, it's pretty clear that the pillars in there came in it, rather than being added when it was bedded, that's why I milled them to size rather than try to replace them.

The nice thing is, this stock was basically trashed already anyway, so if I ruin it I'm not really out much of anything.

 

[230grRN]

Re: Accuracy issues after stock inletting.

How did you mill your DBM inlet? If you did it in a milling machine, a dial caliper would plenty accurate enough to match the pillars to one another without going through all the work of removing the old pillars.

 

[Helter]

Re: Accuracy issues after stock inletting.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 230grRN</div><div class="ubbcode-body">The mag will have some up and down float in it. If its binding it will be basically wedged between the DBM latch and the receiver feed rails. </div></div>

It doesn't appear to be.

 

[230grRN]

Re: Accuracy issues after stock inletting.

As said earlier its awful hard to diagnose over a keyboard, without having a chance to pick it over with a fine tooth comb.

 

[chemist1]

Re: Accuracy issues after stock inletting.

If it is the magazine putting presure on the bottom of the action/bolt shooting groups with out the magazine in the gun might show you something.

 

[Helter]

Re: Accuracy issues after stock inletting.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 230grRN</div><div class="ubbcode-body">As said earlier its awful hard to diagnose over a keyboard, without having a chance to pick it over with a fine tooth comb. </div></div>

yeah of course, I was just hoping to get the first things that I should be looking at.
Thanks, you guys have definitely helped. I'll be looking at all of the things you mentioned. Hopefully I'll have this thing back to it's previous accuracy soon.

 

[AccuSol-ERN]

Re: Accuracy issues after stock inletting.

If the stock has been bedded previously and done correctly screw torque is not as critical as an unbedded stock or chassis system.

I would bolt everything together and then take it apart and look for crushing or marking at the top of the mag well that would indicate contact with the action. There is not much clearance in Badger guards or similar guards so the pillar height is pretty critical. The mags tend to have a pretty healthy tolerance to height as far as functioning, so that shouldn't be a concern. Also you might see if the screws are binding when you put them in. It is not uncommon to get the footprint off a tad and the screws are contacting the pillar holes or at least putting force on the DBM and trying to jam it into the side of the inlet.

Let us know what you find out.

Ern

 

[Helter]

Re: Accuracy issues after stock inletting.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: fng23</div><div class="ubbcode-body">If the stock has been bedded previously and done correctly screw torque is not as critical as an unbedded stock or chassis system.

I would bolt everything together and then take it apart and look for crushing or marking at the top of the mag well that would indicate contact with the action. There is not much clearance in Badger guards or similar guards so the pillar height is pretty critical. The mags tend to have a pretty healthy tolerance to height as far as functioning, so that shouldn't be a concern. Also you might see if the screws are binding when you put them in. It is not uncommon to get the footprint off a tad and the screws are contacting the pillar holes or at least putting force on the DBM and trying to jam it into the side of the inlet.

Let us know what you find out.

Ern </div></div>

I looked at it briefly during my lunch break today, and I think you might have nailed it. I had tried to check that the screw holes on the dbm and the pillars were aligned, but somehow missed that on the rear pillar they're off a bit. It looks like the rear action screw was up against the side of the pillar, or very very close to it.
Looks like I need to cut a little more away, hopefully I can have it lined up and test it tomorrow.

 

[Helter]

Re: Accuracy issues after stock inletting.

Just as a followup, I cut out the inlet a little bit more, until I could line up the DBM with the pillars squarely.
I took it up to the range today and put 40 rounds through it. It's grouping better (good enough for me). But it seems like it' still shifting around a bit. In the first group, the CBS is an inch and a half away from the rest. Ok, so that might be the rifle settling in after the first shot. I dialed the scope after groups 1 and 2, but 3,4,5 were all with no changes.
It's possible that the shift in group 5 was me, I didn't have the stock pack on, so maybe I didn't have my head in the same position. It definitely feels like somethings still going on though.
I have a match this weekend, I'll leave it alone and see how it goes. After that I think I'm going to re-bed it and see what that does.

 

[AccuSol-ERN]

Re: Accuracy issues after stock inletting.

Sounds like you might still have some tension in the bedding somewhere. Check to see if you can see or feel the barrel moving up when tightening the front action screw. This would mean that you have a high spot forward of the front action screw hole. If the action area has had any "patches" to fill air bubbles/voids those are often the culprit.

Let us know what you find out. Good luck at the match.

Ern