A bedding mystery, please advise... **UPDATED***

[TNBillyEarl]

This truly has me befuddled. I have a T3x 7mmRM that in the plastic stock is shooting consistent groups every time. The last 3 times out with it in the polymer stock it has been .6, .7, and .6 with a load it has always liked. Now to my issue:

I bedded this Boyd's in the pics below. The pics have a lot of glare and such so that it hard to tell anything. This is the 3rd stock I have bedded and this was (so I thought) the best job by far. But with the exact same loads above I can't get this to shoot anything but 2" groups. All three times out it has been 1.9, 2.0, and 2.0.

First, what are the things I could have done wrong?
Second, do I just grind it all out and start over?

It's free floated. It doesn't rock. Torque and all is to spec. Centered. Please advise.

B

 

[JD338]

Pressure point on the old or new stock?

JD338

 

[TNBillyEarl]

The polymer is just a plain Tikka stock. The Boyd's has no real pressure point as I can ascertain.

B

 

[JD338]

Try putting a garden hose washer in the barrel channel and torque down the action screws which will create a pressure point on the barrel. Shoot a group and see what you get. I'd she shoots, you will need to add a pressure point.

JD338

 

[jimbires]

you can check your bedding job with a dial indicator , to see if it's stress free . stress can be induced in a bedding job .

Using A Dial Indicator To Check Bedding

www.shootersforum.com

 

[Idaho53]

One trick I have used to isolate bedding issues is to loosen the action screws and then shoot to see if I can replicate the issue. For example, if you have your action torqued to 45 or 50 in lbs now, back them of to 25 or 30 in lbs and see if she shoot better groups. Don't worry about POI shifts at this point. If she shoots tighter groups after loosening the action screws, you found the issue.

 

[TNBillyEarl]

Thank you all. Let's assume it is a pressure point. Is the only way forward to dig out the bedding and start over?

B

 

[salmonchaser]

That’s what makes this so much fun! Some times getting a rifle to shoot, or not, seems like witch craft. I would start with that spot just forward of the recoil lug, looks uneven from the photo. Had the same thing in a Remington action I bedded years ago. Sanded that part out and she shot fine.

 

[IdahoCTD]

If you used the action screws to hold it in the stock you should tighten it down fully and then back the screws off until they just touch. This relieves any stress that might be in stock due to bad inletting. You can wrap the whole thing with masking tape to help hold it in the stock too. I tape off the barrel shank with a wide and thick electrical tape they sell at Lowes. It's super stretchy. That makes sure the barrel doesn't contact the bedding when the tape is removed.

It looks like your bedding compound has some pits in it. Sometimes that is caused by not mixing the bedding compound well enough. It looks like Marine-Tex and I've had that happen with it if it's not mixed really well. You can grind it all back out and try again. Try not to grind the recoil lug or the metal pillars. You can use a razor knife to cut the bedding out close to them. Another potential issue with Tikka's is the recoil lug. Many people will pull and rebed the recoil lugs in the stock. A lot of stocks don't actually glue/bed the recoil lug in, they press them in. If they wiggle the accuracy will be crap. Another thing I do is drill small holes, about 1/8", in all the spots where there is bedding. I try to drill them at several different angles to help lock it in even better. The holes don't have to be crazy deep and make sure you don't drill out the side of the stock. Ultimately you don't want any part of the stock to touch the action except the pillars and recoil lug if your bedding it. You can even check that by sliding a piece of paper in from the sides.

I use shoe polish for a release agent. I wipe it on and let it dry and then do it a second time. After that I wipe it lightly with a paper towel to remove any excess. I cake the front action hole with the shoe polish. It helps keep it from flowing into the action. I also fill all the openings with plumbers putty. Pull the trigger and bolt release and then fill it all along with the magazine port. It just keeps everything from creeping into the action.

 

[wvbuckbuster]

Above info all good. For what it's worth I once had a descent load that I thought would do better if I bedded my rifle. After that the same load got worse. Other loads got better. Not an answer to your question just something I experienced along the way. Dan.

 

[hunter24605]

I was just going to make Dan's suggestion too. Harmonics have changed and maybe that particular load isn't suitable anymore. Don't know, but it's something to add as a trail before starting over on the bedding.

 

[nhenry]

I'll echo the above info, but also grind this out:


It may be nothing, but it's possible that it's creating a high spot that it's just resting on.

 

[filmjunkie4ever]

I had a Remington Model 700 SPS in .270 WSM 20+ years ago that would not shoot out of the box worth a darn. I didn't know enough about glass bedding to try that and was thinking I would sell it. My grandfather had me cut a business card in half, then fold one half in half and put it in the barrel channel near the forend. My first group with the Winchester 150 grain Power Points factory loads shot a 5-shot group just under 1-inch. I shot it like that for the rest of the time I had it. For whatever reason that pressure bump made the difference.

 

[wvbuckbuster]

I had a Remington Model 700 SPS in .270 WSM 20+ years ago that would not shoot out of the box worth a darn. I didn't know enough about glass bedding to try that and was thinking I would sell it. My grandfather had me cut a business card in half, then fold one half in half and put it in the barrel channel near the forend. My first group with the Winchester 150 grain Power Points factory loads shot a 5-shot group just under 1-inch. I shot it like that for the rest of the time I had it. For whatever reason that pressure bump made the difference.

You can also put a square bread wrapper under the front of the action next to the front screw to float the barrel and see if this helps. Dan.

 

[PJGunner]

You can also put a square bread wrapper under the front of the action next to the front screw to float the barrel and see if this helps. Dan.

I do that by cutting up an old expired credit card to fot on the stpck right behind the recoil lug. Works good on Mauser and Winchester actions. It's a little trickier on round bottom actions but can be done. I also used a piece of credit card on ther forearm of a Ruger #1A in .270 Winchester that someone had removed the bump from the fforearm. Rifle went from 4" groups to 1.5" which is what the original owner said it would do when he bought iy. Only cost me $400 when they were selling in the $650 to $900 range depening on caliber and model.
Paul B.

 

[RL338]

I'll echo the above info, but also grind this out:
View attachment 22805

It may be nothing, but it's possible that it's creating a high spot that it's just resting on.

Thisfor starters. I remove any excess material in front of the lug under the barrel.
As others have mentioned your sporter barrel might like a pressure point at the front of the stock.

 

[35 Whelen]

I bought a Howa Superlite last year with Walnut stock, the barrel channel showed uneven distance from sides of barrel. It would not shoot moa with ANY load we tryed. I decided to show it to an old gunsmith friend of mine that has bedded hundreds of guns since the 1960's. After a quick look he determined the inleting of the stock was NOT square to the action. The CNC operator in Turkey had jiged it up about 5 degrees crooked. He wanted me to let him fix it. He reinleted the lug area oversized, squared the action up, bedded it so it's exactly same on both sides of the barrel. Gun shot 1.5/1.75" groups out of the box using Hornady Superformance ammo.
Squared up with lug bedded perfectly it now shoots 3/4" / 3 shot groups with same ammo.
5 shot groups if you don't let the barrel cool between shots will struggle to hold moa.. the Howas have a massive solid lug so would likely show more improvement than some other styles. Of course super lite weight barrels, Heat up fast; and can traditionally show "vertical stringing". And this one is no exception!
Good luck with your project! Hope you get it fixed.
E
Ps. Just for reference I have another Howa (with much heavier barrel) in 223 that came in that same Boyd's laminated Stock you have: It is free floated, and was factory bedded correctly; And that gun will shoot a 3/8" group with the right load. That said, I also have a Weatherby Vanguard, composite stock for same gun, that uses a "forward preasure point" out at end of the forearm. If I switch stocks using the exact same torque on the action screws, the gun shoots 8" HIGH and right at moa. So it certainly prefers the Boyd stock for accuracy.

 

[TNBillyEarl]

***UPDATE***

First, I tried the suggestions above (loosen the action screws, put a pad under the front of the stock, dug out in front of the recoil lug); each group was 1.5" plus/minus a .1". A real improvement, thank you all for the suggestions. (And the pictures above do make my bedding job look much worse than it was.)

I then went the entire way by digging it all out and rebedding it. I added pillars and bedded the metal trigger guard as well. The stock now snaps into place and is perfectly snug. Of all my rebedding jobs this has been the tightest of the lot. The past two weeks I have shot fifteen, 3-shot groups of 6 different recipes that work with the factory polymer stock. Every single group I shot was between 1.1 and .9 MOA. Every single group. Again, another step in improvement but not what was hoped for. This morning I put the polymer stock back on and shot 150g Partitions with 63g of H4350 at 3180 into a .6" group. I am now officially giving up on this particular Boyd's stock and accepting defeat. I'm not sneezing at my fallback here, I've just been humbled by my summer project.

-B

 

[NYDAN]

As Arthur Conan Doyle wrote, "Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth." Apparently, the truth is that your barreled action "prefers" the polymer stock. I am glad you got it worked out.

 

[RL338]

This morning I put the polymer stock back on and shot 150g Partitions with 63g of H4350 at 3180 into a .6" group

By chance does this stock have a pressure point at the end of the forearm of the stock.