Bedding a sporter

[mshelton]

Wondering what folks experiences have been when bedding the first part of the barrel of a sporter taper.

I'm fighting one now that has all signs pointing to bedding, it's a trued 700, Lilja fluted barrel in what looks like Rem Mag sporter contour. It shot decent before bedding, maybe 5/8"-3/4" but I decided to bed the action and recoil lug. Groups all started walking right, first shot was usually in the same spot relative to POA then the following shots went right. Happened with different powders, primers and bullets. I decided to bed about an inch and a half in front of the lug and should have probably gone further. The problems cleared up a little but are still looking like bedding issues, first shot for most all groups is in the same spot then it'll stack the next 2 shots 3/4" of an inch away.

Was never happy with the initial bedding, the job I did was done well but it's with the new Devcon that the hardner dries out some in the can and leaves chunks for lack of better terms once it dries. Action would have little spots on it every time I pulled it and would have to clean it off.

So I'm going to grind it out and rebed the entire thing and was wondering how far up a sporter barrel people have bed and if it's shown positive results.

 

[Alex Wheeler]

Bedding under the chamber is not necessary or desirable in my opinion. What your describing sounds like heat induced walking of the barrel. Usually this is a barrel stress issue not bedding. Maybe you had some barrel contact before that masked this. If it was mine, I'd free float the barrel, sent it to Kelbys to be frozen, if that don't fix it, get a barrel that doesnt walk.
Alex

 

[Preacher]

Bedding under the chamber is not necessary or desirable in my opinion. What your describing sounds like heat induced walking of the barrel. Usually this is a barrel stress issue not bedding. Maybe you had some barrel contact before that masked this. If it was mine, I'd free float the barrel, sent it to Kelbys to be frozen, if that don't fix it, get a barrel that doesnt walk.
Alex

Can you go into detail about not bedding under the chamber ???

 

[watercam]

Personally I used to bed the first 1"-2" of barrel shank on sporters, tried one without it and ground all the rest out. I saw no difference in accuracy with or without with #2 - #5 countours. If one is going to bed most or all of the barrel channel be sure you have a consistent hold on your rifle when you take it afield - POI may change with every change in support position be it hand or field expedient rest.
Considering it is a premium Lilja barrel in question I would agree that bedding may be an issue. I assume you have checked the free float under the barrel when it is hot?

 

[mshelton]

Yeah, the front part of the barrel is floated, HS Precision stock. Rifle is a 280ai and was built quite a while ago by Clay Spencer, owner put maybe 25 rounds through it, shot one Antelope, cleaned it and it sat in the closet for 20years. Borescoped it and it looks good and I've taken it completely down and checked everything, had some issues with the mag box binding and got that fixed. Scope came off a rifle that was a 22ppc/308 switch barrel rig and never had issues. Rings were bedded and lapped. Tried 2 lots of brass, 5 different powders (N560, R-17, H4350, H4381, Retumbo and 7828), 4 different bullets (120 Vmax, 140 Nosler BT, 162 Amax, 168 Berger) 3 primers (BR-4, 210m 215m). All loads have been mild and middle of the book variety, I just want to smack a whitetail with it, no need for a speed demon.

The thing has been a fight to say the least. The one thing that keeps leading me back to bedding is that it shot around 3/4" before I ever bed the receiver then the struggle started. Just wondering if going up past the initial step down in contour on the barrel will help.

 

[Changeling]

I have a 280 AI also, 1909 Argentine custom action worked, Hart Rem Mag taper barrel. Shoots 1/2 inch or better.

I bedded the recoil lug area and the first 2or 3 inches of barrel shank.

It sounds like something is binding and causing a heat problem to me as someone above said also.
Make sure when you stop bedding the shank that there is ample room from there on for the complete barrel channel, at least 1/8 ".

After what you said about lumps in the bedding material I would through away any of that bedding material you have and get new fresh material.

Make absolutely sure that the action/barrel is sitting in position correctly before you start bedding. by this I mean that it is not touching the barrel anywhere in a binding way.

Just take your time and and get the areas to be bedded correct and your barrel channel "Stops" the correct thickness for all.

 

[Alex Wheeler]

Bedding under the chamber is not necessary or desirable in my opinion. What your describing sounds like heat induced walking of the barrel. Usually this is a barrel stress issue not bedding. Maybe you had some barrel contact before that masked this. If it was mine, I'd free float the barrel, sent it to Kelbys to be frozen, if that don't fix it, get a barrel that doesnt walk.
Alex

Can you go into detail about not bedding under the chamber ???

I tested it on a 600/1000 light gun. I originally bedded the chamber, shot it 6 months that way, then ground it out and shot the rest of the barrel out. I saw no accuracy benefit with the chamber bedded and I'd prefer to have nothing touching the barrel to possibly influence it. The only reason I can see to bed under the chamber would be an excessively heavy and long barrel on a flexible action that needed more support, a sporter does not need more support. Sporter stocks are usually thin and flexible and bedding touching the barrel imo could cause an issue. Have you come to different conclusions?
Alex

 

[jsthntn247]

If the action was trued, the threads were cut oversized. Look at the front base screw and make sure it isn't hitting the barrel threads. Take your scope off and all the screws out of the base. Put the front screw in the base and lightly tighten it, if the base will still wiggle, your screw is hitting the threads. Might not be the issue, just something easy to check. I had a sporter rifle doing the same thing as yours and this was the issue.

 

[mshelton]

Thanks for that tip on the scope base screws, I've never come across that before. I bed the bases but didn't check that.

I'm going to strip the rifle down and rebed it so I'll look at what you're talking about when I do.

 

[BoydAllen]

Here is how I check screws, including action screws that thread into holes that are not open at the bottom. I start the screw in the hole, without the stock or scope base (depending on which type I am checking) in place, then I carefully back it out very slowly and listen for a click that will happen when the start of the thread on the fastener passes that of the female thread and the fastener drops down under the pressure of the driver. At that point I note the position of the driver referencing something on the handle or the side of the blade, and start to tighten by half turns as I go. The sequence would go something like half, one, half, two, half, three, etc. When I get to the point where the fastener is stopped by bottoming in the hole, I note the number of turns and partial turns. It might be something like 3 2/3. I do this a couple of times for each screw that I am checking, then I remove them and install the stock or scope base(s) and do the same drill with them in place. If the numbers are the same, with and without the attached part, for any fastener, it is bottoming. I usually try to have a third to half turn difference, shortening any offending fastner until I get that. This problem is more common than might be believed, and the worst cases are when the scope base or stock does not rattle, but is only lightly held, the others are easier to notice. Often, when bedding, the barreled action ends up slightly lower in the stock, causing this sort of problem, or a wood stock can be slightly compressed over time. With proper bedding, screws should tighten abruptly and solidly. If they feel spongy as you tighten them, or they drag in their holes, something needs to be fixed.

Two other things that get missed is contact with the side of action screws by bedding compound that has flowed into the hole, and has not been removed after the bedding set. and people letting action tangs and other parts act as secondary recoil lugs. These should be taped off or clearanced after the bedding sets.

Bedding should be checked using a magnetic base on the barrel, with a dial indicator touching the bottom of the forend tip, alternately tightening (cracking) the front and rear action screws while the rifle is vertical, sitting on its butt. Just because bedding looks good does not prove anything about its quality. In the original post, the evidence was on the targets that the bedding job was at fault. Grinding the bedding out and doing it over is the right approach. Do not draw the action down into the stock by using the action screws. Use headless guide screws, and lightly wrap the action and floor plate with something like surgical tubing. Tightening the screws before the bedding is hard will cause stress in the finished job.

 

[Alex Wheeler]

Here is how I check screws, including action screws that thread into holes that are not open at the bottom. I start the screw in the hole, without the stock or scope base (depending on which type I am checking) in place, then I carefully back it out very slowly and listen for a click that will happen when the start of the thread on the fastener passes that of the female thread and the fastener drops down under the pressure of the driver. At that point I note the position of the driver referencing something on the handle or the side of the blade, and start to tighten by half turns as I go. The sequence would go something like half, one, half, two, half, three, etc. When I get to the point where the fastener is stopped by bottoming in the hole, I note the number of turns and partial turns. It might be something like 3 2/3. I do this a couple of times for each screw that I am checking, then I remove them and install the stock or scope base(s) and do the same drill with them in place. If the numbers are the same, with and without the attached part, for any fastener, it is bottoming. I usually try to have a third to half turn difference, shortening any offending fastner until I get that. This problem is more common than might be believed, and the worst cases are when the scope base or stock does not rattle, but is only lightly held, the others are easier to notice. Often, when bedding, the barreled action ends up slightly lower in the stock, causing this sort of problem, or a wood stock can be slightly compressed over time. With proper bedding, screws should tighten abruptly and solidly. If they feel spongy as you tighten them, or they drag in their holes, something needs to be fixed.

Two other things that get missed is contact with the side of action screws by bedding compound that has flowed into the hole, and has not been removed after the bedding set. and people letting action tangs and other parts act as secondary recoil lugs. These should be taped off or clearanced after the bedding sets.

Bedding should be checked using a magnetic base on the barrel, with a dial indicator touching the bottom of the forend tip, alternately tightening (cracking) the front and rear action screws while the rifle is vertical, sitting on its butt. Just because bedding looks good does not prove anything about its quality. In the original post, the evidence was on the targets that the bedding job was at fault. Grinding the bedding out and doing it over is the right approach. Do not draw the action down into the stock by using the action screws. Use headless guide screws, and lightly wrap the action and floor plate with something like surgical tubing. Tightening the screws before the bedding is hard will cause stress in the finished job.

Thats good advice. A really good job you can take both screws out and tighten one or both and the needle wont move .001" If it moves .002" or more I grind it out. The key is to balance the rifle on its butt like Boyd said as its easy to induce movement.

 

[mshelton]

I'm trying to visualize it, my simple brain may need to read it a few more times to figure it out.

 

[jsthntn247]

I'm trying to visualize it, my simple brain may need to read it a few more times to figure it out.

https://www.youtube.com/watch?v=-P9dk_GWwjs

 

[mshelton]

I'm trying to visualize it, my simple brain may need to read it a few more times to figure it out.

https://www.youtube.com/watch?v=-P9dk_GWwjs

Thank you a ton, I'll be doing that next week. Much appreciated.