Bent Barrel?

[TNBilly]

Had a new one (on me) today with my factory 700 in 243. It's all basically stock at the moment, I've been mostly concentrating on working up loads for it, seeing what it likes and a little about the 243 round in general.
For the sake of argument I have a 95 grain load that shoots right at 1 moa. As the stock is factory I thought I'd shim the action up temporarily just enough to clear the barrel, that way if it didn't improve the group I'd figured on putting it back down and not modifying the barrel channel. The cold barrel shot "usually" is about an inch to the left and occasionally a little high or low depending on the load. Today with the barrel floating the cold shot was dead center and 2 1/2 inches low. The other shots fell right into the "normal" 1" group! The only thing I can think of is (this is a sporter weight barrel btw) either the barrel has a slight bend that changes with heat, or there's stress in the barrel causing the same. Curious what you might think. I'm already thinking a heavy barrel for it, won't take a whole lot of persuasion - lol.......

 

[BoydAllen]

Without writing a book, let me say that jacking up the front of the action to float the barrel is not the way to go. It is like trying to do finish carpentry with a heavy framing hammer, with a milled face, and 16d sinkers. Slow down and do things right. Float the forend, bed the action, check the bedding with a dial indicator, and then try your loads. If you want to put the pressure point back, you can do so with bedding compound.

 

[TNBilly]

Without writing a book, let me say that jacking up the front of the action to float the barrel is not the way to go. It is like trying to do finish carpentry with a heavy framing hammer, with a milled face, and 16d sinkers. Slow down and do things right. Float the forend, bed the action, check the bedding with a dial indicator, and then try your loads. If you want to put the pressure point back, you can do so with bedding compound.

Don't think so - only an idiot would "jack up the front of the action". The receiver was shimmed level at front and rear bedding points. If you can't address the question, perhaps save the assumption.

 

[LHSmith]

Many factory barrels have stress, and the factory bedding is poor. Although you don't like the answer, I recommend doing what Boyd said above......or you can go your own way wasting a lot of ammo.

 

[BoydAllen]

If you go back and reread your first post, it doesn't say that you shimmed it up level, but the problem with that approach is although you do have more even contact (than shimming up the front), there are stability issues that this approach does not adequately deal with. I do not know of any serious shooter or smith that would take that approach. When barreled action is taken out of its bedding, it is not unusual for it to take a couple of shots to settle in. Shimming would probably exaggerate that effect. When a barrel is showing evidence of residual stress, sometime because it was cold straightened, not bent, it may tend to walk the shots as it heats, which is not what you described. One reason that factory stocks tend to have built in barrel pressure points, is that the cost would be too high to properly bed the action, or stress relieve the barrel. By stressing the barreled action, they are able to make ill fitting "bedding" shoot better, and limit the effect of residual stress in the barrel. What I was trying to communicate with my poor attempt at humor, was that by taking the shortcut that you have, you may have limited the performance of you rifle, and gotten a false impression of how the rifle would shoot if the job was properly done.

 

[K22]

All the Model 700's I ever owned with factory synthetic stocks would not group well until I either free floated the barrel or replaced the stock. Once I did that, they all shot well under 1 moa, some even in the 1/2 moa range.

The only exception was the varmint models that had the H-S precision stocks with alumiumn bedding blocks.

 

[K22]

Sorry forgot to add, in some cases after free floating the barrel in the factory stock, I had to glass bed the action to acheive better groups.

 

[243winxb]

When you remove the pressure point or shim up the action, the barrel will droop or hang downward.
Bullet impact will be lower with the same scope setting/point of aim. More noticeable on a bull barrel. Pressure point up pressure, is about 9 lbs.

 

[jo191145]

You cannot shim an action.

That being said if you bed an action raised off its natural setting points (pillars) you will need to bed it twice. Just about any bedding material and epoxy will have a shrinkage factor. Some worse than others.
Try skim bedding it again. You may be amazed at the difference the shrinkage factor can have in some epoxies.

 

[BoydAllen]

Easy Wayne, he was just a little upset. I appreciate the support, but I think we can let this molehill stay its original size ;-)

Now, on to more important things. In my travels, I have done a few bedding jobs for myself, and I think that learning how to do-it-yourself can be a satisfying experience, if you cut yourself a little slack, and don't get too excited or depressed if you first attempts are less than perfect. The main thing is to keep at it, and eventually, you will get the hang of producing a serviceable bedding job. There is nothing quite the experience of shooting a rifle that is performing a lot better than when you first got it, because of improvements that you have made with your own hands.

Having said all of that, let me point the collective you at erniethegunsmith.com and further recommend that your read everything on the site on the whys and hows of pillar bedding. I think that his tooling is an excellent value, and his ideas have a lot of merit. Now go read.

 

[bozo699]

Sorry Boyd, bad night at work and I read this at just the wrong time, I removed it and I apologise to whoever may have read it, it wasn't one of my better Christian acts for sure.
Wayne

 

[bheadboy]

rarely is a bbl bent, you moved the action from its"bed" and thus when firing it had to settle down , once settled the group will not move. factory stocks apply presure and "push the bbl" releave the presure and the bbl goes "home"

The recoil lub is not giving the same support when the action is shimmed, the tang and screws are not working the same and thus rhe rigid base for the action is altered.

wood or synthetic, free float the bbl, bed the action, recoil lug and 1" under the chamber and you should see 1/2-3/4" groups from the 243 easily.

Bob

 

[Jim See]

I think some of you guys are missing the point with this guys idea of shimming the rifle. I have actually done this and seen mixed results, but I don't base that on anything other than one particular rifle liking pressure or not. I only shim the front ring.

Think about this for a minute a factory tuperware stock is going to flex to the action, not the other way around like would be the case with a factory sendero/HS stock. So choose what to do with which stock you own, I have only done this with the injection mold stocks.

So if I cut a buisness card into a shim and place it under the front reciever ring and bolt everything tight, trust me we didn't change the bedding enough to do anything other than raise the front of the barrel off the plastic pressure pad. Now with-out a lot of investment in a POS stock I can shoot the gun and see if there is any change for the better or worse. I have done this a few times and actually seen 1.5" guns drop to 3/4-1" guns. What did I learn? time for a new rigid stock and a bedding job.

I have seen the same trick cause 1.5" guns go to 2" guns and even once a 3" gun. What did I learn? Time for a new barrel.

So as a tool this guy is on the right track, I don't think in his original post he ever thought this would be more than a test to see if it was a bedding/FF issue or a gun/barrel/harmonics issue. And why get so worked up over one guys idea to diagnose and try and improve his rifle?

 

[Jim See]

Had a new one (on me) today with my factory 700 in 243. It's all basically stock at the moment, I've been mostly concentrating on working up loads for it, seeing what it likes and a little about the 243 round in general.
For the sake of argument I have a 95 grain load that shoots right at 1 moa. As the stock is factory I thought I'd shim the action up temporarily just enough to clear the barrel, that way if it didn't improve the group I'd figured on putting it back down and not modifying the barrel channel. The cold barrel shot "usually" is about an inch to the left and occasionally a little high or low depending on the load. Today with the barrel floating the cold shot was dead center and 2 1/2 inches low. The other shots fell right into the "normal" 1" group! The only thing I can think of is (this is a sporter weight barrel btw) either the barrel has a slight bend that changes with heat, or there's stress in the barrel causing the same. Curious what you might think. I'm already thinking a heavy barrel for it, won't take a whole lot of persuasion - lol.......

I would say if the very first shot after the shimming was the only one out of the group, then the recoil set-in the barreled action to the stock with that shot and put it in a consistent position from shot to shot so that you could maintain the 1" group again.

If I am assuming this is an sps stock and you had it shooting 1" with or with-out the shim then I would;
1. bolt it back together and live with it.
2. fill in the fore-end with epoxy to stiffin it and bed the action to float the barrel.
assuming your results are valid it should shoot similarly the same way.
If you can't live with an 1" on a hunting rifle by all means rebarrel and restock.

 

[FroggyOne2]

the only rifles I have tried a shim in was with a Ruger. After the bedding, it tightened up some, but I would cut a .44 mag case and hammer it flat and place it under the action behind the lug and whoa! They both started putting the bullet into the same hole. As I said I did get some luck with that, but only on the Ruger action.