Barrel Bedding: Yes or No (troubleshooting hot barrel vertical stringing)

[Das Capitolin]

Here's the situation: I have a Savage target action with 28" Criterion bull barrel. The action is fully bedded in a H-S Precision stock using Devcon Liquid Steel, and the receiver fits perfectly. In a second phase at the barrel nut, four inches of barrel were bedded. The first 20 shots (approx) impact as intended, but once the barrel gets heated they begin to string vertically by 2+ MOA. I suspect the long bull barrel is making rifle balance is an issue (front heavy), and there's very slight wobble in the bipod pivot, but since cold shooting is typically fine I'm most concerned that the barrel bedding is causing a problem.

So then, do you recommend bedding any portion of the barrel on a rifle that will shoot 60+ rounds in an hour? I'm troubleshooting the causes, and would appreciate the feedback.

 

[roggom]

Put your unloaded rifle in the stock and in a vice. Tighten the front action screw ( you do not have to torque it), then tighten your rear action screw, if the the barrel moves more than a few thousands, your bedding is not effective and you have a high spot.

I tend to bed about an inch or two in front of the recoil lug, but I used 20 mil tape to create a float, there is no contact there. The purpose is to just tie the bedding into the channel but not effect the barrel shank/ or nut in your case.

 

[Ledzep]

Well, my semi-educated feedback is that the bedding forward of the receiver isn't really necessary, and doesn't really do THAT much in the way of supporting the weight. Figure the front action screw is the fulcrum, then you tighten down the rear action screw. Everything is set. The first 4 inches forward of the receiver isn't doing anything for you.

I would knock out the bedding forward of the receiver and give it a go. and see what you get. Only one way to find out

 

[CharlieNC]

Typically suggested to float rather than bed a Savage tang. Also only the back of the recoil lug should contact the bedding, esp not the bottom. How's yours done?

 

[Das Capitolin]

Put your unloaded rifle in the stock and in a vice. Tighten the front action screw ( you do not have to torque it), then tighten your rear action screw, if the the barrel moves more than a few thousands, your bedding is not effective and you have a high spot.

I tend to bed about an inch or two in front of the recoil lug, but I used 20 mil tape to create a float, there is no contact there. The purpose is to just tie the bedding into the channel but not effect the barrel shank/ or nut in your case.

The front (muzzle end) of the recoil lug and all of the barrel nut were floated with tape. There does not appear to be any movement while cinching down the front then rear action screws.

Well, my semi-educated feedback is that the bedding forward of the receiver isn't really necessary, and doesn't really do THAT much in the way of supporting the weight. Figure the front action screw is the fulcrum, then you tighten down the rear action screw. Everything is set. The first 4 inches forward of the receiver isn't doing anything for you.

I would knock out the bedding forward of the receiver and give it a go. and see what you get. Only one way to find out

This could be easily done, and if it turned out to be a non-issue it can be easily re-bedded.

Typically suggested to float rather than bed a Savage tang. Also only the back of the recoil lug should contact the bedding, esp not the bottom. How's yours done?

Everything behind the rear action screw (tang) is free floated, along with the front of the recoil lug and barrel nut (taped).

 

[tomme boy]

Your barrel has stress in it. Thats what happens when they heat up. Have it cryo treated or contact Krieger and see what they say. This is common with button rifled barrels.

 

[Das Capitolin]

Your barrel has stress in it. Thats what happens when they heat up. Have it cryo treated or contact Krieger and see what they say. This is common with button rifled barrels.

This could be true, but it seems unlikely since Criterion removes stress from the steel before and after machining. I would think that if it were stress-related the likelihood of vertical stringing would be 1 in 360 (as in degrees). I certainly haven't ruled it out, since it's obvious that the barrel's temperature is the contributing factor.

 

[tomme boy]

So have you called Krieger?

 

[Das Capitolin]

So have you called Krieger?

By the time I read your message, their business had closed for the day and I got their voice mail. I'll try again tomorrow.

 

[Das Capitolin]

Quick update with my planned action:

- Remove all barrel bedding and relieve the area to create a wider/larger channel for improved cooling.
- Balance the rifle by adding some counter-weight to the back end, since fluting would be a last resort.
- Tighten and improve joints on the bipod, to reduce/remove wiggle during recoil.

 

[CriterionBarrels]

Quick update with my planned action:

- Remove all barrel bedding and relieve the area to create a wider/larger channel for improved cooling.
- Balance the rifle by adding some counter-weight to the back end, since fluting would be a last resort.
- Tighten and improve joints on the bipod, to reduce/remove wiggle during recoil.

I agree that the barrel bedding may be the cause for vertical stringing. Try removing it and let me know if the problem persists. If so, please give us a call at (262) 628-8749 or email me at [email protected]. I'll do my best to help troubleshoot the problem so we can get that rifle up and running!

-Josh

 

[Das Capitolin]

I agree that the barrel bedding may be the cause for vertical stringing. Try removing it and let me know if the problem persists. If so, please give us a call at (262) 628-8749 or email me at [email protected]. I'll do my best to help troubleshoot the problem so we can get that rifle up and running!

-Josh

Thank you, Josh. It's nice to see Criterion jumping into the discussion, even though I'm very pleased with this barrel. If something every comes up, I'll be sure to call.

Regarding the vertical stringing, it was definitely the under-barrel bedding. The 4” under-barrel bedding was done with Devcon Liquid Steel, and after 20-30 rounds fired it would absorb and retain barrel heat. While the rest of the free floated barrel was cooling, the bedded area would remain hot. This seemed to cause cooler parts of the barrel to contract while the heated underside area remained expanded. The end result was vertical stringing with rounds impacting high. Additionally, the barrel showed significant copper fouling, even though it had just been cleaned. All of this points to heat being the issue, and the barrel bedding the culprit.

All of the bedding compound has been removed from barrel nut forward, and the fore-end has been opened up to allow about 1/8" of clearance all around the barrel to help with cooling. I'll know how it shoots in a few days, once the local range has dried up from the recent rains.

 

[Das Capitolin]

I agree that the barrel bedding may be the cause for vertical stringing. Try removing it and let me know if the problem persists. If so, please give us a call at (262) 628-8749 or email me at [email protected]. I'll do my best to help troubleshoot the problem so we can get that rifle up and running!

-Josh

Thank you, Josh. It's nice to see Criterion jumping into the discussion, even though I'm very pleased with this barrel. If something every comes up, I'll be sure to call.

Regarding the vertical stringing, it was definitely the under-barrel bedding. The 4” under-barrel bedding was done with Devcon Liquid Steel, and after 20-30 rounds fired it would start to absorb and retain barrel heat. While the rest of the free floated barrel was cooling, the bedded area would remain hot. This seemed to cause cooler parts of the barrel to contract while the heated underside area remained expanded. The end result was vertical stringing with rounds impacting high. Additionally, the barrel showed significant copper fouling, even though it had just been cleaned. All of this points to heat being the issue, and the barrel bedding the culprit.


All of the bedding compound has been removed from barrel nut forward, and the fore-end has been opened up to allow about 1/8" of clearance all around the barrel to help with cooling. I'll know how it shoots in a few days, once the local range has dried up from the recent rains.

 

[The Gump]

Torque the rear action screw FIRST, then, apply torque to the front action screw while placing your fingers at the point where the forend of the barrel channel and barrel meet. If you feel movement your shit is under stress. A 4" barrel pad is huge. The main function of the barrel pad is to make the stock stiff so it doesn't flex into the barrel while the gun is being used in a slung position. A 1.5" barrel pad is plenty.

 

[Das Capitolin]

Torque the rear action screw FIRST, then, apply torque to the front action screw while placing your fingers at the point where the forend of the barrel channel and barrel meet. If you feel movement your shit is under stress. A 4" barrel pad is huge. The main function of the barrel pad is to make the stock stiff so it doesn't flex into the barrel while the gun is being used in a slung position. A 1.5" barrel pad is plenty.

Although I have always tightened rear first then front, according to this Accurate Shooter article you start with the front screw then the rear screw.
After seeing visible indication of surface wear from vibration movement on the under-barrel bedding, I could never recommend any amount of bedding for the barrel. Since my H-S Precision has an aluminum frame running from fore-end to the rear tang, there's no reason I would need to improve stock stiffness.

 

[cottonant]

Glad to see this thread as I was planing to inquire about this as well.

I bought a used 270 Sendero and has it glass bedded, the action trued and a Shilen 260 barrel installed by a gunsmith in April. About the same time I bought a new Remington Sendero 7 mm Rem Mag and had it bedded by the same gunsmith. The gun shot so bad I had the action trued and a Krieger barrel installed, but by a different gun builder.

The same gunsmith bedded both guns and the bedding was under the barrel about 2 & 3/8 inches in front of the recoil lug. The gun builder that trued the 7 mag action and installed the Krieger barrel removed all of the bedding in front of the recoil lug that the other gunsmith had installed when it was a factory Sendero.

Is there any reason for glass bedding under the barrel in front of the recoil lug?

 

[The Gump]

I'm not saying the article is incorrect with respect to tuning the screws. In all honesty it sounds like tuning the action screws is something that should be done on stocks with chassis or chassis all together since they all will induce tension into the barreled action.

A full bed job should induce zero tension into the barreled action. If it does it should be rebedded correctly. To check for tension in a stock that has a full bed job the rear is tightened first and then the front is torqued, backed off, retorqued, backed off... noticing any movement between the barrel and forend and the screws should be torqued to the same level once the gun is assembled.

I would agree that you're going to have to work real hard to flex that stock and I wouldn't run a barrel pad in it.

 

[The Gump]

Is there any reason for glass bedding under the barrel in front of the recoil lug?

To keep the stock from flexing into the barrel while shooting slung.

 

[cottonant]

To keep the stock from flexing into the barrel while shooting slung.

Makes sense, thanks! Would I be correct in assuming that having glass bedding under the barrel in front of the recoil lug is more necessary on guns with stocks that do not had an aluminum bedding block than those that do?

 

[The Gump]

Makes sense, thanks! Would I be correct in assuming that having glass bedding under the barrel in front of the recoil lug is more necessary on guns with stocks that do not had an aluminum bedding block than those that do?

The barrel channel can be opened up as well to prevent the contact from occurring without a pad. The rifle I'm building at the moment doesn't have a pad. I'm going to see what it takes to make it flex into the barrel and open the channel up as it needs it prior to paint. Honestly, I don't really think it will need much clearance. It's a Manners T5-A full carbon. I'll be one bad mother fucker if I can make it flex.

 

[Das Capitolin]

Makes sense, thanks! Would I be correct in assuming that having glass bedding under the barrel in front of the recoil lug is more necessary on guns with stocks that do not had an aluminum bedding block than those that do?

Bedding under the barrel seems to usually only be worthwhile on wood stocks with a very heavy barrel and light action. I wouldn't recommend it for any gun that fires enough rounds to heat the barrel.

 

[cottonant]

Bedding under the barrel seems to usually only be worthwhile on wood stocks with a very heavy barrel and light action. I wouldn't recommend it for any gun that fires enough rounds to heat the barrel.

Much obliged!

 

[LawnMM]

So I'm confused? Is your problem with accuracy a problem with your bedding job? Or your 'Junk M5Xi' scope?

 

[Das Capitolin]

The problem described above was two things, but removing the barrel bedding did solve one of them. When it was retested without under-barrel bedding and a larger fore-end channel the barrel was MUCH cooler after 40 quickly-fired rounds with absolutely no vertical stringing detected. The scope was originally suspected by two other more experienced competitors who shot the gun to help me troubleshoot, but I was convinced it was unlikely. After retesting today that was proven not to be the case, and I learned that even an expensive scope can fail. From what I was seeing today the wind turret adjustments had no impact, but then suddenly over-corrected. Subsequent testing had erratic results that put the POI far left of the POA, regardless of wind correction. At any rate, I hope that soon both issues will be solved and I'll have learned to be more patient with the process.

 

[LawnMM]

You're still making quite a few assumptions. The mere fact that you've been goofing around with the bedding is a perfect example. Its not that the bedding can't have an issue, or the scope. The problem is when you change 4 different variables its dicky to point the finger at any one of them when you made multiple changes at the same time. That's not how you test things. You change one thing at a time to rule things out. How does your newly bedded rifle shoot with a different scope?