Shooting my 375 Howa today and as usual the first shot is about 2" higher and lefter than those fired after warm up. Purpose of this thing is a dangerous game rifle, so this could be troublesome at some point. So is there any way to stress relieve a factory barrel, for instance can it be run at some elevated temperature for a period and cooled slowly to eliminate this tendency. Would 450* or thereabouts be adequate. I think I remember that steels could be imbedded in lime to prevent the production of scale. Just sort of thinking out loud. I can probably find 12 or so hours when the Queenbee is not around the oven.
Stress relieving a barrel.
- Thread starter rogn
- Start date
jackie schmidt
New member
Your best bet might be a Cryo Treatment rather than a method using heat. I used to think this proccess was smoke and mirrors, but many manufacturing industries are now employing Cryo Treatment.
Just a thought, but you mention the first shot. Is this first shot out of a clean barrel? It is my experience that a bullet from a fouled barrel will have a different point of impact than one coming from a clean barrel.
Also, most major manufacturers expose their barrels to some form of stress relieving. This could be through heat, vibration, or Cryo treatment. There is no guarantee that any subsequent "stress relieving" will have any desireable affect.
If you do decide to use a form of heat stress relieve, make sure the person doing it is aware of the mechanical properties of the barrel steel so as to not take past it's transformation range. Also, in regards to scaling, (which would ruin a barrel), the only sure fire way to avoid scaling at higher temperatures is to perform the task in either a vacuum furnace or some type of inert gas furnace.
Just a thought, but you mention the first shot. Is this first shot out of a clean barrel? It is my experience that a bullet from a fouled barrel will have a different point of impact than one coming from a clean barrel.
Also, most major manufacturers expose their barrels to some form of stress relieving. This could be through heat, vibration, or Cryo treatment. There is no guarantee that any subsequent "stress relieving" will have any desireable affect.
If you do decide to use a form of heat stress relieve, make sure the person doing it is aware of the mechanical properties of the barrel steel so as to not take past it's transformation range. Also, in regards to scaling, (which would ruin a barrel), the only sure fire way to avoid scaling at higher temperatures is to perform the task in either a vacuum furnace or some type of inert gas furnace.
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jackie schmidt
New member
Not being facetious, but if I was going to go to that much trouble, why not go the nest step and install a custom barrel?
Boyd Allen
Active member
Has the barrel been floated and the action pillar bedded?
Ba-da-BOOM!
Butch Lambert
Active member
Jackie, I know all that you have read on the net about cryo, but what does it do for a barrel that you can prove? I don't believe cryo is a type of stress relief.
Rogn,
OK try this:
Shoot the clean cold fouling shot.
Wait a few hours or the next day so the barrel is cold.
Then fire another shot at a target.
If that shot is right on, your problem is solved.
All my hunting rifles have custom fitted barrels and still require that fouling shot to be right on the money.
Soooooooooooo I fire a fouling shot/shots before going on a hunting trip.
Note: I have had factory barreled rifles require many more fouling shots to "settle in". Some of which hated to be clean.
OK try this:
Shoot the clean cold fouling shot.
Wait a few hours or the next day so the barrel is cold.
Then fire another shot at a target.
If that shot is right on, your problem is solved.
All my hunting rifles have custom fitted barrels and still require that fouling shot to be right on the money.
Soooooooooooo I fire a fouling shot/shots before going on a hunting trip.
Note: I have had factory barreled rifles require many more fouling shots to "settle in". Some of which hated to be clean.
Rubicon Prec.
New member
haha
Butch Lambert
Active member
I have a pretty new 700 in 25-06. A friend has shot it for about 8 groups of 3 shots. Changed the trigger and 5 more 3 shot groups. 2 are almost touching. The 3rd is about 1"-1 1/2" away. Changed to a laminated stock with a aluminum bedding block. Skim bedded it. Still shoots the same. I changed barrels, but have not shot it yet. It does have a Leupold 36X scope that just came back from repair. It does it with another scope also. When the weather gets better we will shoot it again. Probably stress in the factory barrel, but not worth fooling with it.
jackie schmidt
New member
Butch, I have read a lot of articles and memos concerning Cryo Treationg, this article gives a simple explanation as to what many believe happens. The word "believe" the key word here.
http://web.vtc.edu/mt/114/Research/Ferland/CryogenicTreatment.htm
Scroll to paragraph 3.
Quite a few industries are into this for criticle parts, such as Diesel Engine Manufacturers and Gear Manufacturers. The theory is that many alloy steels that are tempered to a specific RC hardness do not complete the transformation proccess from Austenite to Martinsite at room temperature, resulting in irregular grain structure and internal stresses.
I had a 30BR Cryo treated after I shot it, (quite well), for a while. I could not see any difference one way or the other after the treatment.
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Butch Lambert
Active member
Jackie, I have had barrels cryo'ed at several different stages, After shooting, after chambering, before chambering, and to the new steel before any drilling or rifling. The only thing that I "believe" is I can tell when chambering is which blank has been cryo'ed. It machines better. I have not personally found that they shoot any better or last longer. I also think some of the cryo companies are not equipped to do a proper cryo. Most companies use Liquid Nitrogen, but Helium is used for the much lower temps.
Control Thermal Technology has done work for me and they are very good in what they do. I think some materials or applications of cryo is beneficial.
Control Thermal Technology has done work for me and they are very good in what they do. I think some materials or applications of cryo is beneficial.
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I couldn't get my Howa 1500 barrel off using conventional methods. However, making a relief cut just a few thou forward of the shoulder did the trick and then it could be unscrewed. No problem if you have a lathe. Of course, that trashes the barrel, but it had nearly 8000 rounds through it, so it was time for retirement and a new life as a tomato stake.
Just an aside.....NOT AN ARGUMENT!, an aside.
Cutting the relief doesn't necessarily trash a barrel... I've several times carefully parted Rem700's and then re-used them for velocity workups, fireforming or recoil sled calibration by installing an over-sized recoil lug. The same could be accomplished with a machined "washer" to make the gap just like a recoil lug. OR, I've done this too when diameter allows, one can thread the rest of the shank and install a Sav-style nut.
I do a lot of weird testing. I'd rather burn up a ter'mater stake than even a worn out custom barrel. So I sometimes save them.
Of course upgrading to a wraparound wrench with a 4ft cheater bar got rid of the whole problem at the rooot.....I no longer have to make relief cuts
EVER
lol
al
Boyd Allen
Active member
A good friend does the parting within the thickness of the recoil lug. That way, he relieves the pressure on the shoulder and leaves the barrel and action untouched.
Been busy the last week. Barrel is free floated. Action in Houge stock on some sort of pillar. Cold, clean or cold, fouled first shot is high left. I think full power 300gr are a bit further out of group. The only 2" critter I can think of would be an end-on snake like a mamba. But then finally the reason to go thru this trouble is"because". Ive always thought Whelan was off-base, Im more inclined to say "only inaccurate rifles are interesting". More fun to fix than keep plinking the same group.
Have to try the barrel shot with nitrogen and the action in front of a heat gun with Tempilac. More fun to fix!
Have to try the barrel shot with nitrogen and the action in front of a heat gun with Tempilac. More fun to fix!