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Barrel contour
- Thread starter Nevrsummr
- Start date
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My ¢2
I think there is more to this than just the contour.
I'm not a metallurgist either but my family has a long history or metalworking in machine shops. There is a big difference between stainless and CMV or chrome-moly carbon steel. Stainless is reflective to heat in nature which works against it when it comes to heat disapation unless it's either white or heavily fluted. Stainless (416R) is usually chosen because it is easier to machine and thus you can "run" precision barrels faster through a machine shop resulting in a high quality bore at an affordable price.
Chrome Moly is 2-3 times tougher than stainless. This means it's 2-3 times harder to machine and achieve the same smooth bore finish without going slower, using more expensive tooling and lots of coolant. (If you don't use coolant tooling will melt under some circumstances). The toughness of CMV means that the inner surface of the barrel will last longer under heat and pressure. It also means that it will take alot more heat to get things to move (POI shift). Also CMV transfers heat quicker so the heat may travel up the barrel away from the chamber/throat area. The bad part of this means that hand lapping may be required to get the smoothness of the bore to a satisfactory point for accuacy.
Processes:
This is actually the most important point I want to make.
POI shift often comes because a barrels internal stresses change the barrels directional/radial shape as is heats up. This happens because heat "demagnetizes" the internal magnetic fields in the barrel and allows for the stress to pull this way or that. The most important process to remedy this is stress releaving. Faxon did an exceptional series on this in an interview style with someone a few years back. Cold hammer forging creates the best barrels for heat because the process aligns the stress in the metal in a way that it doesn't whip rounds as much when hot. Col Nutinfancy did a video on the weatherby Vanguard in 308 (Sporter profile barrel) and reported under fairly heavy fire it didn't whip rounds that much! The same is true of my Tika T3X (stainless Cold hammer forged) as far as I know all the sako barrels are CHF. All machine gun barrels are CHF because of this very thing. Also most machine gun barrels are fairly on the Sporter side (M249)
If you want to save weight without barrel whip find a barreled action you like that comes with a CHF barrel. If you have the money just buy the sako85. I usually shoot 5-10 rounds out of my Tikka super light 7mag and I stop because the barrel is hot and I care about my bore. If I kept going it would still be shooting 1/2moa
Joel
I think there is more to this than just the contour.
I'm not a metallurgist either but my family has a long history or metalworking in machine shops. There is a big difference between stainless and CMV or chrome-moly carbon steel. Stainless is reflective to heat in nature which works against it when it comes to heat disapation unless it's either white or heavily fluted. Stainless (416R) is usually chosen because it is easier to machine and thus you can "run" precision barrels faster through a machine shop resulting in a high quality bore at an affordable price.
Chrome Moly is 2-3 times tougher than stainless. This means it's 2-3 times harder to machine and achieve the same smooth bore finish without going slower, using more expensive tooling and lots of coolant. (If you don't use coolant tooling will melt under some circumstances). The toughness of CMV means that the inner surface of the barrel will last longer under heat and pressure. It also means that it will take alot more heat to get things to move (POI shift). Also CMV transfers heat quicker so the heat may travel up the barrel away from the chamber/throat area. The bad part of this means that hand lapping may be required to get the smoothness of the bore to a satisfactory point for accuacy.
Processes:
This is actually the most important point I want to make.
POI shift often comes because a barrels internal stresses change the barrels directional/radial shape as is heats up. This happens because heat "demagnetizes" the internal magnetic fields in the barrel and allows for the stress to pull this way or that. The most important process to remedy this is stress releaving. Faxon did an exceptional series on this in an interview style with someone a few years back. Cold hammer forging creates the best barrels for heat because the process aligns the stress in the metal in a way that it doesn't whip rounds as much when hot. Col Nutinfancy did a video on the weatherby Vanguard in 308 (Sporter profile barrel) and reported under fairly heavy fire it didn't whip rounds that much! The same is true of my Tika T3X (stainless Cold hammer forged) as far as I know all the sako barrels are CHF. All machine gun barrels are CHF because of this very thing. Also most machine gun barrels are fairly on the Sporter side (M249)
If you want to save weight without barrel whip find a barreled action you like that comes with a CHF barrel. If you have the money just buy the sako85. I usually shoot 5-10 rounds out of my Tikka super light 7mag and I stop because the barrel is hot and I care about my bore. If I kept going it would still be shooting 1/2moa
Joel
Nevrsummr
Well-Known Member
Is that before or after fluting?
Nevrsummr
Well-Known Member
Thanks for the information. Do you know what barrel makers are using CMV? Im guessing its not rust resistant like stainless?
Shillen makes a steel barrel that's hand lapped, I don't know about barrel makers offering CHF blanks, the steel needs to say 4140(good) or 4150(best) I don't know about the others, I'm sure most of them do, for some reason most people go for stainless first.
Just found this place
sandhammerforging.com
I'ma give them a call tomorrow.
This is a great article about CHF
www.thetruthaboutguns.com
Green mountain barrel 6mm 1:7.5tw 4140cm stress releaved.
You can see from the price what happens when you want your cake and eat it too with that one.
Sand Hammer Forging
Cold Hammer Forged Rifle Barrels and Rifle Blanks for the Precision Rifle Industry MADE IN THE USA
sandhammerforging.com
I'ma give them a call tomorrow.
This is a great article about CHF
Inside FNM’s South Carolina Barrel Shop - The Truth About Guns
You can count on one hand the number of firearms manufacturers that make their own barrels. Colt and Remington spring to mind, with Noveske right behind. But not many others. There’s a **** good reason most gun makers farm-out the work: building barrels is a tricky and expensive business. FNM’s...
www.thetruthaboutguns.com
Green mountain barrel 6mm 1:7.5tw 4140cm stress releaved.
Login
www.gmriflebarrel.com
You can see from the price what happens when you want your cake and eat it too with that one.
Last edited:
redrockranger
Member
How many competitive hammer forged barrels do you see in competition ? Thanks
Depends on heat input as well. I have a #1 Krieger barrel on a 6mm Dasher and I can put a 5 round clip through it as fast as I can shoot accurately and have zero POI change. I haven't tested it beyond 5 rounds. I have a Vanguard series 1 in .243 that would start to walk after 4 rounds. Barrel is probably .63" at muzzle. I had a Tikka T3x lite 300 win mag come through the shop for muzzle threading and it was .63" at the muzzle. I have a 338 Norma Mag with a Krieger #6 and it has no POI change after the 5 round mag is emptied. Other factory sorters I've shot appear be good for about 3 to 4 rounds before walking. I think quality of barrel helps out with this as mentioned above.
As for weight, the smaller steel shapes are lighter and they cost a whole lot less. I think CF barrels have another plus when it comes to hunting with a suppressor.
I think proper bedding and floating of the action and barrel helps with POI change.
I do have a good story about heat in a carbon barrel. I was at the range and a gentleman who I've seen several times showed up with his PRS gun sporting a new CF barrel. He proceeded to put about 50 rounds down range at some 500 yard targets. Only breaking to reload the 10 round mag. At the end, he was super impressed that his barrel was barely warm to the touch. He proceeded to walk down the line telling everyone about it. If CF barrels dissipate heat faster than steel, then I would have figured his barrel should have been boiling water, not warm to the touch after 50 rounds. That's my two cents
I feel everyone should own a barrel cooler. Use it after a 3 shot group of a minute or two and you'll never have to deal with POI shift due to heat.
As for weight, the smaller steel shapes are lighter and they cost a whole lot less. I think CF barrels have another plus when it comes to hunting with a suppressor.
I think proper bedding and floating of the action and barrel helps with POI change.
I do have a good story about heat in a carbon barrel. I was at the range and a gentleman who I've seen several times showed up with his PRS gun sporting a new CF barrel. He proceeded to put about 50 rounds down range at some 500 yard targets. Only breaking to reload the 10 round mag. At the end, he was super impressed that his barrel was barely warm to the touch. He proceeded to walk down the line telling everyone about it. If CF barrels dissipate heat faster than steel, then I would have figured his barrel should have been boiling water, not warm to the touch after 50 rounds. That's my two cents
I feel everyone should own a barrel cooler. Use it after a 3 shot group of a minute or two and you'll never have to deal with POI shift due to heat.
How many Sporter profile barrels do you see in competition? The OP is asking about weight for a hunting application.
Also how many stainless barrels do you see in combat?
It's not about which barrel is more accurate, it's about which one costs more to make. Competition shooters use stainless because they change their barrels every other time they change their socks.
Thanks.
Nevrsummr
Well-Known Member
Thank you. Ill check with cody. Thanks for Ll the other info as well everyone. Looks like 3b is similar in weight. Not sure if thats before or after fluting but ill try n check with bartlein
