Winchester model 70

Rbates · July 7, 2013, 10:36 AM

I just bought a Winchester model 70 in 22-250. Gun was manufactured in 1968 and looks pristine. Any recommendations for loads and barrel break in? R W Hart did an accuracy setup for me and said it looked like it was never fired.

**Unclenick** · July 7, 2013, 11:40 AM

Sounds like a good find.

There is no consensus on the value of break-in. I don't know how well it's actually been studied as you would need a lot of barrels to get a statistically reliable result. There's a good chance that a custom, hand lapped barrel that was properly stress-relieved before contouring needs nothing done to it at all, though you could cryo-treat it to extend its life a bit.

Most rougher commercial bores will benefit some from allowing the first bullets to burnish the surface. This typically doesn't take more than a six to ten rounds with complete cleaning inbetween. It is important for this to work, according to Howa distributor Legacy Sports, to get all traces of carbon out between each of the first few shots and not to leave hydrocarbons behind that could turn to carbon at powder burning temperatures. The idea is that the carbon will pack down into the surface irregularities and occupy the spaces the metal burrs are supposed to burnish down into so that if you don't remove the carbon between shots you block the burnishing.

That same distributor suggests that commercially mass-produced barrels, which are not normally stress-relieved, will tends to take a set in early firing that affects their later susceptibility to heat walking. I don't know if this is a belief or has actually been demonstrated. Again, the testing would require a lot of rifle barrels to prove and a willingness to ruin some. But if true, the barrel not only needs carbon removed, but needs to be cooled at least five minutes between shots.

The main argument against break-in is that you waste barrel life. On the other hand, the Legacy method has done most of its work in the first ten shots, and you'll blow that many down range getting sighted in anyway, so I think it's worth doing both those functions simultaneously. This also provides an opportunity to learn the POI of your cold barrel, and then to later compare to a warm barrel POI to check how much walking, if any, you have. If you want to go on to fire even more break-in shots, at least do your load development with the same rounds. May as well not waste anything at today's prices.

Legacy's method is in their FAQ.

Bart B. · July 7, 2013, 02:48 PM

If more than 20 rounds have been fired in its barrel, it's broken in as much as it'll ever be. Just shoot the darned thing.

Some of Winchester's hammer forged barrels (all made 1964 or later) are a bit more rough than others. So, after a good cleaning, it may take 4 or 5 shots to fill in the micro divots with bullet jacket material, then subsequent ones will shoot very well.

I'd replace the firing pin spring if that rifle's made in 1968. Get one from Wolf in a 26 pound rating.

Rbates · July 8, 2013, 02:51 PM

Thanks for the advice. I spoke with an engineer and he told me to shoot 10 rounds then brush and patch the barrel with oil, then repeat until the groups tighten up. After that, scope it in.

**Unclenick** · July 8, 2013, 09:39 PM

I, too, am an engineer.

The problem I have with multiple shot strings during break-in is that is you not only need to expend a lot more ammunition to finish breaking the barrel in, but every shot deposits copper right where you most need the burnishing from the next round to occur, shielding that spot from the friction of the next shot.

Also, if there is anything to the theory suggested in the Legacy FAQ I linked to above, of getting a barrel that has not been stress relieved to take a cold set (and I can argue it pro and con based on rough residual stress estimates and pressure distributions) then firing more than one before letting it cool again for the first ten rounds or so could get you stuck with a gun that walks more than it should as it heats up, and with no convenient way to reverse it.

I suggest you reread the method in the FAQ, and sleep on it before proceeding.

July 7, 2013, 10:36 AM	#1
Rbates Junior Member Join Date: January 20, 2013 Posts: 9	Winchester model 70 I just bought a Winchester model 70 in 22-250. Gun was manufactured in 1968 and looks pristine. Any recommendations for loads and barrel break in? R W Hart did an accuracy setup for me and said it looked like it was never fired.

July 7, 2013, 11:40 AM	#2
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,063	Sounds like a good find. There is no consensus on the value of break-in. I don't know how well it's actually been studied as you would need a lot of barrels to get a statistically reliable result. There's a good chance that a custom, hand lapped barrel that was properly stress-relieved before contouring needs nothing done to it at all, though you could cryo-treat it to extend its life a bit. Most rougher commercial bores will benefit some from allowing the first bullets to burnish the surface. This typically doesn't take more than a six to ten rounds with complete cleaning inbetween. It is important for this to work, according to Howa distributor Legacy Sports, to get all traces of carbon out between each of the first few shots and not to leave hydrocarbons behind that could turn to carbon at powder burning temperatures. The idea is that the carbon will pack down into the surface irregularities and occupy the spaces the metal burrs are supposed to burnish down into so that if you don't remove the carbon between shots you block the burnishing. That same distributor suggests that commercially mass-produced barrels, which are not normally stress-relieved, will tends to take a set in early firing that affects their later susceptibility to heat walking. I don't know if this is a belief or has actually been demonstrated. Again, the testing would require a lot of rifle barrels to prove and a willingness to ruin some. But if true, the barrel not only needs carbon removed, but needs to be cooled at least five minutes between shots. The main argument against break-in is that you waste barrel life. On the other hand, the Legacy method has done most of its work in the first ten shots, and you'll blow that many down range getting sighted in anyway, so I think it's worth doing both those functions simultaneously. This also provides an opportunity to learn the POI of your cold barrel, and then to later compare to a warm barrel POI to check how much walking, if any, you have. If you want to go on to fire even more break-in shots, at least do your load development with the same rounds. May as well not waste anything at today's prices. Legacy's method is in their FAQ. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle Last edited by Unclenick; July 8, 2013 at 11:16 AM.

July 8, 2013, 09:39 PM	#5
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,063	I, too, am an engineer. The problem I have with multiple shot strings during break-in is that is you not only need to expend a lot more ammunition to finish breaking the barrel in, but every shot deposits copper right where you most need the burnishing from the next round to occur, shielding that spot from the friction of the next shot. Also, if there is anything to the theory suggested in the Legacy FAQ I linked to above, of getting a barrel that has not been stress relieved to take a cold set (and I can argue it pro and con based on rough residual stress estimates and pressure distributions) then firing more than one before letting it cool again for the first ten rounds or so could get you stuck with a gun that walks more than it should as it heats up, and with no convenient way to reverse it. I suggest you reread the method in the FAQ, and sleep on it before proceeding. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle

July 7, 2013, 02:48 PM	#3
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	If more than 20 rounds have been fired in its barrel, it's broken in as much as it'll ever be. Just shoot the darned thing. Some of Winchester's hammer forged barrels (all made 1964 or later) are a bit more rough than others. So, after a good cleaning, it may take 4 or 5 shots to fill in the micro divots with bullet jacket material, then subsequent ones will shoot very well. I'd replace the firing pin spring if that rifle's made in 1968. Get one from Wolf in a 26 pound rating.

July 8, 2013, 02:51 PM	#4
Rbates Junior Member Join Date: January 20, 2013 Posts: 9	Thanks for the advice. I spoke with an engineer and he told me to shoot 10 rounds then brush and patch the barrel with oil, then repeat until the groups tighten up. After that, scope it in.