Velocity Differences between barrels.

[370bc]

I have a kimber montana 1-10, in 243 win that use to go 4000-4100 fps w/ 55 NBT.
With my new Douglas, 1-12 barrel, I can only safely go 3800 fps with the same load.
Are those numbers typical between barrels?
Thanks in advance.

 

[savagedasher]

I have a kimber montana 1-10, in 243 win that use to go 4000-4100 fps w/ 55 NBT.
With my new Douglas, 1-12 barrel, I can only safely go 3800 fps with the same load.
Are those numbers typical between barrels?
Thanks in advance.

Sure it not just be the barrel !chamber and free bore. Will do the same

 

[Forum Boss]

We have seen up to 100 fps between a really fast and really slow barrel. What you are listing seems extreme. Are you really sure about the numbers for your original Kimber?

 

[dmoran]

With in a velocity range of 2800 to 3100-fps, I have seen barrels very +100-fps.
So at your 4000-fps (+25% greater), the effect could also be greater.
So I myself would say, yes, 200-fps could be possible variation.
Donovan

 

[dkhunt14]

Sometimes a barrel will speed up some after you get some rounds through it. Matt

 

[370bc]

We have seen up to 100 fps between a really fast and really slow barrel. What you are listing seems extreme. Are you really sure about the numbers for your original Kimber?

I have a pro chrony and a shooting chrony. Not Oehler. Both are 15+ years old.
I told my smith i wanted to shoot the 55's, but when I got the rifle back, the rifling was miles away, like the factory. It shoots 70 TNT's and 88 bergers half MOA, so I am happy. I am just surprised at the velocity differences.

 

[JamesnTN]

You're seeing most of that difference because of the twist rate in your barrel. Can't compare the two to be honest

 

[msinc]

We have seen up to 100 fps between a really fast and really slow barrel. What you are listing seems extreme. Are you really sure about the numbers for your original Kimber?

He very well could be...one thing a lot of folks don't know {unless they own a borescope} is that Kimber uses a bore hone on the drilled bore to get it to size then cuts the grooves. Unlike some barrel makers that use a reamer for the final bore size before rifling. Honing the bore leaves a very nice consistent and smooth finish on the lands. Unlike many cut rifled barrels the lands don't foul, well, at least mine don't. Now the grooves are considerably rougher and they catch a lot of copper resulting in a shooter that {with no borescope} will see a lot of copper coming out of the bore when cleaning and possibly believe the barrel is a fouler.
Bottom line, as smooth and nice of a finish is on the lands, I can see better velocity coming out of a Kimber barrel.

 

[savagedasher]

He very well could be...one thing a lot of folks don't know {unless they own a borescope} is that Kimber uses a bore hone on the drilled bore to get it to size then cuts the grooves. Unlike some barrel makers that use a reamer for the final bore size before rifling. Honing the bore leaves a very nice consistent and smooth finish on the lands. Unlike many cut rifled barrels the lands don't foul, well, at least mine don't. Now the grooves are considerably rougher and they catch a lot of copper resulting in a shooter that {with no borescope} will see a lot of copper coming out of the bore when cleaning and possibly believe the barrel is a fouler.
Bottom line, as smooth and nice of a finish is on the lands, I can see better velocity coming out of a Kimber barrel.

Only thing I have to say I have a 300 WBM with a WBY chamber I put a Douglass barrel on it has a shorter FB .
I couldn't shoot my factory WBY cases . Because of pressure issues . Larry

 

[370bc]

He very well could be...one thing a lot of folks don't know {unless they own a borescope} is that Kimber uses a bore hone on the drilled bore to get it to size then cuts the grooves. Unlike some barrel makers that use a reamer for the final bore size before rifling. Honing the bore leaves a very nice consistent and smooth finish on the lands. Unlike many cut rifled barrels the lands don't foul, well, at least mine don't. Now the grooves are considerably rougher and they catch a lot of copper resulting in a shooter that {with no borescope} will see a lot of copper coming out of the bore when cleaning and possibly believe the barrel is a fouler.
Bottom line, as smooth and nice of a finish is on the lands, I can see better velocity coming out of a Kimber barrel.

It seemed like when the 55's hit, they really hit hard, as far as hydrostatic shock. Even a hit in the non-vital zone would produce a kill.
I hit a yote at 30 yards running straight at me w/88 berger and it took a second shot to finish the job!
I can tell when i run patches down the barrel the smoothness difference between barrels.
My buddy has a bore scope and i scoped both barrels. Night and day difference. I wish I would of got a 1-8. I tried to change, but they said it was too late. Im making the best of it as is.

 

[Wirelessguy2005]

i can't speak to the larger calibers but with the 20 calibers i have ran across many barrels that will vary by 100-200 fps with all other things being equal (ie: same cartridge,brass,chamber reamer used). The only consistency i have found is that all of my 3 groove barrels produce 100 or more fps over the 6 groove barrels.

 

[370bc]

Only thing I have to say I have a 300 WBM with a WBY chamber I put a Douglass barrel on it has a shorter FB .
I couldn't shoot my factory WBY cases . Because of pressure issues . Larry

I didn't think it would be that complicated getting a custom barrel. There seems to be a lot that can change as far as FB and what bullets will be used, port being long enough for VLD's, etc.

 

[WyleWD]

You're seeing most of that difference because of the twist rate in your barrel. Can't compare the two to be honest

From my experience James is on it. Normally, but not always, a 12 twist will shoot a higher muzzle velocity with a faster burn rate powder than a 10 twist. Simply stated, you should or might want to change your powder to a slightly faster powder and work up a new load with that 12 twist. JME. WD

 

[savagedasher]

I didn't think it would be that complicated getting a custom barrel. There seems to be a lot that can change as far as FB and what bullets will be used, port being long enough for VLD's, etc.

WBY has always had long FB that is how they got the speed without excess pressure. Larry

 

[370bc]

From my experience James is on it. Normally, but not always, a 12 twist will shoot a higher muzzle velocity with a faster burn rate powder than a 10 twist. Simply stated, you should or might want to change your powder to a slightly faster powder and work up a new load with that 12 twist. JME. WD

I was using Win 760. I have a couple of old cans of 4320 and 4064 that would be faster than 760 that I could try with the 55's. Thanks for the advise.

 

[Catfur]

I have a barrel, chambered in 6mm Rem, that despite being longer than the standard in every load manual I find, can't get within 150 fps of a "max load."

It shoots well, though.

 

[savagedasher]

I have a barrel, chambered in 6mm Rem, that despite being longer than the standard in every load manual I find, can't get within 150 fps of a "max load."

It shoots well, though.

No manual will tell you that . But you can

I have a kimber montana 1-10, in 243 win that use to go 4000-4100 fps w/ 55 NBT.
With my new Douglas, 1-12 barrel, I can only safely go 3800 fps with the same load.
Are those numbers typical between barrels?
Thanks in advance.

What powder are you using and how much and COL & barrel length ?

 

[stretch257]

I have seen variations in speed based on how the chronograph is set up. If it is not exact you can increase distance between sensors. Temp can effect electronics. Many variations