Why do some barrels create higher velocity than others

[Methow Packer]

Sorry I posted this in a wrong spot. I have Brux barrels on three of my precision rifles. Each one produces higher velocity than what they should based on loading tables. Example is my 270WSM with 140Bergers. Using Re 26 @ 63 grains I'm getting 3155 fps ( Lab Radar). That's 3+ grain less than Alliant states is max charge. At 63 grains is a max charge in my rifle. ( slight bolt lift ). Similar results with my 243Win using 105 Bergers. Re 23 @ 42.0 for 3108 fps. Again more than 3 grains less than max stated but max in my rifle. That's high velocity for a 243 and 105 grain bullets. So is this typical for these Brux barrels? Is it their groove/ land design. boar dimension? Any thoughts? Not complaining. They're all .5 or better MOA rifles without going to a max charge. I haven't ruled out these RE23 and Re 26 powders.

 

[TG-5150]

What is the temp and elevation, jump to the lands or crunched ? What primers ? I know knotting about their barrels, these are just the first ?'s that popped in my head, from a reloaders standpoint.

 

[L.Sherm]

The new RL powders do contribute to extra velocity in my experience. The Brux bore is .236 on your 243 I believe. I have seen over 3100 out of a 243 with 107 sierras in a 24" barrel and it wasn't a Brux and a .237 bore.
I have heard others comment on Brux barrels being fast though.

 

[J E Custom]

There are many reasons that velocities are higher/lower than book loads.
To list a few examples I would start in no particular order with chamber dimensions, Barrel length, loads, bore diameter, rate of twist, free bore, bore finish, number of lands, Chronograph, atmospheric conditions, bullet diameter, neck tension, altitude and many more.

If any one thing is not the exact same as when the test were taken or calculated the same as the test loads in the loading manual it is not unusual for velocities to differ. The book is just a reference and your velocities should be in the ball park as long as all things are equal.

Be happy you are at least higher than the book.

J E CUSTOM

 

[nmbarta]

I have 3 brux barrels, I'm not sure why, but all three run a little faster than I thought they would. I'm guessing bore finish has something to do with it. Brux and Bartlein have been my favorites. I prefer cut barrels for no other reason than my limited background in metallurgy leads me to believe this is a better system. Maybe it has something to do with it.
My cut barrels seem to run a little faster than my buttons, but this is purely speculation, I have no idea if the process has anything to do with the speed.
All three shoot really good, as do all of my custom barrels, but I do have a couple barrels that seem really slow. As J E said, it could be a number of things.

 

[jjmp]

Two Friends of mine that don't know each other have Four Brux bbls between them 3 Full customs n one semi/custom all four left hand,Remington bdl actions Smithed to more or less of being tricked out,two 30 cals 1/300Dakota,1/300 win-mag 1/708 rem1/6.5CM all shoot Fantastic it's not rocket science , it's Great People making a Great Product . All my Cut/Rifled Bbls have been Fantastic ,which includes Kreiger & Chanlynn , sorry if I misspelled ! But you get my Drift pun intended Lol, enjoy them Great bbls !!!

 

[TG-5150]

jjmp, r u a southpaw too? Haha. Couldn't resist.

 

[jjmp]

TG, thks but no ! Gd try bac at you ! Lol

 

[TG-5150]

TG, thks but no ! Gd try bac at you ! Lol

All good. Southpaws are difficult. Raised one that is right eye dominant. And he throws left handed. All messed up. Haha
He shoots awesome though(right).

 

[J E Custom]

Barrel makers normally make there barrels bores to industry standards so they can be chambered using a standard reamer pilot and also depending on the bullet diameter and displacement of the bullet when a bullet is engraved by the lands. It must fill the bore completely, and seal off the gas from the powder to prevent blow by.

If the barrel bore is to big for the bullet by only by a few ten thousandths, there will be blow by and velocity and barrel life will suffer. If it is to small, the bullet will be extruded and loose diameter, gain length, and the pressure will go up for the same load. The amount of these changes can get one into trouble, so the barrel makers don,t have much room to Play with.

I suspect your chamber or loads are the difference, because I have chambered many different barrel brands and only found one barrel brand that often required a smaller bushing to fit. Brux was not the one. All others used the standard reamer pilot most of the time and some require a larger bushing (.00001) to fit properly.

Just my experience with different barrel brands.

J E CUSTOM

 

[Methow Packer]

Barrel makers normally make there barrels bores to industry standards so they can be chambered using a standard reamer pilot and also depending on the bullet diameter and displacement of the bullet when a bullet is engraved by the lands. It must fill the bore completely, and seal off the gas from the powder to prevent blow by.

If the barrel bore is to big for the bullet by only by a few ten thousandths, there will be blow by and velocity and barrel life will suffer. If it is to small, the bullet will be extruded and loose diameter, gain length, and the pressure will go up for the same load. The amount of these changes can get one into trouble, so the barrel makers don,t have much room to Play with.

I suspect your chamber or loads are the difference, because I have chambered many different barrel brands and only found one barrel brand that often required a smaller bushing to fit. Brux was not the one. All others used the standard reamer pilot most of the time and some require a larger bushing (.00001) to fit properly.

Just my experience with different barrel brands.

J E CUSTOM

Thanks to all for the input. Makes sense and I'll enjoy the outcome of these barrels. I like the work my smith has done and the results. Kevin Weaver from Colorado

 

[cgarb]

Have you verified you reloading scale with weights? Both examples are 3 grains off from max...is it possible you are throwing a heavier charge than what the scale says?

 

[KyCarl]

I have a 300 WM with a Obemeyer barrel and my best friend has a Weatherby Mk.V
300WM. Both are 26 inches I have a break and he doesn't. Mine runs almost 200 Fps faster with the exact same ammo??
All it can be is the inside finish ..everything else is the same.

 

[L.Sherm]

Can be finish can be bore dia.or both is what I'm guessing on the weatherby. As JE said bore dia has alot to do with it, I have 4 Green Mountain barrels on some of my varment stuff while they shoot pretty good they have a tendency to be slow compared to other 17 and 20 I have because the bores are on the big side.
If you look on there web they advertise there bores .001 bigger than everbody else.