Gunsmithing Fast Barrels

[wapiti16b]

What makes a barrel fast and who consistently makes fast barrels ?
I keep reading posts where the op claims a fast barrel and would like to know how this occurs .
If you have brand A and brand B with identical specifications and brand B shoots the same load faster than brand A what gives ?
I'm guessing it's barrel materials and harmonics but would appreciate information from those with knowledge of the subject of which I am sadly lacking !
Thanks !

 

[Citius7]

I think it depends on the size of the internal barrel diameter. 6mm being 242 instead of 241 or something. I know the bullet's bearing surface makes one bullet run faster than another. Also how the rifling grooves are cut. Slight gain twist barrels tend to have less leakage of pressure due to the way the bullet obturates. For example. Rock creek uses a very slight gain twist from 8.07 to 7.77 twist if u buy 8 twist from them.

 

[Rthur]

The slight gain twist might be part of the answer.
I've seen them, fast barrels, just can't say I could predict which ones were going to be fast.

R

 

[Pusher591]

Rock Creek has always made fast barrels it seems. I've used them a lot over the years and they have always been fast. Haven't used them since Mike left though. Not sure if things are still the same.

Never used them but I've always heard Broughton 5C's are faster on average.

 

[bogeybrown]

There was a really good break down on this YEARS ago where Mr Green from Bartlein offered some wisdom. IIRC he indicated that another manufacturer typically had a faster barrel, but that Bartlein's tested out to be more accurate than that faster barrel. Perhaps Frank Green may be willing to contribute some of his wisdom to the topic again. I will happily admit to being a Bartlein fanboy.

I know this may seem insultingly simple, but also keep in mind that a good portion of the time the terms "faster" and "slower" are used in reference to the twist rate of the barrel rather than its comparative muzzle velocity.

 

[Hookturnr]

I have a Hart 30 cal. barrel chambered in 300 RUM that is by and far the fastest I've seen. My smith attributed it to being a tight bore possibly but I really don't know just what makes it that fast.
It has simpy become a "powder efficient" barrel for me as I have found the 210gr. VLD to be most accurate at 3060fps. out of multiple barrels and I get that velocity oout of this barrel at 85.5gr. of H1000 as opposed to going 90.4 and 89.7 in my last two barrels.

 

[BangBangBlatBlat]

My Lilja 3 groove barrel has been a pretty fast puppy. It's also got a very short throat too.

My 26 inch barrel is shooting 142 SMKs at 2930fps with 43 grains of H4350, at least it was the last time I tested it. My Kreiger barrel was right around 2850fps with the same load. The 2 other 260 Remington shooters were getting 2900fps with 43.5 grains of H4350.

 

[LRI]

It's bore diameter. The lands don't seem to do much by my research. Ken from K/P and I have played with this quite a bit in my quest of "mile per second" MV out of my ongoing overwatch project.

Thus far I've reached a solid 4500fps with a 34" tube on a 300-338 Lapua Magnum slinging 125 Ballistic Tips from a 1:20ROT barrel.

1/2" groups at 200 and it'll punch a hole through 1/2 mild steel out to 600 yards. Hysterical fun. Someday I'll get enough ambition to ventilate a coyote with it. I made this action over about a 3 or 4 year period when I first opened up shop. -Just because I got sick of people calling me out about it.

Anyways, "one of one" is the serial number. It'll stay that way. No intention of complicating my life that much.


This shows the first barrel. Setup for 220 Scenars. Don't run it anymore.
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[Supersubes]

It's bore diameter. The lands don't seem to do much by my research. Ken from K/P and I have played with this quite a bit in my quest of "mile per second" MV out of my ongoing overwatch project.

Thus far I've reached a solid 4500fps with a 34" tube on a 300-338 Lapua Magnum slinging 125 Ballistic Tips from a 1:20ROT barrel.

1/2" groups at 200 and it'll punch a hole through 1/2 mild steel out to 600 yards. Hysterical fun. Someday I'll get enough ambition to ventilate a coyote with it. I made this action over about a 3 or 4 year period when I first opened up shop. -Just because I got sick of people calling me out about it.

Anyways, "one of one" is the serial number. It'll stay that way. No intention of complicating my life that much.


This shows the first barrel. Setup for 220 Scenars. Don't run it anymore.
[IMG2=JSON]{"data-align":"none","data-size":"full","src":"http:\/\/i165.photobucket.com\/albums\/u64\/nesikachad\/2009%20TO%202014%20BUILDS\/GUN%20PICS\/LRI%20Overwatch%20Magnum%20Rifle\/DSC_0085.jpg"}[/IMG2]



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[IMG2=JSON]{"data-align":"none","data-size":"full","src":"http:\/\/i165.photobucket.com\/albums\/u64\/nesikachad\/2009%20TO%202014%20BUILDS\/GUN%20PICS\/LRI%20Overwatch%20Magnum%20Rifle\/DSC_0081.jpg"}[/IMG2]

That's funny Chad, I was gonna ask you one of these days if you ever considered building receivers. Guess that answers that. How bout barrels?



Broughton 5c's had a reputation as being fast, so I bought one, left it long, and had it chambered in .260. It was super.....average in the velocity department. But it's the closest barrel ive had to what the BR guys call a hummer. It doesnt matter what you put down the thing, they'll group. I'd take that over speed, any day!

 

[Davester]

http://www.geoffrey-kolbe.com/articles/Pressure_Trials_Consortium.htm

 

[Cartman]

http://www.geoffrey-kolbe.com/articl...Consortium.htm

If your intention was to save up for five years and then make one short but sweet post, well played. Well played indeed.

 

[wapiti16b]

So , I ordered a Broughton barrel for my 300WM and when it all comes together I'll let ya'll know how fast it is !

 

[Frank Green]

There was a really good break down on this YEARS ago where Mr Green from Bartlein offered some wisdom. IIRC he indicated that another manufacturer typically had a faster barrel, but that Bartlein's tested out to be more accurate than that faster barrel. Perhaps Frank Green may be willing to contribute some of his wisdom to the topic again. I will happily admit to being a Bartlein fanboy.

I know this may seem insultingly simple, but also keep in mind that a good portion of the time the terms "faster" and "slower" are used in reference to the twist rate of the barrel rather than its comparative muzzle velocity.

There are quite a few different things that effect velocity or what guys call a fast or slow barrel. One is the chamber reamer and what dimensions/spec. it cuts the throat too. Another is barrel length which everyone basically knows. The other is the total surface area of the bore. The total surface area of the bore includes the bore (tops of the lands), groove width and the groove size. The bore and or groove width doesn't have as big of an impact on pressures and velocities but it does have an effect. Changing the groove size has the biggest impact. Typically a tighter groove size (undersize or basically if you will at zero) it will drive the pressures up more and usually with the same load it will give you more velocity. You have to be careful with this. Having a groove size say .0005" under min. spec. can drive the pressures up 8000psi. Doesn't sound like much but if your ammo is already at say 62k to 64k pressure now your at 70k or more.

So when a guy says brand X is faster than brand Z you are not necessarily comparing apples and apples. Unless you know what the chamber reamer cut the throat to and what the exact bore and groove size are in each barrel you don't know what is making the barrel fast or slow etc.....

Also how many rounds are on the barrel is another variable. As the barrel wears and gets X amount of rounds on it etc....it will start to lose velocity. If your handloading you can bump your load and chase the throat etc...to get the accuracy back and velocity usually back up as well but if your shooting box ammo you have to deal with the changes even more so.

I won't even get into the ammo being a variable either.

The reference bogeybrown made in regards to testing.....that was by the military a few years ago. They went with a different barrel maker because they got like another 50fps. faster. I said that was a bull test/answer as the barrel maker they went with at the time supplied tight bore barrels. When they ordered from us they didn't spec. a tight bore and unless you spec. it we make standard min. spec. barrels. They did say though in the accuracy testing our barrels out shot everyone else.

Later, Frank
Bartlein Barrels

 

[700smooth]

following

 

[winniedonkey]

I love learning things on here.

Sent from my HTC6535LVW using Tapatalk

 

[wapiti16b]

Barrel ships tomorrow , Charlie Robertson at Score High will be doing the work and I should be developing loads by the end of July or the beginning of August ! . The barrel will be going on my SAKO AV and will be a 1n9 twist 300 WM for either BERGER 210 to 215 g bullets or HORNADY ELDX's of the similar weight or more if needed .
I plan on this build for my Deer hunt in November . I will keep progress posted !

 

[wapiti16b]

Barrel received !