Custom barrels...some "faster" than others?

[thndrchiken]

While it's nice to say that I have a custom barrel. Shoot the gun, see if the accuracy potential is up to your expectations. Is spending the money for a custom barrel worth the extra 50 or so fps. I say no but It's your money.

[Scott Gags]

I believe button rifled barrels are slightly faster than cut rifled barrels assuming the barrels are equally finished or lapped equally smooth.

I think it is because the button rifiling process starts at the chamber end and pulls toward the muzzle end. As the button is pulled thru it orients the tiny metal particles to face toward the muzzle. This slightly reduces drag kind of like putting in golf with the grain of the grass or against the grain of the grass.

The down side of button rifling is that it can stress the metal particulary in lightweight barrels.

[dylan_b]

Originally Posted by Scott Gags

I believe button rifled barrels are slightly faster than cut rifled barrels assuming the barrels are equally finished or lapped equally smooth.

I think it is because the button rifiling process starts at the chamber end and pulls toward the muzzle end. As the button is pulled thru it orients the tiny metal particles to face toward the muzzle. This slightly reduces drag kind of like putting in golf with the grain of the grass or against the grain of the grass.

The down side of button rifling is that it can stress the metal particulary in lightweight barrels.

i dont think its the direction in which the barrel is rifled, as im fairly sure krieger cuts from chamber to muzzle, and still tends to be a bit slower then most others.

honestly i dont think theres much difference between brands using the same process. i use a broughton 5c barrel on my 6.5 wsm. its 26 inches long measuring from the throat and i run about 100 fps faster then my friends 6.5 wsm of the same setup except with a krieger barrel. i cant really explain why its so much more faster, but my barrel is marked 6.5/270 wsm where as his is marked 6.5/300 wsm but as im told there shouldnt be any difference in velocity between the two. but ive talked to other guys with 6.5 wsm's that where using push button barrels and the difference was only about 35 fps

Depends mostly on the throat that is cut. If you get a lot of freebore, which I don't want, you can really speed up a cartridge before hitting pressure signs.

[Scott Gags]

By Dylan

i dont think its the direction in which the barrel is rifled, as im fairly sure krieger cuts from chamber to muzzle, and still tends to be a bit slower then most others.

The differentce is that as the button is pulled thru it forms the lands that the bullet actually ride on. The cut rifling only removes materal and the bullet actually does not contact the area removed in cut rifling.

[Remnard]

If a barrel is lapped correctly it shouldnt matter which method was used for making the barrel. The burrs inherent in any barrel cutting process will be removed if the barrel is lapped properly. It also prevents fouling buildup with in the barrel and you can maintain accuracy and velocity longer.

[dylan_b]

i thought id mention a late physicst/ballistician from back in the late 80's and early 90's karl hause. he studied the differenced in cut and button rifling in his later work. this information IS NOT PROVEN AND THEREFOR IS NOT FACTUAL UNTIL IT IS, IF IT IS. his work was cut short because of funding and soon after that he passed away.

his theory which he was trying to prove was the in cut barrels the risidual austenite in cut barrel even after stress relieving. he also was trying to prove that although austenite (bad) can be relieved into martensite(good), it is easier to do so when the austenite is stressed. unstressed austenite takes much more heat to remove. he also outlined that austenite (and later martensite after relief) formed in clusters along the cuts so after a relief there was clusters of martensite.

he believed that because of the process used by button rifling created a even surface of more thoroughly stressed austenite which translated to a good surface of martensite.

thats about where he stopped his work on cut vs button barrels. he himself couldnt get around to final testing but he believed that the bliss effect may come into play since no barrel truely has a prefect uniformaty in hardness along the groves/lands but this theory is even to me very questionable.

this is karl hause's thoery (hause, switzerland, 1993), not mine but i do think there may be some fact behind it. im only posting this to give everybody something to think about. if you guys want to start poking holes in his theory, go ahead, most scientists already have. i like his previous work on barrel harmonics which imo is the best kept sercets to contouring a better barrel.

[dylan_b]

just to rectify my last post and for anybody that isnt a machinist

cut barrels forms stressed austenite only along the cuts. if the already existing in the barrel isnt stressed, it might not be able to turn into martensite which will create uneven hardness in the barrel which will upset the barrel harmonics.

to much martensite is bad, it can be remedied with a combination of cryo/stress treating. krieger does so.

button rifling tends to stress the entire unturned barrel so most of the austenite is stressed so it can be turned into martensite. since the martensite is formed throughout the barrel, it does not need to be removed to reach perfection. thats why cryo treatments seem to do nothing to button barrels.

of course all of this depends on if the treatments wheter tempering or cryo is proper. the info in this post is generaly reguarded as true among most majour barrel makers, but as before no one has got around to really scientificaly proving it.
it is proven that austenite and martensite are the why and how of most steel stresses

[mphstigerfan]

if you are rebarreling for an increase in velocity try another cartridge on the front end, $600+ is a lot to spend for a shot at 50-75 fps (which you may or may not see) custom barrels are designed to shoot one hole groups, some do and some don't but thats the primary purpose. and yes the barrel itself may be 295 by the time you get it chambered, etc... its atleast 600 if done the right way. if you are considering a 30-06, think about a 300wsm or 300 win. or win to wby to rum whatever much cheaper way to get the velocity you want.