Bartlein Gain Twist barrels... new standard?

Bartlein Gain Twist barrels... new standard?

This is a discussion on Bartlein Gain Twist barrels... new standard? within the Rifles forums, part of the Sniping Related category; A most interesting read... http://www.snipershide.com/forum/ubbthr ... ost1360575 I'm most interested in Mike R.'s opinion on the matter. Any idea if any of the other top ...

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  1. #1
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    Bartlein Gain Twist barrels... new standard?

    A most interesting read...

    http://www.snipershide.com/forum/ubbthr ... ost1360575


    I'm most interested in Mike R.'s opinion on the matter.
    Any idea if any of the other top barrel companies do this too?

  2. #2

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    Well they have always made excellent barrels, so no big surprise. I wish I could afford one or two or maybe six. :wink:

    Gain twist rifling has been around along time. IIRC the infamous German 88mm used it.

  3. #3
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    The 6.5x52 Carcano rifle also used Gain Twist Rifling. Started at 1-19.25 and ended with 1-8.25.

    Erik
    Just a civilian who enjoys shooting

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    For those of you who don't want to sift through all the posts.... here are the 2 quotes I found most interesting from 2 different people.

    "This is not a Tactical Type Post but alot of guys always ask about Button Vs Cut rifled, Who is making the best barrels Etc. results like these are hard to argue with.



    NBRSA Nationals were last week 13 new National records where set. 3 new world records set.

    All with Bartlein Barrels

    Examples:

    Tony Boyer new Unlimited class record 8 ten shot groups at 100 yards agg. = .189 (previous record was .2195)

    Jack Neary LV record of 5 five shot groups at 100 yards = .1482

    Tony Boyer won the 3 gun with a grand agg. of .199 this was for the Sporter class, LV class, HV class 100 and 200 yard combined. A total of 150 rounds being fired for these three classes if I have it correct. Yes a grand agg. of .199 for 150 rounds being fired at 100/200 yards.


    Top 20 shooters were all using cut rifled barrels.
    65% of the top 20 were shooting Bartlein

    Out of the top 80 shooters (20 from each class Sporter, LV, HV and Unlimited) Bartlein barrels accounted for 60%, Kriegers where 38% and Hart and Shilen had 1% each.


    Congrats for Trace Bartlein and his crew, thats quite an accomplishment for being a less than 5 year old company. "
    _________________________
    George Gardner, G.A. Precision








    "Sorry but this is gonna be kinda long!

    Gain twist barrels have been around for nearly ever. They kinda died away when jacketed bullets came about. Harry Pope (Pope rifle barrels) is probably the best known maker of gain twist barrels. There have been others and I'm not intentionally leaving anyone out. Pope died in 1910 I think it was. Back in his day one of the main types of shooting matches where the German Schutzen fest matches. Guys used guns like the Winchester HI Wall, Ballards, Hepburns, Stevens 44's etc..., the German rifles and others. Nearly all of Popes barrels where gain twist (left hand to boot also). They still where shooting lead bullets and most guys even though they had cartridge guns still muzzle loaded the bullet with false muzzles.
    The advantages listed back then where these. 1.) The twist being less at the breech gives less friction to the bullet, it therefore starts easier and quicker, giving the powder less time to burn on in front of the chamber, which therefore fouls less than in a barrel of uniform twist at the same necessary muzzle twist/pitch.
    2.) The slight change in angle of rifling in connection with choke boring effectually shuts off any escape of gas and prevents gas cutting, which is another cause of imperfect delivery.
    3.) It holds a muzzle loaded bullet in position much better than a uniform/straight twist barrel.

    The above is quoted from the manual of Stevens-Popes barrls literature and remember they are referring to lead bullets.

    Now lets fast forward a bunch of years. There are differences in shooting lead bullets vs. jacketed bullets. I'm not claiming I or let alone anyone else I can think of knows all the real answers but I will share some observations.

    The gain twist type rifling will what we call will give a mechanical choke on the bullet just like with lead bullets. A lot of bench shooters always ask for the bores of the barrels to be lapped with choke in them (this is another subject). Some comments made to us about the gain twist is that is seems to give a broader tune window (i.e. different bullets and different powders and or charge weights) the barrels seem to be more forgiving. One of the first gain twist barrels that went to Lou Murdica (2 light gun barrels and a rail gun barrel). He put a 100 rounds thru the rail gun barrel in his test tunnel in one day. I asked him what it averaged. He said lets put it this way. I shot 5 different bullet makers bullets both flat base and boattails. The worst group was a .120 at 100 yards.

    Now with this being said I will say what I've said for years as to why single point cut rifled barrels are better than button rifled barrels.

    Button rifling does not always produce a uniform twist. The twist is built into the button. If during the rifling process the button hits a hard spot in the material or soft spot the button will slow down. It could even speed back up to what it was suppose to be doing the original twist at. The down side here is a non-uniform twist or a twist that slows down thru out the length of the barrel. If you are shooting bullets in a certain twist barrel that is on the edge of stabilizing the bullets this will cause accuracy problems.

    Some button rifle makers are trying to help guide the rotation of the button during rifling.

    I will also say the button rifled barrels can make a good barrel and have set there share of records over the years and have more than proving themselves but for years after World War 2 there where not really anyone doing cut rifling it kinda died away until guys like Obermeyer and Krieger put it back on the map also. Button rifled barrels are not as consistent from one to the next in terms of how uniform the rifling is like in a cut rifled barrel.

    One benchrest shooter and machinist made a machine that he could check the twist rates and uniformity with. Another guy has access to a machine that can do the same thing (machine wasn't designed for this but does it very well). Both guys have giving/shared inspection data with me. The first guy (in his 70's now) has checked a lot of barrels in his time (and just last year was in the lead for shooter of the year in one of the state's for short range benchrest). What he has noticed that in checking the so called hummer barrels that shot really well they all had either a uniform twist or had a slight gain to them.
    The barrels that didn't shoot well didn't have a uniform twist or had a negative twist to them.

    Are gain twist barrels flat out better than a straight twist barrel. Off hand I don't think so but I can also say for the most part they are showing a lot of promise. There is no loss in velocity as some have said would happen and they have giving up nothing in accuracy at all with jacket type bullets. If anything they might make the barrels more consistent from one to the next.

    Another disadvantage of button barrels is bore uniformity in terms of size and the stress the button rifling induces into the barrel steel.

    How did we start making gain twist barrels. The cast lead bullet shooters shooting the lead bullets asked us to make them. Then the guys shooting the solid copper style jacket bullets with driving bands on them some how where told they need a gain twist barrels.

    The first two guys shooting conventional jacketed bullets in a gain twist barrel from us was the famed benchrest shooter Tony Boyer and the other I mentioned earlier was Lou. What Tony said to us was he had a button rifled barrel that as close as they could check it the twist went from 15 to 14.25. So they flipped the blank around so the twist ended faster at the muzzle. He said it was one of the best shooting barrels he has ever had but until us no one could make him another one with that twist rate. That was last year and the rest is history.

    Also another famous gun maker who builds mostly Palma rifles and F-Class guns started using some button barrels because he wasn't happy with one of the cut rifled barrel makers and service he had been getting. He knew about the twist uniformity problems with button barrels. So he checked all the first ones he started getting from a button rifle maker. He got a batch of four or six 6mm suppose to be 1-8 twist barrels. The twist in this batch of barrels where running as slow as 8.5 to 8.75. None of the barrels would shoot the 107gr. weight type bullets. Since he was a customer that I knew before and when he found out we where up and running has been buying from us since and not using button barrels anymore.

    What twist rates are best? Just not enough data. The twist still has to be fast enough to stabilize the bullet you are shooting. That is where you have to start.

    We have one customer shooting a 30BR for score shooting. He ordered a couple barrels late last year and shot one for the first time in a bench match earlier this year. He ordered a .30cal. barrel and the twist started at 28 and ended at 19. I told him I had no idea how it would work. He insisted we make it and charge his c.c. So we did. The first match he went to the shooting was being done at 100-300 yards the smallest group he shot was somthing like a .150 and the largest was a flat .500. He won the match. So what do you say? He has more on order.

    Guys have shot the gain twist barrels in F-Class, Palma, Benchrest etc...

    Cut rifled barrels are winning more matches and setting more records than button rifled barrels currently are and have been for a while.

    Later for now!
    Frank
    Bartlein Barrels"

  6. #5
    Senior Member Sniper_Beast's Avatar
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    now that, is a very very interesting read. Thanks for sharing it

  7. #6
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    Lawton makes gain twist barrels for the 338. A couple of the ultra high bc turned solids require down near a 1 in 8 twist which is a lot of mass to get turning that fast. The lawton barrels were made at the request of one of these bullet makers and I think they're still producing them.

    Don't tank barrels use gain twists as well?

    Also, here's a clip off of Lilja's web site on the subject:

    "However Lilja has quit using a gain twist. After years of comparing the accuracy of barrels with a gain twist and barrels with a standard twist, he has decided the gain twist offers no accuracy advantages. "You get just as good or better accuracy with a standard twist," he said, "just as long as the twist remains exactly the same the entire length of the bore.""
    Walther P99 9mm/AAC Evo
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  8. #7
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    Here's a link to the Krieger site where they detail their cut method. Slow and steady get the results it seems.

    http://www.kriegerbarrels.com/Barrel_Ma ... wp3379.htm

    Cheers
    "What we do for ourselves, dies with us. What we do for others and the world remains and is immortal." Albert Pine

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    Thanks Johnson. Very informative post.

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    I guess gain twist is one of those things that looks good on paper but bottomline doesnt really do alot for you.

    Most MBT tubed weapon is infact smoothbore, firin 'arrows'. In order to penetrate the thick composite armor more velocity and mass was needed. Unfortuniately rifled barrels couldnt get up to the velocity needed as friction between the rifling and the driven band created unmanageable breech pressures and recoil forces for a confined turret.

    The ever increasin length of the penetrator rod was prone to breakin when it hit the armor plate and torque from rotating overwelms tensile strength. Not rotatin the rod helps keep it whole as it impacted the target. (eventually the muntion designers had to turn to the controverial DU material to withstand impact forces.

    The Roosians found out about 1/4 the propellant is used in overcoming friction from their tank cannon's rifling.

    One other factoid, spinnin a shaped charge warhead, the HEAT round, messes up the hot metal/gas tongue that does the work. The Brits have a slip collar on the HEAT rounds they send through the 105mm MBT rifled cannon.

    Anywho, I'm for good careful rifling matters more than number of grooves, (remember that so-called new n improved concept), or if they gain in twist rate. Perhaps a real good seller would be twist gain exterior flutin to go along with the interior rifling. :wink:

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