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#5572435 - 01/29/15 10:57 PM Who's running a gain twist barrel?
P & Y Online   sick
Tracker

Registered: 11/28/10
Posts: 948
Loc: North East Texas
what are the benefits of a gain twist? Haven't heard to much about them but bartlein seems to put out quiet a few.
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#5572447 - 01/29/15 11:08 PM Re: Who's running a gain twist barrel? [Re: P & Y]
ChadTRG42 Offline
THF Trophy Hunter

Registered: 09/16/09
Posts: 9433
Loc: Lewisville, TX
I am running a gain twist on my 23", 6.5x47 Lapua barrel. Starts at 10.5" and finishes at 8.5" at the muzzle. I have spoken with Frank Green at Bartlein a lot about the gain twist barrels. You keep a more sustained pressure behind the bullet for better consistency. You also get a little bit more speed than traditional rifling. This is the first gain twist barrel I have personally shot, and really like it so far. I have built several other customers' rifle's with great results also.
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#5572452 - 01/29/15 11:13 PM Re: Who's running a gain twist barrel? [Re: P & Y]
Sneaky Offline
The "Grouch"

Registered: 10/22/12
Posts: 15874
Loc: Winters
I don't know much about it, but I could see an advantage for shooting heavy for caliber bullets at high velocity. It may allow you to gradually work up to that more aggressive twist rate needed for longer bullets without tearing them apart when pushing them hard. I wouldn't worry about it unless I were looking for a solution to such a problem. That's just my thinking on it.
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#5572512 - 01/30/15 01:03 AM Re: Who's running a gain twist barrel? [Re: P & Y]
Toxarch Offline
Pro Tracker

Registered: 03/09/11
Posts: 1681
Loc: Parker County
I could imagine barrel wear would be slower. But the problem I see (in my head) is the change in twist. When you fire a bullet, the outside of the bullet takes the shape of the barrel with the grooves. On a normal barrel, it stays the same for the length of the barrel so no gas can escape around the bullet. Now if the twist changes, what happens to the bullet? Can the copper exterior easily reform to keep a seal as the twist changes? Could it rip apart the jacket on a jacketed bullet? I know it's a gradual change in twist. I'd love to see some recovered bullets to see what the outside of the bullet did for the change in twist.
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#5572808 - 01/30/15 08:24 AM Re: Who's running a gain twist barrel? [Re: P & Y]
ChadTRG42 Offline
THF Trophy Hunter

Registered: 09/16/09
Posts: 9433
Loc: Lewisville, TX
Yes, the bullet will have a slight change in the rifling marks left on the copper jacket. But it will still seal up like a normal bullet will without any gas escaping around the bullet. The idea of the gain twist is to increase consistency by keeping a higher and longer pressure behind the bullet than standard rifling. As the twist gets tighter, the bullet has more resistance from the barrel, and builds up your pressures more. So far, I really like my gain twist. Mine is on a 6.5x47, and my extreme spreads (ES), (not SD) are in the single digits. When I did load work up, I tested it at 300 yards. I had numerous test groups that were less than an inch. I selected the load based on what gave me the lowest ES, which was either 5 or 6 ES on 5 or 6 shots. At 800 yards, I had almost no vertical. I think the combo of the barrel and the efficiency of the 6.5x47 case allows for this. My previous 260 Rem barrel was very accurate. It shot a 1 5/8" group at 600 yards. This 6.5x47 will out shoot the 260 Rem hands down, and do it with much lower ES numbers.
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#5572839 - 01/30/15 08:34 AM Re: Who's running a gain twist barrel? [Re: ChadTRG42]
FiremanJG Offline
THF Celebrity

Registered: 12/16/08
Posts: 17893
Loc: Wolfe City, TX
How in the heck does Dave get the 6.5 x 47 to push a 140 gr. at or near 2800 fps?

You're a ways below 2800 aren't you?

But I know consistency trumps velocity. Just curious to how fast yours is.
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#5572895 - 01/30/15 08:48 AM Re: Who's running a gain twist barrel? [Re: P & Y]
ChadTRG42 Offline
THF Trophy Hunter

Registered: 09/16/09
Posts: 9433
Loc: Lewisville, TX
I'm running a 23" barrel, 140 VLD at 2743 fps. I went up to 2780, but I didn't want to push it that hard. The x47 will do it, but I think it's a warmer load. Plus maybe a little longer barrel.
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#5574376 - 01/30/15 11:22 PM Re: Who's running a gain twist barrel? [Re: P & Y]
P & Y Online   sick
Tracker

Registered: 11/28/10
Posts: 948
Loc: North East Texas
Called up bartlein this morning to see what they had to say. They pretty much gave me the same info about more consistent pressure and slightly better accuracy through reduced barrel harmonics. For what it costs I think I will give it a try on the next build. Chad, what kind of velocity increase did you see on yours? They told me not to expect an increase in velocity due to the gain twist.
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#5574848 - 01/31/15 11:38 AM Re: Who's running a gain twist barrel? [Re: P & Y]
ChadTRG42 Offline
THF Trophy Hunter

Registered: 09/16/09
Posts: 9433
Loc: Lewisville, TX
I don't have any correlation from one barrel to the next. So, I do not know. If there is a velocity gain, it would not be much. My 6.5x47 is right in line with the speeds for a 23" barrel.
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#5575933 - 01/31/15 10:31 PM Re: Who's running a gain twist barrel? [Re: FiremanJG]
Dave3575 Offline
Pro Tracker

Registered: 02/12/12
Posts: 1020
Loc: Plano, TX
Originally Posted By: FiremanJG
How in the heck does Dave get the 6.5 x 47 to push a 140 gr. at or near 2800 fps?

You're a ways below 2800 aren't you?

But I know consistency trumps velocity. Just curious to how fast yours is.


I was running at 27" and with a load that that is upper limits. 2860, my new barrel is shorter and I am shooting a milder load for 2760. I don't want to run through 5 barrels this year.

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#5576100 - 02/01/15 07:30 AM Re: Who's running a gain twist barrel? [Re: Dave3575]
FiremanJG Offline
THF Celebrity

Registered: 12/16/08
Posts: 17893
Loc: Wolfe City, TX
2760 is very respectable. Bet your windage isnt any different 800 and in. I just remember us shooting the Heat Stroke Open and you corrections were identical to my 260.
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#5576511 - 02/01/15 12:46 PM Re: Who's running a gain twist barrel? [Re: P & Y]
Dave3575 Offline
Pro Tracker

Registered: 02/12/12
Posts: 1020
Loc: Plano, TX
It was but I was burning barrels at a very fast rate which is why i stepped it down.

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