Gain twist...is it better for pressure or precision?

[Crews]

is it even possible/probable that Bartlein would make a shorty barrel with a GT?

Are there any other mfg’s with this capability? (Not that being stuck with Bartlein is a bad thing)

 

[_Windrider_]

is it even possible/probable that Bartlein would make a shorty barrel with a GT?

Are there any other mfg’s with this capability? (Not that being stuck with Bartlein is a bad thing)

To my knowledge, they are the only ones doing it. Im sure someone else is doing it somewhere, but im a customer for life.

 

[Tim7139]

There have been a few companies doing them, I am told with CNC cut barrels it is no super big deal. Some of the others might only be in 6 mm & 30’s.
Lastly some if not all the ones with slight gain.....it’s all in the last few inches.

 

[lash]

Lastly some if not all the ones with slight gain.....it’s all in the last few inches.

Where did you get this information?

I’m interested to hear from @Frank Green on this subject.

 

[Tim7139]

From others I own, Frank posts here and is surely able to weigh in, since more than a little misinformation tends to get posted up on forums.

 

[Tim7139]

is it even possible/probable that Bartlein would make a shorty barrel with a GT?

Are there any other mfg’s with this capability? (Not that being stuck with Bartlein is a bad thing)

Well in the BR world Bartlein, for instance, does gains that for LV barrels usually come in between 20”-21” to make weight so, why not?

 

[_Windrider_]

Well in the BR world Bartlein, for instance, does gains that for LV barrels usually come in between 20”-21” to make weight so, why not?

I have a 20” bartlein gain twist.

 

[Frank Green]

Where did you get this information?

I’m interested to hear from @Frank Green on this subject.

Twist has nothing to do with pressure per say. Gain twist, vs a straight 1-10 or a 1-12 or a 1-8 etc....twist won't have a huge impact in my opinion and from data I've seen. So far.....more is being done/planned on.

Pressure has more to do with the total surface area of the bore. If you make the overall bore dimensions tighter per say usually pressure goes up and usually velocities jump as well.

Between the bore and groove though....changing the groove size will give you the biggest changes in pressure and velocity. The bore (tops of the lands not as much but will have an effect).

Just a couple/3 years or so ago I seen three pressure test barrels (not ours) and both the bore and groove size where .0005" undersize. This drove up pressures about 8-10k psi and drove up velocities around a 150fps.

What chamber reamer was use to cut the chamber can have an impact as well and compound that with actual bullet size. I've seen chambers where the throat was .0001" to .0002" undersize and bullets came in at max tolerance which put the bullet and throat size on size. This drove up pressures about 6k psi (maybe up to 10k range) and also drove up velocities.

Later, Frank

 

[Frank Green]

accuracy....the gain twist won't hurt ya.

 

[sirhrmechanic]

The structured barrel I have on order for .300 win mag is a gain twist Bartelin.

I’ve wanted a gain twist for ages. It was a no brainer to go gain twist for this build.

Old concept dating back to Pennsylvania rifles and the finest German gunsmiths. But with modern technology ranging from bullet design to powders, etc. they are going to make a huge and well-earned comeback IMHO.

Sirhr

 

[Frank Green]

is it even possible/probable that Bartlein would make a shorty barrel with a GT?

Are there any other mfg’s with this capability? (Not that being stuck with Bartlein is a bad thing)

Define shorty!

Shortest ones I can think of off the tip of my head would be AR barrels that finished at 20". I'm pretty sure we've done some shorter as well in other calibers but the AR ones is what is in my head right now.

 

[Frank Green]

The structured barrel I have on order for .300 win mag is a gain twist Bartelin.

I’ve wanted a gain twist for ages. It was a no brainer to go gain twist for this build.

Old concept dating back to Pennsylvania rifles and the finest German gunsmiths. But with modern technology ranging from bullet design to powders, etc. they are going to make a huge and well-earned comeback IMHO.

Sirhr

Correct....GT barrels goes back to at least the mid to late 1800's. Most likely even before that. You say German gunsmiths...I'll throw some names at ya and most likely not all German....

Pope, Schalck, Zishang and probably some others. Pope copied Schalks rifling for the most part and modified it a little. Schalck was making barrels I know at least around 1860's.

Pope was huge on GT barrels. Also all of his barrels to my knowledge are left hand twist and 8 groove. One of Popes barrels set a benchrest record with lead bullets if I recall correctly was set around 1913ish.....at 200 yards 10 shot group and that record stood till the late 50's or 1960's I think it was. Well past when jacketed bullets came out! LOL!

 

[Blutroop]

Are there any gain twist barrels that are also polygonal?

 

[gunsnjeeps]

Correct. That perhaps one disadvantage to the gain twist. You can’t chop when the chamber is shot out cause you will also be changing the twist and would likely have no clue what the new one is, but there is probably a way to figure it out

Wouldn't the final twist be at the muzzle? You would be changing your starting twist some with a chop but the rest of barrel is the same. Say you started with 10 inch twist and ended at an 8 inch twist, now you might start at 9.8 twist but still end at 8.

 

[_Windrider_]

Wouldn't the final twist be at the muzzle? You would be changing your starting twist some with a chop but the rest of barrel is the same. Say you started with 10 inch twist and ended at an 8 inch twist, now you might start at 9.8 twist but still end at 8.

Yes this is true, but to calculate exactly what it is could prove a little more difficult. And since most GT’s are smaller gains, like 3/4, chopping it down negates any benefit of doing it over a longer distance. But hey am all for longer barrel life in any way possible.

 

[sirhrmechanic]

Correct....GT barrels goes back to at least the mid to late 1800's. Most likely even before that. You say German gunsmiths...I'll throw some names at ya and most likely not all German....

Pope, Schalck, Zishang and probably some others. Pope copied Schalks rifling for the most part and modified it a little. Schalck was making barrels I know at least around 1860's.

Pope was huge on GT barrels. Also all of his barrels to my knowledge are left hand twist and 8 groove. One of Popes barrels set a benchrest record with lead bullets if I recall correctly was set around 1913ish.....at 200 yards 10 shot group and that record stood till the late 50's or 1960's I think it was. Well past when jacketed bullets came out! LOL!

Sir, have you ever read any of the 'serial' stories from the Saturday Evening Post (and others) that were loosely based around Pope? The author, whose name escapes me, used a character named JM Pyne who was based on Harry Pope. Some amazing stories I read as a kid, perhaps in Gun Digest or maybe reprinted in American Rifleman. Totally enthralling, not just for the 'mystery' and 'action' side of the stories, but for all the details about barrel making and gunsmithing. Especially back when it was all done by hand with slivers of paper, sharp cutters and home-made rifling 'engines.'

And as for my reference to German... I use the term loosely. The Swiss had amazing gunsmiths. So did the English. Lord Armstrong and Joseph Whitworth both contributed greatly to the art. I used 'German' as sort of a generic term because so many emigrated to Pennsylvania Dutch country (it wasn't just the Dutch!) in the 1700's and freed from the limitations of the European systems, they massively advanced the state of the art. Generations before Pope.

Anyway, yes, Pope was indeed a legend. The heyday of the American gunsmith until, really, the last 20 years or so. Today is really another golden age in both craftsmanship and innovation, even if the rifles are lacking walnut and skeleton buttplates... ;-)

Cheers,

Sirhr

 

[Frank Green]

Sir, have you ever read any of the 'serial' stories from the Saturday Evening Post (and others) that were loosely based around Pope? The author, whose name escapes me, used a character named JM Pyne who was based on Harry Pope. Some amazing stories I read as a kid, perhaps in Gun Digest or maybe reprinted in American Rifleman. Totally enthralling, not just for the 'mystery' and 'action' side of the stories, but for all the details about barrel making and gunsmithing. Especially back when it was all done by hand with slivers of paper, sharp cutters and home-made rifling 'engines.'

And as for my reference to German... I use the term loosely. The Swiss had amazing gunsmiths. So did the English. Lord Armstrong and Joseph Whitworth both contributed greatly to the art. I used 'German' as sort of a generic term because so many emigrated to Pennsylvania Dutch country (it wasn't just the Dutch!) in the 1700's and freed from the limitations of the European systems, they massively advanced the state of the art. Generations before Pope.

Anyway, yes, Pope was indeed a legend. The heyday of the American gunsmith until, really, the last 20 years or so. Today is really another golden age in both craftsmanship and innovation, even if the rifles are lacking walnut and skeleton buttplates... ;-)

Cheers,

Sirhr

I knew what you meant about the German guys and I didn’t mean to leave any of the other greats out as well like Whitworth etc...

Yes I have read some of the different stories in the different publications etc....in fact I have a few copies of them in my book rack. The story of JM Pyne/Pope has to be a top favorite.

Also not stories per say but got some really neat articles about barrel making in WWI and WWII etc...and it’s pretty cool reading how they did different things and held crazy tolerances like when making the 20mm barrels and the fitting of the threads on the breech end etc....and they did it all with out any cnc machines.

I’ll add to your quote about “ART” some of this stuff from years gone by is a lost art. I wish I could sit at a table and talk to some of these guys!

A few times I got to meet at Shot Show etc.. a guy by the name of Joe Wagner. Would always stop by and see us at the booth and we got to go to dinner one night in New Orleans I think it was. This is when I worked at Krieger. He was a blond hair blue eye German! Drafted into the German Navy in late WW2 at the age of 17 but prior to that worked at one of the German gun manf plants. I know the name but don’t know how to spell it off hand. When I told him the German code for that plant and the different weapons they made....you should’ve seen his eyes light up. We we’re on the same page....and the things he told me he all did after the war covertly then going back home and got his wife and came to the States and the different gun places he worked at. I wish I would’ve had a tape recorder that night at dinner to share with people. I’ll never forget that dinner with Joe Wagner.

Later, Frank

 

[secondofangle2]

Resurrecting this thread.

What’s the latest take on GT barrels? Are they catching on? Do we have any more insights on their purported advantages? Still recommending a gain of 1 Revolution per inch over the length of the barrel (eg start at 1-12 end at 1:11) and does that hold with a 36”+ barrel?

 

[pmclaine]

Finally got mine out past 300 yards.

It shot well and now just has over 200 rounds. It may still have some breaking in.

I wanted to FAFO so I went 9.5 to 8.75 lhgt.

It’s a .308 and I was shooting 175 FGMM.

It doesn’t give me the confidence of my 11.25 rh .308 but we may need to get to know each other better and I am shooting a lot less than I had been.

At 750 pretty beat up from recoil and a long day it was hitting the steel plate consistently if not in a fist sized ball.