Gain twist barrels?

[Jackomason]

@Lowlight "ELR Rifle going Left-Hand, Gaint Twist IS the right formula as you do not compound the drifts," sold. What type of the rifling's for ?

6mm
6.5mm
30 Cal

Correct me if I'm wrong but CE is specific to his range/the direction he shoots most. So I don't fully understand the argument for GT in that regard. I do agree that CE and SD are over stated and I just ignore them but I don't understand why they wouldn't compound in another situation (say shooting north vs south) when using a calculator.

 

[_Windrider_]

Correct me if I'm wrong but CE is specific to his range/the direction he shoots most. So I don't fully understand the argument for GT in that regard. I do agree that CE and SD are over stated and I just ignore them but I don't understand why they wouldn't compound in another situation (say shooting north vs south) when using a calculator.

I think what he’s sayin is LH cancels SD. So I stead of Ce+SD, it’s just CE depending on where in the northern hemisphere you are.

 

[Lowlight]

Everything works with a Gain Twist

 

[AIAW]

Correct me if I'm wrong but CE is specific to his range/the direction he shoots most. So I don't fully understand the argument for GT in that regard. I do agree that CE and SD are over stated and I just ignore them but I don't understand why they wouldn't compound in another situation (say shooting north vs south) when using a calculator.

Ignoring CE yeah sort of, SD not so much. They will definitely compound depending on your DoF.

285g Hornady AMAX - 338LM @ 2805 FPS - 1-10 RH twist

Correct firing solution (verified DOPE):

No SD/CE correction (miss in zero wind):

SD Compensation Only:

And Finally, CE Only (no SD):

Just depends on what your requirements are whether you correct for it or not. We occasionally engage 6" plates at 1400 yards striving for first round hits, accounting for cold-bore, clean-bore, etc. Like everything, it all matters to some degree that only the shooter can assign gravity to (no pun intended).

From the data above, not accounting for SD accounts for a horizontal error of 15". CE alone, 5" at this DoF. 20" POI deviation if not corrected for. Makes hitting those plates very challenging on the first round. Notice there is also a small correction in the vertical as well for CE/Eötvös.

 

[_Windrider_]

Ignoring CE yeah sort of, SD not so much. They will definitely compound depending on your DoF.

285g Hornady AMAX - 338LM @ 2805 FPS - 1-10 RH twist

Correct firing solution (verified DOPE):

View attachment 7071429

No SD/CE correction (miss in zero wind):

View attachment 7071430

SD Compensation Only:

View attachment 7071431

And Finally, CE Only (no SD):

View attachment 7071432

Just depends on what your requirements are whether you correct for it or not. We occasionally engage 6" plates at 1400 yards striving for first round hits, accounting for cold-bore, clean-bore, etc. Like everything, it all matters to some degree that only the shooter can assign gravity to (no pun intended).

From the data above, not accounting for SD accounts for a horizontal error of 15". CE alone, 5" at this DoF. 20" POI deviation if not corrected for. Makes hitting those plates very challenging on the first round. Notice there is also a small correction in the vertical as well for CE/Eötvös.

Now show it with a LH twist

 

[AIAW]

Now show it with a LH twist

Aww man. I knew someone was going to want that! Ok, I'll have to whip it back out and run it again here in a few.

Windows 10 + Windows CE = extreme hatred towards each other with remote screen captures.

 

[AIAW]

Ok, same conditions - LH 1-10 twist.

SD and CE Corrections Enabled:

No SD/CE correction:

SD Compensation Only:

CE Only (no SD):

 

[_Windrider_]

Ok, same conditions - LH 1-10 twist.

SD and CE Corrections Enabled:

View attachment 7071480

No SD/CE correction:

View attachment 7071481

SD Compensation Only:

View attachment 7071482

CE Only (no SD):

View attachment 7071485

So when CE and SD enabled it’s .15 less, but the rest is the same (other than it’s R vs L wind holds)? That doesn’t make sense.

 

[AIAW]

So when CE and SD enabled it’s .15 less, but the rest is the same (other than it’s R vs L wind holds)? That doesn’t make sense.

Yeah, it can get pretty confusing. What you are seeing is the LH twist cancelling out some of the spin drift and CE (since CE is easterly (right deviation) in the Northern Hemisphere).

There are two components to CE though: A vertical and horizontal "apparent" shift. Assuming Northern Hemisphere, vertical if firing east or west (low POI firing towards the west and high POI if firing towards the east).

The horizontal component is always present, no matter the DoF.

Two snips from one of Bryan Litz's books:

 

[_Windrider_]

Yeah, it can get pretty confusing. What you are seeing is the LH twist cancelling out some of the spin drift and CE (since CE is easterly (right deviation) in the Northern Hemisphere).

There are two components to CE though: A vertical and horizontal "apparent" shift. Assuming Northern Hemisphere, vertical if firing east or west (low POI firing towards the west and high POI if firing towards the east).

The horizontal component is always present, no matter the DoF.

Two snips from one of Bryan Litz's books:

View attachment 7071520

View attachment 7071521

I guess what is most confusing is how CE switched from .08R to .08L with the LH twist, that’s a 1.6mil swing. If anything it should remain identical if SD is turned off wouldn’t you think?

EDIT: never mind! It is the same. Details. It’s always in the details.

 

[AIAW]

I guess what is most confusing is how CE switched from .08R to .08L with the LH twist, that’s a 1.6mil swing. If anything it should remain identical if SD is turned off wouldn’t you think?

EDIT: never mind! It is the same. Details. It’s always in the details.

You mean the very bottom pictures in the RH and LH twist pictures I posted?

 

[_Windrider_]

You mean the very bottom pictures in the RH and LH twist pictures I posted?

Yeah, but I fixed my post. I realize there was no change

 

[AIAW]

Yeah, but I fixed my post. I realize there was no change

Ahh ok, no worries. I was wondering what had changed there. It's a lot of data to think about! CE is useless to think about in the field unless a calculator is doing it for you. I couldn't imagine someone doing the long-hand math in the field for this for every different DoF.

That spin drift will get you at distance though... especially the cucumber flavor. Ughh.

 

[_Windrider_]

Ahh ok, no worries. I was wondering what had changed there. It's a lot of data to think about! CE is useless to think about in the field unless a calculator is doing it for you. I couldn't imagine someone doing the long-hand math in the field for this for every different DoF.

That spin drift will get you at distance though... especially the cucumber flavor. Ughh.

View attachment 7071531

I don’t even account for SD until approaching transonic. I wish there was an option for this in calculators.

 

[Jackomason]

So am I miss understanding spin drift? Does LH simply cancel out spin drift or does it just change the direction of spin drift?

My understanding is that depending on DoF it's either

CE + SD
or
CE - SD

Changing the direction of twist would just flip the equation and wouldn't be of any benefit unless you had a set Dof. (?)

(This is looking at it as only North or south shooting to keep it simple)

 

[_Windrider_]

So am I miss understanding spin drift? Does LH simply cancel out spin drift or does it just change the direction of spin drift?

My understanding is that depending on DoF it's either

CE + SD
or
CE - SD

Changing the direction of twist would just flip the equation and wouldn't be of any benefit unless you had a set Dof. (?)

(This is looking at it as only North or south shooting to keep it simple)

That’s pretty much correct except you have to remember that a LH twist in North hem is a technically kinda sorta a negative SD. So it’s really

CE + (-SD)
Or
CE - (-SD)

Which is why we say it negates the effects of SD and helps with CE. Also the most important issue here is that this is a time of flight issue not distance. The longer the bullet is flying the bigger the problem.

 

[natdscott]

Everything works with a Gain Twist

To state the obvious, but represent the devil...everything works with a straight twist, too.

 

[Lowlight]

That coriolis crap is wrong

It's equal to about 15fps of Standard Deviation at 1500 yards...

That 100 to 1200 BS Is crap

I shot at a MILE all day today and just doped the wind.

 

[Lowlight]

Coriolis is Macro not micro

here is a great way to put it since this all comes from artillery anyway

From Canadian Manual:
B-GL-306-006/FP-001

FIELD ARTILLERY
VOLUME 6
BALLISTICS AND AMMUNITION

“In manual computations, rotational effects are not applied in Canadian gunnery procedures at ranges under 15000 metres, as the additional accuracy achieved does not justify the time expended.”


So, if they don't worry about it with artillery under 15,000 meters (that's 9 1/3 miles folks), I doubt if we need to be concerned with any calibers that we shoot at any range.


Now understand too, the AB SD numbers are definitely overcalculating it by a wide measure, it's closer to 3x smaller than being written about.

At Gunsite last month in their XLR Course I watched guys with the AB Kestrel put between .6 Mils and .8 Mils at 1500m to 2000m and the correct answer was .3 Mils at 2000m

How do I know, their shots went the wrong side of the wind and tried blowing my wind calls for them. When the wind coming from the left and you have to hold to the right of the target, you have too much SD dialed on. I was reducing for guys can it worked for them much better than advertised.

Lastly, recall the parachute from space, there is an article on it and the interviewer asked about the Earths rotation and the guys said they ignored it because they did not completely leave the atmosphere. The formula used by shooter had him landed more than 250 away from his starting point, but the reality was, 23 miles away. How can a guy float up to the edge of space, freefall down and not land in the Pacific Ocean.... simple the Earth drags a large portion of our atmosphere with it (How we can breath) thus changing the end results.

Macro, not micro a 2 second time of flight is not pushing near as far off as they claim.

 

[Jackomason]

I really have no dog in this fight and have found that ignoring it all got me more first round hits, probably just because there is less clutter up stairs pre shot.

However does that make the argument for LH rifling, as far as external ballistics goes, kinda a moot point? I'd imagine that the numbers do cancle out still but still have very little riding on them.

 

[Lowlight]

not really, while small it is still there, just to a lesser degree

Its a mechanical fix vs a software one.

And left hand rifling supports a right handed shooter too the recoil pulse works in their favor

 

[clcustom1911]

Well, after reading this whole thread from top to bottom, I guess I'm getting a GT barrel for my 7mm RemMag from Bartlein.

Probably a 9.5-8.75 twist or something. That's just a wild ass guess. That way I suppose I should be able to spin everything from 195 and lighter.

 

[cro789]

Frank,
What twist would you recommend for a 223? It is going on a DT and the length will be 23" . I will be shooting mostly 77 to 90 grains an I will also like a LH twist. Thanks for the help

 

[_Windrider_]

Frank,
What twist would you recommend for a 223? It is going on a DT and the length will be 23" . I will be shooting mostly 77 to 90 grains an I will also like a LH twist. Thanks for the help

Im Sure frank will chime in, but call Bartlein direct they will give you what they deem best. But I would say 1:8-1:7 would be a good choice.

 

[cro789]

Thanks I will give them a call. I know Frank is a busy man and some times he doesn't have time to answer our simple questions. I wonder I might be able to call MHSA and see if they can make one.

 

[cro789]

TacticalDillhole,
Thanks you were right. I just spoke to Mark at Bartlein barrel and he was very helpful. I will get with SAC and order a 1:7.5 - 1:6.5 LH twist for a 223. Mark was able to explain all of the ins and outs benefits of the gain better than I have seen so far.

 

[natdscott]

TacticalDillhole,
Thanks you were right. I just spoke to Mark at Bartlein barrel and he was very helpful. I will get with SAC and order a 1:7.5 - 1:6.5 LH twist for a 223. Mark was able to explain all of the ins and outs benefits of the gain better than I have seen so far.

Call Mark back real quick and ask him to up that to a 1.5" gain, for 8.0-6.5". With a little stub cut off the end, you'll finish somewhere near 6.55" or 6.6".

That amount of gain does not cost more, and I can 100% guarantee you it works "pretty okay" with the 77-90 grain bullets.

My 1,000 yard AR is the same barrel, in 5R, only it is that gain over 20".

I know, I'm just a dude on the internet, but....

 

[natdscott]

Oh, and if you want 90's, be really careful with your reamer selection.

If you go with a tight freebore like 0.2245", you should be fine with the 70-class, provided you don't expect VLD's to jump 200 and like it.

 

[pmclaine]

This thread and the recent purchase of a new to me Winchester Model 70 receiver has me thinking "gain twist" for my next build....

Im a fan of short barreled rifles.

For this Im thinking 30-06.

175 SMKs most common bullet Ill use

22-23 inch, left hand 10 to 8.75 gain twist, MTU maybe a hair bigger contour.

IMR 4350 will be my powder.

Am I realizing the benefits of the engineering/science?

 

[Lowlight]

I would go what the guy shooting a 223 GT barrel says above

The 224V I did is a bit different and it has a 3/4 gain, the service rifle guys are doing a bit more aggressive

If you look GT on Youtube a service rifle builder is a frequent contributor to the discussion there

 

[cro789]

Nadascott who do you use for barrels

 

[cro789]

This is 77TMK with varget 24.4 2798 out of my DT just now

 

[natdscott]

Nadascott who do you use for barrels

I really dig Wisconsin's cut work.

Krieger, or Bartlein, either one...depending on what I feel I need at a given time, and secondarily, availability and price.

I've yet to get a barrel from either one, or handle anybody else's rifles for handloads, that was not a hammer. I buy their stuff because I get a better guarantee of a great barrel.

If I were doing rimfire, I'd do another Shilen Ratchet in a heartbeat.

Do I NEED a $400 Bartlein LH 5R CM 0.224/0.218" GT 8-6.5" in a Service Rifle? Maybe not, but if you examine the costs between a ~4,000+ round cut, or a 2,500 round buttoned, it doesn't come in that far apart. I also know for a fact that nobody's rifle anywhere has more potential, and that is a checkbox that HAS to be checked when I'm competing, even if my hold is only 0.6-0.8 MOA. So far, not cutting corners has mostly worked, especially when I am trying to win matches against open-class guys with 28" .243s, 6XC, etc.

I prefer to spend more money on excellent components and ammunition components, and just burn out my barrels more slowly by spending the majority of my time dryfire and rimfire/air rifle training.

 

[Jackomason]

@Lowlight, hoping to hear an update on the build soon! I've realized the barrel I had installed on my origin is garbage and I'm starting to think of heading towards a .224 valk but I'm curious about if the recoil pulse is noticable on the smaller caliber and if it will possibly extend the already long barrel life of the .224 valk?

As a side note on the .224, do you think it would leave a large hole in my capabilities if I didn't have a 6.5? All my 6.5cm does is shoot targets and coyotes. I have hunting rifles for the rest. I'm sold on it but I want real expectations.

 

[natdscott]

@LowlightI've realized the barrel I had installed on my origin is garbage...

What did you put in it?

I'd do a .22 BR or .224 AR before I'd screw with Valkyrie. I trust the availability of those casings...the Valk has yet to demonstrate longevity beyond the flavor-of-the-week stage.

 

[2aBaC̶a̶]

Damn interesting read.

Makes perfect sense though.

Curious as to why not start at 0 twist and go up? Or even start 0 and then achieve desired twist midway down the barrel?

 

[Lowlight]

big players are behind the Valkyrie,

Between Hornady and Federal alone you have longevity

I would suspect it will continue to grow, even beyond the Grendel and that is still around despite it being a waste of effort

 

[clcustom1911]

Damn interesting read.

Makes perfect sense though.

Curious as to why not start at 0 twist and go up? Or even start 0 and then achieve desired twist midway down the barrel?

I've thought about something similar to that as well. For a 7mm Start with like a 1:15 twist at the chamber and at a 1:8.5 at the muzzle in a 28" barrel.

 

[_Windrider_]

I really dig Wisconsin's cut work.

Krieger, or Bartlein, either one...depending on what I feel I need at a given time, and secondarily, availability and price.

I've yet to get a barrel from either one, or handle anybody else's rifles for handloads, that was not a hammer. I buy their stuff because I get a better guarantee of a great barrel.

If I were doing rimfire, I'd do another Shilen Ratchet in a heartbeat.

Do I NEED a $400 Bartlein LH 5R CM 0.224/0.218" GT 8-6.5" in a Service Rifle? Maybe not, but if you examine the costs between a ~4,000+ round cut, or a 2,500 round buttoned, it doesn't come in that far apart. I also know for a fact that nobody's rifle anywhere has more potential, and that is a checkbox that HAS to be checked when I'm competing, even if my hold is only 0.6-0.8 MOA. So far, not cutting corners has mostly worked, especially when I am trying to win matches against open-class guys with 28" .243s, 6XC, etc.

I prefer to spend more money on excellent components and ammunition components, and just burn out my barrels more slowly by spending the majority of my time dryfire and rimfire/air rifle training.

Krieger doesnt do LH twist, just keep that in mind.

 

[2aBaC̶a̶]

I've thought about something similar to that as well. For a 7mm Start with like a 1:15 twist at the chamber and at a 1:8.5 at the muzzle in a 28" barrel.

If you think about it all bullets start at 0 twist and the .02" jump they slam into the angle of the lands. I imagine the pressure created by inertia of the bullet gripping the angle of the lands is what rips the jacket. And why heavier bullets need slower twist. If you could mitigate the initial force of the crash You could theoretically shoot heavier bullets out of a faster twist maybe even shorter barrel. Just thinking outside the box here.

 

[spife7980]

If you think about it all bullets start at 0 twist and the .02" jump they slam into the angle of the lands. I imagine the pressure created by inertia of the bullet gripping the angle of the lands is what rips the jacket. And why heavier bullets need slower twist Wrong. If you could mitigate the initial force of the crash You could theoretically shoot heavier bullets out of a faster twist maybe even shorter barrel. Just thinking outside the box here.

*Insert the my cousin vinny or billy madison clips here*


The heavier the bullet, the longer the bullet is and the faster the twist you need to stabilize it.

The lighter the bullet is, the shorter it is and the less you need to spin it. Lighter bulelts accelerate faster so they go faster per inch of barrel and they will rotate faster as well Bullet RPM = MV X 720/Twist Rate (in inches)

 

[Jackomason]

What did you put in it?

I'd do a .22 BR or .224 AR before I'd screw with Valkyrie. I trust the availability of those casings...the Valk has yet to demonstrate longevity beyond the flavor-of-the-week stage.

I was taking a chance with a savage barrel I had laying around. I ran some 140 eldm. POI shift down 10-12" at 350 yards.

I trust the valk.

 

[lash]

What did you put in it?

I'd do a .22 BR or .224 AR before I'd screw with Valkyrie. I trust the availability of those casings...the Valk has yet to demonstrate longevity beyond the flavor-of-the-week stage.

Yet, I can walk into Walmart or any local LGS and buy .224 Valkyrie loads off of the shelf. I have yet to see either .22 BR or .224 AR available. You may be viewing things from a wildcat loader’s myopic view, rather than a realistic availability model.

 

[natdscott]

Krieger doesnt do LH twist, just keep that in mind.

?

I am not picking up what you're laying down from my post?

But factually:

Krieger is an INside-the-box barrel maker delivering literally the best barrels humankind has ever known. But creative, they are not....don't have to be, in their business model.

Bartlein is less-so, and will happily take as much of your green monies as you want to give them to deliver some oddball barrel that suits your fancy, provided it is safe. Mark will argue with you maybe, but with exception of the safety caveat, he'll let you do something stupid with your money if you push on it hard enough.

It's a lot akin, in a way, to Sierra v. Berger. Sierra has typically run a more conservative ballgame than Berger, but there have been some performance gains in the yellow boxes.. IF they work. Sierras, while sometimes bland by the numbers, are virtually guaranteed to work. Historically.

I use all 4 of the above, depending on what I need a given rifle to do.

 

[natdscott]

Yet, I can walk into Walmart or any local LGS and buy .224 Valkyrie loads off of the shelf. I have yet to see either .22 BR or .224 AR available. You may be viewing things from a wildcat loader’s myopic view, rather than a realistic availability model.

That's a fair point, but if you want to go that route, then simply go with the easy-button .22-250.

--TONS more ammo options, in nearly EVERY Walmart in the country.
--TONS of rifles and barrels.
--TONS of data.
--TONS of history and longevity.

 

[_Windrider_]

?

I am not picking up what you're laying down from my post?

But factually:

Krieger is an INside-the-box barrel maker delivering literally the best barrels humankind has ever known. But creative, they are not....don't have to be, in their business model.

Bartlein is less-so, and will happily take as much of your green monies as you want to give them to deliver some oddball barrel that suits your fancy, provided it is safe. Mark will argue with you maybe, but with exception of the safety caveat, he'll let you do something stupid with your money if you push on it hard enough.

It's a lot akin, in a way, to Sierra v. Berger. Sierra has typically run a more conservative ballgame than Berger, but there have been some performance gains in the yellow boxes.. IF they work. Sierras, while sometimes bland by the numbers, are virtually guaranteed to work. Historically.

I use all 4 of the above, depending on what I need a given rifle to do.

Nothing specific. You just mentioned Krieger as an option and we were discussing gain and twist directions. Just saying Krueger will not do a LH twist.

 

[nick338]

I was really considering the Valkyrie on a bolt gun but I'm starting to feel like I'm limiting myself to factory ammo if I use a SAAMI reamer and will not be able to push the cartridge beyond that if I want to. Being able to use factory ammo is huge for me because of time but not necessarily the only option. I've started taking a look at 6 BR which has factory ammo available but I believe SAAMI spec reamers will allow me more flexibility with other 105-108 gr bullets.

Either way I'm looking forward to seeing how Frank's rifle performs with the GT and Valkyrie.

 

[2aBaC̶a̶]

*Insert the my cousin vinny or billy madison clips here*


The heavier the bullet, the longer the bullet is and the faster the twist you need to stabilize it.

The lighter the bullet is, the shorter it is and the less you need to spin it. Lighter bulelts accelerate faster so they go faster per inch of barrel and they will rotate faster as well Bullet RPM = MV X 720/Twist Rate (in inches)

Haha yeah, that's what I meant.

 

[lash]

That's a fair point, but if you want to go that route, then simply go with the easy-button .22-250.

--TONS more ammo options, in nearly EVERY Walmart in the country.
--TONS of rifles and barrels.
--TONS of data.
--TONS of history and longevity.

Lol, no doubt that one could go that way and I have zero argument regarding bolt choices. On the other hand, I cannot stuff a .22-250 into a small frame AR and the .224V in that platform is just a fun little cartridge to shoot.

—Plenty of choices already, by ALL of the major ammo makers
—Plenty of BC for consistent hits out to 1000 yards
—Great for varmints
—Plenty of barrel life, especially as compared to .22-250
—Lots less powder when reloading
—Lots of fun to shoot.

Did I mention lots of fun yet?

 

[Jackomason]

So what are the main benefits of a GT in a small bore rifle? I didn't mean to derail this thread. Sorry. The ballistic calculator might care a bit but what are the real world advantages?