Twist, Freebore for 198gr Flatlines and 200.20x

[coolbox]

Hi
I am considering a barrel suited for Berger 200.20x and Warner Tool 198gr Flatlines, to complement my current FTR rig with 11 twist barrel (.120 freebore), 32" Bartlein.
I have mainly been shooting 185 juggs, and a few 155.5FB with excellent results.
Considering the Warner Flatlines as we have occassional matches at 1200 and 1500 meters, and I cant afford another rifle/caliber/scope/reloading dies etc etc. So instead of sitting out, I would just like to gain some experience and have a go. Most shooters in these matches bring out their 300wm with Berger 215/230 hybrids, and one gets to see an occassional 284 or a 300wsm.

I was initially thinking 9 twist, and almost decided upon, but that still does not stabilise the 198gr flatlines (SG 1.1).

Confused.

 

[Kurz]

You're on the right path to recognize the difference between shorter, lighter bullets and longer, heavier bullets. By adding in solids such as the Warner Flat Line then trying to shoot them out of a .308 Win., you will find that Berger recommends a 7.75" twist rate for their appropriate stability factor.

The Warner 198 gr. will hold up to the 1,200 or 1,500 meters range for supersonic but the twist rate needs to be faster. This will bode well for those 230 grain although they will generally work in a 1:9" or 1:9.5" twist rate because they're shorter.

I think if you do some checking, there are a ton of shooters using the 200-20X bullets with great success but you need to narrow the gap in the twist rates by eliminating those Warner or choosing them as your primary bullet then ordering the faster twist rate. I use separate barrels with different twist rates because I enjoy shooting the solids and then the cup/core bullets in another.

Enjoy the process!

 

[Longrange57]

I have 308 10tw Bartlein that shoots 185 jugg and 200.20x with great accuracy! As Kurz has already indicated above.....the 198 is a very long bullet. I never got it stabilized and a friend had difficulty with a 9tw at 1,000 yards. If the bullet can't be shot fast enough even with a tighter twist, the BC will not be what you are expecting.

 

[uashooter]

Hi
I am considering a barrel suited for Berger 200.20x and Warner Tool 198gr Flatlines, to complement my current FTR rig with 11 twist barrel (.120 freebore), 32" Bartlein.
I have mainly been shooting 185 juggs, and a few 155.5FB with excellent results.
Considering the Warner Flatlines as we have occassional matches at 1200 and 1500 meters, and I cant afford another rifle/caliber/scope/reloading dies etc etc. So instead of sitting out, I would just like to gain some experience and have a go. Most shooters in these matches bring out their 300wm with Berger 215/230 hybrids, and one gets to see an occassional 284 or a 300wsm.

I was initially thinking 9 twist, and almost decided upon, but that still does not stabilise the 198gr flatlines (SG 1.1).

Confused.

I have shot both bullets for f-tr. My previous 8 twist would stabilize the flatlines, my current 10 does not. The jump and twist of the 8 twist is a real complication to accurate f-tr shooting, that is why I retreated on twist. I had some brief luck getting the flatlines to group well, but could not sustain it. Their ogive and length are so different from cored bullets that the desired throat lengths are night and day different. To get ‘normal’ jumps with the flatlines, say .005-.020, you need a short throat like a factory barrel, the 200 class core bullets want a .170 class throat. Also, the FLs are Sooo expensive, load development is an exercise in high spending or major denial( I am not thinking about it, I am not thinking about, I am not thinking about it)

 

[Uglybird]

^Yes, Flatlines seem like a way to get another cartridge out of your rifle until you start getting into the details. Gets to a wash at best before you get to projectile cost. Practicality says I'd rather build something for the 215/230's that is proven, cheaper to shoot, and more versatile in the long run. I would love a rifle purpose-built for flatlines, but would have to go into it accepting the cost:benefit ratio. I don't compete, so the allure isn't strong enough for me.

 

[coolbox]

Thank you all for the replies.

The jump and twist of the 8 twist is a real complication to accurate f-tr shooting, that is why I retreated on twist. I had some brief luck getting the flatlines to group well, but could not sustain it.

Could you not sustain the cost? Or was it inconsistencies in the grouping/accuracy?

I would like to put bullet cost aside for now, as once the load is developed, and provided it is good enough, the longer range matches are few and far in between. But, I am keen on participating in them, for now at least.

 

[uashooter]

Thank you all for the replies.



Could you not sustain the cost? Or was it inconsistencies in the grouping/accuracy?

I would like to put bullet cost aside for now, as once the load is developed, and provided it is good enough, the longer range matches are few and far in between. But, I am keen on participating in them, for now at least.

It was really the accuracy, but that comes back around to the cost, due to a reticence to run load and seating studies because of how expensive it was. If I had a short throated rifle, it would have made a big difference I think. In that case it might have worked well enough to chase.

 

[Ned Ludd]

I've shot both the 180 and 198 Flatlines. You really want a minimum of 9-twist for the 180s, and 8-twist for the 198s. The problem with attempting to have a barrel throated to shoot both the Flatlines and comparable weight lead core bullets is that the bearing surface length of the two Flatline bullets is much shorter than a typical 200 gr lead core bullet, such as the 200.20X. I used a reamer that cuts 0.110" freebore for the 9- and 8-twist barrels I have chambered for Flatline bullets, which is just about perfect for them, IMO. In contrast, I use a 0.180" freebore chamber with the 200.20X bullet, which is much too long for the Flatlines.

Can you load the 200.20X bullet in a rifle with 0.110" freebore? Yes, you can, but it's not optimal. The boattail/bearing surface junction will be sunk pretty far down in the neck, which means smaller effective case volume and higher pressure, among other things. I would suggest using a barrel dedicated to the Flatlines if you intend going that route. Although it is technically possible to use some "compromise" freebore so as to load both the Flatlines and comparable weight lead core bullets, IMO you will end up with a chamber that really isn't optimal for either one.

If you haven't already seen it, there is another thread currently going about using the Flatline bullets in F-TR that may be of interest to you:
http://forum.accurateshooter.com/threads/flat-line-30-cal.3996279/#post-37680118

 

[coolbox]

I've shot both the 180 and 198 Flatlines. You really want a minimum of 9-twist for the 180s, and 8-twist for the 198s. The problem with attempting to have a barrel throated to shoot both the Flatlines and comparable weight lead core bullets is that the bearing surface length of the two Flatline bullets is much shorter than a typical 200 gr lead core bullet, such as the 200.20X. I used a reamer that cuts 0.110" freebore for the 9- and 8-twist barrels I have chambered for Flatline bullets, which is just about perfect for them, IMO. In contrast, I use a 0.180" freebore chamber with the 200.20X bullet, which is much too long for the Flatlines.

Can you load the 200.20X bullet in a rifle with 0.110" freebore? Yes, you can, but it's not optimal. The boattail/bearing surface junction will be sunk pretty far down in the neck, which means smaller effective case volume and higher pressure, among other things. I would suggest using a barrel dedicated to the Flatlines if you intend going that route. Although it is technically possible to use some "compromise" freebore so as to load both the Flatlines and comparable weight lead core bullets, IMO you will end up with a chamber that really isn't optimal for either one.

If you haven't already seen it, there is another thread currently going about using the Flatline bullets in F-TR that may be of interest to you:
http://forum.accurateshooter.com/threads/flat-line-30-cal.3996279/#post-37680118

Thank you foe the detailed reply, and the link to the other thread, which I had not seen.
This leaves me with a few more questions.
1. What freebore for the 180s?

2. Will the 200.20x shoot fine in the 8 and 9 twist barrels?
I have shot the 200.20x reasonably well in my 32" Bartlein 5R with .120 freebore, seated to the lands. So i am mot quite worried about a shorter freebore, although I understand its not optimal. I would like a faster than 11 twist for these though.
Would the 8 twist or 9 twist be too fast for 200.20x?

3. In your opinion, in a 308 win, what bullet should one choose for distances in the region of 1200 and 1500mtrs, ELR type matches, with 5 to 10 shots per match per diatance.
The 10 ring is 18" for both distances, meaning 1.3 MOA and 1.04 MOA in size, respectively.

It makes most sense to have dedicated barrels for the solids, and thats what I might end up doing (if I go that route), but if they dont work out (accuracy or availability issues) I would like the be able to use the barrel for other jacketed bullets in 200 gr range. The freebore can be increased, but the twist stays.

 

[Ned Ludd]

1. The 180 and 198 Flatlines both have the exact same BTO dimension. Only the nose length differs between the two. They can use the same freebore.

2. The question of is an 8- or 9- twist "too fast" for a 200.20X bullet is not easy to answer definitively. I would say that on paper, it's too fast. I personally wouldn't try to spin them that fast. But that is not a guarantee or proof that accuracy/precision would necessarily suffer noticeably.

3. I personally would never use a .308 Win for that type of competition. The ballistics of the .308 Win are generally not suitable for those distances, regardless of the bullet used.

As I stated before, I would not try to do what you're thinking about doing. I think you'll end up with a barrel that doesn't really work optimally for anything, and you'll never be happy with it. But that's just my opinion; I have never actually tried it.

 

[coolbox]

1. The 180 and 198 Flatlines both have the exact same BTO dimension. Only the nose length differs between the two. They can use the same freebore.

2. The question of is an 8- or 9- twist "too fast" for a 200.20X bullet is not easy to answer definitively. I would say that on paper, it's too fast. I personally wouldn't try to spin them that fast. But that is not a guarantee or proof that accuracy/precision would necessarily suffer noticeably.

3. I personally would never use a .308 Win for that type of competition. The ballistics of the .308 Win are generally not suitable for those distances, regardless of the bullet used.

As I stated before, I would not try to do what you're thinking about doing. I think you'll end up with a barrel that doesn't really work optimally for anything, and you'll never be happy with it. But that's just my opinion; I have never actually tried it.

Thank you, makes sense now.

 

[Bindi2]

The Match rifle shooters in OZZ are using 308 out to 1500. 1 in 10 twist 180gn to 210gn. Probably Berger.

 

[D-4297]

As I read thru these posts , I kept asking myself why he was engaged in a act of self-punishment . And the words ".300 Win-Mag" kept banging around in my head . That aside ; I shoot F-TR with a Kelby Panda , Kreiger 30" 1/10Tw - 5r , FB - .180 , and shoot both the 200.20x and the 200 Target Hybrid . The 200.20x is my "wind" bullet , and the Hybrid for calmer conditions . Low node velocity : avg. 2585-2625 . High node avg. : 2670 - 2700 .
As Ned Ludd said ; and I agree , .308 don't do 1,200 - 1,500 very good . But a .300 Win can .

 

[coolbox]

As I read thru these posts , I kept asking myself why he was engaged in a act of self-punishment . And the words ".300 Win-Mag" kept banging around in my head . That aside ; I shoot F-TR with a Kelby Panda , Kreiger 30" 1/10Tw - 5r , FB - .180 , and shoot both the 200.20x and the 200 Target Hybrid . The 200.20x is my "wind" bullet , and the Hybrid for calmer conditions . Low node velocity : avg. 2585-2625 . High node avg. : 2670 - 2700 .
As Ned Ludd said ; and I agree , .308 don't do 1,200 - 1,500 very good . But a .300 Win can .

In my first post, I did mention I could not afford another rifle/caliber/scope at this time, unfortunately.
Else, a 300wm would serve the purpose pretty effectively.

 

[Ned Ludd]

In my first post, I did mention I could not afford another rifle/caliber/scope at this time, unfortunately.
Else, a 300wm would serve the purpose pretty effectively.

Obviously, the other consideration would be whether a .308 Win was a specified requirement in the rules for some specific style of competition. If so, you'd have to make it work and do the best you can with it, everyone else being in the same boat. A major issue with any lead core bullet you might choose, such as the 200.20X, would be how it handles the transition to subsonic, as commonly-used .308 loads will probably hit that at around 1300 to 1400 yd. If the bullet behaves well during the transsonic period, there's no reason you can't use it, but you'd still have to read the wind conditions like a hawk. It sounds like the folks already shooting those distances in OZ might be a good resource on that topic.

 

[coolbox]

I will share an update here. I got a new rifle on the way with 8t and 9.5t barrels (both 28"). The 8t barrel might be a failed experiment, and might either end up as a plinking barrel with 200/185gr bullets, or rechamber to some other caliber later. Not sure if the 8t will perform decent with 200gr hybrids.

I got hold of some 198FL in the meanwhile, but could not load them long enough with the 308 die. The gunsmith set the freebore to .150, although i asked for 0.120". The coal with .150fb comes to 3.41" approx.

I have tested a 300wm redding seating die, with a 308 sleeve (for best fit of 308 case), vld stem. This combo loads the 198 Flatlines out to over 3.4" coal for a 308win. The 308 sleeve is just about long enough to fit in the 300wm die.

Will update once i make more progress here.

 

[Kurz]

Excellent!

Thank you for returning with the update, most of us forget to follow up so this is a nice treat.

I'm looking forward to reading about your discoveries.

Enjoy!

 

[Ned Ludd]

I will share an update here. I got a new rifle on the way with 8t and 9.5t barrels (both 28"). The 8t barrel might be a failed experiment, and might either end up as a plinking barrel with 200/185gr bullets, or rechamber to some other caliber later. Not sure if the 8t will perform decent with 200gr hybrids.

I got hold of some 198FL in the meanwhile, but could not load them long enough with the 308 die. The gunsmith set the freebore to .150, although i asked for 0.120". The coal with .150fb comes to 3.41" approx.

I have tested a 300wm redding seating die, with a 308 sleeve (for best fit of 308 case), vld stem. This combo loads the 198 Flatlines out to over 3.4" coal for a 308win. The 308 sleeve is just about long enough to fit in the 300wm die.

Will update once i make more progress here.

I think you might find that running the 200s out of an 8-twist barrel works a lot better than trying to run the 198s out of a 9- or 10-twist barrel. Even though 8-twist is certainly not "optimal" for the 200s, it can still work. Loading the 198 Flatlines is a whole new ballgame as compared to lead core .30 cal bullets in the same weight range. I even went so far as to buy a 10" Mitutoyo caliper, which made measuring CBTO/COAL a lot easier, and new ammo boxes, as none of the ammo boxes I had previously could accommodate the length of loaded .308 rounds with the 198 Flatlines.

The primary issue that myself and other F-TR shooters I know that have tried the 198s was unexplained vertical. As expected, the high BC is exceptional for reducing horizontal wind deflection, but that doesn't always help your score if you're getting nickel and dimed to death by high/low 9s. I did a bunch of testing and I never could figure out the cause of that behavior. I finally decided that shooting the monolithic solids wasn't worth the extreme high cost of the bullets, constant load tweaking, and effectively having to have a dedicated rifle to shoot them that really wasn't optimal for shooting any other traditional lead core bullets. Nonetheless, I would urge you to continue your testing, even if for no other reason than just to have some fun and learn something new. Perhaps you will have a much better experience with them than I did, and they will work well for your intended use at 1200-1500 yd. Best of luck with it!

 

[coolbox]

Got the rifle.
Running in the barrel with 175smk, 2.8" COAL.
Best group 0.3moa, worst group 1 moa, moat groups were about 0.7moa. Trigger was a tad heavy, over 1.5 lbs. Will get it down to 12 oz or so.

How many rounds should I wait till the barrel speeds up enough for me to start load development?

 

[Ned Ludd]

Usually a new barrel will settle down by 200 rounds, give or take a few. However, it's not necessary to wait the full 200 rounds before beginning load development. I typically begin with no more than 20-30 rounds down a new barrel. Yes, that often means I will have to re-tweak the load once the barrel is fully broken in, but you can still learn a lot about the load/rifle while you're still breaking in the barrel. The main issue with the Flatlines is the obviously the price tag (Ouch). So there's not necessarily any good reason to rush into load development either. Once you've put around 50 rounds or so downrange, it's really up to you.

FWIW - in my hands with a 0.110" fb, 8-twist, 30" barrel, both the 180s and 198s tuned in very close to the lands (~.003" off). To be honest, they seemed almost insensitive to seating depth, at least when seated within ~.020" of the lands. I'll be curious to hear your results once you start in with load development. Best of luck with it.