I would strongly warn you to test these in your barrel first. My 24" barrel starts popping primers with Hornady 178s at 2500 fps while spitting sierra 175s at 2720 all day long with primers still nice and round.
I would strongly warn you to test these in your barrel first. My 24" barrel starts popping primers with Hornady 178s at 2500 fps while spitting sierra 175s at 2720 all day long with primers still nice and round.
I even pulled a factory FGMM 175 and replaced it with a brand new hornady 178 BTHP bullet and it still blew primers. I tried handloads, I tried varying seating depth.
It was blowing primers with the Hornady at starting loads.
It was blowing primers with the Hornady at starting loads.
Factory ammunition used to be #1 Lapua 167 Scenar consistently 1/2 moa, Federal GM Match 175 Sierra MK, Black Hills 175 Sierra MK.
"Handloads money loads" Winchester .308 brass, Fed 210 GM Primer, Varget, and either a 175 Sierra MK or the 155 MK Palma. Typically 32 pounds of the same lot of Varget it was time for a new barrel
From a 25" schneider 1/12 I was at 2695 and connecting at 1k no problem.
In a 20" 1/10 it's about 2550 and a 18.5" 1/10 2460.
Ran it through my 16.5 recently but never recorded velocity
Edit: to clarify this was with 175 fgmm
In a 20" 1/10 it's about 2550 and a 18.5" 1/10 2460.
Ran it through my 16.5 recently but never recorded velocity
Edit: to clarify this was with 175 fgmm
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I'm throwing this into the hat as I pulled out my targets from the last range session:
Norma Golden Target (GTX) 175gr .308 for the Lothar-Walther 1:12 barrels, 20" and 24". Putting the data here so hopefully someone else can find it useful. I think it could group tighter, on a day with no wind and better fundamentals by the shooter. It has an unusually high BC of 0.547 G1 and a length of 1.236", shorter than the 175gr SMKs 1.24".
Norma Golden Target (GTX) 175gr .308 for the Lothar-Walther 1:12 barrels, 20" and 24". Putting the data here so hopefully someone else can find it useful. I think it could group tighter, on a day with no wind and better fundamentals by the shooter. It has an unusually high BC of 0.547 G1 and a length of 1.236", shorter than the 175gr SMKs 1.24".
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Reasonable SD in that lot. I don’t have any of the 308 but my 6.5 stuff is over 20ft SD, but the price was right.
There will be more content showcasing this rifle at the_bad_vibe_tribe instagram page and Bad Vibe Tribe YouTube in the coming months.
@HKSniper11B - 20" barrel: she loves them 185 juggs (doubleD - that's 2)...slippin out the crown at ~2580fps (PS Mills Fleet Farm had(s) them for $1.6per). No problem with 1000yd @ mid 10's running just a tad behind the normal curve of 400yd @0.5s, 700y @ 1s, 1000y @1.5 with Strelok saying 1.6x but still holding ~730ft-lbs...
clip on thermal w/ easy 1st rd connections at 600yd (2MOA tgt)
@BurtG ever consider taking a sawzall to your forend - "just the tip" and get a 14"CF bbl (P&W@16ATFyakunts)? I need you to tell me the water is fine before I jump on that
clip on thermal w/ easy 1st rd connections at 600yd (2MOA tgt)
@BurtG ever consider taking a sawzall to your forend - "just the tip" and get a 14"CF bbl (P&W@16ATFyakunts)? I need you to tell me the water is fine before I jump on that
@HKSniper11B - 20" barrel: she loves them 185 juggs (doubleD - that's 2)...slippin out the crown at ~2580fps (PS Mills Fleet Farm had(s) them for $1.6per). No problem with 1000yd @ mid 10's running just a tad behind the normal curve of 400yd @0.5s, 700y @ 1s, 1000y @1.5 with Strelok saying 1.6x but still holding ~730ft-lbs...
clip on thermal w/ easy 1st rd connections at 600yd (2MOA tgt)
@BurtG ever consider taking a sawzall to your forend - "just the tip" and get a 14"CF bbl (P&W@16ATFyakunts)? I need you to tell me the water is fine before I jump on that
Pretty sure our boy did that chop already.... @SkyScrapin
I reach out and use a big stick. None of that sbr bolt gun nonsense for me
Yup, and you have a Bartlein/WinTac 1:10 twist 5R barrel, which is exactly why your AT-X likes 185gr; that round is perfect for that barrel. If I had the same barrel, much of what I'm asking would be moot.
185gr Berger Juggernauts won't stabilize well enough in the older Lothar-Walther 4R 1:12 twist barrel, used on the Arctic Warfare, and AT308. And evidence of this can be seen -- compared with the Fed. GMM SMK 175gr -- on the Berger Bullet Stability Calculator: https://bergerbullets.com/twist-rate-calculator/
So unless you got an Arctic Warfare or Anti-Terrorist in your collection to talk dirty about, your info doesn't help much.
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why not just get the $600 barrel?
ive been in hibernation or awhile but im still lost as to why this is a big deal
and sorry for giving you 2 seconds of my time @HKSniper11B ?? maybe find a different tone Im just trying to help you
ive been in hibernation or awhile but im still lost as to why this is a big deal
and sorry for giving you 2 seconds of my time @HKSniper11B ?? maybe find a different tone Im just trying to help you
The ballistics are notably different in the Bartlein 5R 1:10 twist barrels, and superior to boot. Unfortunately, they are out of stock and are slowly being caught up. I spoke to Bartlein personally inquiring, but it'll be a while. Next year sometime, is what I heard. Further, they're in the $900-1000 range in price, $791 with my military discount. And as long as I'm spending money changing things, I could just switch to a better caliber, or change to a different rifle altogether. But that isn't the point, so I digress...
The Lothar-Walther barrel is extremely capable. What's baffled me is how few on SH and elsewhere have documented ballistics with it, even reviewing this thread and others from many years past. That said, the standard was 168gr FGMM for a long time, along with Black Hills 168gr. And, many at that time saw 800-900 yards as the limit regardless. Even just 10 to 20 years ago, ballistic expectations were different. Recall that the Accuracy International PM was designed to shoot (UPDATED): 7.62×51mm L2A2 144gr Ball Ammunition which absolutely does not have the ballistic capabilities of today's ammunition i.e. SMK.
So, I'm left wondering how today -- with modern ballistics and modern rounds -- are AW and AT owners maximizing the original Arctic Warfare profile 4R 1:12 twist Walther barrel and pushing it to 1000 yards. And if they are, then how, and with what round?
Q.E.D... if you are taking my response personally -- while laughing at my previous posts and disingenuously responding -- then those emotions are yours to own, and not my responsibility. We're all adults here.
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im not an expert on Lothar 1/12 4R but I essentially have never heard anyone say they dislike the shift from 169 to 175's. Try the 175s from federal
Yup. We were discussing that and that's where we started the discussion. FGMM 175gr SMKs are fantastic and both rifles seem to love it the most. It just doesn't have the best ballistic coefficient and as such, we are hitting a transonic limit at about 800-850 yards. While in the trans window, it is the most unstable, making it difficult to have DOPE out to 1000 yards. This also means less accurate and less consistent.
Scroll back up to see more details of the discussion about also testing Hornady, Norma, etc.
If you’re looking for empirical data, why not contact Jacob Bynum? He’s put hundreds of thousands of rounds out of the barrels you have questions about. A five minute conversation with him and you’ll find out everything you want to know…
I don't know the man. I'm going to do some homework on him now. Thank you for the suggestion. If he is on here, and I can send the man a PM, even better.
EDIT: founder of "Rifles Only" - going to contact them now and ask.
Your limits are less about bullets and more about wanting to do it with factory ammo. They just aren't loaded hot enough. My 175 sierras are super out to 1k and it's not even near its max load.
A great bullet for you would be a 169gr sierra match king to play nice with your 1/12 twist and get you a smidge more velocity. But you'll have to hand load it.
Also test the 185gr berger loads. Every barrel is different and barrel length matters as well as twist. For example a 14.5" 1/7 twist barrel stabilizes a 55gr head while my 30" with the same twist literally explodes the bullet. You might be fine with the 185. Calculators are best estimates not hard fast rules when it comes to some of this stuff.
A great bullet for you would be a 169gr sierra match king to play nice with your 1/12 twist and get you a smidge more velocity. But you'll have to hand load it.
Also test the 185gr berger loads. Every barrel is different and barrel length matters as well as twist. For example a 14.5" 1/7 twist barrel stabilizes a 55gr head while my 30" with the same twist literally explodes the bullet. You might be fine with the 185. Calculators are best estimates not hard fast rules when it comes to some of this stuff.
I have said that I have that EXACT LW 1:12 barrel and my FGMM 175 factory ammo is shooting at 2720 which is more than enough for 1K.
What is your velocity you are getting with factory 175 FGMM out of your LW, by the way?
AT308 with 20" Lothar-Walther 1:12 Twist Barrel
Transonic window begins around 1350-1320fps. Subsonic is marked in red.
Um, I think we may have found the problem. I have not noticed any transsonic effects at the velocities you list as transsonic.
Transsonic by definition means crossing the sound barrier. You are nowhere near that until right at 1000. Go out and shoot your gun on a calm day at 1000 and get back to us on how repeatable your hits were. I am pretty sure you will be pleasantly surprised.
BTW, those ballistics you gave are practically identical to the FN MK20 and we took those out to 1K at sea level no problem.
Transsonic by definition means crossing the sound barrier. You are nowhere near that until right at 1000. Go out and shoot your gun on a calm day at 1000 and get back to us on how repeatable your hits were. I am pretty sure you will be pleasantly surprised.
BTW, those ballistics you gave are practically identical to the FN MK20 and we took those out to 1K at sea level no problem.
I'll Caitlyn Jenner my AT-XC once it gets here. It's a little tricky with the Bridge & Upper as two pieces. I don't want to leave more than 2" of rail unsupported, and I haven't measured what length that leaves me with.
Best guess is 12" of barrel without sticking out too far beyond the chassis.
I Use AT308 with 26" Lothar-Walther 1:12 Twist Barrel with 208 ELDM with 760 = 2543 fps SD 7 up 1250 m without problems.
That's the top speed. It's more close to 1080/1000 fps when it breaks into subsonic. Going through the barrier is the issue not entering it.
Charts are close but not exact. Get out and shoot. My 20" 308 going 2550fps with a 175smk makes 1k fine.
Charts are close but not exact. Get out and shoot. My 20" 308 going 2550fps with a 175smk makes 1k fine.
I disagree: I've shot out to 1200 yards with other rifles, specifically my MR762s. Trans window at my altitude at that time was about 1000 yards. I could hit 1000 yards consistently. I could hit 1200 yards consistently. But inside transonic, at 1100 yards, was the most difficult.
So, maybe this was the unsaid part: I'm trying to find a round that barely skims into transonic. Honestly, at this point, going with Hornady TAP ELD Precision 168gr with a box BC of 0.523 G1 and flying at 2600 to 2700fps -- despite not grouping as tightly -- will likely be the most effective round.
I'm just gonna bite the bullet and buy more of that ammo, and collect more data. If it doesn't pan out, then I can always accept what Federal GMM SMK 175gr with a BC of 0.503
So, maybe this was the unsaid part: I'm trying to find a round that barely skims into transonic. Honestly, at this point, going with Hornady TAP ELD Precision 168gr with a box BC of 0.523 G1 and flying at 2600 to 2700fps -- despite not grouping as tightly -- will likely be the most effective round.
I'm just gonna bite the bullet and buy more of that ammo, and collect more data. If it doesn't pan out, then I can always accept what Federal GMM SMK 175gr with a BC of 0.503
I remember going down this same data rabbit hole, especially with reloading. Finally I realized the time it took away from shooting wasn't worth it, I think we'll all be curious to hear your range reports when you get to compare these ammos at distance.
FYI, 185's shoot great from my 24" 1/12 LW
FYI, 185's shoot great from my 24" 1/12 LW
Numbers are for nerds, not AI owners. You didn’t spend your children’s inheritance on a pew system just to lower yourself to number talk. You know what the AI doesn’t have in its name? Numbers. Because numbers are for Remington 700’s…
I think he is having a "not actually shooting his rifle out to distance and merely looking at numbers" issue.
This disease is similar to Borescope Hypochondria — Hypothetical DOPE Mania.
Both conditions will be in the next edition of the DSM.
-Stan
Uhh are you saying if your bullets went wonky at 1100, they magically moved back on target at 1200?
My first AI. Waiting on a proof pale brown 6.5 barrel to ship out and hopefully hunt down a factory pale brown forend grip to replace the RRS. I’ve got a 6.5 TBAC Ultra 7 in route as well. Looking forward to using this thing.
There's nothing magic about this. Having accurate DOPE within the transonic window is highly inconsistent; it is a known and well documented issue. Having dope before -- or after -- the round is transonic, offers a more consistent window. I am not using the words "accurate" or "precise." I am very specifically using the word "consistent" in terms of bullet stability and having DOPE for that round.
C'mon guys, its like you guys have never shot in the transonic or subsonic windows before. This isn't rocket science.
Um, I'm pretty sure you don't understand how this works. Angular deviation seen as dispersion is real, and permanent once it happens in flight.
The snide remark is noted... if I had a 1000 yard range, I'd be testing it. But frankly, I don't and so I need to do the math and run numbers. Its that simple.
Transonic Ballistics Effects Explained by Bryan Litz
What happens when the bullet slows to transonic speed, i.e. when the bullet slows to about 1340 feet per second? It is getting close to the speed of sound, close to the sound barrier. That is a bad place to fly for anything. In particular, for bullets that are spin-stabilized, what the sound barrier does to a bullet (as it flies near Mach 1) is that it has a de-stabilizing effect. The center of pressure moves forward, and the over-turning moment on the bullet gets greater. You must then ask: “Is your bullet going to have enough gyroscopic stability to overcome the increasing dynamic instability that’s experienced at transonic speed?”
Some bullets do this better than others. Typically bullets that are shorter and have shallow boat-tail angles will track better through the transonic range. On the contrary, bullets that are longer… can experience a greater range of pitching and yawing in the transonic range that will depress their ballistic coefficients at that speed to greater or lesser extents depending on the exact conditions of the day. That makes it very hard to predict your trajectory for bullets like that through that speed range.
When you look at transonic effects on stability, you’re looking at reasons to maybe have a super-fast twist rate to stabilize your bullets, because you’re actually getting better performance — you’re getting less drag and more BC from your bullets if they are spinning with a more rigid axis through the transonic flight range because they’ll be experiencing less pitching and yawing in their flight.
The short version: I'm trying to find a round that either can push through the transonic window effectively -- as I have in the past when I had access to 1200 yards -- or, focus on using a round that is effective out to 1000 yards and still supersonic. While my MR762s could do this with the 1:11 twist barrel using Hornady TAP ELD AR 168gr, I am not as confident with a 1:12 twist barrel using Federal GMM SMK 175gr.
And since I cannot test this myself, I was fairly confident that there were SH community members with many years of AW308 experience who could save me the money and trouble. Some of you have answered my question, and I think testing just two factory rounds out as far as I can go is worth it: FGMM SMK 175gr due to it having the greatest stability factor of all the rounds while being heavy enough, and Hornady TAP ELD Precision 168gr due to it having the greatest BC and fastest velocity.
So I'm going to leave this to rest until I can afford to go test these, and will try to find a 1000+ yard range to do so. When I have the data, I will report back.
In the mean time, I'd still like to hear from specifically Arctic Warfare owners on your experiences over the years.
Speaking of being a nerd....
For those wanting to shoot NRL Hunter with your AXSR. I found a way without any excessive purchases or the use of a 9-axis CNC.
For the barrel I estimated the weight for a 20" CF 6.5 CM, using my Proof CF 24" 6.5 PRC (56.1oz) and my Proof CF 18.5" .308 Win barrel (48.3oz). I figured I would try CarbonSix barrels using their Sendero profile.
There's 5.1oz tied up in small parts in the stock alone (extension plate: 1.0oz, QR latches: 0.6oz each, washer: 0.3oz, stock folder latch parts: 1.2oz, and the QD receivers: 1.4oz). The standard grip is 4oz, which can be replaced with an MKM Shadow Crossover Grip (2.3oz).
I am tempted to ask MKM to make a fixed stock adapter similar to the ATX to drop around 3oz potentially.
The other option is to drop the bipods and run a suppressor, and rely on the tripod or shoot from a pack.
For those wanting to shoot NRL Hunter with your AXSR. I found a way without any excessive purchases or the use of a 9-axis CNC.
For the barrel I estimated the weight for a 20" CF 6.5 CM, using my Proof CF 24" 6.5 PRC (56.1oz) and my Proof CF 18.5" .308 Win barrel (48.3oz). I figured I would try CarbonSix barrels using their Sendero profile.
There's 5.1oz tied up in small parts in the stock alone (extension plate: 1.0oz, QR latches: 0.6oz each, washer: 0.3oz, stock folder latch parts: 1.2oz, and the QD receivers: 1.4oz). The standard grip is 4oz, which can be replaced with an MKM Shadow Crossover Grip (2.3oz).
I am tempted to ask MKM to make a fixed stock adapter similar to the ATX to drop around 3oz potentially.
The other option is to drop the bipods and run a suppressor, and rely on the tripod or shoot from a pack.
I’ve put about 2500 rounds of 175gr through a specific 20” 1:12 twist LW barrel.
My experience with it showed it did not group the best at 100m but actually tightened up at moderate distances, almost as if initially the bullet had gone to sleep.
Looking at some of your groups in an earlier post it seems you are doing the same thing by fighting that twist rate.
Especially out past 1000 yards with your bullet selection.
The one round I found to do really well was the 176gr A-TIP, the BC bump and design of the projectile lended well at 1000+ yards.
I do see what you’re trying to do and you’re definitely pushing the limits of your system!
