308 FTR - How critical to hit the high node?

[MikeMcCasland]

Hey Guys,

I just got two new 308 rifles built for TR; both 30" bartleins cut from the same .180fb/.342 neck reamer.

I've got a load for both that seemingly hammers with 200.20Xs, and N150. The 'problem' is that I'm only hitting ~2640FPS, however in both rifles it turned in .3" 5-shot groups at 100, and .4" groups on either side of that charge. 2640 appears to be dead center in the middle of a node for me.

Basically, the rifles are freaking hammering at that velocity, and based on what I saw tuning it in, I feel like they're going to continue to do that, with a lot of cushion on either side.


That said, I hear lots of talk at matches about "you gotta be above 2700" (I think most are using Varget to get there). I'm confident that's true for the guys who are seriously a threat to winning state/national titles, but is 'the high node' required to consistently be 580s/90s at 1k?


Every time I've tried to run them up past 2700 (in other .308s) the recoil seems to really increase, whereas I feel its fairly manageable running mid 2600s.


And before anyone tells me, yes I know it's all about the wind. I'm asking about the node though.

Thanks in advance!

 

[avidflyer]

for me 200/x always tuned in at 2640-2680 depending on powder. that is the node for most of us.

 

[Down South]

I shot the higher node (over 2700 ftps) in my previous barrel with X bullets and H4895. It shot well but is harder on brass, barrels, etc and it's a bit more finicky than the lower node in my opinion. In my current barrel I'm running the 2640-2650 node with N-150 right where you're at. That's what I shot and won with at Nationals last month. The node is wider and accuracy is really good. Much easier on components etc so I think I'll just stay in this spot and not worry about the higher node.

 

[MikeMcCasland]

I shot the higher node (over 2700 ftps) in my previous barrel with X bullets and H4895. It shot well but is harder on brass, barrels, etc and it's a bit more finicky than the lower node in my opinion. In my current barrel I'm running the 2640-2650 node with N-150 right where you're at. That's what I shot and won with at Nationals last month. The node is wider and accuracy is really good. Much easier on components etc so I think I'll just stay in this spot and not worry about the higher node.

I suppose if it's good enough to win nationals, it'll work for my purposes.

Thanks guys!

 

[memilanuk]

I think Jim Crofts put it best back when he first won FCNC with the 200 Hybrids and everyone started trying to find the magic load with 200s...

"Speed kills"

...as in 'speed kills accuracy', as in if your barrel happens to run 'fast' and likes them that way - great. If not, then go with the lower node and enjoy the easier tuning, better brass life, etc. etc.

I run 28" tubes the last few years, and I've had several barrels tune in at 2610-2620 fps. Just a smidge lower than the guys running 30" tubes, about what you'd expect for the difference in length - and you'll never see the difference on target.

I did have *one* barrel - a factory one, at that - that even when throated out and trimmed down to 28" still tuned in @ 2675... but that aside, I'd be looking for the sweet spot somewhere around 2640, +/- 10 fps in most barrels - and adjust that expectation as necessary for barrel length.

 

[Quickoz]

Im running right around the 2620 to 2640 node. Won me grand agg at our nats this year in Aussie. A lot of people say that you need to be faster. Chase what works. I've tried the normal Aussie thing of Moly and 2750 plus with 200s. Not for me I've found. Too inconsistant.

 

[Tony1320]

I have been shooting the 200.20x @ 2640-2660 for the last 2 barrels with N140

I did try the 2710-2730 node with Varget but decided to run 2660 with N140 and haven't looked back since. It shoots well in all temperatures and rain

 

[spclark]

Speed does not win matches.

If your 200.20X’s shoot well at 2,640 fps node out to 1,000 yards, don’t bother looking for a higher node. You’ll pay more for brass, barrels & recoil for a minor gain in windage.

Better to learn to read the wind like those of us (diehard sling shooters with match sights) using 155 gn. bullets.

 

[dcali]

The idea that there is some universal “high node” is not reality- where a rifle tunes well is highly dependent on lots of things that change from rifle to rifle.

That said, with f class barrel lengths and throats, a 200 grain bullet in the 2600s is going to be near max pressure, and it seems like most people find a way to make them shoot in that range. You can trash your brass and/or bolt face (and actual face if you really push it) chasing more, but the returns are slight.

 

[MikeMcCasland]

Yep. I'm going to keep it right where it is.

Reason I ask, is that I've had 308s in the works for some time, but only recently started paying attention to the e-target velocities of the TR shooters I've been paired with. Last 2-3 times I've been squadded up with a TR shooter, they've been putting up faster velocities at 1,000 than my 30" 6.5 CM, and I was running a .301 G7 @ 2820.

In addition, just what I hear some of the top/veteran TR shooters say, it lead me to believe a lot of folks at the top of the pack were running this way.

Hell, I heard of one guy pushing 2,800 with a 200gr (think he was using RL17).

I'm content with 2615 or 2640. Doesn't matter to me so long as it registers on the e-target, and comes back an X.

I just didn't want to be missing out on what the cool kids were doing.

 

[dskogman]

If you want to send them fast get a 300 WSM.

 

[FrankG]

I’ll say the higher node usually has a smaller tune window. That being said....and I say it all the time if you think a 100fps is going to help you win the match.....your worrying about the wrong thing. Focus on pulling the trigger consistently and what the wind/conditions are doing.

Guys get to hung up on velocities.

Get outside that tune window just a little at the high velocities/max loads and the gun usually will start spitting/throwing shots.

Had a customer a few months ago with 6.5cm and was wanting to push 140gr Bergers at like mid to upper 2800’s and the rifles would spit shots. Dropped to a lower velocity of 2800 and the guns would shoot in the upper .1xx’s and low .2xx’s and these where hunting rifles and not even a comp./bench type guns.

Thanks for using our sticks!

Later, Frank
Bartlein Barrels

 

[MikeMcCasland]

If you want to send them fast get a 300 WSM.

I like the idea getting beat by PJ, and Ray at ~75 cents a shot, more than I like the idea of getting beat by you and Tim at $1.50 per.

Maybe next year, hah!

 

[Down South]

Yep. I'm going to keep it right where it is.

Reason I ask, is that I've had 308s in the works for some time, but only recently started paying attention to the e-target velocities of the TR shooters I've been paired with. Last 2-3 times I've been squadded up with a TR shooter, they've been putting up faster velocities at 1,000 than my 30" 6.5 CM, and I was running a .301 G7 @ 2820.

In addition, just what I hear some of the top/veteran TR shooters say, it lead me to believe a lot of folks at the top of the pack were running this way.

Hell, I heard of one guy pushing 2,800 with a 200gr (think he was using RL17).

I'm content with 2615 or 2640. Doesn't matter to me so long as it registers on the e-target, and comes back an X.

I just didn't want to be missing out on what the cool kids were doing.

You're not missing out running 2640 ish velocity with great accuracy.......

 

[Ned Ludd]

Another way to think about the effect of velocity is to use a Ballistic calculator such as JBM Ballistics and plug in the average velocity for the same bullet at the two different nodes. For the 200-20X bullet at 2650 an 2705 fps, the estimated difference in wind deflection for a full-value 10 mph wind at 600 yd is ~0.7", at 1000 yd it is ~2.2". When you figure in that even an average wind reader can usually make a wind call much better than 10 mph, the differences become even smaller. Obviously, the estimated differences in wind deflection are not zero, but IMO unless the difference is at least ~0.25 MOA or greater, it would be difficult, if not impossible, to ever prove any statistically significant difference in scores due to the slight increase in velocity/wind deflection. That tiny little bit of improvement in wind deflection will likely be lost in the noise because other [larger] sources of error are also in play.

So the question becomes is a tiny decrease in wind deflection that is very difficult to conclusively link to improved scores worth the negatives associated with it, such as increased recoil/gun handling issues, potentially poorer brass life, a less forgiving node, etc? As has been stated by others above, I wouldn't be too concerned about running a slightly slower node if the precision and ES/SD [velocity] were solid. The better approach to reducing wind deflection is typically to use a bullet with a better BC. The gains from a higher BC bullet of similar weight are usually more noticeable than a slight increase in velocity. The problem with that concept in this scenario is that you're already using one of the best bullets available for .308 Win. Switching to a higher BC bullet will almost certainly mean a significant increase in bullet weight, concomitant with a noticeable decrease in velocity. When you run the wind deflection numbers for something like the 215 or 230 Hybrid, the reduction in wind deflection is not as great as the BC might seemingly indicate, because you can't push them nearly as fast from the .308 Win cartridge. Greater recoil and gun handling issues may also be a concern with the next higher weigh classes of bullets..

Having said that, there is currently an ongoing thread regarding the use of Hornady's 250 gr A-tip bullet in a .308 Win.

http://forum.accurateshooter.com/threads/250gr-a-tip-in-a-308.3988947/

From the initial information provided in the thread, it appears that the 250 A-tip may be a special case where with the right powder it might be possible to drive it at a sufficient velocity such that with its extremely high BC, it might actually provide a significant reduction in wind deflection over bullets in the 200-215 gr weight class. Only time and testing will tell whether this approach bears fruit and whether other issues, such as gun handling, offset the apparent advantage this bullet offers on paper. In any event, I don't think you can go wrong shooting the 200.20X at ~2650 fps in F-TR. Far too many F-TR shooters (like Jade) are currently generating outstanding scores and winning big matches with this combination for it to be considered "limiting" in some way.

 

[MikeMcCasland]

Circling back to this thread to confirm what everyone was saying lol.

Prior to a few hours ago, I'd never actually never shot a .308 at 1,000 yards, so didn't really know what to expect as far as wind drift (feel wise). It's easy to read what it'll do on paper, but I was apprehensive about how that would play out in practice.

Gun hammered for the first two matches (197/196), but then the wind picked up big-time and happened to disagree with what I could see via mirage; I couldn't make sense of it...picked up a 183 for the final match.

You guys were right. Although you had to hold an extra ~2 rings more for wind, it's very workable in the velocity ranges that were outlined.

N150 also appears to be ultra temp stable. I've only shot the gun 3 times now, but in 35 degree weather it delivers almost the exact same velocity as it gives at 60-70.

Thanks again!

 

[johnnyi]

Circling back to this thread to confirm what everyone was saying lol.

Prior to a few hours ago, I'd never actually never shot a .308 at 1,000 yards, so didn't really know what to expect as far as wind drift (feel wise). It's easy to read what it'll do on paper, but I was apprehensive about how that would play out in practice.

Gun hammered for the first two matches (197/196), but then the wind picked up big-time and happened to disagree with what I could see via mirage; I couldn't make sense of it...picked up a 183 for the final match.

You guys were right. Although you had to hold an extra ~2 rings more for wind, it's very workable in the velocity ranges that were outlined.

N150 also appears to be ultra temp stable. I've only shot the gun 3 times now, but in 35 degree weather it delivers almost the exact same velocity as it gives at 60-70.

Thanks again!

Hey Mike I forgot to tell you this quote a buddy Of mine used to say about dialing to a number, node, or whatever....

he always said... “the only thing that matters, is what shows up on paper”.

 

[Dgd6mm]

Mike do you find the 0.180 FB to be adequate for 200 20X.

Don Dunlap

 

[MikeMcCasland]

Mike do you find the 0.180 FB to be adequate for 200 20X.

Don Dunlap

Don,

I'm just getting into FTR so keep that in mind, but it feels just about perfect to me. Bullet is up out of the donut area of the case, and I'm hitting charge nodes where everyone else appears to be as well.

Both my barrels are stupid accurate too.

Thanks,
Mike

 

[Ned Ludd]

Mike do you find the 0.180 FB to be adequate for 200 20X.

Don Dunlap

I've also been using a reamer that cuts 0.342" nk, 1deg30, 0.180 fb" for a couple rifles set up to shoot the 200.20X. It works very well. The bullet boattail/bearing surface junction is slightly less than halfway out the neck seated at ~.012" off the lands. I personally wouldn't want to go much longer than the 0.180" fb with the 200.20X bullet, but you could probably get away with at least another .020" to .030" if you had some specific reason to do so. The 200.20X would be seated pretty far out in the neck, but I'm certain it would work. The US F-TR reamer cuts 0.170" fb, and works extremely well for the 200.20X bullet. Any freebore in the 0.160" to 0.180" range should work pretty well with the 200.20Xs.

I recently started shooting 215 Hybrids in one of the .308s cut with the 0.180" fb reamer and they also work pretty well. They're obviously seated a little deeper in the neck than the 200.20Xs due to the longer bearing surface, but are still seated above the neck/shoulder. I also shoot 185 Hybrids out that chamber occasionally. So it's pretty versatile...185s, 200s, an 215s all can be loaded without issue using a 0.180" fb chamber.