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F T/R Competition F-TR .308 Win Velocity

lead.rain

Sergeant of the Hide
Full Member
Minuteman
Feb 2, 2020
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Canada
I appreciate there is a myriad of factors that will affect velocity and everyone will experience something different. With that said, I have heard a few competitors mention certain "targeted muzzle velocities" for some F-Open calibers. As I am just getting into F-TR, I was curious if there is a "targeted muzzle velocity" for .308 Win? The general answer would be "whatever keeps it supersonic to 1000", but was just curious if there is a rule of thumb?

Thanks.
 
Well, for starters it depends on what bullet you plan on running. Most of the common powders - N140, N150, H4895, Varget, etc. will work across the entire range of bullet weights below.

From there...

155s in general run really well pretty much anywhere from 2900 fps on up. 2950-3050 seems to be the traditional sweet spot.

185 Juggernaut... 2700+ works well for a lot of people; the US FTR team loads in 2013 were in the 2750-2775 range. Some people push them to 2800+, and there are some accurate nodes up there, but I'm not sure the brass life is going to be all that great, even with SRP cases.

200 H / 200.20X... there are a number of 'sweet spots' that work. Seems to depend on what your barrel likes. 2620-2640 is one, 2650-2670 is another... and in theory there is an OCW node just past 2700 but getting there without wrecking brass is tough. In my opinion you're probably better off going with the lower node at around 2620-2630-ish, and have your brass last longer and give yourself a little bit of a buffer as the weather warms up.

Most of the above is predicated on a nominal 30" barrel, with a 0.170" freebore for the 185s and 200s, jumping somewhere around 10-20 thou. Longer barrels pick up a little bit of speed, and shorter ones give up some - but may be easier to tune. If you pare about 15-20 fps off that 2630 fps lower node for the 200.20X, that's right about where several of my barrels liked to run at.

Then again, you always have the exception to the rule... had a *factory* 12 FTR barrel a couple years back, shortened to 28" and re-crowned, throat extended to 0.170" with the same reamer as all of my custom tubes... and that stupid thing shot great around 2670 fps, with zero pressure signs :unsure: :rolleyes:

Long story short... don't get greedy for speed. As James Crofts has said... "speed kills" (your groups with the 200s) (y)
 
Thank you for all of the great info. I guess I should have given some more info for what I am loading.

Currently, I am working up a load with the following:

Case: Lapua (LRP)
Primer: Federal GM210M
Powder: Hodgdon Varget
Projectile: Berger 185 gr Juggernaut

While I have not completed my load development yet, what I have found so far is a node in the 2670 fps area. Mind you I am shooting at just over 5000' ASL.

Being that I am just getting started, I am shooting a factory R700 ADL Varmint 26" barreled action that has a 1:12" twist.
 
For a factory 26", that's pretty good speed. Figuring the standard 15-20 fps per inch, for four inches less of barrel length, you should be in the right spot as far as velocity. But again, barrels can individually be 'fast' or 'slow' - I'm just referring to 'in general' here.

Load for your best accuracy above 2600 fps and go with that. Even at 0' ASL, you'd still be supersonic. At 5000' ASL, you've got a considerable 'buffer' to help you out.
 
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Thanks for all of the insight!
I was feeling pretty good about my load development so far, but it's always nice to be reassured that you're on the right path.
 
You'll hear a lot of guys talking about speed nodes. That always gives me an uneasy feeling because a speed node is only valid at a given spin rate and speed is only half the story.

Always qualify the barrel twist rate when a guy tells you about speed nodes.

You may get best accuracy with a particular bullet at a particular speed with a 1: 10 twist, but best accuracy with a 1:11 twist will need to be faster, and a 1:9 twist will get best results going slower.
 
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You'll hear a lot of guys talking about speed nodes. That always gives me an uneasy feeling because a speed node is only valid at a given spin rate and speed is only half the story.

Always qualify the barrel twist rate when a guy tells you about speed nodes.

You may get best accuracy with a particular bullet at a particular speed with a 1: 10 twist, but best accuracy with a 1:11 twist will need to be faster, and a 1:9 twist will get best results going slower.

That is a very good point!