F/TR question caliber ?

[Mystic Precision]

With respect, I think Jerry is wrong. Light bullets (.223/90) don't get blown around more than heavier bullets (.308/155 or 185).... _all_ of "how much is a bullet blown around by wind" is incorporated into the "bc" parameter plus the muzzle velocity. Exactly that, and nothing more. If you use an accurate BC (and nowadays, thanks to Bryan Litz, we have *good* G7 BCs for the bullets that interest us, and they are all done on an apples-to-apples basis), then your ballistics program tells you the truth - this goes for vertical wind as well as sideways wind.

For shooting iron sights ("TR"), the rules say that we can use any weight bullet in .223, and any bullet <156 grains in .308.

For scoped shooting ("FTR"), the rules say that we can use any bullet weight in .223 and any bullet weight in .308.

If you do decide to build a .308, any barrel twist in the 1-11" to 1-13" range will do you fine. Get the best barrel you can find (Krieger, MacLennan, etc).

For iron sights, 30" barrels are usually chosen. Part of this is to get every last bit of speed, another part is simply to get the front sight a bit further out (it's easier to keep the front sight element and the target image in simultaneous focus that way).

For scopes, you can have a somewhat shorter barrel. 26" or shorter would be unusual for a 1000yd rifle, we tend to be speed hogs; the vast majority of FTR rifles have barrels in the 26"-30" range.

In scoped (FTR) shooting, the Berger 185LRBT is the "go-to standard". The recently-introduced Berger 185 Hybrid is probably fractionally better. There is also some cutting-edge work being done on shooting heavier bullets (210-230+), however that is not yet well established as a match-winning setup.

Having said that, a .308 shooting one of the modern high performance 155s (Berger 155 Hybrid, Berger 155.5 Fullbore, Sierra #2156 Palma) is *very* close in performance to a Berger 185 load. The top 155s are lower performance, but only barely (in the sense that you still might be able to win a national or international championship match with the 155s; but all other things being equal, the 185s do have a single-digit-percentage edge over the 155s).

I wish you were right and the entire reason why I took the time and effort to develop the 223/90. Accuracy was great and now that we have receipes that work, no more difficult to load for then any 308. Just use a better scale.

At Raton, there was no doubt that mass was important. Lighter objects got tossed around far more then their heavier brethren and that was shown very clearly in F OPEN and FTR. It has nothing to do with BC under those conditions but inertia.

There is such strong localised conditions that spring up and smack you, makes you scratch your head alot....until you see the same condition trash one of the top US shooters who has been to Raton many times.

155.5's simply weren't up to the task and faced a similar level of displacement to me. The 185's were the bench mark and did very well. The heavier bullets went from 200 to 230's. I shot with a top shooter using 200gr Hybrids and he did very nicely scoring one of the few clean relays at that match.

I am not saying that heavy is the only way to go. I am saying that heavier can be more forgiving in really wonky air IF you can shoot it (ie handle the recoil and drive consistently).

The Euro championships were won by a shooter using 155gr Hybrids I believe so this debate is far from settled. A Canadian set a US National record in Montana (?) this fall and I believe he shoots the 155.5gr - this same shooter came in 2nd at the Westerns in SK where the winds were pretty quick for some relays. He used the 155.5's in SK for sure cause I asked him.

There are ranges and then THERE ARE RANGES. No matter the velocity, if a to b is true and stable, anything will work. But when you have air going one way for some distance, reversing for some, twirling for others, I would put my money on the biggest slug going downrange.

How's this for a perspective? F OPen shooters hammering the X ring at 1000yds. The occasional shot a 10. Shooter feeling pretty confident this will be a clean relay. After putting a few X's in a row with waterline elevation, the next shot comes up a 12 oclock "7". The targets on either side of him also showing massive vertical too and missed points. Several targets over X's and 10s with no elevation change.

180gr 7mm Berger Hybrid leaving over 2800fps.

BIG wonky air. And Yes, I WAS watching when this happened.

My FTR rifle has a Shilen 12 twist, and have had not issues up to 210gr VLD Bergers.

Jerry

 

[manitou210]

If I read the Berger site right. If I went with a 1 in 11 say True flite heavy palma at 28 or 30 i would be safe shooting the 155's or 185's? or 185 hybrids?

Thanks

I shoot at Connaught with fellows shooting the .308 win, one fellow TR shooter who shoots 155.5 gr Bergers at 3040fps "stiff load", lapua brass,CCI BR primers, Varget with a tru Flite 30" 1/13 twist, Barnard action. This load I have seen him shoot at 300y with a scope, 1/4 moa groups.
Another fellow shooting TR, 155gr scenars with N150 powder shoot at 2940 fps 1/13 twist Krieger 30" shoot a perfect score at 300 meters all V bulls thats off your elbows all in 3" pretty amazing.
Another shooter FTR Rookie on this site, the heavys in .308win 185gr to 200+ he has a Broughton 30" with a 1/12 twist shoots extreemly well.
The Chou Brothers shoot the 185gr Bergers very very well with I believe is a 1/12 twist.
I would say the 1/13 is way for the 155gr bullets, and maybe like Berger claims 1/11 for 185gr.
Either way you choose will work and you can win with 155gr & the 185gr if you can learn to read wind.
If a guys like Alain Marion Des Vanpleew and many others shooting TR with 155gr where to move to F/TR the would be winning lots of shoots.
manitou

 

[peterdobson]

David Luckman, Great Britain, won the Long Range Championship at Camp Perry this year shooting 155s in .308 Win.