Several registered GB F-Class Assoc F/TR competitors are likely to switch to heavy bullets this season. While the UK, European, and World Champion Russell Simmonds was quite unbeatable with a 1-14" twist barrel and 155s, much of that is down to Russell's unbelievably good wind reading skills. The rest of us need a bit more from the equipment just to narrow the gap a little!
F/TR World Championship Silver Medal winner George Barnard is a long-time Bisley 'Match Rifle' (1,000-1,200yd with .308W and with barrel weight restrictions) shooter and brought his long barrel, high-velocity heavy bullet philosophy to F/TR - and it works for him. His bullet of choice is the 200gn Sierra MK, which although not the best in class for BC was found by the MR guys to give optimum performance at 1,000yd + at Bisley (but pre the latest generation of high-BC tangent ogive bullets from Berger). A GB FCA team training weekend last March at Bisley saw the shooting take place in really dire wind conditions - near gale with large amounts of gusting. Bad enough for national team members to get complete misses. The shoot was 2 sighters; 15 score and the story goes that George only brought 12 cartridges, not 17, but still got the highest F/TR score in these conditions! I was told how much less windage he needed than the 155gn users, but forget it now. Without detracting from Mr Barnard's plentiful shooting skills and his great experience of Bisley, there is no question that his bullets were shooting way, way inside everybody else's.
Accuracy of the 185 Berger? I did some 100yd load testing last autumn off the bench with these bullets in my 1-13.5 Bartlein 30" and got superb accuracy at 2,810 fps which in ME terms is almost a direct match to my 155gn Lapua Scenar load. There was an issue over whether this twist rate would stabilise the bullet, but it did at the time of the tests, alongside the 190gn Sierra MK. This is despite Miller's twist rule giving an Sg of only 1.03 or thereabouts at standard temp and pressure. However, when I tried the load a couple of weeks later at 900yd I had to abandon them and return to 155s, presumably because temperatures had dropped from the high 50s to low 40s (F) and previously marginally stabilised bullets were now marginally unstable. They hit the target but struggled to stay within the three ring (second out from the bull as we work on Bull = 5) with the dispersion as much vertical as horizontal despite MV ES values under 10 fps.
So, 2010 will see a 1-10" Broughton tried with everything up to 210gn VLDs, but the 185s probably the primary bullet. I did a table (below) which was primarily about 223 / 90gn v 308W with a variety of options, but it shows the 185s only give a little away to the 208 A-Max and 210s from Sierra and Berger. All MVs are based on equivalent MEs to a 155 at 3,050 fps which is a little modest by GB FCA F/TR standards, 3,050 - 3,100 fps being the norm at national league level.
On twists, Bryan Litz tells me that he and other Palma / Fullbore shooters use their 1-13" twist rifles without problems in the US summer where no bullet weight restrictions apply - this ties in with my 1-13.5 experience, but neverthless, he is considering a move to 1-12" and doesn't believe that will affect the lighter bullets adversely. As well as the 185 Berger, I know from personal experience that this twist rate works very well with the 190gn Sierra, another fine long-range performer.
F/TR Bullet Ballistic Efficiency
Bullets ranked in descending order of performance judged by Deflection in 10mph Crosswind at 1,000yd
Bullet Make, Model & Wt (Best in Class) I7 Value V0 V1,000 D1,000 (Inches/MOA)
.308 Winchester
*Hornady 208gn A-Max 0.967 2,630 fps 1,417 fps 72.74” / 6.9
Berger 210gn VLD 0.979 2,620 fps 1,407 fps 73.42” / 7.0
Berger 190gn VLD 0.982 2,755 fps 1,392 fps 77.92” / 7.4
Berger 185gn BT M L-Range 0.972 2,790 fps 1,398 fps 78.15” / 7.5
*Sierra 240gn MatchKing 1.092 2,450 fps 1,307 fps 79.35” / 7.6
*Sierra 220gn MatchKing 1.068 2,560 fps 1,322 fps 80.66” / 7.7
Berger 175gn BT M L-R 0.999 2,870 fps 1,454 fps 83.93” / 8.0
*Sierra 200gn MatchKing 1.058 2,685 fps 1,317 fps 84.10” / 8.0
Lapua 155gn Scenar
Berger 155.5gn M Target FB 0.988 3,050 fps 1,331 fps 89.04” / 8.5
Berger 168gn VLD 1.047 2,930 fps 1,282 fps 92.28” / 8.8
*Hornady 178gn A-Max 1.118 2,830 fps 1,213 fps 98.54” / 9.4
*Only suitable long-range bullet available in this weight in the UK. Note – no suitable 180gn L-R bullet.
MVs
155gn @ 3,050 fps used as a base. Other MVs calculated to produce the same ME (3,200 ft/lbs).
.223 Remington
Berger 90gn VLD 0.911 2,825 fps 1,401 fps 78.53” / 7.5
Berger 90gn Match BT L-R 0.979 2,825 fps 1,314 fps 87.16” / 8.3
Hornady 80gn A-Max 0.987 3,000 fps 1,266 fps 94.97” / 9.1
MVs
Assumed on the basis of Jerry Tierney’s Palma Rifle work at Sacramento. 80gn bullets gave good accuracy at around 3,000 fps and 90gn VLDs at 2,830 fps. (Higher MVs are obtainable.)
Free-Recoil Comparisons (18lb Rifle)
.223 Rem 90gn 2,825fps 2.5 ft/lb
.223 Rem 80gn 3,000 fps 2.5 ft/lb
.308 Win 155gn 3,050 fps 9.2 ft/lb
308 Win 208gn 2,630 fps 9.8 ft/lb
Calculations: Sierra Infinity VI ballistics program
Data Sources & Assumptions
Bullet efficiency and ballistics performance from Bryan Litz’s book Applied Ballistics for Long Range Shooting and its associated G7 PC program.
.308W MVs based on 155gn at 3,050 fps MV (norm in UK F/TR ±50 fps) and other bullet weight MVs are calculated on the basis of those that produce the same ME as this base combination. (Actual results from use of 185 and 210gn bullets supports the methodology.)
.223R MVs are those found to give good results in Palma type rifles in tests by Clint Dahlstrom (Viht N550) and Jerry Tierney (Viht N550 + Alliant Re15) in 2008/09 tests. Higher MVs were found achievable, but 90gn VLD MV/accuracy seemed to peak at a bit over 2,800 fps.
Laurie,
York, England