A 77gn SMK doing 2900fps at the muzzle, is still super sonic at 1000. With a 300yd zero, you'll have about a 377 inch drop. [SimG]
'fraid not! With the various makes of 77s listed by Bryan Litz as having average G7 BCs from 0.190 to 0.203, the best of these is calculated to be doing 1,061 fps at 1,000 under standard ballistic conditions. In practice, it'll almost certainly be less as the worst of the transonic zone, from ~1,225 fps down to the sound barrier (1,126 fps) which the bullet will pass through just after the 800 yard mark will produce turbulence around its body and increase drag.
All of the 77s are relatively high-drag, short-range bullets designed to be seated deep in the case to the SAAMI 2.26" COAL to be fired semi-auto / rapid in the 200/300 yard stages of US NRA XTC Service Rifle competition. Competitors switch to single-loaded 80s for the 600 yard stage to reduce points loss due to wind effects in this slowfire deliberate prone section of the course of fire.
The measure of a bullet's ballistic efficiency is its 'form factor' a drag related measurement that compares the sample to the G-whatever reference projectile. The 77gn SMK's i7 value is 1.156, ie it produces nearly 16% more drag than the G7 reference. By comparison, some proper L-R 224s are rated at:
75gn Hornady A-Max ....... 1.010
80gn Hornady A-Max ....... 0.987
80.5gn Berger BT Fullbore 0.982
80gn Berger VLD ............. 1.001
90gn Berger VLD ............. 0.911
where low = good as it means less drag / a more efficient bullet shape.
Of the 80gn 0.224" class, the outstanding if pricey design is the Berger 80.5gn. It can be driven to 3,000-3,050 fps in a 30-inch barrel FTR rifle, over 2,900 fps from 24-inches and over 2,950 fps from 26 inches in suitably set-up and throated barrels. It needs a 1-8" twist, optimal being 7.7" and I'd prefer 1-7 to 1-7.5" for very long-range shooting.
With an average G7 BC of 0.233, that's identical to its 0.308" big brother the 155.5gn Berger BT Fullbore and as both cartridges are capable of similar MVs, their external ballistics are very close .... but 223 is MUCH nicer to shoot due to its lighter recoil characteristics. 308 can be handloaded though to give better external ballistics in disciplines like FTR using high-BC heavy bullets such as the 185gn BTLR Juggernaut and Berger 210gn LRBT.
However, the good old 80gn Sierra MK at half the Berger's price is still a viable bullet and handles transonic flight very well down to and through the sound barrier into subsonic flight. I shot them at realtively low MVs in the very early days of F-Class at Diggle at up to 1,000 yards and could keep them in the standard NRA target 'black' without too much trouble unless the Pennine winds were running hard and variably. One problem was that being subsonic at this distance, you had to keep getting the RCO to radio to have the target pulled as the butts crew missed the quiet bullets and tiny holes. Today's F-Class target with only a quarter of the ring area would be another matter entirely ....!
A standard 1-12" twist HBar 223 shooting 52/53 match bullets is a lot of fun at 200/300 yards, but sees every little wind change blow the bullet all over the paper at 600 yards. 1-9" twist barrelled rifles such as Remington PSS and Cz527 Varmint shoot 69s well at 600 yards, but are still peed all over by a good equivalent 26-barrel 308 in the wind.
It's necessary to go to 1-8" or even 1-7" twists to shoot the better 80s to do really well in mid-range matches and have any hope at all in long-range. the only factory rifles with these twists are the Tikka T3 Tactical (short 20 inch barrel) and choosing the 1-7 inch options on Savage's single-shot 223s, the 26-inch barrel LRPV (Long Range Precision Varmint available in 7 or 9 twist versions) or the 30-inch Model 12 FTR (1-7 inch only twist rate). The LRPV in 7-inch twist rate form is an outstanding performer in Factory Rifle class competition divisions with good handloads and makes a very good short to mid-range FTR rifle for club comps.
