Yes, you can overcome a slow twist with a higher velocity, after all what you are looking for is a spin rate. The spin rate of a bullet is a function of twist and muzzle velocity; increase either one and the spin will increase. However it should be noted that the required spin rate for a bullet is a function of the inherent instability of the bullet and the muzzle velocity. In other words the minimum required spin rate needed to stabilize a bullet will increase as the bullet is made more unstable or its velocity increases. The air resistance is what creates the need for spin and the higher the muzzle velocity, the greater the air resistance and thus the greater the tendency for the bullet swap ends and tumble at so the higher the minimum required spin.
All this to say, that as you go faster, you need more spin on the bullet. So you can make up a slower twist with a higher MV, but only by a small increment.
F-class shooting is very much like NRA HP, except for a couple of things; 1 the targets are similar but smaller and 2- the competitor is allowed to use optics and support for the rifle. In fact a lot of places that have NRA HP matches also have F-class matches running concurrently; the course of fire is the same. F-class originated in Canada when an old Fullbore shooter (NRA HP) wanted to continue shooting in competition but could no longer see the target well enough and could not hold the rifle hard enough to compete. This Mr. Farquharson (hence F-class in his honor,) managed to convince the DCRA (Canadian NRA) to allow him and others to compete with scoped rifles and bipods or rests. That form of competition caught on very quickly.
F-class is divided into two sub-classes but both use the same target. This target was sanctioned by the NRA in 2006 and started being used in January of 2007. I'll come back to it in a minute.
One of the sub-classes is F-Open. This can be compared to prone benchrest shooting, to some extent. The rifles are any caliber up to .33 caliber, they can weigh up to 25 pounds (I think), any sighting system can be used (most people opt for high magnification scopes,) and the rifle can rest on a mechanical device as long as it is not a return to zero gadget. A rear rest is allowed but must not be attached to the front rest. The rifle must be fired from the shoulder.
F-T/R is much more stringent in its rules. The calibers are limited to two: unmodified .223 and .308, any bullet you want. The rifle total weight is 18.18 pounds including anything that is attached to the rifle, such as a scope, sling or bipod. The front rest is limited to bipod or a bag. You can use a rear rest but that is not included in the weight and must not be attached to the rifle.
The course of fire is the same as NRA HP and I will just describe it here quickly for the folks who have never seen it.
The way a match works is that we divide the group of shooters into relays and you need a minimum of 2 relays. I have participated in state matches where we had up to 4 relays, which makes for a long day. If the competition is for HP and F-class shooters, we will have the HP shooters on one series of targets and the F-class shooters on the other, because the targets are different and we do not put new targets for every relay, targets cost money.
So, let's just have two relays. At the start of the match, relay 2 will go to the pits and relay 1 will shoot. The course of fire is usually 2 sighters followed by 20 rounds for record in 30 minutes, at 1000 yards prone slow fire. So, let's say I'm on relay 1. I will guage the wind, set my come-ups on the riflescope and then take my first shot. If I did everything correctly, my target puller will see the bullet hit the berm and pull the target down and find the bullet hole. If I did it correctly and actually hit the target, the puller will put a spotting disk in the bullet hole and a scoring disk in a position that corresponds to my score, in other words, the ring in which the bullet hit the target. The closer to the X-ring, the higher the value; the maximum value is 10. Once this is done the target goes back up. I see where I hit, note the score, make a correction and take the next shot. The target puller sees the shot, brings down the target, moves the spotting disk to the new bullet hole, puts a paster of the appropriate color and the prior bullet hole, moves the scoring disk to the proper position and sends the target back up.
This goes on for the 22 shots, the first two being sighters; they do not count but they help you guage the conditions. For 20 shots, the maximum score is 200 (20 x 10). There are usually 3 matches in a competition. Once relay 1 has finished shooting or time runs out, we swap positions. Relay 1 will go to the pits and relay 2 will shoot.
You are familiar with the SR1 (300 yards), MR63 (500/600 yards) and LR1 (800/900/1000 yards) targets. F-class targets are based on these targets, but have different centers and ring values. Let's look at the Long Range targets and how we use them in matches that have HP and F shooters.
A brand new target will have the LR1 layout which means that it is white (or rather tan), with a black aiming center. This aiming black measures 44 inches in diameter and there are concentric rings inside the black as well as outside the black.
At the start of every match (or rather at the end of a competition so it's ready for the next competition) we resurface the target or actually just paste a new center on the target. We have two centers that we use; the LR-1 and the LRFC. The LR-1 is the standard long range target used in Palma, HighPower and Service Rifle matches. The LRFC has an X-ring in the middle of the black that is 5 inches in diameter. The next ring is the 10 ring at 10 inches in diameter, the next one is the 9-ring at 20 inches in diameter, the next one is the 8-ring at 30 inches in diameter and finally the next one is the 7-ring at 44 inches in diameter. That is also the total aiming black. There is one more ring in the white and that is the 6-ring which measures 60 inches in diameter. Outside the 6-ring, anywhere else on the target is considered the 5 area. This means that if you hit the target at 1000 yards, the minimum you will get is a 5.
The F-class rings have half the diameter of the HP rings for the same value. This means each ring is one quarter the area of the HP ring. At 300 yards, the X-ring is 1.47 inch in diameter and the 10-ring is 2.83 inches.
Let's talk about score. I know you are familiar with that but I am explaining it for others who may not know. When you reach a certain level of scoring, you obtain a classification from the NRA. This means that you have to shoot a number of NRA-certified or registered matches and the scores have to be turned in to the NRA. If your scores are below 92%, you are classified as a Marksman. When you get to 92% and above for 120 rounds, (or two complete matches,) you get reclassified as a Sharpshooter. At 94.5% or above, you become an Expert. At 97% or above you are a Master and at 98.5% or above you are a High Master.
I am a Sharpshooter at LR F-class, I broke the 92% threshold but I have not yet attained the 94.55% Expert threshold. We only shoot 1000 yards at my club, so I do not have the benefit of shooting the same target as I described above at 800 and 900. The only time that I have done that, my scores were higher, but not quite enough for Expert. It's very difficult with a .223 in an AR-15, which is why I am going to my Ruger M77 UM in .308. There are no LR high masters in F-T/R and I think there may be a couple of Masters.