The only thing I can tell you is what works for me and why. It is ONLY my opinion and what works for me. Others will dissagree and will express their opinion as well. But from those opinons, you may be able to peice together the answer you want. Also, like S1 stated, it depends on what you want. If you are trying to set a new world record, I am in the same boat and am still learning what that is going to take. But if you just want to punch paper at 1000 yards for kix and competition, what works for me is the standard 308 winchester with Sierra Match King bullets. I use 155s, 168s, and 175s. I dont generally use the 155s unless I have a need for speed. Out of my barrel they only group from .250-.500. They will almost always group at 7.5" at 1000 yards. The 168 works for 100-600 yard benchrest shooting and Those can be shot out of my gun anywhere from .090-.150 Then comes my favorite, which is the 175. It groups about .250 most of the time and this round fired from my barrel yeilds MOA for MOA at 1000 yards, in other words whatever the MOA at 100 it is the same at 1000. As far as barrel length for the 308, I believe that 24" min and 26" max is perfect. Why? because less and you dont get the right burn rates for long range shooting, and longer and you get too much barrel whip and that hurts accuracy. I choose a 24" becuse it is a little more ridgid than the 26" and I still get good ballistics at all ranges. I also have a twist of 1-11.25" which is optimum for the 175 30 cal, 1-12 is best for the 168, and a 1-13 to 1-14 will suit the 155 best depending on the velocity you choose to launch them. If you want to figure that out, a formula given here can be used, this is the greenhill formula:
T=150(d/r) for velocities from about 1500 to 2800 fps. Substitute 180 for the 150 value for velocities exceeding 2800 fps. "T" is the twist rate. "d" is the bullet diameter. "r" is the bullet length to diameter ratio (length of bullet divided by diameter). In .308, it works out fairly well. Sierra 168 grain Matchking is 0.308 inches in diameter. Bullet length is about 1.210 inches so we have a length to diameter ratio of 3.929. Plugging this value into the formula and using the 150 constant (the proven best velocity for the 168 grain MK is 2550 - 2600 fps), we get T=150 x (.308/3.929); T=150 x 0.078; T=11.76 inches or 11 3/4 inch twist …. One rotation of the bullet for every 11.76 inches of barrel traveled. This is very, very close to the "standard" 12 twist barrels on alot of 26" Remington 700s. The 175 Matchkings do not perform as well in the 12 twist barrels. Again diameter is 0.308 inches. Bullet length is 1.257 inches, resulting in an ld ratio of 4.081. … plugging into formula (optimal velocity is 2500 to 2550 fps so we will use the 150 constant again) T = 150 x (.308/4.081); T = 150 x 0.0755; T = 11.320.
Barrel legnth is up to you, for max velocity 26" can be favorable, for max accuracy, shorter might be the wise choice. You will be suprised how little 40 or 50 FPS makes at 1000 yards vs. accuracy. As far as why I choose the 308, without going into lots of $$$ in experimenting with wild cats, I belive their are 2 standard cartridges that are perfectly ballanced for optimum accuracy, 1. the 308, and 2. the 50 BMG. They are both the prefered sniper weapon of the military and both very popular on the match scene.
I am looking at building a 1,000 yard competition rifle for myself. My experience and background haunt me with thoughts like, " YOU NEED TWO RIFLES TO COMPETE IN DIFFERENT CONDITIONS WITH "
I am torn between a .243 imp. on Lapua brass in a 9" twist Lilja 3 groove, on a Lone Wolf thumb hole with a 3" wide forend, or a 6.5 WSM, similar setup, but 8" twist.
The 6.5 would give me superior ballistics and better wind deflection for gusty or windy days, but I am waiting to see if quality brass is really going to show up from Norma or Lapua.
The inherent accuracy of the .243 imp would be what I would want on a calm day. I believe that we have seen enough at 600 and 1,200 yds. with this cartridge, that it is capable of world record performance, in the right conditions, with either the 95 berger, or the 105 JLK.
Action wise, I like the Nesika if money is no object, however, I will probably wind up using a Panda, or Kodiak that I have previously aquired.
If you measure all the 16.5 pound gun's at williamsport.28 to 30" is where you will find them.....As for the caliber.There are ton's of them that do well.6.5-284,30 Hart,308 Baer,8.59 Titan's.And alot of "Wild" wildcat's................If I were YOU building one.It would be a 300 Weatherby.Accurate,good brass and easy to load for.....JMHO.............
If I were building a light conditions gun in .243 imp. I would choose about a 26" barrel mainly because the brake would operate at a higher pressure, and the historical accuracy at around this length is unbelievablely consistant, I say this with confidence, because I have chambered so many of them.
For the heavy conditions gun, I would go with the 30" barrel because I do not see the last 1/20 MOA deciding much in any serious wind condition. So many calibers shoot so well, I believe any choice with quality brass and well made bullets will be competetive, just look at the records, nothing really dominates for very long. I totally disagree with most of the 1,000 yard boys, about having to have a gunsmith that has built champion rifles, we have 12 gunsmiths that shoot at our club that can build a 1/4 minute gun. Five of these guys have won National championships with guns they built with their own hands, and some even made their own bullets. One is a five time gold Medalist at the bench rest World Championships. You could hand any one of these guys a Rule Book for the class you want to compete in, and they would build you a great rifle, most of them have known guys like Ferris and Walt Berger for years, and have attended 1,000 yard matches over the years.
I would say find yourself an honest gunsmith that you trust, that has built really competetive rifles in some discipline, and won't take a year to get you your rifle.
So I guess if Ferris Pindell offered to make you a thousand yard gun you should turn him down, because his guns have not recently won a thousand yard contest?
How About Tony Boyer's Gunsmith? Just not good enough?
Each gunsmith earned his status at some point, his first title somehow. There are 1,000 guns in this country that ride the bags real nice, just because they have a 14 twist on them rather than a 9 twist does not make the gunsmith inferior.
If a guy does not have the reamer you need he will tell you, its is only a phone call away.
A lot of great information here, many thanks and keep it coming.
I was considering a Savage or Remington Action (I have both to use as donors), but I guess if I seriously decide to compete with it the custom action is the way to go. Boy is this fun!!!!!! I guess I could build another off a custom action if I finally do compete........ LOL, I wonder what the wife will think?? She's been great to this point!!!!!
You said, "7mm is coming on with JLk 168 and 180 bullets. Look at 7WSM and 7 Rem Mag with 1-9 twist barrels."
Can you expand on this?
I've been looking at a 7WSM for long range prone (highpower). I've heard that brass quality has been an issue for 7WSM, but Norma is now making 300WSM, and necked down, it would have a longer neck which IMHO is an advantage. I've also heard that the consistence of the bullets (not cartacucio's or JLK's) has not been up to snuff and guys have been getting frustrated trying to get them to work, as well as supply drying up.
The 280AI has come up in conversations,, but I don't like to fire form.
My goal is to find a cartdridge for NRA Highpower long range prone that will shoot with or better than the 6.5x284's and get 2000 rounds without the need for a set back. It also MUST have light recoil. We hold the rifles up for 30 minutes at a time and even light recoil beats up the lead wrist. Brakes are not allowed, and pain is not conducive to accuracy. (except in SpeedBumps case!!
IMHO, pick one of the many calibers that fit your parameters, build it, then SHOOT the sucker without worrying over the caliber again. Give it one full season, then do an assessment. Lots of good advice above.