hi all , shooting a new rifle i built 22-250 standard rem . . i got a 7 tw douglas heavy varmit contour i plan on shooting 100 - 200 and 300 yd ground hog score shoots. it shoots 52 gr sierra match really well at 100 yds . however i want to use heavy bullets for 200 and 300 yds . powder not and obstacle and i have 77 gr sierra 75 gr vld and  75 gr hornady bthp match as well as eld-m  thanks in advance with any help .
		
		
	 
The Rifler -
Howdy !
Stick with me, and I'll 
My first couple trips to the " Western Pennsylvania World Groundhog Shooting Championship ", held 
@ the Southfork Rifle Club; over by Beaverdale, PA.
I had a  7hr drive to get there from Indiana, so... only attended the Championship shoot that takes place
@ the end of September.    The WX  that time of year showed a pretty good span in OAT from beginning of the match in the cool & morning dew.....then finsihed up in the latter afternoon when the sun was blazin, and the OAT had gone up a goodly amount.    I did not make it a point ( at the time ) to shoot loads that were assembled using a " temperature stable " powder.
My rifle had a  28"  SS  .224" cal   K & P   1-8  5-groove  Palma taper, chambered in my  ".22-35 Remington " wildcat. Case capacity was between that of a stock .22-250, and a  .22-250AI.
My accuracy / target load was the Hornady 75"A"-Max  over 40.5gr  AA3100  and FED LR Match;  3,420fps.
( I was able to get 3,500fps if I switched the primer in the load to FED Large Magnum Rifle Match, but groups were then slightly larger ).    AA3100 was not temp stable per se, and I felt I had some poi shift that corresponded to increases in OAT; as the days went on.   Southfork's shoot goes out to 500, which includes a shot @ an egg.... if shooters want to go for it.   
I  DK  how long a barrel you intend to use on your rifle ?    I also  DK to what extent you might bias obtainable vel  over obtainable accuracy, if you do at all  ?    The following are presented IMHO....
If you prefer a temp stable powder,  I'd say 6.5 StaBal deserves a try; certainly if your barrel is 24-26" or so.
If your barrel lengh runs to 28-29" or so,  I'd say H4831, IMR4955; and RL-23 deserve a look.  RL-22 has been identified as " burning " pretty hot, and  would thusly be hard(er) on barrels. It is not touted as being temp stable,  last time I checked.
Use of longer barrel lengths can shift potential powder choices to burn rates that allow for higher load density.
I myself like to shoot high load density loads whenever I can, and have gotten great performance when I did.
Again..... IMHO.
I  DK  if that helps, any ?
With regards,
                         357Mag