Friend of mine is having a problem with his Rem 700 in .308 with a factory heavy barrel. He gets pretty good groups at 100 yards of about 3/4", but at 200 yards, groups really open up to like 3-4". What gives?

And this is in calm conditions using sand bagged rests and various loads.

What reticle does his scope have and what target is he using?

What bullet is he using? If he is using heavy bullets (above 180gr) he may be losing some stability. Most 308s are 1 in 12 twist. Heavy, long 30 caliber bullets really like a 1 in 10 twist.

is he shooting the same loads? many people mix factory loads with different bullet weights and styles and fully expect them loads to print the same, this just doesn''t work.. rule of thumb is to double your 100 yards group and thats what you should do at 200 yds. many people can shot great and blow this out of the water but it holds every true for the average shooters. bench technic is super important your striveing for CONSINTANCEY, with all due respect it could be manny things, shot more , More Often...jjmp

quote:

Originally posted by sonofagun:
Friend of mine is having a problem with his Rem 700 in .308 with a factory heavy barrel. He gets pretty good groups at 100 yards of about 3/4", but at 200 yards, groups really open up to like 3-4". What gives?

And this is in calm conditions using sand bagged rests and various loads.

Parallax! Not sure if I spelled it right! Although it would seem to make sense that a 3/4" group at 100 yds. should give 1.5" groups at 200 yds., but that rarely seems to happen with any of my groups. Double the distance and the wind, atmospheric conditions, technique, mirage etc. all help to open the groups a bit. I would guess that with all other things being equal (same shooter, same ammo, same bench, same rests etc.) you may have a parallax problem. You didn't mention what scope you were using. Does it have an adjustable objective? If so, check the manual on their procedure for adjusting the A.O. for different distances.

Fouling! Clean between groups.

Bullet weight vs twist! You didn't mention bullets and weights. It may be that your shooting a weight too much or too little for the twist of the barrel.

Trigger pull weight! A 7 pound pull may not bother you much at 100 but will double the error between the intended point of impact and where the crosshairs were when it finally went off. Without a somewhat high magnification scope you may not be able to see the difference.

And last but not least! Welcome to the accuracy addiction! You have started down a long and narrow path filled with sleepless nights, magic recipes and the quest for the One Hole Holy Grail! It's a long and arduous path that no one I know has found the end of but we all spend plenty of time following.

Good luck. Let us know what you find out.

I suspect the bullet weight. My Rem 700 HB shoots best with 150gr, bullets. I believe that they came in 2 different twist rates.
Peter.