Hi, today I went to the range with a friend; we tried his rifle, a Remington 700 BDL cal. 270 Win. At 200 meters, we got some 10/12 cm (4/5 inches) groups, due to some horizontal spread; without it, groups could have been tighter, about 7/8 cm. (3 inches). Some details: almost no wind, the scope is a new Burris S. Select 3-12X, solid scope mounts and fairly well made reloaded ammos; so, which could be the causes of this horizontal spread? Thanks.

It could be bedding,with one side of the stock pressing on the barrel,or it could be poor shooting form.You are also only talking about an inch or so at 200 yards,which isn't very much even if the wind is very light.

The three things that come to mind are wind, scope parralax and shooting form (as mentioned).

Even a 10 Km/hr cross wind will move the bullet three cm over two hundred meters, and you would barely notice it. Even worse is inconsistent, swirling or switching wind. Go 10 km/hr east on the first shot, and then 10 km/hr west on the second shot, and bullets go everywhere. Make some good wind-flags, and try again.

Shooting form can influence it as well, including trigger finger pressure and cheek weld. Someone here can probably expound on that better than I can.

Third, unless your scope is set to correct for parrallax at 200 M, 3 cm is about the amount that an inconsistent rifle mount will cost you. Again, cheek weld consistency is critical. HTH, Dutch.

Two most common causes...

External pressure on the barrel
Wrong loads.

My first suggestion is to cut the distance in half and re-work the loads you are using.

after 3 years of tracking down problems I found that the Front action bolt in my 700 was too short, it would catch but work loose.. If the action is loose try a longer front bolt

Having the action in a bind, or scope parallax, as well as a loose base will cause the horizontal dispersion.

A tight grip on the rifle foregrip can cause this as well.

A remote possibility, which I have experienced is barrel fouling. What I mean is that if you start with clean/oiled bore, as you shoot the barrel will foul and can string the shots horizontally. Just this past week I ran an experiment where I scrubbed and then oiled M700 30-06 rifle bore. Prior to shooting I ran several clean patches thru to reove excess lube. First shot was 12" right, second shot was 10" right, third shot was 8" right, fourth shot was 2" right, and rest of shots were on target. Verticle was never disturbed. I would not have believed it had I not seen it.

If your shots are walking horizontally and you started with clean/oiled bore, this could explain it.