A heavy front rest with "ears" on the bag where you can pinch in on the sides of the forearm are a tremendous help in eliminating flyers. Rabbit ear rear bag filled with "Heavy Sand" is also a great aid.
I also played with Bi Pods vs 1-2x10 plus two 2x6's as a base, with sand bags on top of the filled with "heavy sand" vs Bi Pod using a 22 PPC custom that shot very tiny groups. I got flyers with the Bi pod, never could figure it out. Since I was hiking around lava flows shooting rock chucks and then later on going to p. dog towns in SD, I wanted to see my error created by Bi Pods. I learned to accept the flyers, and did not think my barrel was going south in it's accuracy.
Today, Bi pods are much different, especially the one built by Tubb.
On another note, I did play with a lead sled for a while, I cracked a 460 Weatherby and 340 Weatherby stock in a few range sessions. Groups opened on very accurate rifles with the Lead Sled and I attributed this to the fact that mounting the rifle was not the same from shot to shot. I then shot a very accurate 22/250 with a lead sled, flyers could not be explained.
Wind is a tremendous factor in group size. For some reason, shooters resist getting simple, inexpensive wind flags. The same can be said for using a Tunner to tune in loads that are dumb butt simple to adjust(Harrells Precision, RAS, and Mike Ezel from Gunsandgunsmithing).
High power scopes are another thing that aid in shooting small groups, I use one scope to develop loads with, and another to hunt with often. I am attempting to remove all error in load development.
Recoil is an accuracy killer, how you grip the gun from shot to shot, steering the rifle with cheek weld, how you pull the gun into your shoulder from shot to shot. I started shooting much smaller groups when I started using Muzzle breaks on my rifles, and this is an understatement. Not thinking about the recoil that is about to come, is a great aid in being consistent from shot to shot. Side discharge muzzle breaks are VERY loud, I like the Gentry Muzzle break that throws the sound and concussion forward.
There is a learning curve in shooting off the ground vs shooting off a table vs standing and shooting. A guy that shoots off the ground with a bi pod all the time, will have one heck of a time shooting off a bench, and vise a versa. I am too old and broke down to shoot laying off the ground for more than a few shots, I will leave that to the youngsters.
If you are having trouble shooting very small groups consistently, then re-visit your cleaning techniques, reloading, and bench techniques. Of course, a rifle that is "stress free" bedded, barrel floated is a prerequisite to all pursuits in accuracy. Few factory rifles will shoot constant small groups in the .375 area because the action is in a bind due to bedding, and most stocks with a V block will benefit from a skim coat. Guys do not realize that actions warp a little during heat treat, and the bedding will help relieving the stress on the action. I have seen exceptions where untouched factory rifles will shoot small groups, but they are rare when a guy is wanting to shoot group after group where the bullets open up a single bullet hole.
I don't call 1/2" shooting small groups for a hunting rifle for long range.
This is a hobby, take it to the depths that you want to pursue. In the very least, get two wind flags, at least you will know if the wind is blowing left or right when you start shooting, pick the left or the right, pull the trigger when you see the condition you picked....you will simply be amazed in how much smaller the groups are that you shoot.
Start at the start when you are wanting to shoot tiny groups, Stress free bed the rifle, free float the barrel, tune or replace the trigger, scope. Buy or build simple wind flags, a piece of surveyors tape, taped on the top of a 1/4" steel rod that is 48" long , 15-25 yards in front of your target is a WHOLE LOT BETTER THAN NOTHING!
Reloading is a prerequisite for a guy that is wanting to shoot groups in the 1's, 2's, and 3's at 100 yards. Tuning the harmonics with the powder charge and especially the seating depth, establishing the concentricity of the loaded round is basic stuff along with stock quality, and benchrest set up.
These guns that shoot tiny groups usually start off with a gunsmith that has indicated in a high quality barrel to the 0.0001, with a properly designed reamer, and that gunsmith is a tremendous part of the equation.
