OAP
The Grendel
I bought this to be a useful target rifle, but I miscalculated. It has several weaknesses and overcoming these for a club competition rifle is an ongoing problem. It is the light sporter model with a contoured barrel, it has an impossibly heavy trigger and the stock is not conducive to good aiming. So a Timney trigger, lightened to the minimum and sear adjustment just about to the point of slam firing. A pistol grip, adjustable stock and I am getting somewhere.
Experimentation has shown that it shoots reasonably with a minimum charge and heavy bullet. It shoots a one inch group at 100 mostly but it should be better. So further development with the same powder but lighter projectiles – down from the 123 gr to 100 and 107. Would it shoot these consistently? In a word, no. It appears to favour one muzzle velocity and even half a grain difference in loads will widen the group to unacceptable. Why?
A lot of reading and research and I think I have the answer. The lighter barrels are more sensitive to vibration and whip and vibrate as the shot leaves the barrel. For accuracy, the shots must all leave the muzzle at the identical part of the node. So is it possible to damp the vibration to reduce the amplitude? It would be an advantage and would reduce the vertical spread which ruins the groups.
I found a device on the net, Amazon to be exact, called the Limbsaver Barrel Vibration Damper. It is a synthetic donut that slides over the barrel and, once you have located the nodes, you slide it to that point. But how to find the nodes? They suggest starting at 15 mm from the sharp end, firing a group, note the size and location and move it further back the barrel. A waste of ammo. You can tap the barrel with something like a pencil and listen to the sound. Where it sounds dead, that is the node. Mark it and keep going. I found them at 40 mm, 80 mm and 120 mm which seemed to be logical with a 20″ barrel. I fitted the damper at the 120 mm mark and experimented with the loads which, I found later, corresponded to the minimum recommendations from the powder guide. Perfect with three different projectile weights. Consecutive shots through the same hole, or a cloverleaf pattern at 100 yds.
I am starting to feel more optimistic now. But there is more I can do yet? Bullet seating depth has an effect on the time the bullet exits the barrel. They are seated just touching the lands. Factory loads are much shorter to fit the magazine. Mine don’t and have to be loaded separately, which is fine for a target rifle.
It is a time-consuming hobby but very absorbing and takes my mind off other considerations.
Please share so others can discover The BFD.
