HuntingNet.com Forums - View Single Post

06-28-2006 | 01:07 PM

#4

mightyoakwildlife

Joined: Jun 2006

Posts: 11

Likes: 0

From: Catskill Mountains, Upstate, New York

RE: Ruger Accuracy Question

As simply as I can put it, here's your answer; Your bbl. vibrates as the projectile travels down/out, at each shot.
The "harmonics" of this vibration are the same at each shot, affected bybasically two things: 1) Velocity of projectile (Product of the pressure provided by that little explosion of powder & primer and howfreely it slides along. This is affected by bullet size, hardness, smoothness of bore, any other matters contributing to "lubricity"), and,2) Changing density of the bbl. material, itself. Barrel density changes as the metal heats/cools. As you fire, the friction, etc. creates heat, which in turn expands the molecules of the steel, increasing the density, changing internal stresses, and causing microscopic degrees of warping.
Most likely, you aren't heating your barrel enough to cause the seperate "clusters", as this is what usually shows up as "stringing". More probable is the chance that your rifle is throwing a couple shots on target as you would hope, while gradually expanding & vibrating. After a given point (You have found it to be approx. two shots fired.), the now expanded or "hot" bbl. is "jumping" on an unseen surface.
It could be moving over an uneven contour of the forestock, or if it is truely floated now, it may be coming in contact with the stock at some point. With an action which has not beed "trued", it is also possible that the breach is contacting the bolt face erratically at this point, creating a miniscule change in headspacing, thereby affecting your groups.
The pursuit of all these possibilities is what drives the art of the prescision shooters and gunmakers to insanity, through an endless task. Regardless of how well you make a rifle shoot, there is ALWAYS a measure of improvement available, if you can measure that small, expend that effort, and spare that expense.
Next trip to the range, make certain your action is bedded and torqued properly, then check your "float space." After the change of impact, check again. Maybe a business card initially slid freely, and now only a dollar bill passes. There may now be a contact point you don't have with a cold bbl. Start with this test, and let us know how you make out. There's a good chance that your next project should be the action bedding!

Reply

0