statjunk

Hey guys,

Got an issue with my rifle. I have a Ruger Mark II Sporter in 300 WM. When I took the gun to the range I found that it was shooting all over the place. So I took it home and floated the barrel. Now it shoots much better but here is the issue. For the first two shots I can get the holes touching at 50yds. Then I take a 3rd shot and it moves about an inch away. The fourth shot will touch the 3rd shot. So it is almost like there is a shift in aim point. The two groups are about an inch away.

What could be causing this?

I'm going to shoot again this Saturday to see if it happens again. I'm going to start at 50 yds but I'm also going to shoot some at 100yds.

Thanks
Tom

Rammer

I had a Ruger M77 MKII in 30-06 that did the same thing yours is doing, only mine was moving the groups about 2" apart at 100 yards. Mine was floated and bedded, scope rings were lapped/aligned by gunsmith, and I end up putting 3 scopes on it, tried about 10 different kinds of ammo, and it just wouldn't shoot to my satisfaction. I end up trading it off after about a year of playing with it, decided I didn't trust it come deer season time. Mine would shoot the first group (2 shots) right where they needed to be, the next two would go high an right about 2" from aiming point, the third group would go low and left. It did shoot the groups nicely though!

ShatoDavis

From the sounds of it that sounds like a MOA weapon which isn't bad. Rugers are notorious for swifting in the stock. The angled action screw can be a real bear. I would bet that a bedding job would solve your problem. I also bet that a trigger job would improve your ability to shoot consitantly. Unless you where one of the lucky ones that got a decent trigger from the factory

mightyoakwildlife

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!

statjunk

Thanks for the responses. I already had a Timney trigger put in it and set to 3lbs'ish. I floated the barrel with dollar bill as the measure. I did the fire a few shots and test the float already and it checked out. The gap does not change between repeated shots. I did this for about 20 shots.

My next move is to glass bed the rifle.

Have any of you heard of Kimber or other high end rifles having these problems?

Any other suggestions?

Tom

Squirreldog

If all else fails I would have your smith put a pressure point back in your stock, after having it glass bedded.

jeepkid

Outdoor Life just dida review of a Kimber rifle and they couldn't get it to shoot under 2" groups, so your Ruger is shooting pretty good.

James B

The Rugers that I have had have been spotty on accuaracy. Some are very accurate and some just have not been fixable for me. If they don't shoot from the box, I dump them in a hurry. I expect that with the right load, any factory rifle should do 1 1/2 inches or better. Most will get one inch or very close to it. You might try playing around with the torque on that angled action screw.

statjunk

Accuracy sure is expensive!

I guess I'm spoiled. My first rifle was a Win M70 in .308 and that thing was and is so damn accurate right out of the box. After thousands of rounds through the barrel she still shoots just over an inch.

I'm going to attempt the bedding job myself. Should I try to pick up the kit at Brownells?

Thanks

Tom

mightyoakwildlife

Great idea, you'lllikely be quite satisfied when your done. Since this is your first try at bedding, I will caution you to GO SLOW and take your time. Once wood is removed, it can't be put back.
You will probably find the gel-type compounds easier at this point, as they won't "run" as freely as the others. This leaves you a little more working time, with less mess. Until you gain some experience, that will be important.
I won't fill a whole page with this post, but I will offer some sound advice, based on my experience and that of many others: Use plenty of release agent, start all over again, applying a second coat of release, mask-off whatever you want to don't want over-run to dribble on, and follow the instructions. Adding extra hardener won't make the compound harder, and yes, you really should fill/remove/tape/relieve that part first.
When I was in the trade, I used to get a handful of rifles each year, that had become a one-piece unit, with the barreled action permanently affixed to the stock. Best case was an embarassed customer paying me to "beat" them apart, worst case was a new stock, blue job, parts for the trigger group, and a long wait. Lots of time & frustration can be saved by going slow & careful.