The rifle in question is a Shilen barreled M.70 action in a Bell&Carlson Carbelite stock, wearing a 3x9x40 Vari-X II, chambered in 7-08 Remington.

My delima is that I can get this rifle to shoot concistantly between .45 and .6 at 100 yards with a variety of bullets and powders but all groups always string verticaly. I know that this is a classic sign of a bedding problem but does this rifle shoot to good to mess with or could I expect to get the verticle out by bedding?

I have tried changing the tension on the screws and beleive that I have them adjusted to the point that the rifle shoots as good as it can but still the verticle stringing nags me thinking about what this rifle could do if I could somehow eliminate it.

Also, anyone know of any "tricks" I could try, short of bedding that may work.

This is an old trick that we used to use in high power shooting to experiment with bedding.
Take some RTV silicone sealant and put a thin skim-coat on the bottom of the action. Let this get a little firm (about 1 hour or so) then put the gun together and install the action bolts about 3/4 tight and let it cure for 24 hours.
At the range, right before you shoot it torque the bolts to your usual amount and shoot the gun for score. After every 5 shot group check the action fit in the stock and check that the action screws are tight. You can usually get about 20 shots through it before the action rubs the RTV out.
Any remaining RTV peels right out of the action and stock with your fingernails.

Call it "Automatic range miscalculation compensation" and enjoy an accurate rifle.

.......or you could spend the life of the barrel screwing with it and maybe learn something from the exercise.. it IS fun to try different things to solve a problem.

Yours could be as simple as the verticle distance being equal to the slop between the bolt body and the rear bridge.....or something equally hard to find and correct.

Fjold and J. Belk, thanks for the replies. Will try the silicon "trick". Got nothing to loose with that one.

Jack or others, Would it be feasable to try other M70 bolts (short action standard face) in this rifle just to see if it makes a difference?

Trying other bolts will more then likely not help, infact you will be changing the head space wich is a no,no. If you want to go that route, have the barrel set back and reamed to the correct head space and a tighter chamber.

I would try bedding the stock first using acriglas or other epoxy based compounds, the barrel may need free floating or may need a little pressure at the end of the forearm.

I would also take a good look at the crown, scope, bases, rings, trigger.

I think I would check the bedding using a dial guage at the forend and, if there was more than a couple thou of movement I would rebed. If the Bell And Carlson stock was not glass bedded in the first place, I think it should be.
Vertical dispersion can come from a lot of other areas though including ignition inconsistency. This could come from a load just not being "right" or a flaw in the striker system in the rifle. Sometimes a slightly stiffer striker spring (I don't like to go more than about 4# heavier than stock) will help.
The sloppy bolt as described by Jack can cause some vertical but my experience has been that it usually accounts for about 1/10 moa or less. I use dovetail inserts at the rear of the bolt body to eliminate any play. I prefer these to sleeveing the bolt since they are less noticable when operating the bolt and only take effect when the bolt is locked. This is not an original idea by the way but my way of retrofitting Jim Borden's "Borden Bumps" idea to a factory action. It works well.
To be honest, I would bed the rifle if it was mine and I suspected the bedding to be faulty. In actual fact a true 1/2 moa 7mm-08 is pretty good! Regards, Bill.

If you find excess play in the bolt at the rear bridge there is a fix, but it's not an easy one. It's called sleeving the bolt and there is a good explanation in this month's (November 2003) issue of "Shooting Times" magazine. It's in the article titled "A Blueprint for Rifle Accuracy" by Rick Jamison.
It involves attaching a larger diameter sleeve around the bolt at the front and rear bridges and then machining them down to get an exact fit into the bridges of the action. Usually it is done by target shooters, but for a hunting gun Jamison only recommends doing it for the rear bridge area.

A M 70's screws should have the front one tight the second one loose so as just to hold the trigger guard and the rear screw not so tight.

The problem with the Carbelite stocks is that they keep compressing under the screw tension. One must bushing bed them.

If your barrel is bedded then first make a bushing for the rear screw and try that. It may tighten the groups right up but of course the rifle may not stay sighted in as the stock compresses under the front screw.

Make a bushing from a 30-06 case. Just cut it to length. Drill a larger hole in the stock and tighten it up. Some fitting is reqired.

If you want to you can bed it also at any time with whatever stuff you want to but do the bushings first. They are fast, clean, easy and they work.

If it was my rifle, I would try some very small load and shooting adjustments before I putzed with the bedding.

One benchrest competition trick is to tune already good loads to match the day's humidity, barometric pressure, and temperature by increasing (usually) or decreasing loads from "standard" in steps of just about 0.2 grains weight of powder once a really nice load has already been found. With a truly accurate rifle and shooter, you can watch the groups' shapes change from round to vertical, to horizontal, to vertical, to round, et., etc., etc., as you increase or decrease the powder charge.

In some sporters, similar load adjustments can change "stringing" groups (either horizontal or vertical) to round ones.

Vertical in one's groups can also be a sign of poor bag technique (not saying that yours is, but that is certainly true of many at benchrest matches).

Too hard a front sandbag causes "bounce" during firing, which will in turn cause vertical stringing. Also, it pays to make sure your rifle is sliding exactly the same through the bags when trying to take vertical out of groups.

What I do with any rifle which requires other than the very lightest touch to open and close the bolt is this...run the rifle forward to the exact same spot as the previous shot, then pull it back and run it forward to the same spot again. This "seems" to "iron in" the forend to the bag and "correct" any slight misalignment in the bags caused by the recoil of the previous shot. (Misalignment on the bags can also be caused by rotational force on one side of the rifle, such as by closing a bolt which takes ANY noticeable effort to turn it down.)

And, of course, I use a good "lubricant", such as spray deodorant, baby powder, Johnson's spray wax, or a good hard car wax, on surface of the bags where the stock rides on them.

It is very important to have the rifle exactly the same distance forward on the bags when you shoot, to help minimize vertical in groups. If you don't, a slightly different point of the stock is on the forend rest, and you can't expect the "system" to vibrate the same.

Sounds like a lot of bother, and it is. But, the last little improvements in groups come from uniformity of small details.

Good luck,

AC

[ 11-10-2003, 23:35: Message edited by: Alberta Canuck ]

Bill Leeper,
I too would be interested in hearing about your dovetail inserts. Could you elaborate?

Heavy Varmint I would try tweaking the load slightly and I would start with a primer change. Jim

[ 11-11-2003, 01:34: Message edited by: Jim White ]

Re. dovetailed inserts,
I use dovetail blank stock from Brownells. I simply cut two dovetail slots .062 deep opposite one another and in line with the locking lugs. These slots are located so they are within the rear bridge of the receiver when the bolt is closed. The slot blank material is inserted and loctited for extra security (the inserts are actually so tight that the loctite is superfluous but I figure it doesn't hurt).
To set the bolt up I always put a plug into the recessed boltface and turn a center in the plug while the bolt runs in the steady. Now I can support the bolt on the tailstock center and turn the inserts to a snug fit in the bore of the action (usually about .702-.703). Now dress the edges of the inserts down a bit so there is no interference in the locking lug raceways and there you have it.
In use the inserts are not noticable until you close the bolt. The bolt moves back and forth freely with it's normal sloppy clearance but when the handle is turned down there is no movement whatsoever. Because they don't interfere with the stroke of the action they can even be used on hunting rifles to tighten up a really sloppy bolt.
I dreamed this up when a customer asked if there was some way to retrofit the "Borden Bumps" to an action. I had no real idea what these were, not having seen one of Jim Borden's actions, but to avoid seeming ignorant said, "Sure".
My first thought was to sleeve as we have been doing for twenty years then set the thing up in the rotary fixture in the mill and remove the excess material leaving the bumps. This seemed like a lot of work and I'm kind of lazy so I sat down to think of some other way. When I woke up I happened to be looking at a sight slot blank and decided to go with the dove tail slots.
I suspect Jim Borden, being an engineer, doesn't use the "take a nap and see what comes of it" technique of design and planning. Guys like him rely instead on designing to calculated design parameters (whatever those may be). In other words, they know what they are doing befor they do it. Must be nice.
Anyway, that's the story on the dovetail inserts. I find them preferable to sleeving. On top of that they were, up 'til now, exclusive to Leeper's rifles!! Regards, Bill.

[ 11-13-2003, 05:58: Message edited by: Bill Leeper ]