How much stock fore-end pressure

[dgeesaman]

I'm accuracy testing an older benchrest style rifle for a friend and so far this rifle has produced wild groupings.

It has a hand-inletted custom stock with bedding by the rear action screw and first 5" of the fore-end against the barrel. The forward action screw touches nothing.

Any suggestions as to how firmly i should torque the action screws? Or other tips to determine the accuracy of this rifle 'as-is'?

FWIW I've run two different powders and two different bullets through it. The group sizes ranged from inches to an inch. I've been through scopes and mounts.

 

[jackieschmidt]

Not knowing the brand of action, I would venture that this is not a good bedding.

From the way you describe it, the front action screw has no bedding under it, causing the action to flex as the forward screw is tightened. The purpose of any good bedding is to allow the action to be firmly secured in the stock without placing any deflection in the action in any manner.

A good picture would help.

As for testing the rifle as is, keep in mind any torque you place on that forward screw will probably result in problems associated with the bedding.

Any other info will be helpful.

 

[Flyshooter]

Sir,
If what your saying is: The barrel is in contact with the stock directly above where the rifle sits on the rest or bipod. Additionally the front guard screw is not secured to the front of the action, and this is not a “glued in” bedding system....Well, in my small opinion what you have there is the perfect set up for a shooting large groups.

If the rifle is not a collectible of some sort, then pillar bed the action, completely free float the barrel......it won’t shoot any worse. If you want it “as is” then you’ll have to endure or settle for the groups your getting. Not much improvement will be recognized by changing components if the rifle is set up as discribed. However if you shoot the rifle in the exact same atmospheric conditions each time then some consistency regarding groups and POI may be realized.

 

[dgeesaman]

I have no experience with stocks bedded with fore end contact but I know they exist and it can be a highly accurate setup.

This custom stock is definitely not contacting the forward part of the action based on the unfinished inlet surface there. So it seems to be intended to contact only the barrel and the rear of the action, with the front action screw torque putting the stock in tension. Maybe that’s the wrong way to achieve fore end contact, I don’t have experience to say yes/no.

Since it’s not my rifle I won’t re-bed it (yet) but the idea I should have already tried finally occurred to me. I have a Sako L579 varmint repeater of my own with a factory stock. By adding some gasket material under the front action screw area I mounted the custom Sako action in that stock with a couple dollar bills worth of barrel clearance. I will report back with results after this weekend.

 

[K22]

First, I'm not gunsmith - I always defer to my rifle smith for advise on bedding - he's been building and bedding rifles for over 30 years.

He beds the front and rear screws at the contact points with the stock. He free floats the barrel. He seats the barrel action so the recoil lug seats against the rear slot in the stock and is not touching the bottom or front of the slot, finger tightens both screws then tightens the rear screw first then the front screw to a specified inch lbs. torque based on the type of stock.

This seems to work quite well for all the rifle he's built and bedded for me.

One exception is the Weatherby Vanguard which has a pressure point at the tip of the stock forearm. I don't know why it shoots better that way but it does. Everything other rifle I have shoots better with a free floated barrel and bedding. This rifle has an after market B&C metalist stock.

One other exception - My Weatherby Mark V super varmint master has a pressure point about 2 inches in from of the recoil lug. I've never mess with it since out of the box w/ no modifications this rifle shoots sub 1/4 moa groups with tailored reloads.

 

[joshb]

It sounds like you need to carve out the bedding in front of the action and re-bed the action. I’d also put a borescope thru the barrel, just to see the condition.

 

[CharlieNC]

Sounds like a nice setup to test ambient temperature and humidity, as it will reflect deviations in either.

 

[Kurz]

The occasional discovery of a bedding method unfamiliar to most of us is an insight into the thinking about the past questions of solving consistency and group size. But without pictures and some significant improvement of the information regarding the rifle, we can choose several paths to follow as to what the original thing was.

It was not that long ago when a substantial number of factory rifles came with pressure points built into their stocks. We can guess as to why it was a nearly universal solution but it has been proven in some situations that 'slight' upward pressure on the contours which were more flexible, created better consistency when group sizes from factory rifles were usually larger than 1".

Bedding, being a fairly new process for rifles, was placed in every conceivable spot, in every conceivable amount in attempts to bring about more consistency and smaller groups.

During that same time, barrel making went from the dark arts to modern precision machining providing us with consistent, accurate tubes capable of shooting small groups without the need for the pressure points. Sometimes it even negated the necessity of a small amount of bedding under the first inch or so of the barrel in front of the action face. This feature is still debated.

Wood stocks were replaced with fiberglass and now carbon fiber and filling. Much less flexing and very stable.

So, you have a little piece of historic thinking and experimentation from an unknown gunsmith through a friend to give us some perspective on the thinking at that time.

It was a nice try but totally unusable without the front action screw being bedded. The front pressure point or bedding has been proven to be mostly unnecessary with modern, stress relieved barrels.

Your friend should be made aware that his rifle might still provide him with consistency and possibly improved accuracy by changing the bedding and replacing it with new bedding.

Also be sure to check the crown and the whole chamber including the throat looking for unsatisfactory wear.

Enjoy!

 

[dgeesaman]

It seems I’ve aroused more general curiosity about this specific rifle than I expected.

Its a Sako L579 single shot action with Canjar set trigger. Barrel stamped “C. Grossman”. Varmint taper heavy barrel, unknown barrel maker. 22-250 chambering. Bore is pretty clean and chamber isn’t rough, but I had some headspace issues until we confirmed with gages that it is chambered .010 deeper than no-go. (Needed to false shoulder the brass to get a crisp first forming). Nuisance only for me but not good for factory ammo.

I put about 100 rounds thru it already in discovering these things. I finally discovered the floating front action screw after I bought special punches to remove the canjar set trigger shoe. The shoe is wider than the action slot so I couldnt see the inletting until I had the tools to properly remove the trigger shoe.

K22, does your Weatherby front action screw still pull firmly to the stock? It sounds like both actions screws pull up tight and the fore end is just lightly preloaded in that condition.

The stock is a pretty piece of wood. I suspect it may be worth rebedding if my swapped-stock experiment shows promise. That and getting the barrel re-shouldered or rechambered to specs. My friend was initially leaning toward a whole new barrel and chamber job from Hart. He’s no cheapskate but personally I want to figure this thing out a little more and see if this nicely blued barrel can shoot.

 

[CharlieNC]

If mine I would live with the HS and fire form for accuracy. Also remove the bedding from the forend, add pillars, and bed the action slightly past the recoil lug.

 

[Dusty Stevens]

Once high speed cameras gave us an insight into what happens frame by frame the barrel bedding went away very fast. I bet if you look where its bedded you can see wear on the bluing where it slaps it on every shot

 

[epc308]

I have an early Remington Mountain Rifle with the pencil thin barrel. The original wood stock had a pretty good lump for a forend pressure pad. I swapped it to a synthetic stock after a serious rain soaking at the end of deer season one year. I free floated the barrel when I bedded the barreled action in the new stock. The rifle went from 5/8-3/4” groups to dinner plate size. I cut up a bunch of various thicknesses of plastic shim stock I had and went to the range. As I slipped in shims to tighten up the forend pressure like the original stock had, the groups shrunk back to normal. I epoxied them in place and have never looked back.

 

[Old Navy]

I have an early Remington Mountain Rifle with the pencil thin barrel. The original wood stock had a pretty good lump for a forend pressure pad. I swapped it to a synthetic stock after a serious rain soaking at the end of deer season one year. I free floated the barrel when I bedded the barreled action in the new stock. The rifle went from 5/8-3/4” groups to dinner plate size. I cut up a bunch of various thicknesses of plastic shim stock I had and went to the range. As I slipped in shims to tighten up the forend pressure like the original stock had, the groups shrunk back to normal. I epoxied them in place and have never looked back.

You post is the exact same story as mine except it was Ruger 77.