No. 4 Mk1/2 Sear lugs bedding

[muffett.2008]

I went through this process earlier in the year, started with 2 No.1 and 1 No.4 receivers and rebuilt complete rifles using parts aquired.
These 3 rifles were assembled using Peters articles, This work is on a thread called "It's Time" on the gunboards forum, each one of these rifles was capable of groups of 1inch at 100 yards by the time they were completed, this is with the bedding techniques on wood and groups obtained back to 300yds all recorded.
Tbone has also been through this process recently, his articles can be found also, both he and I used Peters information, maybe added a little of our own to get the end results, they do work.

I see where you are coming from with your need to deepen the draw area.
Normally this is a sign that the action is seated too low in the forewood, the timber either having been crushed down or cut too low originally.
It may have been easier to build up the seat area rather than deepen, the draws are a relatively weak area as it is, by building up you negate the need to shorten the spacer and continually trim wood to get the necessary clearances, its not to late to rectify, as long as you haven't started to carve out the front barrel channel yet.

[Gnr527]

Peter/Muffett
Not sure I have been through all your articles but have had a good trawl through and am still fourpence short of a shilling.
I would, in my simple terms, describe the mechanics of a stock-up as follows:-
a) The action/barrel can be likened to the unbending plank of an unequal see-saw with the short leg of the plank (from screw to sear lugs) being 4½” and the long leg (from screw to muzzle) being 22” (i.e. approx 5x).
b) The pivot point is the screw collar.
c) A complication is the addition of the reinforce 1” long set 1” along the long leg and of a height very close to that of the pivot.
d) If the sear lug end lowers (or rises) by say .010” the pivot will produce a raising (or lowering) of the muzzle of approx .050”.
e) Any reduction of the pivot height will reduce the height of the muzzle relative to the sear lugs.
f) A good bedding of the fore end to the butt socket is achieved by the sloping cam action of the draws faces sliding down the cut draws on the fore end.
g) A good ‘stock-up’ is achieved when:-
i. The cam action of the draws forces the fore-end uniformly into the butt socket
ii. The height of the pivot fixing tightly grips the fore end between trigger guard and action front without crushing wood.
iii. The action is firmly held in the fore end without unequal side pressure.
iv. The barrel base is firmly supported at reinforce – this should closely relate to the height of the adjacent screw fixing so they act in concert.
v. The height of the muzzle is such that it exerts the required downwards pressure (3 – 7lbs in a No.4 and circa ½lb in a No.9) on the fore end.
vi. The barrel is otherwise free of fore end and hand guards.
My No.9 had been stocked up with an unused stock and it looked as if the only work done had been to fit the faces of the draws to ensure a good socket fit. Otherwise bearing was to the feet of the sear lugs, a tight screw of trigger guard onto collar(and thus guard onto fore end), and an 11lb muzzle bearing(also possibly some bearing to the bottom and sides of the knox form in front of the reinforce) .
In response to Peters comment I am certain that the depth of fore-end timber under the feet of the sear lugs was such that the body of the action was not bedded down hard onto the fore end. By relieving the timber under the lugs and fractionally (.030”) reducing the screw collar length I am still not quite bedded down at rear of action but have got light bedding at front of action and reinforce and a reduction in bedding pressure at the muzzle.
If my logic is correct very careful/small gnats knacker adjustments to sear lug foot bedding and possibly screw collar length will enable me, with an equally careful muzzle bearing exercise, to play with different up-muzzle pressures.
The alternative is that I have wasted a certain amount of time on a lot of old man’s b------s.
In either event all advice gratefully received.

John