Bolt fitting on a No1 mk111

[tbonesmith]

Hi guys, I recently got a few ex range rifles and sporters (all no1 mk111 and 111*). 2 have H barrels in excellent condition and two have their original barrels that are clapped out.
I want to make the 2 best H barrelled rifles I can out of the parts.

My questions are: is it indicative of some fundamental flaw in the bolt/receiver fittment if only the lug at the back of the reinforcing rail on the bolt body is polished(ie worn bright) and the other (the small one oposite) appears unworn?

if so is there any correcting this situation? ie. lapping etc


FYI the rifle in question is 1918 BSA mk111, the bolt is matching, and the original barrel is cactus. The rifle looks in reasonable condition, headspaces a little long, will close on a .067 but not a .074. I am suspicious it may have been reblued once upon a time.

Just wondering if this is one to built on. But I'm only interested in building excellent shooters.

Information

Warning: This is a relatively older thread This discussion is older than 360 days. Some information contained in it may no longer be current.

[jmoore]

Having only one lug bearing is a Very unhappy situation, both from an accuracy and engineering standpoint. Don't think lapping is a good idea at all in this case. Either use another action to start or find a bolt that at least bears somewhat better (and isn't flogged out on the front end) before proceding.

Captain Laidler has written extensively on fitting new bolts to No.4 rifles in this forum. I reckon the practice is the same w/ a SMLE. Don't know how late he reads this forum, but there's sure to be more detailed info coming.

[Alan de Enfield]

Here follows some notes from Peter Laidler (dated December 2007) re fitting bolts etc.

"First things first. Bolts could only be fitted at Field and Base workshops because they were the only ones that had a 'GAUGE, Inspectors, Bolt'. This is a brand new, calibrated bolt. Still in white metal and marked as such. If my memory serves me right, the slot in the long/top locking lug is machined right through to identify it. So that's the reason if you have ever seen one. This bolt is bare. Clean the locking lug surfaces of the rifle and put a smear of 'engineers blue' marking dye onto the corresponding locking surfaces of the inspectors bolt. Insert this bolt RIGHT FORWARD, rotate it closed, then draw it backwards and forwards a couple of times to mark the mating locking surfaces of the rifle. Push it forwards, unlock and remove.

Examine the locking surfaces of the rifle. The blue witness marks should be evident. This ensures that whatever wear that has taken place on the rifle locking surfaces has taken place equally. If its not, then I'm afraid that the rifle is unserviceable.
BUT, that's not quite the end of the story because you won't have this 'Gauge, Inspectors, bolt' but it's only right that I tell you. Now for a little secret. If you have ever bought a rifle that has a sploge of red paint on the left side, adjacent to the internal left side locking lug, then you now know that the rifle was condemned for 'worn locking lugs'.

If you are going to fit a second hand or new bolt, then do the same thing. If the dye pattern is one sided, then stone the high surface of the bolt until BOTH locking lugs bear evenly against the locking surfaces of the corresponding surfaces in the body. BUT DO NOT ATTEMPT to stone the rifle to get a bolt to fit (you can only get to the right hand surface in any case ....). The rifle body is induction hardened at these points to a depth of .004 - .006" but we have found it deeper.

Now that you have got the bolt fitting, with the locking surface bearings matched, it's time to fit a bolt head. Any one will do. Screw it into the bare bolt and test the CHS against the .064" GO and .074" NO GO gauges. Disregard the numbers on the bolt head or treat them as a bit of a rough and ready guide but not as the bee all and end all of life as we know it! Once you have got a fitted bolt, with CHS, we'll come onto bolt head overturn.

The bolt head should not overturn the long/top locking shoulder by more than 16 degrees but if you have a No4T or L42, it should not overturn buy more than a 'few' degrees. Mine were always 'in line' through selective fitting but you won't have a big tray of bolt heads to select from! The reason for this is because over a 'few' degrees (it doesn't define 'a few' but use 2 or 3 as your MAX), the recoil is taken on the bolt head and bolt threads. That is OK, but on an accurate No4T and L42, we want the recoil to be taken on the face of the bolt and transmitted radially, down through the bolt head and onto the front flat surface that mates up to the bolt head. Got it?

[jmoore]

Here's why you don't want to "lap it in"!:

From Captain Laidler's post- "The rifle body is induction hardened at these points to a depth of .004 - .006" but we have found it deeper."

Given that the body already has some wear, most likely, there's not much metal removal that you can do w/o removing the hardened "skin".

[tbonesmith]

Thanks for that Alan de Enfield, could you help me in pulling up the whole thread, as I can't seem to find it. Remember what it was titled?

[Alan de Enfield]

Thanks for that Alan de Enfield, could you help me in pulling up the whole thread, as I can't seem to find it. Remember what it was titled?

It was part of a series on the old Jouster forum :
Fitting bolt heads, fitting bolts, fitting butt, fitting forend, fitting triggers etc. etc.
Unless Badger kept it it is not on here.

I have them in word format (copied and pasted from Jouster) so can post them if there is demand (or if Peter doesnt want to re-post them himself)