Thread: No1 Mk3 Bolthead
Retrieved: 06/01/2014

My current bolt head is long enough, just barely. I ordered a longer bolt head and found it fit properly and square. Should be good. It is just long enough to bring me to the minimums as to headspace.

Curiously the new bolt head appears unused. My old bolt has a slot cut through the threads and the new bolt does not. The slot, when the bolt head is installed, is indexed to allow the firing pin to reach through the bolt head. My previous No1 Mk3's, both Lithgows, did not have this cut that I remember. Do I cut the new bolt head, or is it the wrong type?

I do not believe the new bolt head is for a No4 Mk1 as it is not properly marked, but being unused, it make be marking free as my other new hardware was (nothing but enfield acceptance stamps, no serials etc).

Alan de Enfield
02 November 2009

As you have found out there are in fact two types of No1 bolt head - an 'old' type and a 'new type'

(Old & New being relative - they are both 60+ years old)

Depending on which bolt body you have depends on which bolt head you can use.

I built up a No1 Mk3 from scratch and just could not get the bolt head (with the slot) to screw correctly into the bolt body, it wouldnt screw all the way in, it was almost as if the threads were too long or a slightly different pitch.

Swapped the head for one without the slot and it went straight in - sweet as a nut.

If your bolt head threads in correctly then use it - if it doesnt then you'll have to get another one.

Don't forget to check your headspace with the correct military gauge of 0.074" NOT the nasty American SAMMI gauge of 0.070". You could be condemming a perfectly servicable rifle.

LE Owner
19 December 2009

If a rifles headspace can be improved why not do so if the parts are available.

The .074 was a max acceptable not the ideal, headspace for a new rifle after proof testing was supposed to be no more than .068 IIRC, with .074 the max allowable before trying a new bolt head or bolt if needs be.

My MkIII came with a slotted, or more precisely scallopped bolthead, in new condition and doesn't over clock, but the thread fit is loose to the bolt threads allowing too much side play.

I just ordered an unissued Bolt Body and new condition bolt head, with the condition that the bolthead fit the bolt body.

The bolt and bolthead I now have give about .069 as is, and the bolt head mikes at the minimum size so whatever I get should be either an improvement or still well towards minimum, with little likelyhood of being a looser fit.

Should the new bolthead also be a good fit for the old bolt body, I'll just use that bolt body and put the new one aside. I sometimes run on to otherwize good SMLE rifles that are either missing a bolt or have a badly worn bolt, so a spare bolt body is a good investment.

This rifle has an excellent bore and tight chamber, fired cases don't show a ring, even the Winchesters. Even a .069 allows a decent caselife with this particular rifle, so a couple of thou tighter should ensure long useful life for decades to come.

I hope the new bolthead fits the old bolt body, since besides being numbered to the receiver wear pattern indicates a very even seating of the lugs, which is necessary for good accuracy.

The body I ordered is un-numbered 1950's production for the BSA rebuilds.

englishman_ca
27 December 2009

The bolt head with the slot cut in the threaded shank is from the days of the Sht LE Mk.I. The firing pin had a lug on it which allowed the bolthead to be used as a wrench to remove the firing pin without tools. The lug on the firing pin would be indexed and key into this slot on firing.

Most firing pins (strikers) that are found these days do not have the lug and will work fine with the early boltheads. Not the other way though, a striker with the lug on its collar will not work with a later bolt head without the slot.

Look to your front, mark your target when it comes!

LE Owner
27 December 2009

Thats interesting, and a few of the SMLE MkI rifles have been showing up lately so if an owner of one of these needed a good replacement bolt head I or the thread starter might be able to help them out. Those scalloped heads can't be that easy to find if you need one.

Also should I be in need of a replacement pin and a MkI pin be all I could find, which is a bit unlikely but always a possibility.

Alan de Enfield wrote:
Swapped the head for one without the slot and it went straight in - sweet as a nut.

I found the same thing when I tested the fit of the old bolt head to my new bolt body. It was more like the threads were tapered.

The scalloped head fit the body numbered to the action body a bit loosely.

It could be the scalloped heads were sometimes used when a MkIII body began to show excessive thread wear, the difference in threading allowing the bolt to remain usable.

Might also have been an old MkI bolt body fitted to this MkIII body at some point.

On the other hand.

If the MkI threads are tapered or slightly off pitch that might lead to increased wear of the body threads.