No.4 Mk1 Headspacing: How?


December 14, 2006, 02:47 AM
yep, as question stated above: How does one Headspace a SMLE No.4 Mk1?

I have all the guage doohickies purchased online through my random major supplier. I have the "no" guage in there and it says "no"

How does one adjust this?:confused:

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December 14, 2006, 09:56 AM
To adjust the headspace on those rifles,there were different length bolt heads.

The trick is finding them.
There should be a number on the bolt head you have.
Once you know that,you can find one with a higher number to shorten the headspace.

I see them offered from time to time on:

I'm sure there are other sites to check,any curio and relect site should have someone who has some to sell from time to time.

December 14, 2006, 10:46 AM
The bolt head sizes are 0-3; finding a #3 is quite hard and it'll set you back close to $50 on average. The bolt head size is stamped on the head guide/boss just above the extractor recess, right next to the factory stamp. The bolt head just unscrews and the new one screws on by hand. Piece of cake to do.

Have you pulled the firing pin/spring/cokcing piece off to check the headspace? You should.....

December 14, 2006, 12:05 PM
dont think that's necessary, my freind's grandpa has already prove the gun needs headspacing back in the day when they used the shoelace method and hid behind the truck.

i was hoping the guage would tell me a degree of severity on how much to adjust :banghead:

anyone have a lead to bolt faces?

Jim K
December 14, 2006, 03:23 PM
First, do you know how to check headspace on that rifle? It should be done with the firing pin and spring removed. What exactly do you mean "it says NO." Do you have a GO gauge? If so, the bolt should close on a GO gauge. Only a little pressure should be needed with any gauge, which is why working with the bolt fully assembled is difficult since the force required to close the bolt gets in the way of "feeling" the gauge.

If the bolt won't close on the NO-GO gauge, you are in good shape. If it closes on a NO-GO, it is no real problem. Only if the bolt closes on a Field Reject gauge is there a headspace problem which can often be (not always) solved by use of a longer bolt head.


December 14, 2006, 04:51 PM
it's closing with the no gauge :banghead:

December 14, 2006, 06:35 PM
Closing on a NO-GO gauge doesn't mean that have to stop shooting the rifle. it just means that the rifle is approaching the point where it is unsafe to shoot. You need to closely monitor the headspace.

I had a Springfield 1903 Mk1 rifle that closed on a NO-GO, but not a FIELD. I safely put about 500 rounds through it before it was time to call it quits.

If your bolt closes on a FIELD gauge, then you have problems.

A gunsmith with a set of good match headspace gauges (in .001" increments) can tell you exactly what the headspace is on your rifle.

Jim Watson
December 14, 2006, 06:42 PM
Do you plan on reloading for it?
Did granpa have a casehead separation or other unpleasant result when he fired it with a string?

December 15, 2006, 01:53 AM
what happened with the casing was split from the neck to the shoulder. Also, we noticed that the hammer/striker ejected back during operation. The gun fired, and the bolt was still cocked when we went to inspect the aftermath.

I dont want to toss this rifle as the wood and finish is very near immaculate.

Thanks for answering, guys

daniel (australia)
December 15, 2006, 06:12 AM
That sort of split sounds like it could be a symptom of an oversize chamber rather than headspace. Oversize chambers are common in war-years No. 4s, partly due to manufacturing pressures, as well as an attempt to make them functionally reliable even with dirty, corroded or dented ammuntion and in the worst conditions. Measuring some fired brass will give an indication of whether this is the case, and the cure is either setting back and rechambering or a rebarrel.

December 15, 2006, 06:24 AM
I've considered that much, which is why I put up a wanted ad. :banghead:

Is it possible to rebarrel my gun to another caliber? (despite ruining such a beautiful relic) I'd like to rechamber it to something more common like .223 or 7.62x39

How does one go through this process?

daniel (australia)
December 15, 2006, 07:02 AM
These conversions are quite feasible, and not uncommmon here in Oz, though a bit more involved than you might think. Have a look here (

December 15, 2006, 08:52 AM
NUmrich has all the bolthead sizes EXCEPT#3. When they have them in stock, the #3 heads are only $21US. Other boltheads are in stock and cheaper.

Jim Watson
December 15, 2006, 09:24 AM
Agree with Daniel. It sounds like an oversized trench mud chamber and will not be cured with a new bolt head for minimum headspace.
If it is a particularly nice example of a No 4, you could get it professionally examined (Anybody here know a Enfield 'smith?) just in case.
I think it needs a new barrel, though. A friend has an Enfield with a pristine bore and reasonable chamber; except for a large rust pit in the neck that causes stiff extraction. We figure when it was cleaned and stored that a frayed patch left a thread there that absorbed humidity and rusted that one spot. He can't find a cheap barrel, I don't know a source.

December 15, 2006, 12:10 PM
Barrels and other interesting bits: (shows in stock) (call for availability)

Info here:

December 16, 2006, 12:42 AM
Bolt heads go from 0 - 3 though I've heard of one 4 and 5 being found.

Measurements are here.

I'm not sure if it would be possible to install a replacement bolt face to the old and then cut it down, a machinist would know.

December 23, 2006, 03:13 AM
Progress Report!

:D got the new barrel and it didnt work correctly right away, after buying a #2 bolt head, she's alive!

range report coming soon. Merry Christmas guys!

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