Question about changing bolt to fix headspace

[Peter Laidler]

Which proves the point that you only need TWO gauges. .064" GO and .074" NO-GO. Everybody take that on board. You don't need a gauge that tells you something inbetween.

[fliefishing]

First time postimg. Just picked up a 1916 No1 MkIII. All the numbers match. Wll probably have some questions to follow.

[STG-98]

Which proves the point that you only need TWO gauges. .064" GO and .074" NO-GO. Everybody take that on board. You don't need a gauge that tells you something inbetween.

From other threads this headspace maxim was becoming apparent, and Captain Laidler's emphasis in this thread seals it.

I ordered the Okie gauges a while back, and was shocked, SHOCKED, when my Lee-Enfields passed the GO (.064), failed the NO-GO (.067), and passed the Field (.074). Then after consideration, confirmed by these threads, that the Field gauge is what matters, forget .070. Also I may have missed it somewhere, what is the NO-GO (.067) about anyway? Long way from .074

I feel much better after prowling the archives here. Aside from learning some more Enfield-craft, having a good time getting familiar with the denizens of the boards.

[muffett.2008]

the GO (.064), failed the NO-GO (.067), and passed the Field (.074

Trust me mate, if that no go says no than no it is. Field was just giving service rifles a bit more leaway when there was little time to correct the problem.
These days you will not find field gauges in anything other than military calibres, and with modern pressures you should always err on the side of caution.

[Son]

Just to follow up on Peter's words above... the .067 gauge did not exist for the purpose of testing an in-service rifle. It belongs on monofilament about a foot above a hook...

From "The Armourer's Handbook, Part I, The Rifle.
In the chapter on the No1 MkIII and III* rifles,
Gauging.
2. Cartridge Head Space.
.064-inch low.
.074-inch high.
(a) The bolt should close over the .064 gauge but not over the .074.
(b) When the bolt is found to close over the .074 H.S. gauge, the dummy bolthead gauge should be substituted for the existing bolthead, and if this combination is tight, another bolthead giving correct head space should be fitted.

No3 Rifle.
Gauging
2.Cartridge Head Space
Use No2. gauges: .064 and .074
Never allow the action to cock when applying the gauges.
The bolt should close over .064 but not over .074

No4 Rifle, Mark1 and Mark1*
Gauging
2. Cartridge Head Space.
.064-inch low.
.074-inch high.
(a) The bolt should close over the .064 gauge but not over the .074.
(b) When the bolt is found to close over the .074 H.S. gauge, the dummy bolthead gauge should be substituted for the existing bolthead, and if this combination is tight, another bolthead giving correct head space should be fitted.

The Ross Rifle MarkIII
Gauging
2.Cartridge Head Space
Use No2. gauges: .064 and .074
Never allow the action to cock when applying the gauges.
The bolt should close over .064 but not over .074

This little booklet covers the testing and gauging procedures to be carried out by armourers on the above weapons as well as the No2 MkVI and the Browning Automatic Rifle .300-inch.

[jmoore]

If you are reloading for your .303, then headspace can be made irrelevant if you conduct the first firing of the new case or loaded factory ammo with either an o-ring or monofilament around the base of the cartridge to remove the fore and aft slop. Search posts by parashooter and Edward Horton for useful info . (and some wild threads!!)

ETA: In actual fact, the o-ring method works if you DON'T reload, but it is not condusive for rapid fire. Bolt turn down WILL take some effort.

Some links:

https://www.milsurps.com/showthread.php?t=9026&page=2

The same thread, but from the beginning:
What to do about headspace after #4 bolthead?


There's plenty more back from the "old" days, but that may be the best of the lot.

Oh, and the difference between a "no-go" and a "field" gage is the the first is the manufacturer's standard, and the second is the user's (or armorer's -who is doing the check for the user) maximum standard for non-tailored ammuntion.

[Pablo]

I added a '41 Lithgow to the gang last week.
It's all matching (including the timber) cept for the H barrel thats dated 1956.
Do i need to get the head space checked on this thing even though its all original and number matching apart from the barrel?
The dealer i bought it from had no info to pass on from the previous owner as it been sitting out back in storage for years.