Enfield No4 Mk1 Question...

[Gunsmithinflorida]

The head space should be checked with no-go gauge. (Midway USA $30) If the bolt closes on a no-go, it should be checked with a field gauge. If the bolt closes on the field gauge, the rifle is un-serviceable. I noticed in one of your pictures that your bolt head has a number 2 stamped on it. Armorers kept a supply of replacement heads starting with #0 thru (I believe) 4. I recently paid $100 for a #2 bolt head to correct a head space problem. A number 3 or 4 is extremely hard to find. These rifles will develop head space. The 303 cartridge is more than the design can bear for 3 to 5000 rounds. Think of head space as: punching someone in the arm from 1" away. As you increase the distance you increase the impact. As head space develops in a rifle, the faster it develops. Some rifles can live a long life at the no-go area but not a 303 rifle. If it closes on a no-go without resistance, you need the next size bolt head to regain +- .010" of head space.

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.

[Alan de Enfield]

The head space should be checked with no-go gauge. (Midway USA $30) If the bolt closes on a no-go, it should be checked with a field gauge. .

For Lee Enfield Rifles there is officially no such thing as a 'Field Gauge', there is only 'Go' (0.064") and 'No-Go' (0.074")
SAAMI have decided to implement their own modern requirements onto historical British military rifles.

I imagine the Midway no-go gauge is well below the required 0.074" as the SAAMI specifications stipulate 0.067" for '30-cal' rifles.

There have been 100s (1000s?) of Lee Enfield's scrapped due to using the wrong tests and testing equipment.

[Gunsmithinflorida]

[QUOTE=Alan de Enfield;479318]For Lee Enfield Rifles there is officially no such thing as a 'Field Gauge', there is only 'Go' (0.064") and 'No-Go' (0.074")
SAAMI have decided to implement their own modern requirements onto historical British military rifles.

I imagine the Midway no-go gauge is well below the required 0.074" as the SAAMI specifications stipulate 0.067" for '30-cal' rifles.

Interesting. I measured several case rims and .056" seems average. My no-go gauge is like you said .067". Forster offers a field gauge and now I am curious about its dimension. The required .074" is .018" over the cases I measured.

[Alan de Enfield]

Interesting. I measured several case rims and .056" seems average. My no-go gauge is like you said .067". Forster offers a field gauge and now I am curious about its dimension. The required .074" is .018" over the cases I measured.

Despite your forum 'name' I presume you are not familiar with head spacing rimmed cartridges, or, the Lee Enfield Rifles.

Your previous statement about using the 'numbers' for sizing the bolt-head is a little confusing to newbies if taken literally as it is not unusual to find a Number 0, or a No1, or a No2 bolt head larger than a No3 bolt head. The 'numbers' are supposedly indicative of size, but at the end of the day the actual dimensions are the critical measurement. You cannot just say replace a No2 with a No3.

Also, It looks as if you are measuring USA SAAMI cases rather than military 303 specification cases.

The Likes of Win & Rem are 'built to a price' and tend to be way down at the bottom end of the specification (the specification for Rim thickness is 0.054" - 0.064")

Maybe looking at this will show the difference :

One of Win's 'better offerings' at 58 thou & PPU at 62 thou

[nelsonhoneyfarms]

Thanks Alan. Great thread there. This makes perfect sense, I just have a question on the method. By the way, I am not a reloader and don’t pretend to be one.

To get the “fired primer to start into the case’s unfired primer pocket”, I will need to remove a fired primer from a spent casing and likewise remove an unfired primer from an unspent casing. What is the best method to do these removals without special reloading equipment?

[Alan de Enfield]

Thanks Alan. Great thread there. This makes perfect sense, I just have a question on the method. By the way, I am not a reloader and don’t pretend to be one.

To get the “fired primer to start into the case’s unfired primer pocket”, I will need to remove a fired primer from a spent casing and likewise remove an unfired primer from an unspent casing. What is the best method to do these removals without special reloading equipment?

Pull the bullet out of the unfired round.
Tip out the powder.
Put the unfired round (empty) over a partly open vice (or something that will allow the primer to 'fall' out)
Take a metal 'bar' about 1mm (1/16") that is longer than the length of the cartridge
Put 'bar' into cartridge with the end against the primer, GENTLY tap the primer out. It will just 'fall out' as long as you have supported the rim but left a gap under the primer.

Ideally it would be done using 're-loading components' without having to knock-out a 'live' primer.
Keep your face clear (don't look down into the cartridge whilst knocking the primer) JUST IN CASE !

[nelsonhoneyfarms]

Roger that - thank you again. Common sense is king here! I will post once complete.

[nelsonhoneyfarms]

Back again. I did the procedure for estimating headspace and came out with 0.066”, 0.067”, 0.068”, and 0.066” in four spots around the rim. The picture shows how I measured, my caliper is on the right in the shot. Please let me know if this is the correct measurement. If correct, this estimation seems to be within specifications for this rifle, so I am very pleased!

The only thing I did differently from the instructions is that to get a spent primer (which I did not have), I removed the bullet and powder from an unspent casing, fired the PRIMER ONLY and removed it to use for the measurement. I used that same casing for the measurement as well. I assumed that the force from just the primer, with no powder or round, would not cause deformation on the casing, and it could still be used for the measurement. If this is inaccurate, please let me know.

As a non-reloader, the best thing I could find to remove the primer from the casing was a straight shaft gasket puller. I filed the sharp point on the end to approximately 1/16”. It worked very well.

Many thanks!

[Alan de Enfield]

Back again. I did the procedure for estimating headspace and came out with 0.066”, 0.067”, 0.068”, and 0.066” in four spots around the rim. The picture shows how I measured, my caliper is on the right in the shot. Please let me know if this is the correct measurement. If correct, this estimation seems to be within specifications for this rifle, so I am very pleased!

The only thing I did differently from the instructions is that to get a spent primer (which I did not have), I removed the bullet and powder from an unspent casing, fired the PRIMER ONLY and removed it to use for the measurement. I used that same casing for the measurement as well. I assumed that the force from just the primer, with no powder or round, would not cause deformation on the casing, and it could still be used for the measurement. If this is inaccurate, please let me know.

As a non-reloader, the best thing I could find to remove the primer from the casing was a straight shaft gasket puller. I filed the sharp point on the end to approximately 1/16”. It worked very well.

Many thanks!

Close, but doing that you will get the variation due to not holding the case vertical.
Measure the rim thickness in 4 places using the gauge jaws and take the average.
Once the primer is 'pushed home' use the 'depth gauge' (as you are now) to get the height of the primer.
Add the two together.

[nelsonhoneyfarms]

Yes, that makes sense and would be more accurate.

The average rim thickness was 0.062” and the primer is protruding by 0.004”. Totaling 0.066” for the estimated headspace.