Lee Enfield Headspacing

summerside sniper

summerside sniper

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I just received my 1950 Lee Enfield #4 Mk1. It came with a #1 bolthead. How do I tell what number bolthead is on the bolt? Although I know its history, before I get it to the range, should I get the headspacing checked anyways? Is this something I could do at home with the right tools? Finally, what are the right tools?
 
"...came with a #1 bolthead..." A bolt head for a No.1 rifle or a bolt head stamped with a No. 1? The bolt head number is stamped on the lug.
"...get the headspacing checked anyways...do at home with the right tools..." Yes and yes, with headspace guages. Brownell's sells the guages at $30US each for Clymer. $25.40US for Forster. You need a No-Go and a Field.
Slip the guage under the extractor and gently close the bolt. It should not close on the No-Go, but if it does, try the Field. If it closes on the Field, the headspace is excessive and you need another bolt head. Try a No. 2. However, just going up one number does not guarantee a fix. Gunparts is listing No. 2 bolt heads at $11.30US each. Marstar lists bolt heads at $19 each, but doesn't list what numbers they have.
 
summerside sniper said:
I just received my 1950 Lee Enfield #4 Mk1. It came with a #1 bolthead. How do I tell what number bolthead is on the bolt? Although I know its history, before I get it to the range, should I get the headspacing checked anyways? Is this something I could do at home with the right tools? Finally, what are the right tools?
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Is your 1950 like most of them, matching bolt and receiver numbers and very little use on it? Almost like new?
If so, please don't let all the talk about headspace scare you too much. I've checked a couple of dozen No 4 rifles of various heritages and they've all passed easily with a SAAMI Field gauge of .070. Yes, I've yet to see one fail. A 1950 Long Branch is a very well made rifle indeed and unlikely to be sloppy...(although nobody can guarantee that including me)

I will say, if the numbers aren't matching it's more likely that you should check it. I bought my Forster gauge on ebay. A member on here also fabs repro .074" Military spec Field gauges.

During the war, I've heard they stretched the allowable spec to .084" which is really really loose but they still considered it acceptable for combat use. Biggest deal with tight headspace is for reloading, if you're reusing those cases time and again the tightest headspace will help with case life.
 
Armourer's guages are .064" and .074". Cartridge cases fired in a rifle that gauges toward the high end spec. will be showing signs resulting from rather loose breeching. Not a safety issue, but certainly a factor if you intend to reuse the cases. They may not be reusable, without a separation being probable.
If you go to milsurps.com, the Milsurp Knowledge Library, click on the link, there is detailed information available about .303 headspacing.
 
John Sukey said:
I would use CANADIAN MILITARY headspace gage rather then a SAMMI gage from Brownells. There IS a difference.
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If a rifle passes SAAMI .070 spec, it's better than a rifle that passes .074". I have both gauges. As I say, I've never had one fail yet the .070 spec. It's just the thickness of the rim that differs.

A matching 1950 with little use- highly unlikely it would fail. I'd bet a case of beer if I could help drink it if I lose...;):D
 
Cantom, you've been lucky. I've had Lee Enfield rifles come into my shop that would swallow the .074 gauge, and have play in the bolt.
A rifle in decent condition should be fine, problem is, you don't know what has been done to it, over the past 60 years or so. Its easy to swap parts on a No.4, including boltheads, and there is no way to know for sure what has been done, so checking isn't a bad idea.
By the same token, a Lee enfield with excess headspace does not instantly become a bomb. Matter of fact, only consequences I've noticed were the odd separated case, or protruding primers. I've never seen a Lee Enfield damaged by excess headspace, nor a shooter suffer harm. Generally a rifle with minimum headspace will be a better shooter.
As far as other military rifles go, many will accept a SAAMI No Go, and that includes Swedish Mausers in nice shape. Probably different specs. in gauging.
 
I'll defer to your experience, I've only had my gauges less than a year and the total number is no doubt far less than yours.
Were the rifles that failed No 4's or SMLE? SMLE is apparently a different story.


tiriaq said:
Cantom, you've been lucky. I've had Lee Enfield rifles come into my shop that would swallow the .074 gauge, and have play in the bolt.
A rifle in decent condition should be fine, problem is, you don't know what has been done to it, over the past 60 years or so. Its easy to swap parts on a No.4, including boltheads, and there is no way to know for sure what has been done, so checking isn't a bad idea.
By the same token, a Lee enfield with excess headspace does not instantly become a bomb. Matter of fact, only consequences I've noticed were the odd separated case, or protruding primers. I've never seen a Lee Enfield damaged by excess headspace, nor a shooter suffer harm. Generally a rifle with minimum headspace will be a better shooter.
As far as other military rifles go, many will accept a SAAMI No Go, and that includes Swedish Mausers in nice shape. Probably different specs. in gauging.
Click to expand...
 
Both. I used to encounter some pretty horrible rifles. SMLEs are 80 or more years old for the most part, and may have been in use for much of that time. Have seen rifles that would fail .074 with a #3 bolthead, having been brought in with a #1. I have also inspected a fair bit of .303 brass fired in Ranger rifles currently in active service. Not unusual to find cases with incipient separations (up to 15-20% cull rate), suggesting that rifles in service can be pretty darn loose.
Absolute worst .303 headspace I ever encountered was on a Parker Hale sporter which had been rebarrelled with a commercial barrel when it was rebuilt in England. You can spt these because there is no flat on the barrel breech. No idea how it got through the Birmingham proof house. I'm sure it would have gauged .090" or even worse. Had to remove the barrel, set it back and recut the chamber to make it right. This wasn't an issue rifle, of course, but one of the more expensive PHs.
I agree that summerside's '50 LB is most likely just fine.
 
You can have a rifle that gauges absolute minimum...... and STILL have excess headspace if your ammo is not up to snuff. I have seen (and gauged) commercial ammunition with rims as thin as .042", which automatically will give you 21 thou of headspace in a perfectly set-up, absolute minimum rifle.

The .303 round headspaces on the rim; this is why rim thickness is so important. Thankfully, the more responsible manufacturers make the stuff very close to the military spec, which called for a rim as close to .063" as possible. The rifles were headspaced to .064" minimum, so with a min rifle and max ammo, you would have 1 thou of headspace. BTW, that Canadian WW2 ammo that you sometimes see, stamped with the date and DI Z, is the closest I have ever seen to absolute perfection of manufacture. This was Defence Industries make, a Crown Corporation that stopped production at the end of the War (sob!). Beautiful ammo, but starting to get old (like me).

Headspace is important if you want good shooting, but it is not the be-all and end-all, either. If your extractor grabs the rim of the cartridge, it can be considered safe to fire, all other factors positive.

Military FIELD headspace gauge measures .070".

You don't need gauges to check headspace, but a micrometer and some shimstock sure helps. Remove the extractor, gauge your specimen casing, insert casing in chamber, close bolt. Bolt should close. Now start placing small shims between the boltface and the case base; the thickness of the shimstock before there is a NOTICEABLE pressure to close the bolt, is the headspace of that rifle with that bolthead and that ammo. Accuracy will suffer if this figure is more than 10 thou.

Most important thing is to have fun.
 
If you want to get clever you can put some layout or engineer's blue on the face of the bolt, after you polish it flat on a diamond lap that is, and then check that it is square to the chamber by seeing whether the marking of the blue on the guage is even all around. You can also use your diamond lap to clean up ugly boltheads and shorten them slightly when required. If you want the tightest, set it up so that you can just close the bolt handle with a slight tension on the GO gauge.
 
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