Lee Enfield .303 British Head Space

[Coote]

I'm in awe of the collective knowledge here... and the apparent vast knowledge held by certain individuals.

I have a question about head space. I've done a search here and found some information, but I'd like to get some views on some measurements I made today.

I cut some small strips of soft lead (used for lead light windows). I chambered new empty cartridges into 3 different Lee Enfields, placed the strip of lead on the back of the cartridge, and forced the bolt shut. I then measured the thickness of the lead with my micrometer. I did this several times, and it proved to be a fiddly job trying to avoid lead spilling over the edge of the case and filling the writing on the base etc.

Anyway, the lowest measurement I got was around .011", and the largest was a tad over .014". Up until recently I thought the maximum clearance should be .006"

Two of the rifles are 2-groove number fours. The other isn't.... I think you'd call it a No 1 Mk iii. I am aware that different bolt heads may be available for the number fours, and both of these rifles have a "1" stamped on the bolt head.

At least a couple of these rifles have been used by members of my family with absolutely no trouble, although generally we've been shooting Berdan-primed military ammo and not attempting to reload it. I am hoping to reload cast boolits to use in these rifles.

As far as is practical, I intend to keep the brass from each rifle separate and to just neck size the cases. I will mostly be reloading with the softest cast boolits that will shoot well, and I will keep my velocities low. I have had encouraging results using Trail Boss powder, so that is what I will be using unless I get a better idea.

So... please give me your thoughts on using Lee Enfields with this sort of headspace.

Thanks in advance.... Coote.

[Multigunner]

Well the clearance you are measuring is called "headgap" as opposed to headspace. Headgap is dependent on the thickness of the rim of the cartridge you are using.
A milspec case usually has a thicker rim than most available commercial .303 brass.

I'm told Privi Partizan brass has a good thick rim.

Commercial specifications for the .303 British were minimum headspace of .064 and maximum of .068. Military specs for the Lee Enfields allowed for a maximum headspace of .074.
Milspec brass was designed to hold up for a single firing in a greatly oversized chamber if necessary so its generally, but not always, thicker at base web and side walls than commercial brass.

Reloading can be a problem if head gap is loose enough to allow the case to stretch past its elastic limits, leaving an internal annular groove that can lead to case seperation later on.

I was lucky in finding replacement #3 boltheads for my own No.4 and those belonging to friends at a very low price back in the 90's, around 8 bucks apiece if memory serves. These #3 boltheads are rare as hen's teeth these days.

Using the #3 bolthead I reduced headgap to within commercial specs and never lost another case to annular rings or cracks, reloading till the necks wore out from resizing too many times or got damaged by a bad mag feed lip.

My SMLE was within commercial specs when I got it, and though I later had to replace both bolt body and bolthead because of worn out threads the headspace remained practically the same, perhaps one thousandth tighter.
So I have no problems in reloading.

Its uncommon to find a Lee Enfield with tight headgap, so don't be discouraged at the gap you've measured unless the cases you use had the thicker type of rim.
Most commercial cases have rims of about .059 so a .011 gap would put the headspace well within milspec limits.

headgap of .006 is about the limit for long reloading case life, but some have found ways around this by fireforming using a ring of fishing line or a thin rubber o-ring to give the effect of a thicker rim. I haven't had to do this, so I'm sure someone who has will tell you more about the procedure.

To compensate for the often loose milspec chamber, which is made looser by extra headgap because of the sidewall taper, I mark each rim and rotate 180 degrees on second firing, afterward the case remains perfectly centered.
I neck size only 2/3 of the neck, the expanded portion along with well centered case body holds the bullet in perfect presentation to origin of rifling with no canting, greatly improving accuracy.
The Hornady .312 flat base bullets work best for my rifles.
My best loads are with IMR 4320, but we don't generally post exact charge weights here, best to look the loads up in a manual and start out on the light side. I got best accuracy with the stoutest charge recommended in the manual I found.
The stouter charges improved bullet bump up in oversized bores.

PS
Since you plan to use light cast boolit loads I'd suggest you start out with fresh unfired cases. The light loads should prevent case stretching and fire form the cases. Case life should be longer this way.

[Coote]

Head gap. Got it. Thank you. Very helpful and encouraging. I appreciate all the time you put into composing and typing your reply.

I've just seen some information on packing the case back against the bolt using monofilament nylon fishing line, so nobody needs to go to the trouble of explaining that.

Thanks again.

[JeffinNZ]

Coote, fire form you cases to begin with as I outline in my .303 accuracy article (sticky), neck size only and forget about the entire headspace thing. As long as the case head is hard against bolt head and you have a shoulder tight against the chamber shoulder....life is sweet.

[Coote]

Thanks very much Jeff. I will check it out.

Over the past couple of days I've been a bit bewildered... and worried that my reloaded brass might not handle the strain. I would have been easily tempted to set the Lee-Enfields aside and save up for a modern gun to devote to cast boolit hunting. Now that I've had some reassurance I'm back with the original plan. I like Lee-Enfields.

[Mavrick]

Headgap, smchmedgap....It's all headspace!!
Headspace is the distance left when the case is all the way forward and the "bolt" is all the way back. Over .006" is EXCESSIVE!!
What you want to do is get the case fireformed so the case is stopped at the right point by the shoulder instead of by the usual method, in this case the rim.
What you need to do is get the case to NOT stick to the chamber wall, so that it will slide back to the boltface, and the shoulder will expand forward to the chamber. You'll THEN have formed a new "wildcat."
There were guns designed in the early days of the 1900s that used a lubrication system to "grease" or "oil" the cartridges so they wouldn't stick to the chamber. The systems didn't work because the lube attracted dirt.
So...put a SMALL amount of lube, ie 3in1 oil, on the cases and fireform them. It increases the boltthrust, so don't use it with excessive loads. It was used with military loads, so factory ammo will work. If a military rifle won't take this amount of boltthrust, it isn't safe with any other ammo, either!
When you're through fireforming the number of cases you're going to, clean the lube from the chamber as you don't NEED to subject the gun to more.
The cases are now headspaced on the shoulder, and since you are not going to load hot ammo, you've no need to full-length size back to factory specs. YOU DON'T HAVE A FACTORY SPEC CHAMBER. Just neck-size as much as you need to hold the bullet.
Have fun,
Gene

[Ragnarok]

I bought a No4 MkI that had so much headspace it wouldn't fire a cartridge!!

The rifle had a #1 bolthead in it..I robbed a #2 bolthead off my Jungle carbine..and it would fire..but could use a longer bolthead still.

#3 boltheads are hard to find..but I managed to get one, and this fixed it right up.

The Chambers are big on both my No4 rifle..and No5 carbine...however my old No1 MkIII* has a nice tight chamber.

[longbow]

So far I have been lucky in that I have 2 No. 5's and a No. 4 and all three share brass. The No. 4 is slightly tighter than the No. 5's but just slightly so I get away with neck sizing only for all three.

Another comment for cast boolit loads.

The .303 chambers are "generous" as mentioned and that includes the neck area. I find I need a 0.315" boolit to fill the throat. Using standard .303 dies for neck sizing takes necks down to 0.310" inside then I am seating a boolit of 0.315" so not only working the brass a lot but also swaging the driving bands of some boolits (I have one mould with quite narrow driving bands and they suffer). Annealing often helps.

My solution was to make a new expander button to give me 0.314" inside neck after sizing. That worked pretty well and improved accuracy but I was still working the brass a lot. Next, I bought a Lee collet die and made a mandrel at 0.3135" which gives me just enough neck tension and doesn't work the brass much.

Apparently the Lee collet die can be used without the mandrel as well so allows whatever neck diameter you want. I haven't tried that yet.

As stated, fire form then neck size only and you shouldn't have any problems.

Generally I am not a "small bore" fan but I am really enjoying shooting my Lee Enfields.

Longbow

[303Guy]

Headspace is the space the rim fits into while what Multigunner is referring to as headgap is the gap left when a case is chambered. Excess headspace is too much.

The 'O' ring trick looks like this.
http://i388.photobucket.com/albums/oo327/303Guy/001-3.jpg


What you need to do is get the case to NOT stick to the chamber wall, Exactly. I never fire a dry case - I always keep them lubed. I get zero head separations and zero case elongation. The problem one may find with light cast loads is there is insufficient pressure fire-form the case. But it should partially fire-form I'd think. Either way, I'd keep the cases lube with case-lube so they will settle back onto the bolt face.

It is possible to seat a boolit into an unsized case neck. There is no danger of not having clearance in the chamber to 'release' the boolit. I've done tests and if anything, the pressure seems to be lower with a tight fitting boolit and neck. That may be due to the use of thicker paper and a smaller core. In my case, the boolit was chambered hard into the leade, was heavy and it was a 'full load'.

Personally I'd recommend Trail Boss for safety reasons - it being so bulky as to be able to tolerate a full case of the stuff.

[Multigunner]

Lubing the case can cause problems with full power loads. Enfields were proof tested using an oil proof cartridge for two reasons, one was to complete the fit of the locking lugs in their seats by inducing controled set back, the other was to give the same conditions as a higher than normal pressure and oily or wet casing to prove the rifle could withstand at least a few such incidents, as any military rifle might have to under combat conditions.

Theres some confusion about the use of oiled ammunition. The regulations for musketry define the term "oiled in the service manner" well enough if you read closely. Cartridges were wiped with a flannel rag moistened with preservative oil and left to dry to the touch. This microscopic layer did nothing to lubricate the case, it was there to discourage corrosion and dirt clinging to the case from handling with dirty hands while reloading.
Oiled or wet ammunition can cause cracking of the action body. This is warned against in many military and non military sources. Oiled or wet ammo can also throw shots wild of the group.
In part the staked primer of milspec ammo preventing any backing out and cushioning effect of the primer would have increased the battering effect on the bolt.

When light loads are used the effect of a lubed case is far less, and should be within safety limits.
Even then a load too light for any drag of case to chamber wall can result in the case head battering the bolt a bit.

The best compromise is the case expanded enough to allow some friction in slowing the contact between casehead and bolt face, but not enough to lock the case to the chamber wall so that the case stretches. That should also be enough to take care of fireforming.

[303Guy]

The best compromise is the case expanded enough to allow some friction in slowing the contact between casehead and bolt face, but not enough to lock the case to the chamber wall so that the case stretches.Exactly.