Enfield headspace issues

[Cantom]

I unashamedly cadged this excellent post from Jouster Enfield Forum just now- what more can anyone say.



Headspace on an Enfield is measured using British gauges: the minimum is supposed to be .064", which is the rim thickness of a military round, and .074", which therefore allowed .01" tolerance (in wartime, this tolerance was further increased to .084").

You will see that there is a lot of fuss by people who believe that their Enfield is out of spec. This is because the SAAMI gauges retailed by several manufacturers are different to the British gauges, and give a false reading. Part of the reason for this is that commercial US .303 brass often has a thinner rim than British or other manufacture.

Despite what you may read elsewhere, headspace does not cause a safety issue. Consider the bald facts that c.12 million Enfields of all models were made, and there is not - to my knowledge - even one case of one "blowing up" whilst using normal ammunition.

The "accuracy" aspect is debatable: target shooters, particularly in Australia, did indeed measure rim thickness and try and tighetn up the headspace - usually to .067", which is the optimum measurement. However, the rifle do not neccesarily react to tighter headspace, and can in fact become less accurate. I've tested dozens of rifles, swapping between long and short boltheads, and there is rarely any significant improvement. The overwhelming factors that determine accuracy are (1) correct stock fit (2) barrel condition (3) shooter ability. No(3) is significant: I've witnessed a sample of about 350 people shooting Enfields; only about 10% of those shooters were capable of the tight grouping from which other factors can be deduced. Ergo, for most people, tinkering with the rifle isn't going to help.

Other small warnings:

(a) the only reason an Enfield usually needs a change of bolthead is if it has been rebarrelled or ahd a new bolt fitted. The rifles were designed to be fired with wet ammunition and cope with extreme conditions. Most Enfields are still perfectly in spec with the bolthead they left the factory or service with - 100+ years ago, for some of them!

(b) over-tightening the headspace, by using the wrong gauge and then buying a longer bolthead, can cause premature wear to the rifle lugs.

(c) When an Enfield military armourer came to fit a new barrel, bolt or bolthead, he had boxes of spares from which to pick suitable components. This is vital, because the bolthead also has to be fitted for "over-rotation" as well as for length: if the bolthead rotates past the locking rib by more than a certain amount, then the recoil forces may be passing through the screw thread, rather than the bolt body. Civilian owners who go out and buy a single "longer" bolthead by mail order obviously take a chance that it will leave their rifle in spec - I suspect that most have in fact put their rifles "out of spec".

Before you go tinkering with your rifle, deduce what its best accuracy is, and if in fact it has a problem. Most No4s in average will shoot a 4" group at 100yds with any old milsurp or new commercial ammo. Many will shoot much better than this. Its always a good idea to obtain several types of .303 ammo, and see if your rifle "likes" one more than the others. Most Enfields will shoot best with flat-base bullets in milsurp MkVII ammo.

Most No4s can have their accuracy improved by just checking that the stocking-up is correct as per standard military issue. Sometimes a small corrective adjustment can dramatically improve grouping ability.

Information

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[sdh1911]

Correct head space is simply leaving just enough room to allow the gun to operate safely. If too tight it will cause pressure on the case and influence shot to shot consistency as well as potential feed issues. Too loose and the excess space causes the bullet to back out under pressure, very dangerous. When I build a sporter I go 0.004" over go gage and when I build a comp gun I go 0.002" over go. This has worked well for me. In terms of accuracy many other things impact bullet flight other than headspace.HTH-SDH

[tiriaq]

Good find, Cantom! I think that the headspace issue becomes more important when handoading enters the picture. Cartridges fired in loose rifles may well separate if reloaded. I have been able to acquire cases fired in service grade rifles, and these must be inspected carefully, and culled mercilessly, because some rifles are loose enough that the case becomes internally grooved on the first firing. It has been my experience that when a case separates in a Lee Enfield, the break is far enough foreward that there is no untoward leakage of gas.

[Cantom]

Good find, Cantom! I think that the headspace issue becomes more important when handoading enters the picture. Cartridges fired in loose rifles may well separate if reloaded. I have been able to acquire cases fired in service grade rifles, and these must be inspected carefully, and culled mercilessly, because some rifles are loose enough that the case becomes internally grooved on the first firing. It has been my experience that when a case separates in a Lee Enfield, the break is far enough foreward that there is no untoward leakage of gas.

I recently sold off my progressive press, long ago got rid of my Lyman single stage...however, I am thinking about gearing up to load .303.
Would a Lee single stage press with Lee dies work, or is there a better recommendation? I see old Lyman c presses at gun shows for cheap, or would Lee be better? I know to neck size only, thus what dies to get? What bullets, powder, primers?

One thing that Steve Redgewell highlighted on his informative site is the importance of bullets being of sufficient diameter to engage the barrel fully. Apparently the Americans made undersized bullets for the Enfields that killed a percentage of their accuracy potential and by going a couple of thou up in diameter the accuracy potential is considerably expanded.

[tiriaq]

Pretty much any press would work - a good used one would be fine. The Lee would do the job as well. I like the Lee collet dies for neck sizing. As far as FL and seating, any make will produce decent ammunition. Nothing wrong with Lee. I have dies by all the major makers, they all work. If the cases haven't been fired in a particular rifle, they will probably need some sizing. Maybe not FL, but size them until they chamber freely. Lee Enfields tend to stretch case bodies, resulting in separations. If you neck size, or use a FL die, but size the case so that it is headspacing on the shoulder, case life will be better. Bore sizes do vary, and bullet that matches the barrel should theoretically work best. In practice, .311, .312 bullets should be fine. Steve's bullets are well thought of, but I've not used them myself. Low recoil shorter range loads can be put together with the 125 gr bullets intended for 7.62x39. I use Federal primers myself. Most of the medium rate powders will work in .303. Some folks have preferences.
.303 brass does need to be inspected carefully for incipient separations.

[ireload2]

Close control headspace will improve accuracy. It is especially noticably in front locking actions shooring rimless round. Many reloaders strive to matain only .001 to.002 clearance between the head to shoulder lengths of the chamber and loaded cartridges.
Having proper fit of the bore to the bullet is important also. Military rifles are sometimes designed to use a bullet that is slightly smaller than the nominal groove diameter. There there are rifles know to have an extremely large groove diameter from time to time. To know what conditions you are dealing with you might consider slugging your bore to check the groove diameter.
While saying this can happen with Lee-Enfields seems to offend some it is common knowledge that German GEW 88s have about 4 different possible bore and groove combinations. So you might want to check your rifle.