Lithgow stock finish...

[mhb]

And now, the bad news...

I decided to measure the headspace more carefully, and have now determined that the actual measurement is .076", even longer than the generous Brit maximum, and I'd certainly like to bring it as much nearer to the minimum figure (.064") as possible.
The bolt head measures .629", from the shoulder which contacts the face of the bolt body to the face of the bolt head itself. In order to achieve the desired headspace measurement of .064", I'd need a bolt head which measures .641" - .012" longer than this one. I don't know whether such a measurement is available, but hope so, or that one as close as possible to that length can be found, so as to bring the headspace into the desired (near minimum) range. I thought about making a shim to fit between the bolt body and bolt head, but realized that would throw-off the bolt head timing.
Well, I knew this was a project when I bought the rifle, but I think it's worth the effort.

mhb - MIke

[p246]

Yes shim will not work. Brits had an emergency gauge of .078 for war time use (I think that's the measurement someone can correct me if I'm wrong.) I checked my stash which is all use bolt heads. I don't have one that is .641. You could call Sarco and see if they would look for a old stock OEM bolt that slightly exceeds what you are looking for. You could send it to Brian Dick or see if Chuck in Denver does L.E. if you decide fitting the bolt head is more than you want to tackle. I've only done it twice and it was under the watchful eye of an old dude that knew what he was doing. He wouldn't do it for me, but would walk me through it. I can tell you without his help I would have never tried it. Just my 2 cents. He was a retired machinist I met through a friend. He was a hard core Lee Enfield guy, but lately has started messing with old double barrels. I think he got bored with L.E.s and moved on to another challenge. He also had some project L.E.'s that he sold me cheap. They are in the corner for retirement projects if I make it that long.

[Parashooter]

mhb - your recent posts on this thread indicate you're concerned about slightly generous headspace in your SMLE. Perhaps a review of the basics and some thoughts on handloading will help alleviate your concern.

Several generations of American shooters have been convinced by bad information that "headspace" should be checked and re-checked on almost any surplus rifle, especially Lee-Enfields. The truth is less interesting but still worth knowing.

Stripped to its essentials, with a rimmed cartridge like the .303, headspace is simply the distance between the front of the bolt and the back of the barrel. It's the space where the "head" (rim) of the cartridge fits when the rifle is loaded.



Since there has to be some room to allow for varying rim thickness, the headspace is normally a bit more than necessary - giving what I call "head clearance" (or "end play"), a little extra space so the bolt can close easily, even on the thickest rim allowed.

In addition, Lee-Enfields and their ammo were often made with a fair amount of space for dirt, mud, snow and other battlefield debris between the chamber and the cartridge's body and shoulder ("Body/shoulder clearance"). Since the cartridge is controlled by its rim, this clearance doesn't do any harm (except to handloaders who insist on full-length sizing).

When a full-power .303 cartridge is fired, a whole string of events occurs.



1. The firing pin shoves the case forward, rim against the breech.
2. The primer detonates. If it's not heavily crimped in place, it backs out, shoving the bolt and barrel as far apart as it can.
3. The thin, forward part of the case expands to fill and grip the chamber while the bullet moves out of the case and down the barrel.
4. The solid case head can't expand and grip the chamber, so it moves rearward, re-seating the primer, stretching the case walls just forward of the head, and stopping when it hits the bolt face. (In rear-locking actions like the Lee, the bolt and receiver also compress/stretch to add a little more movement. The higher the pressure, the more they move.)
5. If (and only if) the amount of head movement exceeds the elastic limits of the case, the cartridge separates into two pieces.

New cartridge cases can normally stretch a lot before breaking. Even with a minimum rim .054" thick and maximum "field" headspace of .074", the resultant .020" head clearance is well within the limits of new brass and it's very unlikely a new case will separate even if the headspace is somewhat more than the field maximum.

Unless you're consistently getting broken cases when firing new ammo or brass, there's not much reason to be worried about headspace in the sturdy old Lee-Enfields. Relax and enjoy!

If you handload for a .303 with generous headspace, there's no need to mess with bolt heads - changing the rifle's clearances to yield longer case life. You can control head clearance simply by changing technique.

When you fire a new case for the first time, use an improvised spacer ahead of the rim - anything from a precision metal washer to dental floss can work to hold the the cartridge head firmly against the bolt face and eliminate or reduce stretch even if head clearance is significant. Another way of accomplishing the same end is to use a bullet seated out far enough to jam into the lands, "headspacing" on the bullet instead of the case. Such techniques are useful only if the rifle has excess headspace. With normal headspace, initial stretch isn't enough to worry about.

After you've fire-formed your new cases they will fill the chamber fully, stopping on the shoulder just like a rimless cartridge. If you neck size, you'll have zero "headspace". If you have to full length size, adjust the die so the cases chamber with just a bit of resistance in the last few degrees of bolt rotation.

Finally, don't try to turn a .303 into a magnum. Keep the pressures below the limit and you reduce the small amount the bolt and receiver compress/stretch on firing in a rear-locking action.

With these techniques you can make your .303 cases last for dozens of loading cycles, even if your "gauge headspace" is well beyond the .074" field spec.

[mhb]

p246 and Parashooter:

Thanks for the additional effort and info. I'd be happy with a bolt head which came close(r) to the minimum headspace (say, in the range of .638" to the desired .641").
I was aware of the facts concerning headspace, case stretch and the methods of dealing with it. BUT: I build rifles, and firmly believe that it is best to keep headspace at or near the minimum established figure (when possible) to avoid the need for special handling of the brass, and to allow for maximum case life, as well as longer service life of the action itself. I neck size only, so long as the case treated so will chamber without excessive effort, and keep loads well within the established maximum for the caliber and rifle - the load I have been shooting in my LE rifles is relatively mild, but gives good accuracy. Rim thickness, per-se, does affect headspace, but none of the available commercial brass I have measured exceeds the .064" nominal dimension, and is mostly less than that, which increases the effective headspace in the rifle - this, too, militates in favor of reducing the rifle headspace.
In this case, changing the bolt head for one of greater length will permit correction of longer-than necessary headspace, and I definitely want to do so, so will keep looking for one - I believe it possible to acquire one of the desired dimension. Given that I have a fairly complete range of tools and machinery, and experience as a machinist, toolmaker, barrel maker and riflesmith, I do not anticipate any insurmountable difficulties in fitting a new bolt head, and am willing to try it.
The search continues...

mhb - MIke

[bigedp51]

Below is once fired factory loaded Winchester .303 British case that stretched and thinned .009 on the first firing, The rifles head space was just under .067 and within SAAMI limits.
"IF" I had fire formed the cartridge using the O-ring method the case would not have stretched at all.





I fire form my .303 case with a 100 grain .312 pistol bullet, a rubber o-ring with reduced loads. The reduced loads make the brass butt plate softer when forming 100 plus cases at a time.





The o-ring holds the case against the bolt face, and when compressed centers the rear of the case in the chamber.



Thereafter you neck size and let the case headspace on its shoulder and not the rim.

[p246]

bigedp51 can I ask what O ring you are using. I use dental floss but its kind of a pain. I got some black O rings from the auto parts store once but for some reason after a few firings they broke so how the dental floss got introduced. I will add it works in all but one Ishy. That one blows the case mouth open much further. Since the bore is in really good shape I think it was how it was cut (over cut) at the factory.

MHB good luck, Sarco will have the bolt head if you want to go that route. I'm out on whether to do it or not, as that's your call. The bolt heads I had help fitting were for rifles that were bought without an entire bolt in one case and the other was missing the bolt head only. I have two more sitting in a corner with missing bolts and good action and bores but probably won't mess with them for a while. Your rifle is shooting pretty good though so all in all it must be fitted well and the bore in decent shape.

[mhb]

p246:

I am going to acquire another bolt head, and, possibly, a new bolt body (Springfield Sporters has them, and, failing that, I'll check Sarco).
This rifle is such a nice one, and shoots so well, that I think it's worth the effort to 'optimize' it - the barrel is perfectly new, and all the other parts are either new or have been re-finished to appear so.

mhb - Mike

[JB White]

Mike, is this a Jovino import or a Jovino in-house build from spare parts? You never did show the rifle as far as I recall. What is the date and serial number alpha prefix?
Since you started gunsmithing on it I decided to step aside. If it's a collectible Lithgow you may want to stop. If it's a parts special then go ahead and learn all you can.

Just so you know where I stand. I'm not one that caters to all the "must do's" the target shooters insist upon doing to a surplus rifle. It's good to know though. If you plan on using the O-ring trick...save your money and use it. Don't bother with all kinds of new parts for this and that.

[bigedp51]

bigedp51 can I ask what O ring you are using. I use dental floss but its kind of a pain. I got some black O rings from the auto parts store once but for some reason after a few firings they broke so how the dental floss got introduced. I will add it works in all but one Ishy. That one blows the case mouth open much further. Since the bore is in really good shape I think it was how it was cut (over cut) at the factory.

I worked on aircraft and had access to small hydraulic system o-rings and my supply is going down. But just use the smallest o-ring you can find and lube the bolt lugs to prevent lug wear.

I remove the extractor when fire forming because it cuts into the o-ring. With the extractor removed the o-ring lasts forever, and I use my fingernail to flick the case out of the chamber.

I highly recommend using Prvi Partizan brass, it has thicker rims, thicker case walls in the base and has a larger base diameter.

[Parashooter]

Don't get hung up on finding and buying O-rings if you don't have a supply on hand. There are plenty of other ways to do the job, some of which are very low-cost like this old fishing line.


(Ed, it's still not "weedwhacker" cord.)

[mhb]

JB:

I did say it is a Jovino gun, but neglected to state that it is apparently one of those built-up from spares. The receiver is dated 1943, while the stock parts are 1942. The serial number is 771A, which is one of the series applied by Jovino, as I understand it.
It looks good, and shoots so well, that it is an irritant to have excessive headspace. I bought the rifle as a shooter, and would much prefer to have its mechanical aspects up to spec., and avoid the need to resort to dodges to save the brass for reloading.
It appears possible to correct the problem with new parts, and I'm going to try that.

mhb - Mike

[JB White]

Mike, the A suffix sums it up as would a prefix of G or higher. It's a spare parts rifle so no harm is being done. Have at it!

Keep in mind the chamber itself is oversized. Even though the headspace can be reduced to help save the web area, thin and undersized commercial brass is still going to stretch quite a bit.

[mhb]

JB:

Thanks, again!
FWIW, I have shot it with my customary mild load, and bulging was not very noticeable - no worse than in my #4, which was FTR'd in 1948.
I'm gonna keep after this thing until it's as 'right' as I can make it.

mhb - MIke

[bigedp51]

Don't get hung up on finding and buying O-rings if you don't have a supply on hand. There are plenty of other ways to do the job, some of which are very low-cost like this old fishing line.


(Ed, it's still not "weedwhacker" cord.)

You forget Parashooter in your first headspace 101 you told the readers to lube their cases to fire form them. I told everyone that lubing cases increased bolt thrust and should not lube their cases.
You didn't change your headspace 101 to weed wacker/fishing line until I posted this from the 1929 British Textbook of small arms.



And rubber o-rings are used for two reasons.
1. They hold the case against the boltface to prevent the case from stretching.
2. When the rubber o-ring is compressed it centers the rear of the case in the chamber. Meaning the case does not just lay in the bottom of the chamber and warp when fired.

Your thick weed wacker/fishing line does not compress and center the case like a rubber o-ring would and being harder increases lug wear. The rubber o-ring trick has been around for a very long time and works. And your weed wacker/fishing line idea died at birth and wasn't a good idea, and you just used it because I promoted the rubber o-ring method and you wanted to be different. And the problem is your idea never caught on and your the only one in the world who uses weed wacker/fishing line.

Signed
bigedp51 the non case greaser

Below is from the H.P. White Testing Laboratory and why you should never lube your cartridge cases that greatly increases bolt thrust.

"1.4 Failure of a gun assembly from internal pressure may be from either
of two (2) failure mechanisms.

1.4.1 The general perception is that those failures are the result
of a single exposure to a CATASTROPHIC PRESSURE level. This
may be an over simplification in that the strength of the
assembly may have been degraded by previous repeated exposures
to excessive, but lesser, levels of pressure whose cumulative
effect is to reduce the ultimate strength of the assembly.

1.4.2 Repeated exposure to pressures which exceed the elastic limit
of a material will continually reduce the ultimate strength of
the material until the ultimate strength is exceeded by a
relatively low pressure level causing fatigue failure."

[p246]

Thanks bidedp51 for the info.