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| Case separations. Thin Winchester brass and full sizing are not the best idea for wartime .303 British chambers. |
I learned about the perils of full sizing twice fired .303 brass the hard way at the 2013 CMP Western Games. Had five case separations and a number of other incipient cases during the Vintage Military Rifle match. The gun was a Savage No.4 Mk1*, one of the British Lee-Enfield family of rifles popularly known as SMLE's.
When a rimmed cartridge like the .303 British fires, the main body of the case expands and locks to the chamber. The tail of the case is what expands and thrusts on the bolt stretching it. If you full size them, they separate. If the headspace is on the long side, maybe even on first firing.
The condition is not inherently dangerous. With a known safe powder charge what actually happens is the round comes out slower, barrel time is increased and with it recoil motion rotation. The round will impact high on the target. At 200 yards, around the top of the target frame above the scoring rings. This yields zero points for that record round. Do it five times and your score plummets.
Triage
When a rimmed cartridge like the .303 British fires, the main body of the case expands and locks to the chamber. The tail of the case is what expands and thrusts on the bolt stretching it. If you full size them, they separate. If the headspace is on the long side, maybe even on first firing.
The condition is not inherently dangerous. With a known safe powder charge what actually happens is the round comes out slower, barrel time is increased and with it recoil motion rotation. The round will impact high on the target. At 200 yards, around the top of the target frame above the scoring rings. This yields zero points for that record round. Do it five times and your score plummets.
Triage
I did finish the match digging out each separated case and carrying on. Never DNF if you can. The best learning often comes from debacles. True to form from the shooting community, info and advice appeared almost from the moment I stepped off the line.
I was offered insights by other competitors about the idiosyncrasies of managing .303 brass and how that differs from setting up other match ammunition. By nightfall that network of shooters had expanded globally over the internet with links galore. There is nothing as cool as being part of the high power community.
Old military chambers and bolt head spaces leave much to be desired. The voodoo magic trick with the .303 British is to use 7/16" o-rings serve to pre-thrust the bolt backwards on first firing so the case fire forms to the chamber enabling gun specific base to shoulder head spacing in future firings. In other words, it is wildcatting. Once fire formed, collet dies and the occasional body die to ease feeding take over from there. The literature says 10 or more firings. The cases are obviously married to that particular rifle for the duration.
I found the o-rings at the faucet replacement parts shelf at the hardware store. The reason to o-ring the first firing is so that when the case blows out to fill the chamber it does so flowing forward at the neck. If you don't do it this way, the case will still fire form but the normal way a .303 British round works with the main body expanding in the chamber pinning it to the case wall with the bottom of case taking all the movement as the bolt is thrust back on firing. The o-ring changes the dynamics of the fire forming process positively. Whoever originally figured this out was quite clever.
I found the o-rings at the faucet replacement parts shelf at the hardware store. The reason to o-ring the first firing is so that when the case blows out to fill the chamber it does so flowing forward at the neck. If you don't do it this way, the case will still fire form but the normal way a .303 British round works with the main body expanding in the chamber pinning it to the case wall with the bottom of case taking all the movement as the bolt is thrust back on firing. The o-ring changes the dynamics of the fire forming process positively. Whoever originally figured this out was quite clever.
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| Fixings. A Redding body die for bumping the shoulders from time to time. A Lee Collet die for neck sizing most of time. O-rings for centering cases for fire forming. European brass with thicker case webs. |
The literature says to make things a little easier on the brass by tightening the head space of the UK military "work in any dirt" to something closer to SAAMI spec. I tested a couple of my rifles. Both close on a SAAMI NO GO gauge which is expected with a military gun. One I tested did not close on a FIELD gauge. The other - the one I use for CMP Vintage Military Rifle matches - did close on the FIELD gauge. Later model No.4's adjust head space easily by changing bolt heads; a remarkable innovation really. Mine both have #0 heads. I ordered some #1's from SARCO. They once came in #2 and #3 sizes as well but those are long gone. If I can get my guns to close on GO and not on NO GO cool. But I'm fine with just not closing on FIELD and using the o-ring fire forming method to marry the brass to the gun.
Improving the Head Space
By installing a #1 bolt head into the bolt body, I was able to get the rifle to barely touch a SAAMI FIELD gauge. The improvement just by doing this was dramatic. The photo below shows where the bolt stops when closing onto one of the cases I fired in Phoenix out of the same gun. Definitely an improvement in the head space.
I also compared bolt bodies with some other No.4's and found that the lug dimensions on some are longer than others; probably manufacturing differences. These old Enfield rifles - like many surplus guns - are very often mismatched parts guns as the years go by and the idea struck me that perhaps replacing the bolt body in this particular rifle might be a way to improve head space even more without having to stalk the online auctions for the elusive #2 and #3 bolt heads.
Gracious Elves
So I put in an online order to U.S. parts supplier SARCO for a bolt body with a note in the comments section requesting one on the longish side if possible. To my surprise and delight, I got an email back from them asking for clarification of what I was looking for. I wrote back explaining my plight about only being able to get to barely closing on a FIELD gauge with a #1 bolt head and my hope that a longer bolt body might improve the head space further. The next email I got from them said they had rummaged their entire parts bin of No.4 bolt bodies and were sending me the longest lugged one they could find. I cannot tell you how grateful I am that a mail order company would go to this trouble for a customer. The people at SARCO are awesome.
Improving the Head Space
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| Head space gauges and bolt heads. There used to be 0's, 1's, 2's and 3's. Today you're more likely to catch a unicorn under a rainbow than find a 2 or 3 bolt head. |
By installing a #1 bolt head into the bolt body, I was able to get the rifle to barely touch a SAAMI FIELD gauge. The improvement just by doing this was dramatic. The photo below shows where the bolt stops when closing onto one of the cases I fired in Phoenix out of the same gun. Definitely an improvement in the head space.
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| Quite a difference changing the bolt head makes. |
I also compared bolt bodies with some other No.4's and found that the lug dimensions on some are longer than others; probably manufacturing differences. These old Enfield rifles - like many surplus guns - are very often mismatched parts guns as the years go by and the idea struck me that perhaps replacing the bolt body in this particular rifle might be a way to improve head space even more without having to stalk the online auctions for the elusive #2 and #3 bolt heads.
Gracious Elves
So I put in an online order to U.S. parts supplier SARCO for a bolt body with a note in the comments section requesting one on the longish side if possible. To my surprise and delight, I got an email back from them asking for clarification of what I was looking for. I wrote back explaining my plight about only being able to get to barely closing on a FIELD gauge with a #1 bolt head and my hope that a longer bolt body might improve the head space further. The next email I got from them said they had rummaged their entire parts bin of No.4 bolt bodies and were sending me the longest lugged one they could find. I cannot tell you how grateful I am that a mail order company would go to this trouble for a customer. The people at SARCO are awesome.
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| Bolt bodies differ in length. This offers another path to solving head space issues. |
The replacement bolt body was indeed longer lugged; visibly so even when holding the two side by side. So much so that I had to go back to the #0 bolt head. The rifle now closes on a GO gauge and as the photo below shows, barely touches but does not quite close on a NO GO gauge. That friends, is what one calls good as new!
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| Mix and match. A longer bolt body an a 0 bolt head got this rifle back into the sweet spot. |
Proving the Pudding
This is a standard NRA SR target at 200 yards shot using 174 gr. Sierra Match King ammunition with a conservative charge of Hodgdon H4895 powder. Ignore the shots in the shoot and see sticker. Those are just me touching up the zero on another scoped rifle for an upcoming match mid-range match. The real gem in this photo is that group in the white area. It was shot using this Enfield with the fixed up head space. Iron sights in fading afternoon light. A blind run string just to see if it groups. And how! I'll tinker with front sight blades and micrometer settings to center up the group later. For now seeing that it will print 10/X ring is good news.
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| 1 1/2 MOA is not bad for military surplus machine bought out of a forgotten rifles bin in the 1970's |
My main reason for test firing the gun was to collect an updated set of brass casings to measure to begin to load better ammunition. Below is the product so far. The case on the right is the unfired .303 British reference. The one on the left is the one mated to this specific rifle. Notice that the body and shoulder have fire formed to fill in more of the chamber. The case has been processed using a Redding body die to bump the shoulder just enough to make feeding smooth. A neck size die takes care of the rest.
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| Fire formed case on the left. That shoulder filled in quite a bit. |
That's where we are at for now. Waiting for a taller sight blade. Then I'll re-zero the rifle and run test sets of both neck sized and first firing ammunition through it to check both accuracy and feeding. Will update the article again after that.
Update:
The rifle has since gone to the range to be fitted with a properly centered and height selected front sight blade for the ammunition I'll be using in competition.
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| Setting up a better mechanical zero for CMP competition on 200 yard targets. |
Armorer time again. The front sight blades came from the U.K. The front sight/firing pin tool came from Numrich. Makes it easier when tools and parts come together.
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| Front sight tool and a selection of blades. |
Next comes making neck sized ammunition and checking to see how the cases fare fired from the rifle much closer to the shape of the chamber.
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| Quite the change from the first photo. Left to right, a full sized loaded round, a neck sized loaded round, and four test fired empty cases. |
So far, so good. Sample cases made from firing rounds made from both Winchester and PMP cases look promising. The cases do not appear to grow, bulge or show signs of incipient separation. Shots remain in the 10 ring so the rifle is still shooting acceptably for competition use. Hodgdon H4985 looks to be a very good powder for .303 ammo. Time to load up enough to shoot two or three practice matches and give it a go.
I will yet get my coveted CMP achievement pins and medals with my Made in the USA Savage No.4 Mk1* to go with the other kinds I've already collected.
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