Is a British No. 4 Mk. I, or any within the series, oversize chamber fixable?

[Naphtali]

I have noticed that most No. 4 Mk. I series rifles have "wartime" barrel chambers. Probably for a shooting war this is useful. For civilian, for reloader's use this feature not not so useful. It eats brass. One solution is to rebarrel - kind've expensive.

Is it feasible AND economical to turn off an [unknown by me] amount of chamber, then rechamber properly?
- Do barrels have sufficient diameter forward of chamber to allow rechambering?

- How expensive is it to rechamber, rethread (or add thread), and cut chamber's mouth for bolt head compared with rebarreling?

- Are commercial barrels available? While I would not expect ease of rebarreling common for Mauser M1898s, rebarreling might not be nightmarish?

- Is there a "tried-and-true" method for economically fixing such chambers? I specifically do not mean letting severely bulged brass be neck sized only as an acceptable "fix."

[lefty o]

there are different length bolt heads available. its been a while but if i remember correctly the higher number bolt head the longer it is. in other words if you have a 0 head, try a 1,2, or 3.

[Blackwater]

Another solution is to just neck size cases. This is what many do in these rifles, and I once had an old Hornet that had excessive headspace, and just neck sizing the cases helped tremendously with my case life. That Hornet brass is so thin it's really easy to get splits, and if it fixed that, with its very gentle shoulder angle, it should work with the .303. I think Lee offers a single neck sizer die for it, but don't trust my memory. That's what I'd do first. And being a brass hoarder, case life is a big issue with me.

And BTW, FWIW, I also adjust my sizer dies for most of my guns so that a sized case will just fit the chamber when FL sized. I just take a case, back the sizer out, and run it down in increments until it'll just chamber (the empty case) in the rifle with a little "feel" on the bolt knob as it's mashed downward to close it. This also prolongs case life, and I've heard it's particularly useful for prolonging case life in the belted magnums, too, but haven't done enough of the belted cases to provide any testimonials on that. Just size the cases the bare minimum to get them to chamber, and it's likely that your case life should be significantly longer. Don't push that shoulder back to std. factory dimensions, but just size the neck, and when you have to resize, push it back just enough to chamber again. It's a slow, cut and try process, but usually yields good results.

[Ragnarok]

Ehh?...The chambers on those are cut deep yet headspace on the rim. As in the case shoulder is blown considerably forward on the No.4 and No.5 rifles/carbines. About all you can do with the factory chamber is neck-size your cases. I do own a 1918 vintage No.1 Mk.III and it has a more 'normal' chamber that leaves you with a reloadable spent brass. This what Naphtali wants to see....it ain't a headspace issue..it's a really deep chamber issue....

I imagine a good barrel-smith could cut the barrel back, rethread and rechamber. Probably be about as cheap to have a new Criterion barrel installed and properly chambered.

[Ballistics in Scotland]

It is indeed possible to adjust the headspace, and it might do a little good to the brass life problem, but it is only the small end of a solution. Neck sizing, leaving the body unsized or bumping the shoulder very slightly back, is better, but not a perfect answer in this springy action. A lot of American brass is undersize at the head, and forming cases from .30-40 Krag might be of some help.

The perfect solution, other than serious gunsmithing, would be to obtain or have made a FL die which mimics there width of the military chamber, and perhaps (though with less importance) its slightly rounded shoulder. That would be expensive if nobody makes such a thing, the best thing being a reamer from one of the major chamber reamer makers (though with a smaller neck diameter than a chamber.)

It might or might not be possible to set back the barrel enough to cut a normal chamber. To determine which, the best way is to make a and measure a chamber cast with Cerrosafe or car body filler, and plot the sizes on a piece of old-fashioned graph paper. There is a rarely seen National Special 1in. x 14 die which can be used to extend the existing barrel threauld d. I have seen it done and prove reliable with nothing but file work, using feeler gauges and the hardened steel die as a guide. It would have 60 degree V-threads while the Lee-Enfield thread has the 55 degree Whitworth thread form. But American gunsmiths habitually mate up these different angle threads, and it works as long as they are screwed up tightly.

[Frank46]

I've read a couple articles whereby the author set the barrel back one thread and rechambering. But have concerns about the diameter of chamber either before or after the rechambering. I still wonder to this day about the 1914 U.S. made rifles though. You rarely hear about gross headspacing with them. The one P14 I had was good to go regarding headspace. And I do realize that British enfields were chambered so as to allow dirty or rough ammo. Another wonderment regarding the British enfields is that I've never heard or read about someone taking a 1914 barrel and fitting it to one of the British enfields. Frank

[Ballistics in Scotland]

It could be done, and P14 barrels are generally good quality, nicely contoured ones. But it would involve just the same work as rethreading any other rifle barrel to a smaller thread diameter. The Lee-Enfields used the same 1in. x 14, 55 degree Whitworth-form V-thread as the Martini-Henry, and I believe (though don't lay out money on this strength of belief) on the Snider conversion of the Enfield muzzle-loader. The American-made P14 and the M1917 adaptation for American use had a 1⅛in. square thread.

The early Lee-Enfields had a pretty good chamber shape and groove diameter. I have taken a chamber cast from a Long Lee-Enfield dated 1897 in which both were as good as you could wish for. I don't know if the change was made during the service life of the SMLE, which was routinely used in about as foul conditions as any rifle ever has been. But it is mostly in the No4 that we hear of the oversized chambers.

The explanation for excessive groove diameters is pretty clear. In large-scale production the rifling tool had to be resharpened, and finally replaced. With the old type, which rifled one groove at a time with many passes of slowly increasing depth. A little bit of reduction by resharpening can be taken up with adjustment. But in WW2 this was largely replaced by a pushed or pulled broach, rather like this but rifling shaped, with the twist built in.

http://www.ebay.com/itm/Round-Serration-Spline-Pull-Broach-30-Overall-Length-0-6975-Diameter-/380637860950?hash=item589fc8d456:g:VY8AAOxyyUtSbyd y

This would rifle a barrel, not to the highest standard but usually well enough, in a single pass. But it was expensive, and the diameter couldn't be adjusted. Sharpening reduced the groove diameter, so it paid to start with it oversized.

Setting back the chamber by one thread wouldn't be quite enough to completely cure some chambers I know about. Two threads is more likely but not certain to do so. Both will make some improvement, and can do no harm f you think it is worth the trouble. Two should be the maximum. The same thread, 0.088in shorter and more cut away by extractor slots, was used on the Martini-Henry, to which .303 barrels were fitted on a large scale.

[Frank46]

Ballistics in Scotland. Thanks for the information. I suspect the generous chambers in the MkI #3's came about with the British experiences in WWI what with the conditions in which those battles were fought. But have never seen anything in print to qualify that statement. If that were the case then it would seem logical as to have been carried over when the #4 series of rifles were introduced. I've always wanted to take a 1914 .303 barrel and have it fitted to a #4 action and see what happens. Someday maybe. Thanks again,Frank

[leadman]

I use a Lee Collet Die for my 303 reloading. This has let me use the brass for at least 5 loadings, but I reload with boolits and around 1,600 to 1,800 fps. My #4 MKII has a decent chamber on it but my 2 groove Savage #4 MKI is somewhat larger in the chamber.

[screwcutter]

I have monkey'd with 3 No.4 barrels, put a No. 1 barrel on a No.4 I* set back half turn,
set back a 2 groove Savage barrel 1 turn and another back a turn & half. My Clymer reamer
is still new! the chambers are still on the large side.
I have not heard about how the chambers are on the Criterion barrels but they are spendy,
I'd like to try one.
Privi brass and ammo measure the biggest, I have tried the 30-40, but they appear to be
the same size as 303. I have a MK II with a nice bore and a large chamber, I am trying
brass formed from Hornady 405 Win.
Here is a pic, 405 on the left & Privi fire formed with O ring on right.
157618

[BigEyeBob]

I have noticed that most No. 4 Mk. I series rifles have "wartime" barrel chambers. Probably for a shooting war this is useful. For civilian, for reloader's use this feature not not so useful. It eats brass. One solution is to rebarrel - kind've expensive.

Is it feasible AND economical to turn off an [unknown by me] amount of chamber, then rechamber properly?
- Do barrels have sufficient diameter forward of chamber to allow rechambering?

- How expensive is it to rechamber, rethread (or add thread), and cut chamber's mouth for bolt head compared with rebarreling?

- Are commercial barrels available? While I would not expect ease of rebarreling common for Mauser M1898s, rebarreling might not be nightmarish?

- Is there a "tried-and-true" method for economically fixing such chambers? I specifically do not mean letting severely bulged brass be neck sized only as an acceptable "fix."

The chamber would be cut to the British specification so I doubt it's over size. Chances are that the brass you are using is made to SAAMI spec which is not correct for the 303 British chamber . If you insist on American made brass you will always have problems because it's way under size ,and the last lot of Winchester brass I ran the micrometer over was even undersized for SAAMI specs. Its the brass that needs" fixing " , not the chamber. I gave up on American made 303 brass ages ago and tossed all the Winchester and Remington 303 brass in my dead brass bin and then sold it to the scrap metal bloke.Never tried Hornady brass but I suspect its the same as the other stuff. I use PPU brass exclusively because its made closer to the British spec.
I have 4 MKIII's ( 2 x 25/303 2 x 303Brit) ,a Lee Metford (303Brit) and a M96 (25/303) and a K98(270/303 ) and use PPU brass in all of them
I neck size only and have set my brass up to head space on the shoulder rather than the rim.
To head space on the shoulder you need some "O"rings about a 1mm or less in cross section and that fit the case head right in front of the rim ,you place one of these on a loaded the case and roll them down to sit in the front of the rim. Chamber the cartridge , and you will feel resistance but you should be able to close the bolt
fire the cartridge eject the case and place the fired case back in the rifle and close the bolt ,there should be some resistance or possibly it wont close .
Set up your fl size die so it just sizes the neck and size it down to the shoulder ,and try to chamber it again . If it doesn't chamber set your die down a fraction more and try again ,keep trying until it chambers with a very slight resistance on the bolt you at where you want it to be .
You can do the rest of the cases with the O ring and then size them in your die that is set up for that chamber.
I have used fishing line instead of O rings , I get a length of line and drag it over a knife edge , it makes it curl up like a spring , cut it up into single loops and use that in front of the rim .I took the extractor out of the bolt because it mangles the o rings , and used a cleaning rod to pop the fired case out of the chamber.

Lothar Walther does 303 barrel replacements for MKIII and possibly the No4 , very pricey and are probably cut to British specs so you may be no better off with a new barrel anyway.
I have one of my MKIII's that has had one complete thread machined off the chamber end and had the extractor groove recut , known here in Oz as a 7.7 x54R ,this was a conversion done to get around a ridiculous law concerning military rifle in civilian hands . A standard 303Brit cartridge wont chamber , but if you trim 2 mm from the case it chambers. You use the same load data as a normal 303 .I doubt this would help you though .

CH4D will make custom dies , I believe you need to send some fired cases to them so they can make the dies to your chamber specs . I also beleive that Lee also offer this service . Much cheaper option than friggin about with barrels and chambers. If you want a recessed bolt head , look for a P14 Enfield in 303 or a Mauser 98 chambered for 303 .

[EDG]

Actually US brass meets the standards that exist for both SAAMI and CIP. The trouble is no one can produce the standard that the British used. That standard would be fully dimensioned and toleranced drawings for both the cartridge and the chamber. I think the original British standard was appropriate for US size brass before WWI. I think the fiasco in the trenches resulted in the chambers being enlarged for the marginal ammo produced back then.

The best way to deal with it at this time is to use PPU brass which measures .454 to .455 diameter on the case head just ahead of the rim.
If you don't need a lot of brass you can form it from .405 Win brass too. But that brass is very expensive and difficult to find.
You don't really need custom dies - just get a Lee FL sizer and put it in a lathe and polish the base of the die opening out until it is about .003 smaller than your chamber. Check your work with a small hole gauge and a micrometer or just use a set of .001 increment pins.

Criterion in Germantown, Wisconsin is manufacturing new #4 barrels. However if they normally manufacture them with the same huge British chamber then I would try to get an unchambered barrel and buy a custom reamer. Domestic US or PPU brass is about the only only game in town.


http://criterionbarrels.com/barrels/lee-enfield (http://criterionbarrels.com/barrels/lee-enfield)




There is some restriction on owning rifles chambered for military round in France so they seem to have an entire group of what I call short cats where they use a shortened chamber very of a cartridge to enable the use of what would otherwise be prohibited rifles.

The French version of the .303 is called the .303 Sporting.

http://i51.photobucket.com/albums/f392/Duncaninfrance/303--303-Sporting-web.jpg

[Frank46]

Don't remember the magazine but think it was Precision Shooting and they mentioned that PTG had a 303 match chamber reamer. And that one of the authors for the same magazine had done a #4 in 30-40 Krag. Frank

[EDG]

I have made a few .303 cases from both .444 Marlin and .405 Win.
Both can be made to work but with the Obama component hoarding going on neither are readily available or affordable.

.444 Marlin -
The head is about .466 so it has to have the head reduced to .459 to .4595. I cracked (2) .44 Mag steel sizers forming the case heads.
If some of your cases bind at the head you may have to turn or polish the head down to fit your chamber.
Ideally you should get an extra FL .303 sizer and polish the base out in a lathe following the original taper to give you a sizer that does not size the base too much when you form the case. Size it to headspace on the shoulder. I did not have to turn the case necks.

.405 Win
The head is about .460. This case is easier to form than the .444 but it is too thick in the neck so the necks have to be turned after case forming.
My rifle has a #2 bolt head and some .405 rims are too thick. You MIGHT need to thin the rims depending on your rims and your brass. If you don't want to thin the rims you can switch to a shorter bolt head.

Be sure to anneal the necks and shoulders to make your cases last after all that work.

SAAMI drawings for the chamber show that the .303 body has .032" taper per inch.
My chamber is .460" at the face of the rim. To reduce my chamber to .454" I would have to reduce the length of the chamber by (.006/.032) = 3/16" or .1875" or about 2 full threads (11 TPI X 2 turns) or about .1818. Then I would have to ream the chamber with a custom reamer. Or you could try to sleeve the chamber or just rebarrel the rifle and use a custom reamer.
One way to deal with the chamber would be to buy a big lot of new brass of your choice and buy a reamer that produces a close fit chamber.
If your reloading dies do not work with the new chamber then you may need to work on the dies or have custom dies made. Use the new reamer to chamber a new barrel. While you are at it consider using a .308 barrel so you have a better choice of bullets. You will be handloading anyway.



I have monkey'd with 3 No.4 barrels, put a No. 1 barrel on a No.4 I* set back half turn,
set back a 2 groove Savage barrel 1 turn and another back a turn & half. My Clymer reamer
is still new! the chambers are still on the large side.
I have not heard about how the chambers are on the Criterion barrels but they are spendy,
I'd like to try one.
Privi brass and ammo measure the biggest, I have tried the 30-40, but they appear to be
the same size as 303. I have a MK II with a nice bore and a large chamber, I am trying
brass formed from Hornady 405 Win.
Here is a pic, 405 on the left & Privi fire formed with O ring on right.
157618

[W.R.Buchanan]

Correct answers were stated in posts#3,4 and 9. Unless you have a new barrel chambered exactly to the .303 drawings you are going to get an "Oversized Chamber." They were made that way on purpose.

They were made that way to accommodate ammo from a variety of sources not generally directly controlled by the Crown. Also since the military was only firing Factory Loaded Ammo nobody cared if the cases were smaller than the chamber. Since it headspaces on the rim whatever happens in front of that is of no consequence.

Dirty ammo was another factor to contend with.

If you use a Lee Collet Neck Sizing Die to Neck Size your fire formed brass, all of your problems will magically disappear.

See Pic : The round on the right is an unfired PPU Factory load. The right is Fire Formed to my chamber with a new bullet.

My #4 Mk1 moves the shoulder forward about .020 and sharpens the angle to around 45 degrees however it doesn't change the length of the neck at all. Once this is done, neck sizing does not disturb the shoulder and the round goes right back in where it came out of after it is reloaded. Also note that the case appears to be fuller at the shoulder. It is in fact .008 larger than before firing. Point here is the fact that there was plenty of room for the unfired cartridge to enter the chamber with no obstruction whatsoever. You will find your reloaded and neck sized cartridges will go right back in the hole with no resistance to,,, they will simply fit the hole better than they did originally.

Incidentally SGA Ammo in OK is a good source for Privi-Partisan Ammo. $13-14 / box.

There is absolutely no need to rechamber one of these barrels and there is nothing to be gained by doing it.

Randy

[Outpost75]

This Winchester drawing from 1940 is what my reamer was ground to. The microfiche print is not really clear, but I think the critical dimensions are at least readable. Compare the max. cartridge and min. chamber dimensions and you can see how much shoulder blow-forward was considered "normal."

158133158134

[MtGun44]

Neck sizing so it headspaces on the shoulder seems to work in a lot
of milsurps.

Bill

[egg250]

I scanned the thread, I think the oversize chamber question has been answered. If you are still concerned and don't reload your ammo, you can look for the larger bolt head for the headspace issue. If the diameter of the chamber is the concern you should plan for a re-barrel job. That military barrel will likely not come cleanly out of the action and I don't think you'll find a gunsmith willing to make the attempt.

[EDG]

Some chambers are even sorrier having a radius at the shoulder that terminates at 90 degrees to the neck. The forward location of the shoulder does contribute to case stretching. You can even separate cases made from 30-40 Krag brass when you fire them the first time.
If you are rebarreling a .303 there is something to gain by cutting a better chamber.

If you do not use PPU brass then a better chamber is of some advantage with brass that has a smaller head.
If you buy once fired .303 brass you will find partially separated cases when the case was fired the first time as factory ammo. The first time I saw this was with some Norma cases that I bought nearly 50 years ago and I have seen it since then with other brands.

All the crown had to do to control the ammo was to put tolerances on the drawings and reject ammo that did not meet the drawings.
The drawings are part of the legal requirements of a contract.



There is absolutely no need to rechamber one of these barrels and there is nothing to be gained by doing it.

Randy

[EDG]

This drawing has 6 revisions in the history block and the latest is dated 1953.
The 3-1-41 change (ditto marks) permitted the case head to be larger >>was .4572 changed to >>>is .4591

The original format of these drawing is more clearly understood if the cartridge drawing is on top of the chamber drawing on your screen.

You really cannot compare the worst case clearance condition because the maximum chamber and the minimum cartridge dimensions are not given and the drawing is not toleranced. All you are given are the best case conditions which is a min chamber and max cartridge.

The numbers show that the shoulder blows forward by only .0107 when in reality in many chambers with some brass it is more like .035.


This Winchester drawing from 1940 is what my reamer was ground to. The microfiche print is not really clear, but I think the critical dimensions are at least readable. Compare the max. cartridge and min. chamber dimensions and you can see how much shoulder blow-forward was considered "normal."

158133158134

[Outpost75]

EDG thanks for the explanation of the revisions. I hadn't looked at this in a LONG time!

In the several .303s which I have owned and still owned, chamber base diameter has never been an issue, but the head-to-shoulder distance and shoulder profiles seem to vary, some wartime British barrels not having the 24 deg. 50 minute angle at all, but instead a double-radius shoulder with the head to neck dimension being as long as 1.90", which is VERY hard on brass unless is neck sized only.

My Cdn. Long Branch No.4 chamber cast measures very close to this drawing and the JGS reamer I bought to this print, cuts a chamber which shoots very well with the Sierra .311" 174-grain Matchking.

[W.R.Buchanan]

EDG: the headspace on a Enfield is .064-.074 (Bolt Face to End of Barrel) During wartime they increased the allowable to .064-.084 to insure that all or "most" ammo would work. Rim Thickness did vary considerably. They couldn't be too picky as they needed as much ammo as they could find. The ammo they had the most problems with came out of India and as a result chambers were enlarged slightly to cope with this. This "fix" worked simply because the brass was new and could take fire forming without failure. Also the actual case head goes pretty far up the case. When they separate they usually let go about 1/4" above the rim, and usually about 2-3 loadings when F/L sized.

My gun was made in 1943 and the barrel is pristine and a good shooter so the chamber is what was done by BSA Shirley at that time. You can see the difference between the unfired and fired cases above. The only reason this works is because of the Rimmed Cartridge, if it was Rimless like a .30-06 it wouldn't work at all.

Randy

[rondog]

I don't have the time, money, resources or patience to deal with this BS and my five Enfields. They're just not fun to shoot at all because of this and the variations in the barrels. Maybe I should just sell them all and get rifles I'll enjoy.....

[W.R.Buchanan]

Or you could just sell 4 of them, and keep the good one, and then you wouldn't have those problems.

These guns are a bit more challenging than most, and each one has to be figured out on its own. Trying to figure out 5 at once is a pretty big challenge.

When I hit a 500M Ram with mine offhand,,,, it is a pretty good feeling.

The level of Satisfaction is directly proportional to the level of the Challenge.

Randy

[abunaitoo]

I have a Ross rifle that has the hogged out chamber shoulder.
I was thinking about doing the "recut chamber and set back the barrel" fix.
Could never find anyone to do it.