303 British Chamber Diagram

[cprher]

Please point me towards an official chamber diagram for the Lee Enfield Rifle. If different depending on model/arsenal then I'm looking for the one used last for the No. 4 Mk 2 at Faz. I'm particularly interested in the dimensions of the neck, throat and lead.

I found this one with the help of Google. Anyone have a better one?



Thanks.
Keith

Information

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[Parashooter]

Seems you found one of my image compilations. Top portion is SAAMI. Bottom is from a UK military blueprint of the SMLE MkIII*. Not really much difference between the two - once one subtracts headspace from the SAAMI lengths.

Despite tales of wide variation, I find no significant difference between chambers of my 1943 Lithgow SMLE III* and 1953 ROF(F) No.4 Mk.2. Fired cases interchange perfectly and shoot the same loads with comparable accuracy. Fired cases also interchange in my ROF(F) No.5 Mk.1 - but accuracy isn't on par.

Are you planning to make a chamber reamer?

[cprher]

No, not a chamber reamer, but custom match bullets. The guy who is helping me is a bench rest guy and needed info on throat and lead to determine if the bullet design he has will work.
Keith

[Bruce_in_Oz]

The trick would be this:

1. If using "commercial" bullet forming equipment, such as supplied by Corbin, etc, go with a flat-based, hollow-point design.

2. Match the exterior profile of the "proper" Mk 7 bullet.

3. Select a core that will give correct weight for the finished bullet.

4. Don't bother with the aluminium / fibre "nose filler", just leave an air-space to "replicate" as best as possible, the "base-heavy" balance.

Some "fiddling" will be involves as the original jackets are a bit thicker than many modern "sporting" jackets.

The key characteristics are:

Overall length

Total weight

Balance

And, of course, diameter. On this last item. give serious thought to a nominal diameter of 0.3125" instead of the "usual" 0.311".

Final "touch" would be to slightly "dish" the VERY flat base: ABSOLUTELY NO boat-tails.

Get the profile / shape wrong and they will not seat or feed correctly. Neither will they come close to tracking "original" exterior ballistics much past 200m.

Always remember: Any Lee Enfields (or P-14), and we can probably include the Ross, made much after 1912, and certainly post WW1 SMLEs, No4s and 5s, were built AROUND Mk7 ball. The rifles were tuned to the ammo,, not the other way 'round.

[rickv100]

In Corbin terms, you want a concave open base with base round over die set, 8.2 ogive

[Peter Laidler]

Wise words there from Bruce in Oz, (thread 4; last para.) that Armourers were told to ignore at their peril. That the BULLET is the weapon. The case and propellant are the means of moving it on its way and all the rifle does is to point it in the right direction and impart gyroscopic effect to aid its accuracy

[ireload2]

I have asked for official British ordinance drawings many times but I have never seen one. There are no drawings to date that dimension and tolerance both the chamber and cartridge.

I got all of the data used by a leading maker of reloading dies. All his data was from both commercial and military sources in the UK. None of the drawings were fit to manufacture anything.

I have once fired brass from probably a dozen different rifle #4 rifles and the chambers vary significantly.

[CINDERS]

Some other considerations;

1. Make the jacket thick as possible depending on material costs

2. The projie even made to the Mk VII spec's may not have the same ballistic properties of the original round Why - simple we do not use cordite any more and the differential in burn rates could or may send different harmonics along the barrel maybe not enough at say 100m but a 600m it could be a different POI than whats on the sight ladder so more range time to get the correct elev thats gotta be good for us all!

3. I would make them a FBHPSB at .312 as these girls are getting older the .312" obturates better as I found with two other types the 170gn FBHPSB Taipans and the 150gn Hornadys FBSPSB both at .312" and shot well out of all the ones I use at the range

4. Cost/round like all things we like they are getting more expensive so cost and freight come into play especially when you are interstate or o/seas

5. And I suppose it is coming as those that cuddle trees demand we have lead free projectiles as we are polluting the earth may be another consideration for future production

6. Why don't you contact Ian Skennerton or Brian Labudda or even try the Lithgow Museum and see what they can do for you some one will have something

[Bruce_in_Oz]

CNC turned solid bronze with several grooves to accommodate the metal displaced by the lands? Look, Ma; NO LEAD!!

Good point about the Cordite as well. It burns fairly quickly compared to modern ideas about "ideal" burn rates.

However, given that the U.S. and Canada made vast quantities of "Mk7" ball ammo, in BOTH world wars, What were they using to fill all those millions of rounds?

Some Canadian production used Cordite propellant and Mercuric primers, but to the best of my knowledge ALL U.S. production was fuelled by granulated, double-based Nitro-Cellulose propellants and ignited by lead-based Boxer primers.

And then there is the substantial output of .303 Ball and Tracer from the FN plant, especially post WW2. I suspect that they would have put some effort into matching "standard" Mk7 ballistics at least for the ball ammo, especially as much of this production was shipped in cases and packets labelled, "Pour BREN".

[Bruce_in_Oz]

I will dig around in the crypt.

Somewhere there should be complete drawings for SMLE and No4 barrels, complete with dimensions and tolerances for the chambers.