Sunday, March 29, 2009

Hand loading the .303 British: Sizing concerns

.
Headspace, (in a firearm, not a teenager) refers to the distance between the base of the cartridge and the head of the bolt. It can also refer to the index point on the cartridge that contacts the chamber, and controls how far into the chamber the round is inserted. With a rimless straight wall cartridge (.45 acp), the round usually headspaces on the front lip of the case. On a rimless bottleneck rifle cartridge (.223 ect) the cartidge headspaces on the shoulder.

The .303 British is a rimmed cartridge, and headspaces from the rim
of the cartridge, not the shoulder. This is a carryover from an age when all rifle cartridges were rimmed, when positive extraction took precedence over other considerations. Developed during the 1880's, the.303 British is a venerable old design, but can be a bit persnickety at times.

Military rifles chambered for the round can, and often do, have large chambers of unusu
al dimensions. The chambers were often large on purpose, as fouling and dirt can close those dimensions in a hurry during military operations. Despite that these rifles will function fine and shoot with decent military accuracy despite the chamber tolerance.

The idea of an over sized chamber actually has some good thought behind it, at least with rimmed rounds such as the .303. A chamber a bit over sized makes the rifle much less fussy about manufacturing variances in the ammunition. During a war time rush, this could be critical. Also consider, the British empire had armories on several continents at once, and tolerances sometimes had to be loose to make the ammo from colony 'A' fit the rifle from colony 'B'.

Military forces are not concerned with reloading their cases, with the possible exception of elite folks like the US Army Marksmanship Unit, where extreme accuracy is the stock in trade. For regular armed forces, it's going to be new mad
e ammunition every time, and what happens to the cartridge when it's fired is not really a consideration, as long as it works and is safe to the soldier. This leaves the civilian hand loader with some interesting technical issues to deal with, especially with the .303 British fired from a military Lee Enfield.

The .303 British cases shown are a military round (Greek HXP), a case fired from an Enfield No4MkII, and the same case ready to reload. Notice the fired case compared to the unfired case. This pushing of the shoulder forward is caused by the case expanding to fill the chamber. (click on the photos to enlarge).

This rifle is not worn out. In
fact, it appeared nearly unfired when acquired. The chamber is normal for an Enfield of this type. Case expansion in a Lee Enfield is not unusual, and therein lies the concerns for a hand loader.

When shooting factory loaded .303 ammunition, military or commercial, this large chamber makes no difference to the shooter. A Lee-Enfield owner who wishes to reload his cases had better pay attention to the phenomenon.

In resizing the case, the shooter has many choices. It's here the reloader can make or break his case life, and his accuracy, so choose wisely. When dealing with a rimmed cartridge like the .303, proper sizing can drastically effect case life and accuracy.

If full length sizing, care must be taken regarding setting this shoulder back and overworking the brass. On the other hand, if more than one .303 rifle is owned, then the fired case will sometimes only fit that chamber and no other unless it's fully sized. Hand loading owners of .303's usually segregate their cases by rifle. This applies to other rifles as well, but seems to really come into play with rimmed military rounds fired from military rifles. The Russian 7.62x54 is another prime example. Handloads that fit one rifle may not chamber in the next.

Perhaps the best policy, when loading rimmed cartridges to be used in elderly military rifles, is to segregate the cases by the rifle. Maintain a boxed set for each weapon, marked to the rifle by serial number or distinguishing factors. Then, reload those cases with the neck sizing method, or a full length sizing die which is backed off to leave the shoulder untouched. As long as the reloaded cartridge functions well, over working during sizing is not necessary and will shorten case life tremendously.

There is an opinion that the .303 is very hard on brass. Maybe, in some cases, it is. I believe the real culprit is not the rifle nor the cartridge, but the hand loading process. As for myself, my thirty year old .303 brass is on it's fifth or sixth loading with no issues apparent. Below-maximum pressure loads and careful sizing have given me .303 ammunition that functions well, is surprisingly accurate, and lasts as long as any other high power cartridge brass.

13 comments:

Anonymous said...

I seem to recall that the Bolt heads on these rifles came in different sizes and were easily replaceable to address this problem.Lee-Enfields are an early example of modular design in firearms and do what they were designed to do superbly well.

YeOldFurt said...

What about annealing case necks? Or maybe an article on "improving" 03A3 sights for older eyes? I like the peep rear but it's a little small for me. Got my first buck with a 303.
YeOldFurt

Carteach0 said...

Anon, you are correct! The replaceable bolt head to correct head space issues was a brilliant idea.

Carteach0 said...

YeOldFurt,

Hmm.... I can do one on annealing case necks, and I have a set of cases that should have it done, too. That just might happen.

Improving O3A3 sights? If I had one... if I only had one (g).

Barry said...

This is exactley what I do for my (3) 22 hornets. Brass is seperated by firearm and neck sizing only. I've gotten very long life on old brass by keeping it designated to a certain chamber, accurracy is phenominal.One can even go so far as to insert each round into the chamber in the same postion. (Mfg. mark always at 12 o'clock.) It's just my quirk.

Old NFO said...

Excellent post! Since I don't shoot anything of that class, I guess I just never thought of the issue... I do keep my .308 ammo separated for each rifle though, so by default I guess I've been doing it right! :-)

AKA Angrywhiteman said...

P. O. Ackley Handbook for Shooters and Reloaders, a two volume set has some really good data for reloaders. Not so much the load data, (somewhat dated by powder selections) as the where, why, and how of reloading and a good deal more.
I got mine through Brownell's and I think Midway also has them. I recomend them to any who wish to dig a little deeper into the subject.

Kevin said...

One of the weak points of the Lee-Enfield design is the fact that the locking lugs are at the back of the receiver, and not at the front of the bolt. This means that the entire receiver stretches, and it isn't perfectly elastic. Given the state of metallurgy at the time, it's not unusual for Enfield receivers to stretch to the point that even a #2 bolt head won't tighten up the headspace enough to prevent the bolt from closing on a "field" gauge. I have a #5 Mk. 1 in that condition. It's a wall-hanger.

Neck-sizing is the only thing I recommend, but as you say, then you have to segregate your ammo by rifle.

My first long-gun was a No. 4 Mk. 1* Savage, and I've purchased a couple more No. 4's and another No. 5 that I can shoot. I'm a cock-on-close enthusiast because of that first No. 4. It just makes more sense to me to put all the effort of lifting the bolt into opening the action rather than cocking it.

TJP said...

Kevin said...
"One of the weak points of the Lee-Enfield design is the fact that the locking lugs are at the back of the receiver, and not at the front of the bolt."

Yes, it does not have the mechanical advantage of having TWO lugs immediately at the rear of the chamber. That's why the receiver is so huge and heavy. However, the design is more than sufficient to handle 49,000 psi of the 7.7 round, and the thicker Ishapore 2A is more than sufficient to handle the 50,000 psi of 7.62 NATO.

I don't understand why so many people complain about this. Are they rechambering in Winchester Short Mags and blowing up their rifles? Every .17 rimfire, .22 rimfire and 22 Hornet bolt rifle I've ever handled was an asymmetrical rear-locker, and no one complains about them. Probably because the design is appropriate for the cartridge.


"This means that the entire receiver stretches, and it isn't perfectly elastic."

How many rounds are we talking here, and at what pressure? If the steel is that close to its elastic limit, all surplus LEs would have a bowed bolt, and a bump on the left side of the receiver. That's because there is only one lug, and it's at the rear-right. The only photographic evidence of a Lee-Enfield KABOOM! that I've ever viewed failed in this manner: the bolt had bowed (to the shooter's left) so far that it snapped in the middle, fractured the receiver, and supposedly sent chunks of wood into the user's arm.


"Given the state of metallurgy at the time, it's not unusual for Enfield receivers to stretch to the point that even a #2 bolt head won't tighten up the headspace enough to prevent the bolt from closing on a "field" gauge.."

Although older LE rifles had threaded bolt heads, the numbering system came along with the No.4. By this time, modern hardening techniques and modern steels were in use. (The older No.1s had a case-hardened bolt head which, along with the body, was much thicker.) The purpose of the standard bolt head lengths was to eliminate the labor cost of hand fitting the parts for proper headspace--which, by the way, was purposely made generous enough to allow room for "an extra pair of dry socks."

If the gun closes on .074" with a #2, there's always a #3. But wait! There aren't any floating around, because there was so much hyperventilating that everyone with a headspace over .067" wiped out the world's supply of #2 and #3 bolt heads, along with the strategic paper lunch bag reserve. I have no actual evidence of this, but the market being what it is, I'm sure perfectly good rifles got short bolt head swaps so that the longer ones could be sold to people who put American SAAMI no-go gauges in British military rifles.

The stretching you need to worry about with excess headspace is case stretching. Military brass seems to hold up better. My Enfields headspace around .070", despite the fact that one is "pre-war", 18 years older, and well-used--having been in three countries in its 82-year history. And yes, my guns are harder on brass than a British au pair on a baby that just won't stop crying.


"I have a #5 Mk. 1 in that condition. It's a wall-hanger."

Considering the recent manufacture of the weapon, and the lack of popularity of a late-model, reduced-weight bolt rifle with the infamous "recoil concentrator", I'd judge you were likely a victim of bolt head swapping. (Or bolt-swapping; do the numbers match?) Unless your weapon's headspace drastically changed from the day you bought it--in that case, it's a very interesting rifle. Or maybe you really got screwed and ended up with a counterfeit No.5 or a parts gun?


p.s. I neck size, segregate by rifle, and the only time I FL-size is when I grab someone else's once-fired brass, or when I prep new brass.

Ed Foster said...

Much of the "flex" in the Lee-Enfield is the bolt head moving back on it's thread while under load.

I recall seeing hardened washers that would fit behind the bolthead, transferrint the compressive load directly to the body.

The master of all things Enfield is a gent named Ellwood Epps up in Canada. I hope he's still around. A great gunsmith, and a grand gentleman with many amazing stories.

Carteach0 said...

Ed,

I recall hearing of 'Epps' prepped Enfield target rifles cleaning the field back in the day. I too wonder if he's still around.

Weapons said...

This is a fantastic explanation. Thanks. I'm passing it along.

Anonymous said...

Sad to say, Ellwood Epps passed away a few years ago. He was a true expert when it came to guns and many outdoors activities.