Brittish Enfield 303 No4 Mk1 - Case Separation

[ping]

I have a Enfield 303 No4 Mk1 with 5 groove. It is in really good shape and just started reloading for it. I really need some help. I just started reloading for this rifle and went to the range this weekend. I shot 40 rounds that I reloaded and had 8 of these separate. Base part of cardtridge from rest of cartridge. I might have the terminolgy wrong but anyway. Here is what I had as to reloads:

Bullet: 174 grain Sierra HPBT
COAL: 3.075
Powder: Varget
Powder weights: 10 of each - 36.0 36.5 37.0 37.5 = 40
Cartridge: Remington & Winchester

I did notice in almost all instances of the cartridges that the primer was backed out slightly of which I have never noticed on any other reloads with other rifle cartridges that I have done.

I have reloaded for about 3 years and need some guidance. Do I have these loaded to hot? I thought i was below maximum but got it from a book. If anyone has any input on this i surely would be appreciate. It is sort of disturbing.

Thanks

 

[Steve in PA]

Case seperations come from excessive head space, not "hot" loads.

Get the head space checked.

 

[neal7250]

The 303s are kind of rough on casings. That is why you should neck size, and use the reloads only in the gun that they were fired in. You should get longer case life.

 

[ilbob]

+1 on having the head space checked.

 

[rcmodel]

+1

Par for the course with a Lee-Enfield.
They are very stretchy actions, and generally have loose headspace to start with.

Try neck-sizing once fired new brass.
The object being to headspace off the shoulder, not the rim.


rcmodel

 

[ilbob]

if you have excessive headspace, is there any way to fix it?

 

[ping]

Hmmm, ok on headspace - someone explain exactly what this really is. Is it where the base of the cartridge seats sealing the gases etc once you close the bolt. Never really understood this. Also can you check headspace your self or do you have to take it to a gunsmith. Funny this is I bought it back last november from a gun dealer at a gun show who is there every month. He had a card attached to the rifle with info etc one of which was "has a tight head space". The rifle is fantastic looking and the rifling etc looks great. Did i make a mistake. Mannn. thanks

 

[mgregg85]

Yeah thats the problem with reloading for the enfield, the chambers are slightly oversize so they can chamber dirty ammo.

 

[ilbob]

Also can you check headspace your self or do you have to take it to a gunsmith.

you can buy guages from midway or brownells.

 

[rcmodel]

someone explain exactly what this really is.

In simple terms, headspace is the distance between the bolt face and the head of the case when the action is locked.

Rimless cartridges like the .223 and 30-06 headspace on an imaginary line on the shoulder of the chamber.
Rimmed cases like the 30-30 and .303 headspace on the rim.

The trick is, you have to leave enough extra headspace for the bolt to close on any round that is within spec tolerances.

But excess headspace allows the case to go too far foreword in the chamber when the firing pin hits it.

Then as the pressure of firing increases and it expands, it gets a grip on the chamber walls.
When pressure builds to the maximum, the rear of the case stretches however far it needs to stretch to slam back into the bolt-face and reach zero headspace.

A case can stretch a little with no harm done, and they all do.
But when the headspace is "excessive" it has to stretch so far the case cracks, or separates and pulls in two.


rcmodel

 

[Horsemany]

The gauges for the 303 Brit are only marginally usefull. Since the 303 Brit is a rimmed case, the gauge is only measuring the thickness of the rim. This is ironic because it's the caliber whose chambers need the most scrutiny. Cases without a rim are gauged from the back of the case to the front of the shoulder. This is what we'd love to measure on a 303 Brit, but the gauge will not tell you that. One can only assume their chamber is oversized(I've never seen one that wasn't) and neck size only. That's the only way to go on these giant chambers. If you full length size on a 303 I'd expect 3 loadings max on the brass. Even then I'd always be waiting for a ruptured case.

 

[armoredman]

Get a paperclip, and straighten it out. Now bend a little L at one end, almost like a pick, and scrape it up the side, from the bottom, inside an empty fired case. You should be able to feel it fall into the thinner portion near the base where the brass has stretched, if the case is stretching to a dangerous degree. If you feel that, toss the case into the recycle bin.
Neck sizing for each individual rifle is a must with such a caliber - I have gotten about 4-5 loads with one brass, so far, with my No4Mk1*. Love that rifle!

 

[dmftoy1]

The good news is that if you have excessive headspace on your No4. you can fix it by swapping out the bolt head. On the side of the bolt head you should see a number (0,1,2,3,4). If you've got a zero or a 1 then it's a simple as swapping in the next higher bolt head. If you've got a 2 then you've got a bit of searching to do! (#3 is hard to find). There is a guy and his son in Austrailia who seem to have a couple in stock but they're not cheap.

FWIW.

Regards,
Dave

 

[Sunray]

"...gauge is only measuring the thickness of the rim..." Nope. Headspace has nothing to do with the cartridge. Cartridges do not have headspace. It's a rifle tolerance thing only. .303 guages check the space between the bolt face and the chamber where the rim fits into.
"...should see a number (0,1,2,3,4)...." 0 to 3. There is no 4. Just changing the bolt head to the next number does not guarrantee that the headspace will be fixed. You must use proper guages. It is easy though.
Be thankful you don't have a No 1 Lee-Enfield. No numbers on their bolt heads. You need a handful of bolt heads(at $11.30 each from Gunparts) to try with guages until you find one that is good.

 

[dmftoy1]

0,1,2,3 are the "standard" bolt heads but 00 and 4 have been observed.

(Pg. 57 "British Enfield Rifles - Volume 2, 2nd edition revised " - Charles Stratton.)

Regards,
Dave

 

[BEARMAN]

What brass were you using? New? Range pick ups? Brass that had been fired from another .303 you own? Best would be new brass sized to just chamber in your No.4 for first load and then using only neck sizing for the next reloads and then only fire them in the same gun..

 

[ping]

Sure appreciate everyones input. Man i have learned alot about that rifle. Now i understand headspace. So there does not sound like alot i can do unless i search for bolts with the appropriate numbers. I guess i will do what everyone is recommending and full lenth resize after the first shooting of new brass and than neck size after that. Does not appear you get many reloading from the 303 cartridge.

Some one was asking what cartridges i was using. All the ones i have used have been new. They have been RP, Winchester & S&B and they all have separated. I am trying to remember though if when i used brand new not reloaded if i had any separations. I will have to try that.

Got one more question on headspace though. what causes it to increase. Is it from the number of rounds shot and slowing eroding where the case fits into the chamber. Just wondered.

Interesting note on how to check your case to see if it has stretched. I will have to try that out with the paper clip.

Man I love this forum. Thanks alot guys for the info.

 

[armoredman]

No prob - BTW, mine LOVES the Hornady 174gr FMJ/BT, if you get a chance to try that bullet out.

 

[Clark]

Per SAAMI:

The rim of a 303 case is .064" - .010"
The chamber rim of a 303 is .064" + .015"

[ My 303 brass collection varies all over the whole .054" to .064" range.]

[That is 5 times the slop required to get most rifles red tagged "unsafe to shoot"]

Per my calculations:

The No 4 rifles have .19" firing pin holes and .58" OD putting the cross
sectional area at .23 sq. in and the compression length is 4.2"

movement = [Force] [ length]/[[area] modulus]
movement = [chamber pressure][case ID][length]/[[area][ modulus]
movement = [ 60 kpsi] [.107 sq. in][4.2 in]/[.236 sq. in[30 M lb/ sq.
in]
movement = .0041" @ 65k psi chamber pressure
movement = .0038" @ 60k psi chamber pressure
movement = .0029" @ 45k psi chamber pressure
movement = .0019" at 30k psi chamber pressure

What does it all mean?
The 303 Brit rifles [when with in headspace and pressure specifications] stretch the brass worse that all your other rifles combined.

You either load LOW pressure or replace the brass often.
If you load at 20kpsi and partial FL resize, you can make the split necks be the limit of life.

 

[Leatherbark]

You can control the headspace on your enfield by fireforming your cases to fit your chamber. Neck size only enough to hold the bullet. Seat the bullet so it touches the rifling thus holding the case against the bolt head. Upon firing the brass will flow forward from the shoulder up forming your case to the chamber. (If the brass is not tight against the bolt then upon firing the brass grips the walls of the chamber and then forces the case back against the bolt head thus stretching the brass.) From here on out make sure you only neck size so as to not set that shoulder back any at all.............These are the only cases you can use in your enfield...I shot and reloaded for a No1 MKIII for 20 years and the only time I ever had a case separation is when I first started just like you. Now your cases will still show signs of separation eventually. Throw these away. Feel down inside the case with a bent paper clip and feel for a crack down in there.........You might want to back off a few grains while your fire forming your cases...............Also you can fire form 30-40 Krag cases I read somewhere to fit your enfields chamber. I believe its thicker brass, but a new load may have to be used as case volume may be different.....Talk to the guys on a Lee Enfield talk forum and they will set you up with all the info you need on loading for the 303 British..............Good Luck.....................Bob

 

[cracked butt]

^^Leatherbark got it!^^^

Use virgin brass, and fireform it with the bullets seated so that they jam into the lands.

 

[rcmodel]

I guess i will do what everyone is recommending and full lenth resize after the first shooting of new brass and than neck size after that.

Do not full length size after the first firing.
If you do, you will be right back where you started.

The first firing will fire-form the case to the chamber.
If you ever full-length size it after that, it will have to stretch again.

Neck size only after the first firing, and from then on.


rcmodel

 

[ping]

Thanks again for all the info. I will reload some more this week and try the neck size only treatment. I have some new remington brass i got so i will neck size only and see what happens.