303 case head serperation

[4296]

Experienced my first case head seperation in my NO1-MKIII and am now waiting for a case extractor from Numrich. I now see that I will not get 4 full power loads from my brass in this rifle. I do shoot CBs at 1600 fps in seperate brass in this rifle and was wondering if others have experienced incipient and or actual case head separations even with reduced loads- as I will discard the brass earlier if this happens. I usually retire cases because of loose primer pockets and neck cracks. I now see that the Lee-Enfield is not "reloader freindly" and will require a much higher attrition rate with the cases it fires.

[Hurricane]

You may be setting the sholder back too far when you are full length resizing the case. When that happens the case will streach making a thin place inside the case. After a few firings the thin place will come apart. You will need to resize your cases to fit your chamber. Try neck sizing the cases. Also make a feeler tool from a piece of wire or a paper clip. Straighten the wire and then put a right angle at the bottom for about 1/8 inch (like a letter L). Feel the inside of the case with this. If the case has been streatching a groove will develop on the inside of the case just above the primer end for a rimless case. For a rimed case like the 303 the groove will probably be at the top of the case. The groove will be very easy to feel if it is there. I have had one case separation 40 years ago and ever since I have included the feeler in my case preparation routine. Better safe than sorry.

[Char-Gar]

What you have experience is very common. The Brits made those rifles with very generous chambers and if you full length your brass every time, you will get separations in a few round.

The British military does not reload, so they were not concern about case life. Headspacing on the rim as the round does, there will be no problems with the long/large chamber on the initial firing. They were more concern about the rifle working dirty, full of mud, dirt and so forth.

Buy a neck sizing die and only neck size after the first fireing of the new case. You brass will now last quite a long time.

[onesonek]

Experienced my first case head seperation in my NO1-MKIII and am now waiting for a case extractor from Numrich. I now see that I will not get 4 full power loads from my brass in this rifle. I do shoot CBs at 1600 fps in seperate brass in this rifle and was wondering if others have experienced incipient and or actual case head separations even with reduced loads- as I will discard the brass earlier if this happens. I usually retire cases because of loose primer pockets and neck cracks. I now see that the Lee-Enfield is not "reloader freindly" and will require a much higher attrition rate with the cases it fires.

Two things,,,, first it sounds like that particular rifle may be a tad roomy in the chamber, and when sizing you are work hardening the brass at the neck, maybe the entire length. Annealing every 3-4 firings should help with that neck cracking issue. Besides the shoving the shoulder back during sizing, could becausing seperation.
Second,,,,,,Back Off atleast 1 full grain!!!!! Brass lasting only 4 loadings with seperation and or primer pocket opening is running hotter than the design can handle with the chamber dimensions of the rifle. No offense, but if you want that kind of performance, get a .308 or .30-06. You might just get bit or ruin a rifle otherwise.
Take a piece of fairly stiff wire and put a bend in the last 1/4" so it will go down in the case,,, you will feel if the incipient ring is there. If so discard those before they seperate in the rifle again.
But for sure back off your "full power" load!!!!

Addition as others posted,,,, I would not full length size. Back off your FL die 1/2-1 turn and partial size. It will help with case stretching, but do nothing for the large primer pockets.

[Dan Cash]

+1 on Hurricane's response except that rimmed cases will separate at the head just like rimless. Neck size and keep cases segregated by rifle if you have more than one enfield; you should have relatively normal case life there after. Very heavy loads in the SMLE and #4s will drastically shorten case life with case head separation. This is not a particularly dangerous event, though it is disconcerting; the case head (first 3/8 to 1/2 inch of case) is what seals the breech.

Try inserting a .45 bronze brush from the breech until it is in the remains of the cartridge case then pull it back out. The case will like ly come out with it.
Dan

[LowPE]

Try the RCBS X-die. Works for me at extending case life.

[Bullshop]

+1 on the bristle brush, should pull it right out.
+1 on the neck sizing only
One thing that seems to have been over looked is the first firing, the one that initially stretches the case. That first shot stretching from a factory small base size should be avoided. You can do this by first necking up to a larger caliber that will not allow the brass to chamber, like 338. Then partial size until the cases chamber with some resistance to the bolt closing. Thus chambered the brass will not streach forward causing the thin area ahead of the web. This way the brass will only streach outward to form to the chamber. Once formed to the chamber length this way never never never push that shoulder back again.
When treated this way I have no issues what so ever with case life in a milsurp smle 303.

[Larry Gibson]

+1 on the X-die if you want to FL size. Better is to neck size as Charger mentions. Cases will last much longer that way, even with your full power loads.

Larry Gibson

[onesonek]

I may be speaking out of place here as I don't have such a rifle in question. It is obvious form other's statements and in my own thoughts, that it has a large chamber and corrective sizing proceedures will help with the case seperation issues. And as much as I beleive in each to his own, I still think that the primer pocket situation and 3-4 round case life do to primer pocket getting big that soon is putting alot of stress on the receiver. In such a chamber it is hard to measure the exact casehead expansion if the brass is larger just ahead of the web, one only has the primer pocket to go by. In my experiments, I found that casehead expansion of .0005-6" on tight chambers was shortening brass life down to that 3-4 somtimes 2 loading level. Most readings from years gone by said, that is pushing the pressures to beyond max.
I guess that is fine if you don't mind the brass cost,,,, I wonder though how long of prolonged shooting at those pressures will the receiver take it?
Personally if it was my rifle, I would back off 1 gr. as that is what I have done in the past when find out what is max for a particular firearm. Brass liffe is at least 2 fold, and it is easier on the firearm.
Just looking out for the survivability of the rifle and shooter here...Hope I'm not off base or arrogant with stating such,,,not my intention at all!

[dualsport]

Lee Collet Die?

[4296]

I am only neck size the brass. The j-word loads are below max.

[onesonek]

Hmmm, well that does sound like a pressure thingy to me. I have always stated that loading manuals are not manuals, but rather guides. The individual firearm determines what max is. I have several that I can't reach max listed loads, albeit, that I expect that from extremely close tolerence chambers. And yet on one I am over listed velocity by nearly 200 fps with no signs of pressure after 5 loadings so far in the same brass.

[onesonek]

Just curious,,,,what powder you using?

[243winxb]

I am only neck size the brass. The j-word loads are below max. The damage to the brass can happen on the 1st firing with full pressure loads if the rifle has excessive headspace. Not sure if it would with reduced loadings.
I usually retire cases because of loose primer pockets Reduce your load.

[JeffinNZ]

I cover it off in this:

http://castboolits.gunloads.com/showthread.php?t=49003

I run mil spec velocity cast loads in my No1 Mk III and my No4 Mk II and both get very good case life. Follow my fire forming and neck sizing suggestions to duplicate.

[mpmarty]

Check your bolt head. Enfields have a field replacable bolt head that comes in different "sizes" to adjust headspace. Gun Parts Company (old numerich) has a selection of bolt heads availabel to correct the headspace.

[onesonek]

Good read Jeff!

[bruce drake]

mpmarty,

He said he had a No 1 Mk III which requires a gunsmith to fit the head. A No 4 Mk 1 Enfield will allow you to swap different sized bolt heads to regain the proper headspace.

Necksizing and easing up on the load a touch should save his brass.

[Larry Gibson]

I am only neck size the brass. The j-word loads are below max.

That being the case (is that a pun;-) ) then I'd say headspace is the problem. On the intial firing the cases are pushed a bit too far into the chamber and the case body and shoulder grab the chamber. The case head is then pushed back against the bolt face stretching the case in the web area.

Starting with new cases use a medium powered load and seat the bullet far enough out with the bullet firmly against the leade so the case is held tightly against the bolt face. Then on firing the shoulder is blown foreward fire forming the case. Then continue with neck sizing.

If the throat is too long for the above then use a 8mm, .338 or .35 expander and expand the necks of the new cases. Some case lube inside the necks helps a lot. Then back the .303 neck size die out and size the necks back down creating a false shoulder so the cases are a "crush fit" when chambered. The fire form with a medium powered load and continue to neck size.

The fired cases you have might be salvageable but probably not. Before you get a seperated head i would retire them and just use them for one of my favorite plinking and small game loads. Load a Lee TL 314-90-SWC or a Hornady 90 gr swaged lead SWC over 3.2 gr of Bullseye. Velocity will be 800 - 900 fps and accuracy, if the barrel is decent, will be very good. Great fun and even the cases you currently have will last for many, many, many firings with that load.

Larry Gibson

[nicholst55]

Jeff: I just read your article and really enjoyed it. I must admit that fire-forming new brass before the initial loading never occurred to me before; great idea! I have some unfired brass in storage now; I'll definitely fire-form it before I load it the first time!

After some discussion with Stephen Redgwell (www.303british.com) a few years ago, I settled on a Lee collet die, a Redding body die, and a good quality seating die as the best combo for loading the .303 cartridge. It's worked well for me so far.