Help dating rifle

[Liam]

Well took the rifle to the farm last weekend to fire a few after groundhog hunting all day. Only got off 4 or 5 shots before I realized my backstop for .22-250 varmint rounds wasn't up to the task with this .303 180 gr ammo. Will have to return soon and go to a better backstop. However, I fired a few and noticed the drastic change in the fired case's profile. I reload, so I can trim to length and neck size, but wondering how many times I will be able to reload. I am on 6 reloads for some of my .22-250 brass, but accept that this new (to me) round has its limitations.
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[JB White]

PPU is decent brass and you should get a pretty fair number of reloads from it. Providing it isn't overworked. Stick with the neck sizing.
I've always bumped the shoulders back a wee bit, but I usually chuck all my bottleneck cases at around the 5th of 6th time.

[Parashooter]

. . . wondering how many times I will be able to reload. I am on 6 reloads for some of my .22-250 brass, but accept that this new (to me) round has its limitations.

To demonstrate how we can control .303 axial clearance ("headspace") using only the shoulder, I filed off the rim of a once-fired Remington .303 case. After adding an extractor groove to fit a Mauser-size shellholder, I neck-sized, reloaded and fired this case 19 more times.

The load was a 180-grain jacketed soft-point over a lightly-compressed charge of IMR 4350 (giving an average velocity of 2310 fps for the 19 shots and listed at just under 39,000 CUP in my IMR data booklet). The test rifle was a 1943 Lithgow S.M.L.E. Mk.III*.

20 shots was enough for a practical test, I sectioned the case to examine the web/body junction area where thinning normally occurs. This case, fired 19 times with no rim, did not stretch or thin at all. I'm sure it could have continued for at least another 20 of these moderate loads.

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[Liam]

Good to hear. I use a shop-made steel wire probe to "feel" the inside of case for hints of thinning. I think your method of the occasional sacrifice would be more informative. Thank you.

[Parashooter]

No need for sacrifice - except to show folks something they might not otherwise believe. Incipient case separations are readily visible from the outside - once we've learned what to look for -

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[The Armourer]

It certainly seems to be a 'mix' of parts with South African furniture.

If you can do a good, clear photo of the 'cross' to the top left of the BM (proof mark) it will tell us what year it was prooved..
The problem is that it only tells us when it was sold into the UK civilian gun market, not when it was made.