Fireforming .303 with O rings

[Catch-22]

I’ve recently acquired my first .303, a  early LE No.4 MK 1* Longbranch.

Ive read previously that when fire forming the brass, to use some little rubber/nitrile O rings to prevent brass stretching too far.

Ive sourced the O rings but my question is; do I need to remove the extractor from the bolt to work with the O rings? Or can I leave the extractor in?

Thanks!

[terryh]

C-22, 

If you have the right sized O rings then ‘no’ you do not need to remove the extractor - least I did not find the need to? 🤔

You should just feel the bolt ‘snug up’ as it closes on the O seal i.e. you know the case is held against the bolt face.

Once you have fired the cases hold them up against an unfired case - you might be surprised how much difference there is in the length of the shoulder area.

Brgds T

[Catch-22]

Terry - thank you for the helpful reply.

Ive yet to collect the rifle from my RFD, so cant check the ‘crush’ fit, but I believe I’ve got the right sized o rings as they’re only 1mm cross section and essentially emulates the size of the rim.

Once I collect the gun, I shall try with the extractor as you note and see if that works.

I assume that with the o rings in place, you can’t  use the stripper clips but rather single feed?

Thanks again!

[terryh]

C-22,

That sound about right re. O seal section, the O seals I used were a bit under size so the section went down when I stretched them over the case.

You are correct, stripper clips will not work, think from memory my rifle fed from the mag though??

good luck but the effort is worth it 😉

T

[Andrew]

Interesting. I shoot cast bullets from my collectible 303's so I simply seated the bullets snug to the lands on the first firing with new brass and carried on with neck sizing. Never thought of o-rings. You learn something new every day!~Andrew

[terryh]

Andrew,

Same effect really, but I was using jacketed and wanted to avoid reduced loads - just used the normal load but ‘held back’ the brass 1st time out.

T