Radical fire forming a new 303

[uhjohnson]

I took my internet purchased Ross 1905 to the range assuming it was a British 303 because it doesn't have any rechambering stamps on it and 303 is what the seller claimed it to be was. Without doing a chamber cast i fired 5 rounds and looked at the fired cases ( i should have only fired one) noticing the shoulders were pushed forward .20 and the necks were much shorter as well as the mouth rolling inward. Also the cases were almost straight. The unfired case tapers from .448 to .396 and the fired cases are .448 to .420. The inside of the mouth is .336 and the rolled in part is .312. I would say the reason the case is rolling inward is because as the case shoulder is moving foward it is being forced into the end of the chamber. The case length is 2.215 and would be longer if it was not rolled inward. The primer does not appear to show any signs of high pressure and the barrel bore is .302-.310. I have since tried using a 308 sizing die to just neck size and it appears to work. I have since found out that my chamber was reamed out for the trenches in WW1 and is not marked as such.
Is this rifle dangerous to shoot because of the excessive head space and if is not than why is there so much talk about too much head space being dangerous and the action/bolt can have a catastrophic seperation

[BK7saum]

It's not dangerous because the case headspaces on the rim. I this was a rimless case it might not even fire. IF it did fire, the case would have been pushed forward by the firing pin. The case neck and walls near the shoulder would grip the chamber first because of the thinner brass. As pressure built, the case head would get pushed back and seated against the bolt face as the case body about 1/4" forward of the rim stretched and likely had a catastrophic separation.

When folks talk about a catastrophic separation, they are referring to the case itself not a bolt/action separation. Rifle doesn't blow up, but the case can and does sometimes separate.

Brad

[elk hunter]

The cases from my Ross look similar, neck size only and you should be fine.

[skeettx]

No issues, but may wish to trim the cases to remove the curl.
Mike

[TRX]

I think the .303 Epps had a sharper shoulder, but I can't find a case drawing at the moment.