Strange Ross fired Brass

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I fired off afew rounds in my ross MK3 today and this happened? anyone know why the bases are like that? some are DA imperial and Remington brass.

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That is just the expansion ring, at the point where the solid web transitions to the thinner sidewall of the case. It is more pronounced than you are used to seeing because of the generous chamber re-reamed into Ross rifles. Does you rifle's barrel have "E" or "LC" stamped over the chamber?
 
From the looks of it, your chamber is oversized somewhat i.e. worn and/or eroded as it is obvious that your cases have expanded substantially.
These cases are narrower at the bottom because that area was not able to expand.
You might want to have a gunsmith check it out and see if you chamber is within safe limits...
 
Next time you get some range pick up brass, just run it through the Full Length sizer enough to size about half way down the neck. Do a handful of cases and then see if they will chamber.

If they do, carry on and load them. By only partially sizing, you don't set the shoulder back and you will get less case stretching.
 
From the looks of it, your chamber is oversized somewhat i.e. worn and/or eroded as it is obvious that your cases have expanded substantially.
These cases are narrower at the bottom because that area was not able to expand.
You might want to have a gunsmith check it out and see if you chamber is within safe limits...

This is NOT wear or erosion. The Chamber on the Ross rifle was originally done to tight tolerances to chamber the high quality Canadian Ammunition. The Wartime ammunition produced by the British was sometimes "generous" in tolerances to say the least. After the problems with the Ross using this ammunition, the chambers were reamed out to larger dimensions. (The famous "jamming" of the Ross rifles in the trenches was attributed to Birmingham Iron and Metals Lots B14 and B15, ammunition that had been condemned by the British Inspectors, but was issued to the Canadian front line troops.)

Most of us who shoot the Ross will use SMELLIE's trick of buying small rubber bands or use "O" rings before the first firing. This makes sure that the base of the cartridge is pushed against the head of the bolt because Military rims are a bit thicker than the Commercial rims. Once fired, we NECK SIZE our brass and keep it segregated from other .303 brass. FULL LENGTH SIZING of .303 brass will overwork it, and you will almost surely get case seperations and a stuck case in the chamber if you do it too often.

If you use the "SEARCH" function here on GunNutz, you should find many Posts and Replies on this subject.
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ROSS RIFLES and their chambers?????? The pics you have appear to indicate more expansion on one side of the brass. It may be a oval chamber in the opening of the chamber , but most likely it is the fact the brass is not centered when fired and that's where the O-ring comes into play.
Bill
 
Not normally an oval chamber the case lies on bottom of chamber, firing pin strike moves the case forward, neck expands, brass isn't uniform one side stretches more, until rim is in contact with boltface. Try the oring trick and compare the cases. Most likely combo of close to max headspace, and an overly generous chamber. If so necksize and use reduced loadings to make brass life longer
 
If the chamber has been reamed generously (and the LC marking confirms this), then you will get this with absolute minimum headspace and absolute maximum rim thickness.

Rimmed cartridges headspace on the RIM. RIM thickness spec for the .303 is .063" MAX, about .057" Minimum. (Working from memory on the Min.)

Rosses as built were headspaced to the low end of the scale: many were right at the Minimum of .064" which gave ONE thou clearance between the Cartridge and the Bolt Face.

A point to remember is that the Ross has a Mauser-type extractor and Bolt Face to assure Controlled Feed. The Cartridge rises UNDER the Extractor, is STOPPED from popping out by the LIP on the Bolt Face and is held firmly by the Extractor all the way into the Chamber. It is not at all like a Rimless cartridge in a push-feed rifle with the Bolt Face cluttered by both Extractor and an Ejector pushing the round AWAY from the Bolt.

Expansion thus is RADIAL. GRAVITY pushes the Cartridge to the bottom of the oversize Chamber and keeps it there. When the cartridge is fired, it expands UPWARDS first...... and that gives the weird look.

Prevention is simple: use "Ed's Famous O-Rings" or my own (cheaper: I am Scots) version, a Pony-tail Tie, which you can source at your local Dollar Store in the girls' department. Last ones I bought were TACTICAL Pony-tail ties; they were BLACK and cost a whole dollar for 500. Put one of these around the base of each FRESH Cartridge. It will tend to hold the Casing CONCENTRIC with the Chamber and also push it back against the Bolt Face, reducing effective Headspace to ZERO. Your brass then expands FORWARD and you reload it by neck-sizing only. Keep the case-mouths annealed and I have no idea how long it will last. I have some here with 20 firings on them. "Big Ed P-51" reports up to 35 firings with .303 brass as a result of this practice.

Hope this helps.
 
I like the hairtie idea. As of mid morning I'm getting my ears lowered...a lot. And as I've not cut my hair since before I last saw Smellie, hairties were required.
I've found the O-ring to be a PITA, they don't want to close and then don't extract properly. We'll try the hairtie trick on that 'CRB' Ross this aft. I had also acquired a set of Lee Collet dies with this in mind.
Thanks Smellie.
 
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