Why lap it, just use a guided counter bore. You can still use the threaded guild to put pressure on the BB.

While the 223 pressures are a bit high, chamber for 222 and use that data, that should be ok, bringing thrust pressure, in line with the larger BP cases. Hoop and thread strength aren't a issue, with modern steel barrels. After all they were made in 30/40 and 7mm Mauser. The 30/40, gives a little more breech thrust than the 223 and so does the 7mm.

I would feel safer with a RB, made from alloy steel and would use that, over the original ones, made from a close relative of mild steel.

I posted about venting the FP, at least a few years ago. It's not hard to do when making a bushed BB. I didn't get any flax at that time.

For myself, I have more issues about milling the receivers rings octagon and CCHing. 

The '03 is much more prone to catastrophic case failure than a RB and doesn't handle gas well, either. Low numbers can and have blown up, altogether at lower pressures. I think many more people have been harmed with the '03 than RB's.

Frank

Quote:


Now that brings back a conversation I had with Higginbotham nearly 20 years ago. I think he did mention using a stub of a barrel, although it seems that was to center mark the end of the firing pin hole on the breech face. Regardless, your technique makes eminently good sense.

Thanks Frank
Was really looking for some other experience in caliber/chamber pressure info. Seems you have been down this road a while ago.
Along with ssdave this is good info. 
And Bill, I did mark the barrel with .223 only

Milling the receiver rings to octagon is no different than Remington did originally IF the receiver ring is the late version with the larger receiver ring. 
I wont use an earlier smaller receiver ring milled to octagon for anything but a .22RF myself. It just leaves far too little metal to make me feel comfortable for any CF cartridge I'd want to use in a Rolling Block.

Are those pressures for 7x57 and 8x50 the pressures used for loading them back in the early 1900's when Rollers were chambered for them? Or are those modern pressure ratings? 
I've been told that those cartridges were not loaded to the same levels then as they were later. And I've seen a large number of #5 actions chambered in 7x57 that were loose from shooting that ammo. It's pretty common to see headspace issues in original 7x57 Rollers.

The Lebel number appears to be the old CIP crusher indicated psi, likely for the later Balle N machine gun rounds. The rolling blocks were likely for Balle D or maybe even for surplus Balle M. I have seen a claim the WW-I rounds ran 41 ksi, which given the case diameter, would have been a quite high load on the breech.

I've read the "7 mm" was not quite the Mauser but an approximation made by Remington and not loaded to Mauser pressures in the ammo Remington supplied for them. 

I'm not sure where the "published .223 max pressure of 39kpsi" comes from. Hodgdon has data close to the 55 ksi (piezo) SAAMI limit, and the CIP rating is 62 ksi which is likely the NATO limit.

The "max stress capable of the breech roller is 52,000 psi" is likely taken off the Tippmann site and looks suspiciously like the typical SAAMI max for CUP pressure ratings, for 52 ksi is rather low for a modern gun steel. 

I did some back of the envelope stress calculations once. I recall thinking the maximum stress is in ring surrounding the breech pin, but it's been a while.

KWK
The 39.000 psi came from Hodgen for Varget max loads, granted not Rem factory, so I ran the stress numbers on the 55 kpsi:
The Tippman steel is identified as 52 kpsi
Breech Roller max force = 6071 lbf
Sigma for the breech roller at minimum cross section = 12065 psi
Sf= 4.31
Shear load in same= 6780 psi
Sf= 3.83
Double shear in the roller pins= 27500 psi
Sf= 1.42
Made a model in Solidworks and loaded as above and the model stress analysis agrees with the calculations, the max stress is located at a a change in geometry where the pivot pin flanges meet the larger breech roller block, which is where you would expect. However this is a concentrated spot and not a broad area of stress, could be rationalized that the high stress is "spread" to the larger mass surrounding it. Typically in modeling these kind of stresses are considered very low in critical analysis. 
The calibers the RB used certainly have varied over their life span, don't doubt the lower charges for the same caliber. The Brownell video implied that a lot of RB's were "abused" with loads that were not recommended but used anyway in time of war. Just goes to the mystic of the RB holding up to the overpowered loads. May have been detrimental to the RB action in many forms but seems they held together on a larger scale'
This has been informative for me to gain the insight of those experienced and knowledgeable of the RB.
The .223 RB has been performing really well and groups at 50 with iron sights has been less than 1" and I don't shoot that well. Tried a 16" gong plate at 300 yds and rang it 3 out of 4 times, quit after that , Quigley moment, and probably couldn't repeat that on a bet!
Cheers

marlinguy, the failure is in the pin flanges on the roller, sigma = F/A, with 15,558 lbf applied to the face of the breech roller the flanges fail in tensile failure, pins will fail before this happens. This would be a catastrophic failure. One would have to load a super hot double load to get this kind of force. 
However, the failure mode for a block like this is probable fatigue failure, repeated firing of excessive pressure rounds would do this, a crack would start and propagate. Probably one flange would fail, and block would become to loose to function. Material properties of the breech rollers and pins would have to be tested to verify the real values of tensile strengths for old guns. 
This is were the caution of "old" guns and experience is invaluable.