Post by Lee Martin on Apr 21, 2012 15:05:29 GMT -5
Don't get excited, they're not offering one.
A few weeks ago there was discussion around why Ruger hasn't done a 5-shot 480 Bisley. I speculated they haven't because the frame wasn't designed for 40K - 45K PSI on that big a hull. But custom smiths have been doing 475's on Blackhawks for over two decades, right? They have but these conversions are held to much tighter tolerances than a factory gun. Bolt bearing blocks are often used, the cylinders are line-bored or line-indexed, over-sized bolts are matched to the stops, frame windows are opened to accommodate 0.030" over cylinders, etc. Now Ruger could do all that but it would involve custom shop-like production.
I'm just guessing but I suspect one Ruger concern is the barrel shank. When Sporting Arms prototyped their 454 Seville some forcing cones cracked under proof. That lead Sig Himmelmann to create a 454-specific frame mold with a heavier barrel shank. Very few of these guns were produced so it's hard to say how they've held-up after thousands of rounds of 454. But when Magnum Research switched from the D-Max casting to the BFR frame the most noticeable difference was heavier barrel support (note: the D-Max frame is pure Blackhawk).
Here's a photo of a stock 41 Ruger:
And here's a photo of a 475 BFR:
Pretty noticeable difference, ehh? And when you're talking 400+ grainers hitting a cone at near 50,000 PSI things need to be well aligned. If not, the force imparted on the cone by a slightly off-center bullet is considerable. That's why line-boring or line-indexing is the norm on custom 475s (to include the BFR). 11 degree lead and even free-boring can also aid bullet alignment.
Now honestly, a 480 Ruger on a Bisley with current production spec would be safe. And it would probably hold-up fine. Knowing Ruger though I doubt the margin of safety and durability would be to their liking.
Just a thought.
-Lee
www.singleactions.com
"Building carpal tunnel one round at a time"
A few weeks ago there was discussion around why Ruger hasn't done a 5-shot 480 Bisley. I speculated they haven't because the frame wasn't designed for 40K - 45K PSI on that big a hull. But custom smiths have been doing 475's on Blackhawks for over two decades, right? They have but these conversions are held to much tighter tolerances than a factory gun. Bolt bearing blocks are often used, the cylinders are line-bored or line-indexed, over-sized bolts are matched to the stops, frame windows are opened to accommodate 0.030" over cylinders, etc. Now Ruger could do all that but it would involve custom shop-like production.
I'm just guessing but I suspect one Ruger concern is the barrel shank. When Sporting Arms prototyped their 454 Seville some forcing cones cracked under proof. That lead Sig Himmelmann to create a 454-specific frame mold with a heavier barrel shank. Very few of these guns were produced so it's hard to say how they've held-up after thousands of rounds of 454. But when Magnum Research switched from the D-Max casting to the BFR frame the most noticeable difference was heavier barrel support (note: the D-Max frame is pure Blackhawk).
Here's a photo of a stock 41 Ruger:
And here's a photo of a 475 BFR:
Pretty noticeable difference, ehh? And when you're talking 400+ grainers hitting a cone at near 50,000 PSI things need to be well aligned. If not, the force imparted on the cone by a slightly off-center bullet is considerable. That's why line-boring or line-indexing is the norm on custom 475s (to include the BFR). 11 degree lead and even free-boring can also aid bullet alignment.
Now honestly, a 480 Ruger on a Bisley with current production spec would be safe. And it would probably hold-up fine. Knowing Ruger though I doubt the margin of safety and durability would be to their liking.
Just a thought.
-Lee
www.singleactions.com
"Building carpal tunnel one round at a time"
