Vermonter,
The standard cones on Ruger and other pistols as well as the majority of the after market cones are made from a steel alloy. They may be anything from simple carbon steel to a stainless alloy. As mykeal told you the Treso are made from high strength Bronze alloy (Aluminum Bronze). They buy it from Ampco as a "proprietary" alloy. I won't divulge what it is because that is a trade secret between Ampco and the House of Muskets.
We do business with Ampco and one of the metallurgists there gave mine a good idea of what it is. We use an almost identical alloy from Ampco because of it's resistance to flow erosion in a very, very hot environment with aggressive gases.
But the really cool differnce is the geometry. Below is a piicture of the exit holes on a Ruger cone and the corresponding Treso cone where you can see the larger OEM exit hole:
This is a simple model of a Treso cone and a Uberti OEM cone:
These models were created from actual measurements.
The company (either in Germany or Italy depending upon the year) who makes them for Uberti doesn't worry too much about the internal geometry, hence the double step from the drilling operation. I'm sure it isn't a critical feature to Uberti.
However on the Treso cones the depth and diameter of the major bore diameter is very consistent. The diameter of the terminal hole (exit hole) is very consistent and the actual length is very consistent due to the depth of the major diameter being controlled.
The Treso surface finish diameters and taper of the cones are very consistent from cone to cone. The edge breaks and internal chamfers are also very consistent.
Treso recommends Remington #11 caps on their cones, but you will find many people swear by #10s. There are two reasons for this:
- The shallow and very uniform (from cone to cone) taper.
- The unique geometry of the newer Remington caps. The #10 and #11 caps have the same internal diameter, the fit is controlled by the length of the skirt.
I don't believe I have ever heard of shooters using both #10 and #11 CCI caps on the Treso cones.
The small exit feature on both modern cones attenuate the back blast from firing which helps limit, but doesn't stop the cap fracturing. The Treso cone was designed and then refined to directly address this.
Do I like Treso cones? Yep, I am jealous, I wish it was my idea. Are there other good cones out there? Yes there are, and I'm sure some of the shooters here such as Abitnutz will give you their testimony. Isn't it great to live in America and have a choice?
Regards,
Mako