460 Rowland, Decocker on a Rock Island?

[jadecorte]

I have read some RIA threads that lead me to believe an RIA's frame is too soft to accept a 460 conversion. Is this true? Also, is it possible to install a deccker on my RIA(i do carry condition 0 but I would love to do something a little out of the norm). I know both of these issues have been discussed before, but I am looking for some insight from the gunsmiths side. I also know that this is not the RIA forum, but again I am seeking a little more insight into my quest. Thanks for any and all help.

[1911Tuner]

Howdy and welcome aboard.

Any time that the operating pressure approaches what is essentially proof levels, I can't put enough emphasis on a proper barrel fit...full vertical lug engagement, fully equalized in the horizontal plane, with mimimum endplay...preferably none...and minimum or near minimum static headspace.

On the decocker...Cylinder and Slide offers something like that, but not exactly a decocker. Expensive, and potentially problematical to make it work reliably. Best to keep an old saw in mind:

"The more gadgets it's got, the more Murphy it gets."

[jadecorte]

thanks 1911 tuner. I appreciate the welcome, but actually I have been a member for a while. Work has kept me occupied more than should be allowed. On the rowland, thanks for the insight, although a little confusing. I have read other posts by you and I am blown away everytime. You are very knowledgeable. If I were to get the conversion would it work if smithed correctly? Oh, the decocker thing, I was throwin it out there as food for thought. I kinda like the looks from fellow glockers when they see me at the range holstering a pistol at condition 0. Some dont understand the beauty in a 1911.

[1911Tuner]

Ah! Okay. When I see Junior Member, i don't think in number of posts, but in time on the board. :o

You wrote:

> On the rowland, thanks for the insight, although a little confusing.<
************

Allow me to simplify...

The locking lugs on the barrel and in the slide are slammed into one another on firing...front barrel lug faces to rear slide lug faces...as the barrel and slide are driven in opposite directions. Several things modify how that affects the gun.

Are all three lugs bearing equally? Most factory-fit barrels don't, and in fact...
many only bear on one lug, and it's only occasionally the most supported one...namely the first one forward of the hood. (The one without a slot behind it.)

Are the lugs engaged vertically to their full depth? Again...most factory barrels don't make it, and vary from 80-90% of what is available...or .040 to .045 inch. A look at the surface area of the radial lugs in a 1911 will open your eyes as to just how little that is. All three combined just barely top one-half square inch, and the peak pressure in Hardball-spec ammo is 17,500 CUP...or about 20,000 PSI.

Heavier bullets at a given velocity offer more impact forces on the lugs than lighter ones, just like pressures do. A bullet that's 15% heavier increases the
impact by 15%. A 250-grain bullet at 800 fps as opposed to a 200-grain bullet at 800 fps hits the lugs with 25% more force. Add that to the higher peak pressures generated by the Rowland or Super...and you've got the makings of a cracked or sheared lug...or lugs.

Lastly...How much endplay exists between barrel and slide? Stick the barrel and bushing in the slide and push it back and forth to see how much yours has. The amount of endplay is the amount of breech opening that your pistol will produce when it fires.

Endplay also accelerates the normal wear and deformation of the lugs because it gives the lugs a longer running start at each other before they engage. Push two hammers together under 500 pounds of force, then slam them together from a foot apart with the same force. Which will batter the hammer heads faster? Now...Offset the heads so that they each impact one another with half their surface area, and you can start to understand how a cartridge like one of the ones mentioned above can quickly damage a slide and barrel beyond repair, not even considering the rapid increase in working headspace that comes with lug deformation...and it's in the kaboom direction.
As the lugs deform, they allow the slide to back away from the barrel farther.
As the slide backs up, so does the cartridge case. Case head support starts to reach the dangrous point with each .001 inch that the breech opens. If a lug should fail...shear off...the opening occurs sudeenly, without warning...and the next lug that takes the brunt may be as much as .010 inch to the rear.

Approach these hot rod wildcats with all due caution, and stop at the first sign of bulged cases or extruded primers. See...There's this road called "The Highway of No Return" and it's a long, hard road to travel without eyes or fingers.