dockholidaiy wrote:
I have never heard of anyone machining the trunnions out of the original block of steel. If you can find one let me know. It would be a first for me. Im not saying its never been done I just cant imagine all that waste of steel.
If you look at the barrel M&T from seacostartillery did in the thread below...
http://www.gboreloaded.com/forums/index.php/topic,256445.0.html Many finished, rifled ordnance barrels are built up by over-sleeving a rifled mil-surp tube which has been turned down to look exactly like M&T's test barrel in the thread above. After turning the OD of that tube to a very consistent dimension (probably no more than .002" total variation), they get some precision boring company (if they don't have the tools and abillity themselves) to drill/bore/hone sleeve(s) which are .001" to .003" smaller than the core's OD. The sleeve(s) are then heat shrunk over the outside of the rifled core and welded at the interfaces on the OD (between sleeves) and the ID (both between sleeves and at the ends). In many cases the sleeving will take the form of not a single sleeve the total length of the barrel but two or three. Most of my designs call for a single sleeve leading up to the trunnions and two additional sleeves forward of the trunnions. All the OD welds are planned so they will turn down smooth when the finished barrel's profile is machined. The reason whole-length sleeving is avoided is to reduce the chance of the sleeve locking onto the core as it is heated and slid onto that core before it is fully seated into its planned position. And of course after all the work above is added turning a cascabel and profiling the finished barrel's OD.
For some of us designer/fabricators there is another sleeve added to the OUTSIDE DIAMETER sleeves...
The pic is of the 4" thick plate trunnion section sleeve stock... It is set up on the mill and precision bored the hole which goes over the rifle core. Mounted in the lathe and turn the trunnions, rim-base faces and start of the rim-base shoulders. Include the sleeve in the sleeving buildup over the rifled core. After turning the profile of the fininshed barrel, hand blend the balance of the rimbases and diameter sections where the trunnions prevented lathe turning that part of the OD.
For those of you left still reading... THIS is why M&T's offer to do blind hole drilled and rifled tubes
WITH SUFFICIENT OD TO TURN A FINISHED BARREL is such an enormous time-saving offer...
At the Casper, WY shoot a couple years ago I questioned all the rifle shooters and MOST had gone through the long, arduous procedure above. A few others had full-length sleeved and welded trunnions onto the outer sleeve. Anyway other than a Seacoast Artillery barrel blank is a TON of work... and that will be work enough for most!!
GOW/George
