Webley Mk VI question


PDA






Ailog
December 11, 2005, 09:38 PM
Looked at a couple of mk VI this weekend. For any body with familiarization with this revolver, the cylinders on both guns seemed to have a lot of cylinder slop in rotation with trigger relaxed. But were tight when locked up. Can anybody point me in the right direction for some tech details so I know what I'm looking at the next time. Thanks

If you enjoyed reading about "Webley Mk VI question" here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!
P95Carry
December 11, 2005, 10:22 PM
Ailog - this one in pic was one I rebuilt - had to strip it right down, refinsh surfaces and reblue - only multi stage cold blue so - keep it well wiped with CLP.

I had to get a new main spring and also a replacement spring for top break lever - which sadly was not a ''V'' like original but a rather crappy affair - but it works.

Cylinder slop is typical - always seems almost severe but yeah - checked under lockup it should pretty tight.

One prob I have with mine - something to check on another - it does D/A just fine but if over cocked for SA - gets sorter locked trigger and so needs carefully released, and try again. Some issue I think with trigger notch/sear.

If that is OK and bore looks fine then probably worth considering. If allowed - take off grip panels - state underneath can tell you a lot about the way it has been stored/kept.


http://www.acbsystems.com/boards/thr/cb_gun2/web_mkvi_s.jpg

Ailog
December 11, 2005, 11:49 PM
P95Carry
Thanks for the feedback. Looks like you did a fine job on your mk VI. The revolver sort of speaks to me. Built like a tank. Plus I am looking for something older that I can fiddle with. I'll look out for the trigger issue you have experienced. Of the two that I looked at, one was refinished by an amory I believe while the other was original finish. I will have another look see. You must load your own ammo.

P95Carry
December 11, 2005, 11:55 PM
Yep - and as I said do look under grip panels - it can tell a lot!!

Ammo - sorry I forgot to mention that. I do load yes - brass is Fiocchi - forget where I found it but it should be around with some searching. I cheat with bullets and as you see in the picture - just cast LRN's - same as I use for .45acp, 230 grain but sized larger - try and leave them about .454 if I can. Powder is a modest charge of a shotgun powder - can't remember details without looking but it is a safe quite low power loading.

Good luck with your search.

jondar
December 12, 2005, 10:21 AM
Just pulled my MK VI out of the holster and checked it. Uncocked, no pressure on the trigger about a little less than 3/16" play. Cocked about the same. Trigger held back against guard less than 1/16" play. Hope this helps.

Ailog
December 12, 2005, 11:52 AM
jondar
Thanks for checking yours. From the posts I have read and looking at a few it would seem that may be normal. Still looking for a cutaway or parts drawing.

bermbuster
December 12, 2005, 12:30 PM
.....

Cylinder slop is typical - always seems almost severe but yeah - checked under lockup it should pretty tight....

I have a IV. I was worried about "slop" but a good gunsmith told me it's normal. He confirmed it's tight under lockup. He said they are sometimes known as "Wobleys" for this reason.

roo_ster
December 12, 2005, 12:34 PM
Mine has cylander slop when , uhh, "at rest."

If you perform the revo check-out (see top of this sub-forum), however, it has little/no slop when the cylander is ready to fire. I did the complete check-out as well as had a 'smith gawk at it & got a clean bill of health.

Cylinder play.

1) With the gun UNLOADED (check for yourself!), close the action.

2) Thumb the hammer back, and while pulling the trigger, gently lower the hammer all the way down while keeping the trigger back - and KEEP holding the trigger once the hammer is down. (You've now put the gun in "full lockup" - keep it there for this and most other tests.)

3) With the trigger still back all the way, check for cylinder wiggle. Front/back is particularly undesirable; a bit of side to side is OK but it's a bad thing if you can wiggle it one way, let go, and then spin it the other way a fraction of an inch and it stays there too. At the very least, it should "want" to stop in just one place (later, we'll see if that place is any good). The ultimate is a "welded to the frame" feeling.

unspellable
December 12, 2005, 01:22 PM
At rest, the cylinder will have a fair amount of rotational play. Cocked, there will be much less play. The play should be evaluated with the hammer down and the trigger all the way back. If properly timed, there will be NO rotational play what so ever. It should have a "cylinder's spot welded in place" feel.

It has two cylinder bolts. One holds the cylinder when at rest and allows a fair amount of play. The other stops rotation in only one direction when cocked or hammer down. The hand should push the cylinder around against this bolt when the hammer is down and trigger back.

Ailog
December 12, 2005, 03:42 PM
unspellable
I saw the two bolts and watched their action, and cycled it thru. It was all very smooth. The gun had 6 tons per sq in. on the barrel.

unspellable
December 12, 2005, 04:46 PM
The 6 tons per square inch is one of the proof marks. It refers to a working pressure of six long tons per squre inch. Six long tons per square inch converts to 13,440 psi. (Ignoring the usual confusion between mass and force.) How ever, this pressure is measured with the traditional British method of measurement and cannot be converted into a corresponding cup or piezo figure. (Of the three methods, piezo will always give the highest number, SAAMI cup the middle number, and the traditional British method the lowest number, all for the same load.) For our purposes, it just means the revolver passed proof.

Ailog
December 12, 2005, 06:24 PM
Mine has cylander slop when , uhh, "at rest."

If you perform the revo check-out (see top of this sub-forum), however, it has little/no slop when the cylander is ready to fire. I did the complete check-out as well as had a 'smith gawk at it & got a clean bill of health.

jfruser
I looked at em pretty closely and ran thru some tests and looked inside the grips. As in anything its the details that count.

Ailog
December 12, 2005, 06:38 PM
unspeakable
Interesting on the pressure conversions. The barrel walls are not very thick, and combined with maybe the lower strength of steel back then it is not surprising that the pressure rating is on the low side (compared to today). Do you know if the barrels were actually pressure tested, or the proof mark just means that a particular batch of steel passed a strength test?

jondar
December 12, 2005, 06:54 PM
Allog,
I believe that where the pressure counts is in the cylinder walls. Where most six shot revolvers are weak is that the bolt cuts are directly over the chamber, leaving that one small area where the metal is thinner. There are Webley owners that will tell you that .45 ACP is too "hot" to use in Webleys. I have been comparing the thickness of chamber walls of my Webley with a Colt SAA and can see little difference. However I shoot loads averaging a little over 20,000 c.u.p.s all the time in my SAA with no extraction problems. I don't have the answer of why the low Webley pressure restrictions. It could be because the Webley is not a solid frame. ? ? ?

Ailog
December 12, 2005, 10:32 PM
jondar
Interesting points. With the pressure proof mark on the barrel I would assume that means for the cylinder also, or maybe the weakest link. It would be hard to pressure test a cylinder to burst so the mfg must have rigged some test up for the steel and then calculated what the cylinder and barrel could take then added a safety factor. And maybe you have something there about it being a break open gun with no top frame. Also it would be intersting to see how the steel specs compare for your SAA and the Webley.

unspellable
December 13, 2005, 09:57 AM
Under British law the revolver must have both barrel and cylinder actually proof fired. The proof load will generally run around 30% more pressure than the service load. The pressure marked on the barrel is the sevice pressure, not the proof presssure. The pressure appears somewhat low to our eyes because of the difference in the method of measurement. It would be higher if measured using the SAAMI cup method and higher still measured using the piezo method. Not that the 455 is what you would call a high pressure round to begin with.

With most revolvers and loads the pressure will peak as the bullet is passing through the cylinder gap, in general the cylinder is subjected to higher pressure than the barrel. The weak point in most cylinders is not the bolt notch but the web between chambers, the principal reason for five chambers in the super revolvers like the 454 Casull. It is possible to offset the bolt notch in a six shot, as is done in a Colt or Dan Wesson.

The latch is a weak point in some top break revolvers, but the Webley is not one of them. If grossly overloaded, you will blow the cylinder apart before the top latch fails.

In my ignorant youth I managed to overload a Webley Green (An earlier model of Webley that incorporated design features by a guy named Green, much used for target shooting.) and the forcing cone split but the latch showed no signs of stress.

jondar
December 13, 2005, 11:51 AM
The weak point in a cylinder IS the bolt cuts, not the web. If you look at a MK 6 cylinder, there is very little difference in thickness between the web and outside chamber walls. However the 1/16" (approximately) depth of the bolt cuts reduces the strength in that area. Forgive my ignorance but I have never heard of a web blowing out, only the chamber wall.

P95Carry
December 13, 2005, 12:20 PM
Let's illustrate that re the MkVI cylinder.

Look at the pics below - and on the oblique view notice how deep is the machining on both notches - probably effectively halving wall thickness. Of course there is always a small degree of reinforcement just from a brass case but it would seem logical that, in most instances of over pressure - this is where things are weakest. Not to say webs cannot let go - have seen one KB where a whole chunk of cylinder blew away - just that odds IMO favor outer wall for failure.

With the Webley too - there are two areas of thinning .. with most revo's it is just one. Smiths are spot on center of cyl usually, Rugers have a bit of offset.


http://www.acbsystems.com/boards/thr/shoot6/webcyl-339-ss.jpg


http://www.acbsystems.com/boards/thr/shoot6/webcyl-340-ss.jpg

unspellable
December 13, 2005, 12:24 PM
Determining the weak points in a cylinder design requires careful analysis and they are not intuitively obvious. The bolt notches are not necessarily the weak point. It's not just a question of how strong the metal is, or where it's thickest or thinnest. You also have to take into account how the stresses are imposed on it. While cylinders do sometimes fail at the notch first, the more typical failure occurs in the web between chambers. Such a failure will typically tear the web loose on both sides of the chamber and send the outside chamber wall through the top strap. A care full analysis of the fracture and tear points will reveal the sequence of events. (And donít forget the old joke about the janitor at the jet airplane works.)

As a practical matter, we see this in the revolvers chambered for the super cartridges such as the 454 Casull. The five chambered cylinder provides thicker webbing between chambers. If it were merely a matter of the bolt notches, they could simply be off set as in the Colt and more so in the Dan Wesson (The large frame Dan Wesson six chambered cylinder has the notches well off center of the chamber.) or the outer wall could be thickened slightly. However, thickening the web will often increase the cylinder diameter and the primer center ring diameter enough to require a larger cylinder window and new frame design where as going to five chambers requires no increase in cylinder diameter.

There are a number of surprises in revolver design when you really dig into the matter. One of the biggest surprises is that for a hundred years nobody did dig into the matter. Itís only in very recent times that research into this sort of thing has been done, Dan Wesson being the first company doing so in modern times, while most of the rest of this sort of research has b taken place in the private or cottage industry sector. A few years ago, Dan Wesson undertook a study of the effects of rifling rate, barrel, and throat dimensions to determine their effects on accuracy. Very obvious points to study, but no one in the US had done so since the days of the cap and ball revolver. Webley did some research in this are at the end of the 19th Century. This sort of research has paid off too. Today we can build a minute of angle revolver, something undreamed of only a few years ago.

Itís only fairly recently that we understand the pressure peaks as the bullet goes through the cylinder gap. Much of the stress on the S&W frame is not imposed where and in the manner you might intuitively think.

Itís common knowledge that end play develops because the cylinder recoils to the rear on firing. However, common knowledge is dead wrong. The cylinder is blown forward. Only in the cap & ball revolver does it recoil to the rear.

P95Carry
December 13, 2005, 12:47 PM
Actually yes - your post has led to me thinking harder on this.

During the pressure max - the point at which the case requires max confinement - the two webs of the cylinder under stress will be subjected to near pure tensile loading on reflection - the outer wall ''wants to break loose''.

The notch areas however, while wanting ''expand'', so still a tensile stress - are suffering a different vector and one which perhaps lags that of the effects on webs.

Just musing - but certainly there is more than one way to view this - it ain't necessarily simplistic!

Ailog
December 14, 2005, 11:30 PM
Cylinders and pressures

Good info and discussion on the cylinder testing and strengths and weaknesses. Pictures were excellent too. A cylinder is a real work of art and design. It can withstand very high pressures and do it 5 or 6 times in a row, then do it again. My dad had an old colt cylinder burst . He found all the pieces and was going to try to weld it back together. I believe he was one of the founders of the cheap bastards club.

It would be interesting to test a Mk 6 to bursting and see what kind of pressure it could withstand, and where the failure would occur. If you were holding a Webley during a failure it appears that the stout rear frame and topsides would probably offer good protection for the shooter. I wonder how much of a "pressure relief" the barrel to cylinder gap accounts for, or how much loss is incurred due to the gap. Well, I have been rambling but its fun to talk about this stuff.

P95Carry
December 14, 2005, 11:42 PM
I agree - with a failure I doubt the shooter would be very injured.

Re the cyl gap - I can't substantiate this but seem to recall someone mentioning a loss of 4%.

I have posted this pic a lot but add it now simply to illustrate just how much gas does in fact exit at the gap!!!


http://www.acbsystems.com/boards/thr/shoot/jb_shoot/454_flash.jpg

Ailog
December 15, 2005, 03:38 PM
Love the picture. Hot gas and steel! And just think, your hand is only inches away from super hot temperatures and immense pressures.

Carl N. Brown
December 17, 2005, 03:08 PM
http://www.thehighroad.org/attachment.php?attachmentid=32704&stc=1&d=1134846365

Ailog
December 17, 2005, 08:32 PM
Thanks for the picture. I found an inexpensive technical publication with some excellent information, "S.A.I.S No. 9". Also thumbing other books at a local firearms dealer.

Went to a gun show today. There were two Mk 6s. One was a rusted out hunk of junk that the guy wanted $400 for. Crazy. The other was in not much better shape that was asking $800 for. Given it was a gun show, but come on now.

Carl N. Brown
December 19, 2005, 01:23 PM
Mo' modern cylinder lockup:
http://www.thehighroad.org/attachment.php?attachmentid=32771&stc=1&d=1135012792
I paid $150 for my Mark IV. The gun show guy asking $400 for a rustpot Mark VI and
$800 for a good one reminds me of the the guy who wanted $600 for an Iver Joihnson .38 top
break when the guy next to him had one asking $100. Some guys at gun shows don't
know much and think you know less than they do.

unspellable
December 19, 2005, 02:48 PM
They have gone up a lot though. I paid $25 wholesale for a mint condition Mk VI in '66 or '67. Now I see rough looking ones for $400 retail.

If you enjoyed reading about "Webley Mk VI question" here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!