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Fishbreath

Revolver Supply S&W 627 moon clips in a Super GP100?

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In pursuit of improved reloads, I'm looking to try some alternate thicknesses of moon clip. Revolver Supply's 627 moon clips look identical to the Super GP100 moon clips I bought from SpeedBeez, and the chambers are spaced the same—the moon clip testing block I use has '627' printed on it, and fits the GP100 moon clips fine.

 

Does anyone have first-hand experience with this, or will I have to be a pioneer?

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The Ruger rep told me that they make the cylinders the same hole spacing as Smith cylinders so the same speedloaders and mooclips will work in both.

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I've seen reports from others on this forum that 1) the cylinder chambers are tighter than S&W's.  If so that would likely be the issue with seating differences between the two.

I'd bet the moon clips that came with the Ruger would be similar to those that came with a S&W and are so loose as to be ineffective in competition.

You can get a  Reamer from Brownell's or send it to a 'smith.  David Olhasso has a shop that does it also.

If it was me I'd get the best Moon Clips I could, tight and set for 1 particular brand of brass, that is consistent, and then clean up the chambers so they work the best.

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17 hours ago, Toolguy said:

The Ruger rep told me that they make the cylinders the same hole spacing as Smith cylinders so the same speedloaders and mooclips will work in both.

 

Just tested.

With pristine 9mm Winchester white box these work in a 929 and Super GP100.

https://www.revolversupply.com/moon-clips-extreme-9-mm-38-super-s-w-929-stainless-steel/

 

They are listed at 0.040" and I measure them at 0.044. 

 

These also work in both guns with the same pristine never fired ammo. 

https://tkcustom.com/products/moonclips/ruger-8shot-supergp-100-035-b-s-9mm

 

They are listed at 0.035" and I measure them at 0.035"

 

With real world ammo the Ruger is damned particular, the most particular gun I have owned and by a margin. Full moon clips that check fine in the 929 may or may not be ok with the Ruger, anything that goes in the Ruger is a breeze in the 929. Am tempted to consider a roll sizer or having the cylinder reamed to match the hole diameters of the 929 (as noted above), passing a Hondo case gauge after being sized by a Lee U die is not good enough. I had D.Olhasso bob the hammer on my gun and ream the chambers deeper to accept longer ammo & 0.358's but maybe I screwed up by not asking him about increasing overall whole diameter as well. 

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How "tight" are the rounds in the moon clips you folks are using ?

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Posted (edited)
21 minutes ago, 10mmdave said:

How "tight" are the rounds in the moon clips you folks are using ?

 

Winchester in the revolver supply clips that I measure at 0.044 is too tight for me to be able to use a BMT sooner/demooner, or at least to want to. The brass does turn freely after loading.

 

Same brass with the 0.035 feels right to me, but maybe the real revolver gurus would want tighter.

 

Got this in an email from David Olhasso, referring to the 9mm Super GP 100:

 

I personally prefer TK .040 moons. I use RP brass and special TK moons cut to hold the RP brass properly. If I wasn't using RP brass, I would be using Winchester.
 
The issue is, depending on your Crane length and b/c gap, you may not be able to use .040 without some modifications. I suggest getting.035 and .040 samples and determine which is best, or just resign yourself to using .040 and cut back the crane and barrel if necessary.
 
-dave
 
 
 
Would be interesting for me to try the TK Custom clips (likely would measure at 0.040 instead of 0.045). 
Edited by IHAVEGAS
too many zeros

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15 minutes ago, IHAVEGAS said:

With real world ammo the Ruger is damned particular, the most particular gun I have owned and by a margin. Full moon clips that check fine in the 929 may or may not be ok with the Ruger, anything that goes in the Ruger is a breeze in the 929.

 

Thanks for the tests. My 627-spec loading block does accept .38 Special more readily than my Super GP100 does. I've been shooting PPU factory ammo to generate a stock of brass, and it drops into the loading block cleanly and sometimes gets stuck in the Super GP100. The PPU stuff is taper crimped, so I think it's the edge that's binding somewhere. I'm hoping the chamfering I'm having Mr. Olhasso do this winter, along with thicker moon clips, will help there.

 

Whether I stick with .38 Special or move to a shorter .38, I think my long-term plan is to stock up on 0.025" clips and Starline brass.

 

 

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Posted (edited)

I am going to start cutting my own moonclips for a 929, but also want to make some for the GP100. I am currently working on creating some samples and already have a guy, here in the U.S, that will mass produce them for me. 

 

I will mail you a few when I have them. 

Edited by Pnut

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5 minutes ago, Pnut said:

I am going to start cutting my own moonclips for a 929, but also want to make some for the GP100.

 

For what it is worth, I'm wondering if the majority will move toward having their 9mm SuperGP100 cylinders honed out to match the larger 929 dimensions?

 

Seems like having a tighter than needed cylinder bore will not be a great thing for reloading consistency during a match (when cylinders are not clean and pristine). 

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You’d have to have moons cut tighter to shoot RP brass with TK.  
TK moons are looser than DAA and before I knew better and used range brass occasionally a RP round would fall out of a TK .04 929 moon.

 

 

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On 8/1/2020 at 2:16 PM, Fishbreath said:

In pursuit of improved reloads, I'm looking to try some alternate thicknesses of moon clip. Revolver Supply's 627 moon clips look identical to the Super GP100 moon clips I bought from SpeedBeez, and the chambers are spaced the same—the moon clip testing block I use has '627' printed on it, and fits the GP100 moon clips fine.

 

Does anyone have first-hand experience with this, or will I have to be a pioneer?

the recess on the back of the cylinder on a 357 Super GP100 is slightly smaller than the one on a 627 causing the 627 moon clips to hang up on the tips of the arms between the rounds and not work in the gun. I ground the tips back on a hand full of 627 clips while I was waiting for my TK super gp100 clips and those work just fine.

 

I plan to at some point enlarge that recess so I can just use all my clips in either gun but have yet to do it.

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On 8/3/2020 at 12:05 PM, Pnut said:

I am going to start cutting my own moonclips for a 929, but also want to make some for the GP100. I am currently working on creating some samples and already have a guy, here in the U.S, that will mass produce them for me. 

 

If ever you branch out into the .38/.357 realm, I'd certainly be interested.

 

4 hours ago, MikeBurgess said:

the recess on the back of the cylinder on a 357 Super GP100 is slightly smaller than the one on a 627 causing the 627 moon clips to hang up on the tips of the arms between the rounds and not work in the gun. I ground the tips back on a hand full of 627 clips while I was waiting for my TK super gp100 clips and those work just fine.

 

Thanks—I guess I'll bite the bullet and order some from TK Custom for now, if I want 'em thicker. We'll see how my thin SpeedBeez ones handle Starline .38 Short Colt over the winter.

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6 hours ago, Fishbreath said:

 

If ever you branch out into the .38/.357 realm, I'd certainly be interested.

 

 

I'm starting with 9mm because that is what I have and can test. If that works, .357 will follow. 

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On 8/3/2020 at 12:18 PM, IHAVEGAS said:

 

For what it is worth, I'm wondering if the majority will move toward having their 9mm SuperGP100 cylinders honed out to match the larger 929 dimensions?

 

Seems like having a tighter than needed cylinder bore will not be a great thing for reloading consistency during a match (when cylinders are not clean and pristine). 

That is interesting, because everyone complains the 929 is a pain to develop a load for due to the cylinder. I have to shoot .358 out of my 929. 

 

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11 hours ago, Pnut said:

That is interesting, because everyone complains the 929 is a pain to develop a load for due to the cylinder. I have to shoot .358 out of my 929. 

 

I think you mean the barrel rather than the cylinder. I shoot .358's in my 929 also & a friend sent me the paragraphs below, excess wear due to oversized bullets is claimed in the last paragraph. I do not know if we are screwing up the 929's by running 0.358's. Others comments would be very welcome. 

 

I just finished some very unscientific testing with my 929 & SGP100, with 0.356's on both guns it is easy to push the bullet through the throats of the cylinders with a little finger pressure (possibly if both guns were not dirty from a range trip the 0.356's might have dropped through), with 0.358's you are not going to get through the cylinders with just finger pressure, it seems like they go in the SGP100 a smidgen farther before being stopped. 

 

 

 

 

Iowegan

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Retired Moderator & Gunsmith
Joined Aug 31, 2006
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16,101 Posts 
Endshake and B/C gap are two totally different animals, but they are related. As Seneca stated, endshake is the fore/aft movement of the cylinder. B/C gap is the distance from the cylinder face to the rear of the barrel when the cylinder is held to the rear (measrued with an automotive type "gap gauge"). If endshake becomes excessive, bad things can happen ... such as misfires from excessive headspace, dramatic loss of velocity, excessive "gap spitting", accelerated top strap flame cutting, or worse yet ... in extreme cases the cylinder can jump out of lockup and result in a very dangerous situation.

Here's what happens when a round is fired: the outside surface of the bullet contacts the cylinder's throat and pushes the cylinder forward until it stops when the face of the internal crane tube contacts the bearing surface inside the cylinder's center hole. When the base of the bullet crosses the B/C gap, chamber pressure thrusts the cylinder to the rear until the ratchet column strikes the recoil shield. This "jack hammer" effect will eventually cause endshake to increase. Once endshake exceeds .005" the cylinder will develop more momentum as it moves fore/aft and the jack hammer effect will accelerate wear even more.

B/C gap specs for nearly all revolvers is .006" +or- .002" (.004~.008"). Endshake always increases the B/C gap at the most critical point in bullet travel ... when the base of the bullet is flush with the rear of the barrel's forcing cone. This will cause more pressure loss, lower muzzle velocity, more "gap spitting", and more top strap flame cutting. Endshake specs depend on the brand and model .... S&W revolvers are way more sensitive to endshake so their specs are tighter ..... typically from zero to .003". Ruger DAs have a more massive crane tube so they aren't as prone to wear. As noted above, a Ruger DA revolver should have no less than .002" of endshake and no more than .005". When a new revolver leaves the factory within these specs, chances are it will last for many many thousands of rounds. 

There are four areas of "wear" that affect endshake .... the end of the yoke tube will peen, making it slightly shorter, the bearing surface inside the cylinder's center hole will develop a "channel" which allows the yoke tube to seat too deep, the ratchet column will peen and make it shorter, or the recoil shield will develop a divot that allows the cylinder to move back too far. Generally, in a well used DA revolver, all four of the wear areas will be affected and add to the total endshake. The way you measure endshake is to wedge the cylinder to the rear and measure the B/C gap. Next you wedge the cylinder to the front and measure the B/C gap again. The difference in the two measurements will be total endshake. In a Ruger DA revolver, if endshake is too tight (under .002") the cylinder will bind, causing DA trigger pull to be harsh. After a box or two of ammo has been fired, endshake will usually open up a few thousandths and make the cylinder rotate easier. S&Ws work different ... their max endshake is only .001" different than a Ruger's minimum, so ... don't try to apply one gun's specs to a different brand.

Repairing endshake: First you have to do some trouble shooting to find out where the problem(s) may be. If the cylinder moves too far forward where the B/C gap is less than .004", it's either a peened yoke tube face or a channel cut inside the cylinder's center hole bearing surface ... maybe both. This condition is repairable. Next is to measure headspace. This is done by inserting a "virgin" case into a chamber and aligning the chamber with the firing pin hole. Again, use a gap gauge to measure the minimum and maximum distance between the case head and recoil shield by holding the cylinder to the front and again by holding the cylinder to the rear. A typical DA revolver will have a headspace of .008" +or- .002". If headspace is under .006", it means the ratchet column has worn or the recoil shield has a divot .. or both.

There's virtually nothing you can do to repair a frame when a divot develops in the recoil shield ... short of replacing the frame. Likewise with the ratchet column on the cylinder ... short of replacing the cylinder, there's no fix. Shims between the ratchet column and the frame (recoil shield) won't work because the hand that rotates the cylinder won't be able to advance the ratchets. Fortunately, these two conditions seldom are the sole source of excessive endshake.

When the yoke tube wears or a channel is cut inside the center hole bearing surface (the most common cause), there is a way to repair the gun. First you must use a rotary grinder bit to "dress" the inside bearing surface and remove the channel. After the channel in the bearing surface has been removed, it's just a matter of installing endshake bearings, which are nothing more than very thin washers (.002" thick). Endshake bearings can be stacked to bring endshake back into spec. Installing endshake bearings without removing the channel usually doesn't work ... the first time you fire the gun, the thin washers will form into the channel and bind up cylinder rotation. Likewise, if you use endshake bearings to compensate for ratchet column or recoil shield wear, you will end up with a headspace that is too tight. A slightly thicker case rim or a slightly "proud" primer will bind up cylinder rotation.

Preventing endshake: There are two primary causes of endshake wear .... shooting hot loads and shooting bullets that are oversized. As an example .... 10,000 rounds of 38 Specials will cause less endshake wear than just 500 rounds of 357 Mags. So .... shoot 38 Specials for practice and shoot 357 Magnums sparingly. Check your cylinder throats ... if they are too tight to allow a bullet to pass through with just finger pressure, the throats are too tight or your bullets are too fat. As noted above, the cylinder slams forward when the circumference of the bullet contacts the throat. If the bullet is larger than the throat, it causes the cylinder to be forced forward much harder than with a properly sized bullet. In the thousands of revolvers I have worked on in my gunsmithing career ... I've found without exception ... tight cylinder throats or oversized bullets always result in excessive endshake wear. There's absolutely no advantage with shooting bullets that are larger than the throats because they will get sized down as they pass through.

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That is interesting I too would like to hear other opinions.

 

Before factory 9mm became impossible to find, I tested a few factory jacketed rounds (.356) through my 929 and it shot much better than. 356, .357 and even .358 cast. 

 

I am waiting for extreme bullets 160gr to be back in stock to order a few and try those. 

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