Redhawk B/C Gap and Headspace Specs

[tacotime]

Can anyone confirm what the ideal number or range is for the B/C gap and headspace on a 44 Redhawk?

Thanks.

 

[k22fan]

For both of your questions I don't think the specific revolver model or even the brand matter.

Cartridge and chamber dimensions are standardized by the Small Arms and Ammunition Manufacturers’ Institute, SAAMI. Here is a link to their specification sheet for the .44 magnum. http://www.saami.org/PubResources/CC_Drawings/Pistol/44%20Remington%20Magnum.pdf
Minimum and maximum headspace for the .44 magnum are 0.060" and 0.070".
The height of the center of the ratchet determines head space assuming there is no significant end play. End play is ideally set at 0.001" to 0.002". I haven't seen official end play tolerances for any brand nor have I seen Ruger's b/c gap tolerances, but S&W's b/c gap numbers should be about the same.

S&W's acceptable b/c gap range used to be 0.004" to 0.010", but I've read that more recently they've extended the maximum to 0.012". I don't like b/c gaps under 0.005" because it takes too little lead or fouling build up to add irregular drag to the DA trigger pull. However, if you only fire SA you may not feel cylinder drag that would be objectionable firing DA.

 

[tacotime]

Excellent info.

Question - the SAAMI drawing appears to show headspace measured between the the breech face and front of the cartridge rim (which I assume should equal the rear surface of the cylinder) at .06.

Do they define headspace as the gap between the breech and cylinder or the breech and the cartridge butt?

Mainly I asked because of the cylinder and ratchet (only) swap I just did on a first year Redhawk SS. With luck the headspace (if measured with cartridge in place) ended at .006 but the B/C gap is tight at .003 pushed back and .002 pushed forward, so it looks like .001 endplay. Timing seems right, locking before the cock click an all cylinders and cylinder not bound up while cocked.

The only kink was the ratchet was rubbing slightly on the recoil plate so I smoothed it slightly (only on 1.5 lobes) which suggests the ratchet surface was not true flat across I suppose. Recoil plate had sloppy finish, sanded lightly. Also, the ejector rod ended up slightly long for its frame pocket and I had to relieve the frame pocket slightly or the cylinder would not close. I suppose the new ejector shaft was a hair longer than the old one? The old one could not be used because the pins were 180 degres out of phase with the new cylinder.

No lead spitting and 18 hard cast rounds did not produce enought gunk to clog the B/C gap. No leading with the .431 bullets which was my goal for the swap away from the other cylinder with .432-.433 throats.

My first swap is declared a success so far unless somebody shoots me down with an angle I omitted...

Thanks.

 

[Snyd]

Congrats on the successful cylinder swap. I did the same thing a couple years ago to make my 4" 454 Redhawk. Here's some info from an old thread around here regarding endshake and headspace.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Well said flatgate! Actually there are two things that can cause endshake ... space between the front gas ring and frame or space between the rear of the cylinder's ratchets and the recoil shield. Before you can identify a "fix", you must first determine if endshake is off far enough to require a fix. I like to see about .002" of endshake but no more than .005". This will give the cylinder the needed freedom without being excessive.

To compute endshake, insert and note the thickest feeler gauge (AKA gap gauge) that will fit between the rear of the barrel and the clean front face of the cylinder (B/C gap). Next, insert a wedge between the cylinder and the recoil shield that will push the cylinder fully forward. Measure the B/C gap again and subtract this measurement from the first B/C gap measurement. The result will be endshake.

If endshake is .005" or less and the cylinder is not rubbing on the barrel, forget it and go on with life. If endshake is greater than .005", you need to figure out where it is coming from so corrective action can be taken. It could be a combination of both sources.

Headspace is the distance between the case head and the recoil shield.
Ruger uses the thickness of the ratchets to set actual headspace at .010" +or- .002" (.008-.012"). To measure headspace, insert a new case (not a loaded round) in the cylinder and index it under the firing pin. Place a wedge in the B/C gap to force the ratchet surface against the recoil shield. Find the thickest feeler gauge that will fit between the case head and the firing pin hole. This will be actual headspace. If headspace is less than .008", you will need to shim the rear of the cylinder ... between the recoil shield and the ratchet.

On the front end ... if the B/C gap is less than .004" with the cylinder forced forward or if the cylinder drags on the back of the barrel, you will need a shim between the front of the gas ring and the frame.

If you have both a reduced headspace and a reduced B/C gap, you may need to shim the front and back to get endshake in spec.

Note: Endshake is a dangerous condition in S&W revolvers that can cause the cylinder to unlatch when fired. It really isn't a big deal in Ruger SA revolvers where at worst case you may get light primer hits, a loss of velocity, or excessive gap spitting. Funny how people tend to transfer their worries from one brand to another.

 

[tacotime]

Thanks. Curious though - I have never heard of shimming the end of the ratchet at the recoil plate. How would that be done? Also not heard of shimming at the gas ring. I had only heard of shimming at the end of the "yoke" between it and the inside of the cylinder.