Super Blackhawk - poor accuracy, any idea where to look?

[sasu]

I have a brand new Ruger Super Blackhawk Hunter 44 Magnum.

The problem is myself and a friend can only get about 4" or way larger groups at 25 yards, shooting from a solid rest, with different factory ammo and handloads.

We are both used to getting 1"-2" groups at 25 meters, even with hard kicking single actions.

The base pin is very tight. There is no abnormal play in the cylinder. The chambers and throats are finished to a nice mirror finish.

Using my inside diameter micrometer I get a throat diameter of 0.430", 0.431", 0.432", depending on the calibration of the micrometer. I cannot get even a 0.001" difference between the throats. I also miked the chamber diameters and did not get any difference between the chambers, at least not within a 0.001" resolution.

The muzzle crown is very neat. The forcing cone looks good.

My friend tried shooting groups using only one chamber at a time. One chamber shot very tight 1" groups, two shot quite well and three chambers shot larger groups.

When shooting from all six chambers, the gun seems to do two separate three shot groups.

I would suspect there is something fishy with the chambers, but how could I determine what it is?

I am overseas so sending the gun to the factory is out of the question. I am on my own, or I could send the gun to a gunsmith for a check up.

Any suggestions what I should be looking at in the gun?

 

[flatgate]

I bet you've hit the nail on the head. The chambers are the problem. They need to be of uniform dimensions. Now, getting the tooling "across the water" may be interesting.

Call one of the "big boy" gunsmiths here in the states and describe your problem. Perhaps you can air mail the cylinder to them for some massaging...

JMHO,

flatgate

 

[sasu]

The chamber throats are uniform, I cannot see any difference between them with my 0.001" resolution inside micrometer.

The different values (0.430" to 0.432") I got were the result of different calibration of the inside micrometer. The inside micrometer does not give absolute measurements, it only shows the difference from a calibrated value.

Every time I recalibrated the inside micrometer, I got a slightly different value, but every chamber throat measured the same relative to the other throats.

The rear sight is pretty solid, too, so the fault is not there, either.

 

[c.r.]

This might sound silly, but check the 5 (i believe) screws that hold the grip frame to cylinder frame. Make sure none of them are loose.

it's a quick and easy check
~c.r.

 

[sasu]

check the 5 (i believe) screws that hold the grip frame to cylinder frame.

Done. Thanks for the tip.

One screw was ready to fall out, two were in need of tightening, two were OK.

By the way, here are some photos of the chambers and details of two suspicious looking area on the muzzle crown.

 

[45Colt_Man]

You say you have handloads so you access to bullets. Can they be pushed through all the throats with uniform pressure?

Dana

 

[sasu]

A jacketed bullet falls through three of the chambers, and cannot be pushed through the other three.

For some reason I am not able to measure any difference between the throats, but the bullet test shows they are different to some degree.

 

[eric conrad]

Give cas a call. www.cylindersmith.com
He does beautiful work.
Eric

 

[flatgate]

As I mentioned, the chambers MUST all be the same.......

Ouch, it appears you have a "burr" at the crown, as well.

flatgate

 

[Rob72]

A jacketed bullet falls through three of the chambers, and cannot be pushed through the other three.

For some reason I am not able to measure any difference between the throats, but the bullet test shows they are different to some degree.

So the question is: are the tighter (no-pass) chambers the more or less accurate ones?

Dunno where you are, but Midway and Brownells ship internationally.
A crowning cutter will clean up your crown (and may improve things somewhat). Your "tight" chambers may not be fully "finish cut", in which case a finishing reamer would be a DIY solution. All told, the tooling is $200-250 USD (cutters, pilots, handles- for both the crown and chamber sets), but, on the bright side, you'll be able to standardize any other .44s you and/or friends may have. :wink:

 

[eric conrad]

Unless you have a lot of cyl. to ream cas is the way to go.
Eric

 

[Johnnu2]

+1 re: send it to CAS....the man is totally reputable, fast and accurate. You can send just the cyl for I think under $50 ??? and get it back wherever you are....prices are on his website....www.cylindersmith.com Then, if that doesn't cure your ills, you can mess with the crown later. JMHO

 

[edlmann]

+1 re: send it to CAS....the man is totally reputable, fast and accurate. You can send just the cyl for I think under $50 ??? and get it back wherever you are....prices are on his website....www.cylindersmith.com Then, if that doesn't cure your ills, you can mess with the crown later. JMHO

linky thingy

 

[wickerbill]

Something else you can check. If you have access to a set of plug gauges, check to see if there are any tight spots in the barrel, especially where the barrel screws into the frame.
Bill