.357 BH shoots erratic - need guidance

[wavehopr]

I have a newly acquired .357 OM Blackhawk(1970) that I cannot get to shoot consistent. I get 1-2 flyers out of every cylinder.

I have visually checked the crown and it looks OK. I just now got through slugging. The barrel slugs at .357. All the cylinder throats are consistent at .359.

I've used 2 type cast bullets(RNFP and RN). Although I haven't checked their diameter, I have to push them through the throats with some force. The loads I'm using consist of 6 gr. Unique for both the 180 gr. RNFP and 158 gr. RN. Any ideas?

 

[SAJohn]

Are the flyers from the same holes in the cylinder?

 

[wavehopr]

Are the flyers from the same holes in the cylinder?

that I don't know and it's something that I thought of after returning from the range yesterday. I plan to notice whether the flyers are from the same chamber the next time I'm out.

 

[SAJohn]

If so then I suggest you do a range rod test of the barrel to cylinder alignment. Assuming you do not have a .357 range rod, take a strong light sideways to the front of the cylinder with the loading gate open. Then slowly cycle the action though all 6 of the EMPTY cylinder holes while looking down the barrel. Poorly aligned cylinder holes can be visually detected.

A standard .357 range rod has a .3446 inch diameter. A poor man's substitute is an 11/32 drill rod.

Cylinder wobble might also be a cause. A visual check for this is to rotate the cylinder while watching and/or measuring the gap between the top front of the cylinder and the cylinder frame. This is just theory on my part as I have never seen cylinder wobble on a Ruger Blackhawk. I have seen where the entire cylinder is low to the barrel.

Hopefully one of our real gunsmiths will see this post rather than just you humble engineer amateur smith.

Humble John

 

[flatgate]

Number the chambers and keep records when you shoot it a couple more cylinders full. If it's consistent then you'll know which chambers are "abnormal".

So, next step would be to carefully inspect the "bad" chambers. You'll need some pin gauges to check the cylinder's throats and a caliper to check the headspace. Also inspect the "exits" of the chambers on the face of the cylinder. A small nick or an "un-square" cylinder face can raise havoc!

I'd also, as SAJohn mentions, check the "tightness" of the cylinder latch.

Range Rod? Not very useful on a Ruger unless it's one produced by the Iowegan from RugerForum.net


As usual, JMHO,

flatgate

 

[Bucks Owin]

Number the chambers and keep records when you shoot it a couple more cylinders full. If it's consistent then you'll know which chambers are "abnormal".

So, next step would be to carefully inspect the "bad" chambers. You'll need some pin gauges to check the cylinder's throats and a caliper to check the headspace. Also inspect the "exits" of the chambers on the face of the cylinder. A small nick or an "un-square" cylinder face can raise havoc!

I'd also, as SAJohn mentions, check the "tightness" of the cylinder latch.

Range Rod? Not very useful on a Ruger unless it's one produced by the Iowegan from RugerForum.net


As usual, JMHO,

flatgate

Thanks for the tip...I've used the "sweet chambers" to shrink group size before, but wasn't aware of what to look for in the "not so sweet" chambers other than throat size... :wink:

 

[jungleman]

try a different ammunition, all ammunition will group differently

 

[Hondo44]

Are the flyers always in the same location on the target? Like jungleman suggests, shoot some factory loaded rounds just for kicks. Let us know what you find.

I had a 44 Mag that did that. The same two chambers were always responsible. Factory replaced the cylinder free of charge. Your lucky now that Ruger is making 357s in mid-size frames again, they will have replacement cylinders on hand to fit your OM 357.