NM Blackhawk Convertible Bore Size . . . MERGED THREADS

[sjs]

Is the .357/9mm bore sized correctly for the .357 cylinder or for the 9mm cylinder, or is it a compromise bore size?

 

[woodperson]

I am pretty sure the convertible has the same bore as the .357 only guns. I am pretty sure that bore is within SAMMI specifications for 9 mm as well. I am pretty sure that some manufactures use the .357 barrels on some 9 mm guns.

Now here is what seems to be special with the Ruger. The 9 mm cylinder. The cylinder throat is tapered from .356 at the end of the chamber to .357 at the end of the cylinder. So the bullet expands a little before it hits the forcing cone. Mine shoots 9 mm pretty good.

 

[Kevin]

I’ve got one too, and it’s one of the more accurate revolvers I have in either caliber. The 9mm is a joy to shoot because of the weight of the gun. The one I have has a steel grip frame and with 9mm’s the recoil is about the same as with a single six.

 

[sjs]

Thanks guys, think I'll look for one.

 

[Biggfoot44]

I've read that 9mm accuracy can be variable .

Mine is less accurate than the .357 cylinder , but More accurate than any of my 9mm semi's . So yes , I am pleased .

 

[woodperson]

Other than velocity and bullet weight is there any reason the 9mm cylinder shoots to a markedly different POI than the .357 cylinder?

Acutually shooting 124 grain in 9mm and 125 grain in .357 at about the same velocity (around 1000). The 9 mm hits 2-3 inches lower and 1 inch to the left at 10 yards. Does that sound right? My 158 grain XTP loads at just a little more velocity hit to the same POI as the 125 grain plated.

 

[woodperson]

My 9mm cylinder seems pretty accurate but it does shoot to a different POI than the .357. Not sure why. I was told that would happen when I had a red dot sight added. And it does.

 

[NikA]

1000 fps for a 125gr .357M is pretty slow, are you sure about that number? I'd expect 1200-1300 is more typical and would probably account for the POI difference.

 

[daveg.inkc]

The bullet diameter is never mentioned in these convertibles. .355” to .357”. I’ve not owned, shot, or compared the 2 calibers in a Blackhawk. I would expect a 9 mm to print in a different spot. I do have an OM .45 convertible. .451”-.452“. I shoot the Auto cylinder occasionally,, seems anemic after 18–20 grs of 2400 and a 250 XTP.

 

[Dan in MI]

I'm with Dave. Even with everything 100% identical, the bore diameter is going to have an effect.Something somewhere is going to be a little sloppier, or a little tighter.

 

[Ale-8(1)]

Velocity and bullet weight are two big factors in bullet trajectory. The bullet diameter has an effect on the muzzle velocity, even if small.

 

[woodperson]

Update to old thread instead of starting a new one. This spring I have been marooned in Fl with only one gun. My Blackhawk convertible. I have also run out of reloads and have shot some factory loads. A rare thing for me. What I found though is good news for me. The Federal 158 grain .357 and the Federal 147 grain 9 mm shoot to the same POI at 20 yards. And both are pretty darn accurate. (Burris reflex site on a no drill mount so it is fairly high above the bore.) I am extremely pleased because most of my 9 mm reloads shot to a lower POI than my .357 loads