throats&groove diamiter

[two dogs]

just measured my ruger blackhawk 45 colt throats,they were .4524,4520,4520,4510,4250,4250.groove is .4515.shooting a 230 gr lee bullet,i got 3to4 inch groups at 25 yds,shooting a 250 gr bullet i got 4 to 5 inch groups.will reaming the throats help shrink my groups?should i send it to the cylinder smith?all measurements were taken with a micrometer by a good gunsmith.

[outdoorfan]

Although those dimensions aren't great, they're not terrible either (except for the one that is .451). Yes, it would greatly help if you opened them up to .4525, but that won't make it accurate. Good chance you have severe constriction in the bore where the the barrel is threaded into the frame. You'll need to firelap that out. Sucks, but it works. Longer boolits will help, but you should still firelap.

Read this article. It's very educating, and has everything to do with what you're after:

http://www.beartoothbullets.com/tech_notes/archive_tech_notes.htm/59

[two dogs]

thanks for reply.i read the article very informative.going to open cylinders ,and try fire lapping.any recommendations for fire lapping bullets or compounds?

[mtgrs737]

Take another look at your post, did you really mean .425" on those last two throats?

[two dogs]

yes 4250 measured them twice.

[jandbn]

Are you absolutely sure you did not mean .4520, not .4250? I don't think even dead soft lead in the .451-.454 diamater could be discharged through a .425 throat! I wouldn't want to try it.

[two dogs]

he might of wrote the numbers backwards.

[outdoorfan]

I assumed that .425 was a typo. Has to be. I can't imagine Ruger letting anything that terrible out of their shop. Still, you better verify that. It should be OBVIOUS!!

As to firelapping, you can get a kit from Veral or from Marshall at BTB's.

The basics of firelapping:

Lead bullets of around 12 bhn (optimal), but 10-14 bhn will work fine. Don't go harder than that or softer. You want as much bearing surface as possible (will make it go quicker). NO BORE RIDERS!!! If you don't have your own mold to make these boolits, than you can get them from Veral, Marshall, or somebody here. You will be impregnating the bearing surface of these boolits with valve grinding compound. Marshall only recommends the Clover brand silicone carbide in a grease mix. He likes 320 grit. For Rugers, it would be good to use 280 grit, and then do the final little bit with 320 grit. You will be shooting these at air gun velocities (400-600 fps). You need to clean often (every 6 rounds is about right).

Do a search for "firelapping" on the BTB website/forum, and you'll figure it out. If you do it right, you'll drastically improve your revolver. If you do it wrong, you'll be bitterly disappointed, and then you'll be like so many other people who claim that firelapping will ruin your gun. blah, blah, blah. :grin:

BTW, I highly recommend getting the firelapping kit from Marshall. It comes with what you need, including his very very excellent write-up on the whole procedure.

http://www.beartoothbullets.com/bulletselect/index.htm

[Ricochet]

How did you measure the throats? Sticking a caliper inside them isn't very precise. Driving an oversize slug through and measuring that is a lot better.

[44man]

Yes, stay away from calipers, you will never get the right size.
If those two measurements are right, it needs reamed and would not hurt to even them out anyway.
My Vaquero started with 4" at 25 and 50 was a dream--a pipe dream! I didn't have a reamer at the time so I carefully lapped them until my boolit would just push through. I did nothing to the barrel.
I worked up loads at 50 yards and when sighting with 2 different boolits at 75 yards, I had 2, one inch groups side by side. It has taken many deer since.
I have not found that big a problem finding tight spots at the frame like it used to be.

[runfiverun]

if they were 425 you would have seen the leading all through the bbl and on the cylinder and...

[two dogs]

all measurments done with a 500 dollar micrometer.

[jandbn]

I would ask the smith to verify .425. I think the numbers were inadvertantly transposed but would rather be safe than sorry.

[Grampie not Grumpie]

My wife presented me for our 50th anniv. last month with a "old model" 1999 SS Ruger Vaquero with 5 1/5 barrel complete with a "drop loop holster." When I was checking it out I tried pushing a .451 jacketed bullet through the throats. they wouldn't even start to go through. I have no way to measure the size accurately but whatever it is they are way too small. It shoots jacketed bullets "OK" but I'm sure the pressure spikes passing through the throats. I have a .4525 throat reamer coming and I am holding off shooting .452 cast lead until they are reamed to size. If I don't the lead boolit will get sized down to under the bore size and rattle up the bore shedding lead all the way.

Grampie not Grumpie,

ps: The gun is beautiful and the holster rig is comfortable to wear. I feel self-conscious wearing it but I'll get use to it.

[Grampie not Grumpie]

I would think you could look down the cylinder from the chamber end and see much larger "bump up" on those two if they really are .4250.

Grampie not Grumpie

[mtgrs737]

Looks like Ruger missed the finial reaming of those two throats! Send it back to them and they will make it right!