Just slugged my NM Blackhawk 45 Colt.

[Topside]

Just slugged my NM Blackhawk 45 Colt. Tough to sound intelligent about something your new to so I won't even try. I just drove a .452 cast bullet through the 4 5/8 barrel. Not difficult with proper sized wood dowel. All I have to measure the bullet with is a plastic dial caliper that has seen better days. Do I measure the bullet at it's widest diameter....maybe on the driving band? I'm a little lost I guess. Help appreciated. I have been needing to replace the caliper for a while. Looks like it's time.

I'm next going to slug the Marlin Cowboy same cal. and then the Blackhawk .357 and maybe the Series 70 45 ACP too so your help will help me get it done right. Thanks in advance.

T.

[salvo]

Yes, at the widest diameter.
And be sure to measure the cylinder throats also, Ruger has a reputation for being undersized.

Also when you are slugging the barrel, be mindful of the feel of the slug as you push it through, you will be able to feel any constricted points that may cause accuracy problems.

[Sixgun]

Yes, at the widest diameter.
And be sure to measure the cylinder throats also, Ruger has a reputation for being undersize.

Yes, this is the most important. Instead of measuring the cylinder mouths, (hard to do unless you have the right plugs) try pushing a .452 bullet through them. It should be a snug push through. If you have to pound it through, you need to have them opened up as 99% of Ruger barrels I have measured are .452. Our very own CAS can do it for you. His e-mail is somewhere on this site.

Sizing bullets for a revolver is done by measuring the cylinder mouths as long as the cylinder mouth is as large are the barrel's groove diameter.

If the cylinder mouth is small than barrel groove diameter, you need to have the mouths opened up.

If the cylinder mouths are a thou. or maybe two over, usually the barrel diameter is fine for sizing the bullets.

If the clylinder mouths are two or four thou. over, use that measurement for sizing.

If the cylinder mouths are 5 or more over, get rid of the gun--(or replace the cylinder)--yes, I have seen that on double action 'Smiths and a few SA Colts.

The most accurate combination is when the cylinder mouth equals or is a thou. over barrel groove diameter.

There is a lot more to all this but this will get you in the ball park for a decent shooting revolver-------------Sixgun

[Topside]

Thank you both. I have now tapped a .452 bullet through all cylinder mouths. I couldn't push them through, but they did go through tapping lightly with a hammer on the dowel. I have not even really put this revolver through its paces sitting with a good rest from a measured distance. Soon as I've given it a good test, I'll know whether to go further on any cylinder adjustments. If it shoots well, I'll stick with the .452 dia. bullets until time to order more, and at that time I'll consider doing some accurate measuring of diameters and maybe try some .454's.

This is an interesting subject. Lots to learn (big understatement). I appreciate you all taking the time to help out.

I have one other question. How do you know if your barrel is leading? What's it look like in the bore or on a patch?

T.

[J Miller]

Thank you both. I have now tapped a .452 bullet through all cylinder mouths. I couldn't push them through, but they did go through tapping lightly with a hammer on the dowel. I have not even really put this revolver through its paces sitting with a good rest from a measured distance. Soon as I've given it a good test, I'll know whether to go further on any cylinder adjustments. If it shoots well, I'll stick with the .452 dia. bullets until time to order more, and at that time I'll consider doing some accurate measuring of diameters and maybe try some .454's.

This is an interesting subject. Lots to learn (big understatement). I appreciate you all taking the time to help out.

I have one other question. How do you know if your barrel is leading? What's it look like in the bore or on a patch?

T.

Topside,

If you had to tap the bullets through the cylinder throats, the throats are undersized. A .452" bullet should be a snug pencil push through the throats. That is how the throats on my Uberti are and it's one of the most accurate .45s I own.
Cylindersmith.com - CAS here on the forum
( http://www.cylindersmith.com/ ) is the person to contact to get them properly reamed out at a very reasonable price and good turnaround.

Leading is lead deposited in the barrel. Take a bristle brush and push it through the bore. The bristle brush will rough up the lead, but won't touch the barrel.
You can also see it by looking down the cylinder or muzzle end. The leading will appear as dull streaks of grayish silver against the darker steel.

Joe

[Sixgun]

Topside,
You have a good cylinder. Its probably running right at .452 or a half thou. under. Bullet lube and slight out of roundness of the bullet will give it that tight "push through". A bullet that is a thou over cylinder mouth dimensions will require some sharp raps to get her through, especially with a hard cast bullet.

My suggestion is to stay with .452 but.........weird things happen. Test with .452 first, then try .453 or 4. I do have one old pre-war Colt New Service that measures .454 but don't like .454. It likes .452! Go figure.

You can see the leading in the barrel. Its a gray color. First, Look at a clean barrel real good, using a light--then take a photographic memory After shooting a bit, you will notice that it accumulates ahead of the forcing cone. (back end of the barrel--nearest the cylinder) The lands and grooves will not be as sharp. After a while, it might work it's way down the tube.

Its no big deal to have a moderate amount of leading. It will still shoot good. Its when you see chunks of the stuff filling up the lands when it becomes a problem.

Shooting a bullet that is AT LEAST the size of the barrel groove diameter. (preferably, a thou over) will eliminate most leading. Also, common sense items of keeping the velocity normal, using the right alloy and lube will keep it all at bay.

Your thinking too much---don't get all paranoid over leading. I've shot hundreds of cast bullets through revolvers at maximum speed without cleaning. You get some leading but it usually stays at that--some.

There was a time in my youth when I was shooting dead soft wadcutters at 1400 through a Ruger SA. After about 10 rounds, I could no longer see the rifling. I did not know any better and kept shooting. I was wondering why I could not hit a washtub at 20 yards! A half dozen or more jacketed bullets cleaned her right out. ---------------------Sixgun

[markinalpine]

There is a good article at Shooting Times that is still available: The Lowdown On Lead Fouling
http://www.shootingtimes.com/ammunition ... index.html
It explains bullet fit and leading.
Good Luck,
Mark

[DixieBoy]

Topside - You're getting pretty good advice here. I've been dealing with a Blackhawk myself lately. Mine came from the factory with wayyyy undersized cylinder throats. Couldn't push a .452 bullet through any of them to save my life.

If your cylinder throats allow you to push .452 (lead) bullets through them then I'd say that you're reasonably alright there.

A simple little trick to spot leading is (after removing the cylinder in your Blackhawk) to stand with a decent light over your shoulder, with the light pointing towards the muzzle. Take any kind of white paper you might have laying around and hold it about an inch away from the forcing cone.

On a revolver that is leading when you shoot it you'll see leading in there easily, even when you've cleaned the barrel of most of the powder fouling. I've had lead that looked like little scabs hanging on to the inside of the barrel. It's not always stuck just in the grooves; sometimes it's right there on the lands too. Believe me, you'll see it.

A good quick remover for lead is to take one of the copper wire type pot scrubbers you find in WalMart, pull some strands off of it, and wrap them around an old wire bore brush. You can pull or push this through the barrel, but pulling it through (you'll have to screw the rod onto the brush, with the brush sitting under the topstrap) will be easier.

Getting these throat, forcing cone, and other issues resolved has been a little bit of a pain in the keister for me, but I'm finally getting close to some serious accuracy out of mine. Learning a fair bit about the revolver along the way has made it that much more satisfying. - DixieBoy

[medicdave]

Undersize is an understatement. I just did three of my rugers throats, two I had to use the .4480 pilot, and the third used a .4495. All much better now at .4525. Not hard at all to do yourself. Takes about 10 minutes per cylinder. You'll spend more time cleaning the reamer betweek cylinders than actually reaming.

[Old Savage]

Three screw 45 Colt that is very accurate seems to measure .452 in all throats with Keith bullets that measure .452 on the front driving band.

[Topside]

Thanks everybody. You all sure know your stuff!

T.

[adirondakjack]

I never slugged a bore on a ruger .45, and don't need to. The throats are almost always a little undersized, but as Dave Corbin, the king of swaged bullets explains, a little undersized is GOOD, so long as they are EQUAL (for group therapy, EQUAL THROATS ARE IMPORTANT), because when smacked in the behind, a bullet, like a rivet, WILL be the size of the hole, and when smashed through the barrel's forcing cone, WILL BE bore size. OVERSIZED THROATS, those that allow gasses to escape past the bullet, boiling lead on the sides ruin accuracy. Most rugers will be tight throated. If you simply insert a .451 JACKETED bullet backward into the throat, it ought to almost go but not quite. If the place it hangs up is the same in all the throats they are equal. If one is noticeably tighter, use a dowel wrapped with 1500 paper or paper towel doped with polishing compound to make em equal, but do NOT get em so that 451 bullet will fall through. if you do, you may as well have a 1960's vintage colt, which was known for oversized throats (.45 or so) and .451 barrels, and most wouldn't shoot worth beans.

My BH and both vaqueros run right around .450 throats. They print very tight groups if the bullets are right, load development good, and the nut behind the hammer isn't too loose.

[J Miller]

Topside,

I'm afraid I must disagree with A-Jack. Undersized throats, even or not, are not conducive to good accuracy for jacketed bullets, and they can be downright disastrous to accuracy with most cast bullets available for the .45 Colt.

Jacketed bullets are somewhat flexible. If the throats are not too far under size to the grove diameter, and if there is enough pressure behind them, they will expand to grab the rifling. They won't seal the bore though unless you're shooting magnum level loads. Since they don't seal the bore you'll loose pressure and velocity due to blow by. (An example of this is to shoot a 45ACP jacketed load through a Ruger BH. If you can recover the bullet you'll see it's sides are black from powder blow by.)
However accuracy is usually OK due to the fact the jacket has grabbed the rifling and stabilized.

Soft lead bullets such as those used by Winchester, Remington and Federal will sometimes expand to seal the bore if the throats are not too undersized. But here is the problem. Most factory .45 Colt lead bullets are far larger than most people realize. Winchester = .456", Remington = .455" others I've miked at .454". Now imagine how hard it is on a bullet to get squished down from it's nominal diameter to say .450" then try to re-expand back up to maybe .451" or .452". That is very hard on bullets, even soft ones and there may not be enough pressure to expand them.

Hard cast bullets are a total nother matter. It takes more pressure to expand a hard cast bullet than most .45 Colt revolvers are capable of handling.
When fired through undersized throats it will jack up the pressure because of the resistance to being compressed in the throats, and they will be compressed. No choice there. You will also feel increased recoil because of the pressure.
Once the bullet clears the cylinder it will be undersized and the powder gasses will boil around it's base and soften the sides. This causes leading. And if you are using a bevel based bullet, the problem is exacerbated. And for the first couple inches of the bore they will be skidding instead of grabbing the rifling and that will add even more lead to the bore.

Most hard cast bullets are cast from 92-6-2 alloy (92% lead-6% antimony-2% tin) . This is a very hard alloy. Great for full house .357s, .41 and .44 Mag max loads. But way too hard for 99.9% of the .45 Colt loads you'll every shoot.
Go to this site and read it.
http://www.lasc.us/CastBulletNotes.htm
Down towards the middle of the page is a section that tells you how much pressure various alloys can take. And a section that give a formula to calculate how hard an alloy you're pressure should be used with.
Back to the .45 Colt, it's SAAMI max pressure is 14,000 psi, the 20-1 lead-tin alloy should be used with a minimum of 14,220 psi.

I've typed all this to say that for optimum accuracy a revolvers chamber throats should be slightly larger than the barrels grove diameter, and the bullets you shoot should be the same as the throats or slightly larger. This seals the throats, then the bore without undue distortion of the bullet, and minimal or no leading.
"Most" Ruger .45 Cal barrels run .451" to .452". This is why the almost universal suggestion of .4525" throats. This allows the bullets to seal nicely.
...............................................

In your first post you asked how to measure the bullets you used to slug the bore. Well, here's some suggestions;
A caliper if used must be a good one capable of at least .001" measurements. Dial or digital preferred. I prefer a micrometer that measures .0001".
And here is how I slug the chamber throats. I go to Wal Mart or any fishing store and buy hollow egg sinkers. I use the 1/2 ounce size for .45 Colt cylinders. And make sure you get the lead ones. They come in zinc too.
The hollow egg sinkers will compress quite a bit and due to that won't bounce back as much as solid lead slugs will.
Use the micrometer and you'll be as close as you can get without using a pin gauge. (Those still confuse me as there is several accuracy levels or tolerances to figure out.)
Then don't throw the slugs away, use them to slug the bore.

After that toss them in your scrap lead bucket. Never ever throw any lead or brass away. There's always scrap value if you can't use it.


Joe

[Lefty Dude]

Right on Joe, I Agreed 100%

I just slugged my new Cimarron/Uberti 5 1/2" artillary BP frame 45. The bore slugs .452", then I used a pin gauge and measured the chamber throats. All the chamber throats measure .4525".

I was very surprised as this piece chambers were completed with a finish reamer. On close inspection of the throats I could see the difference between the throat finish and the actual chamber reamer marks.

This one was done right at the factory, and is a shooter.

For a 44 shooter I am impressed. This 45 is very accurate.

BTW; It likes 255 gr. pills and dumps them all in the same hole at 15 yards.

[adirondakjack]

Joe, yer missing it. I make my own cast bullets and size em all to .452. I buy .451 JHPs and they mic out at .451. A .450 throat will work beautifully with either, regardless of hardness (cast can be dead soft or straight lino or hardened to 30 BH) and they all work if driven at velocities appropriate to the bullet. Six shot, six chamber groups from a gun not cleaned in years that run to 1.5" at 25 yards are boringly common.... Ya want more? Get a rifle or a pistol with a match chamber and fixed barrel ala TC contender.

NOTHING is perfect, and since we cannot control everything exactly, a hair smaller is better than a hair too big which WILL cause leakage as the bullet passes through the THROAT. That "squeeze" through the tight throat causes enough pressure on the base to assure it bumps up beyond throat size as it exits, pasta through an extruder. Too big a throat you get zero obduration or seal until ya get to the forcing cone, at which time the gasses can leak around the throat as they try to push the still oroginal sized bullet into it.... Tight throat, hard ram into the forcing cone by gasses still trapped by that tight throat, all is good.

Next, if yer BUYING .45 bullets that are .454 and more, and are billed as .452, get ya a new supplier, as his SIZING/lubing dies are shot (that's one process, buddy)

The absolute worst .45 I ever owned was a Virginian Dragoon with .455 throats and .451 bore. It would ONLY group JHPs at OOH MY GOD! pressures, and leaded so bad with cast you couldn't see the rifling, as boiled bullets pased down the bore half liquified from cavitating gasses around em at the forcing cone.

My buddy had a post WWII Colt that was the exact same story. yet slightly undersized throats routinely work well if equal. Many times a pesky recurrant flier is a single waaaaay too small throat, a different issue.

IF yer bullets are always ,452, and if the throats are always .4525, and if yer bore is exactly .451, all is well. But if ya gotta have tolerance, a little undersized throat is the way to go.

[J Miller]

A-jack,
Nope, I'm not missing anything. Like I said, I have to disagree with you on this one. Might have something to do with different life's experiences, different guns etc. Don't mean I'm saying you're wrong or only I'm right, just disagreeing.

We can agree about the Virginal Dragoon though. The one I had was crippled by throats so huge even the .456" bullets of W-W factory ammo was hopeless.

Joe

[Nate Kiowa Jones]

Joe, yer missing it. I make my own cast bullets and size em all to .452. I buy .451 JHPs and they mic out at .451. A .450 throat will work beautifully with either, regardless of hardness (cast can be dead soft or straight lino or hardened to 30 BH) and they all work if driven at velocities appropriate to the bullet. Six shot, six chamber groups from a gun not cleaned in years that run to 1.5" at 25 yards are boringly common.... Ya want more? Get a rifle or a pistol with a match chamber and fixed barrel ala TC contender.

NOTHING is perfect, and since we cannot control everything exactly, a hair smaller is better than a hair too big which WILL cause leakage as the bullet passes through the THROAT. That "squeeze" through the tight throat causes enough pressure on the base to assure it bumps up beyond throat size as it exits, pasta through an extruder. Too big a throat you get zero obduration or seal until ya get to the forcing cone, at which time the gasses can leak around the throat as they try to push the still oroginal sized bullet into it.... Tight throat, hard ram into the forcing cone by gasses still trapped by that tight throat, all is good.

Next, if yer BUYING .45 bullets that are .454 and more, and are billed as .452, get ya a new supplier, as his SIZING/lubing dies are shot (that's one process, buddy)

The absolute worst .45 I ever owned was a Virginian Dragoon with .455 throats and .451 bore. It would ONLY group JHPs at OOH MY GOD! pressures, and leaded so bad with cast you couldn't see the rifling, as boiled bullets pased down the bore half liquified from cavitating gasses around em at the forcing cone.

My buddy had a post WWII Colt that was the exact same story. yet slightly undersized throats routinely work well if equal. Many times a pesky recurrant flier is a single waaaaay too small throat, a different issue.

IF yer bullets are always ,452, and if the throats are always .4525, and if yer bore is exactly .451, all is well. But if ya gotta have tolerance, a little undersized throat is the way to go.

AJ,
I think you are wrong on this one. For most folks it's not going to make a lot of difference. There are so many other thing that come in to play.
I come from the IHMSA silhouette games (International Handgun Metallic Silhouette Assoc.) These folks regularly shoot out to 200 meters at goat size target using open sights. Most common is the single shots but there is a production revolver class and a 100 meter Hunter class (standing off hand).
For years the Dan Wesson’s ruled but now days the Freedom Arms SAA's own it. As for accuracy to start the ideal setup would be a revolver that would take a "match" range rod in at least 5 of the 6 chamber. A service range rod is not close enough.
But, even with a gun that will "match" range it may still be off by .005 or so (the difference in groove and land). This it because the range rod is sized to lands, not the grooves. If it were sized to the grooves you would not be able to insert it into the bore.
That said, to get accurate range the cylinder throats have to be at least larger that the land dia.
So, now you have a cylinder fitted to the barrel that may have a .005 run out. So to compensate for that you need a funnel to line up your bullet as it exits the cylinder, the forcing cone. I'm not going into forcing cone length other than to say in general a longer more gentle angle is better for lead.

Next is selecting the correct dia. for your bullets. The only way to know for sure is slug the bore. How you do this is where folks get into trouble. This is how I do rifles but it will work for handguns as well.
Here's how I like to slug a bore. I like to use a slug of soft lead that is at least 1 1/2 times long than the bore that's being slugged. This extra length assures that the slug doesn't wobble or try to turn in the bore as it's hammered through. This can be verified with short slugs. Measurements will vary depending on where you measure it. The longer slug yields more consistent results. Make sure the bore is clean lead free and lightly oiled, as in an oiled patch pushed though it.
You can drive the slug in from the muzzle if you use a leather or rubber mallet so as not to damage the crown. I like to drive it all the way through to feel and high spots or bulges. I like to use a brass or hardwood dowel that is close to bore size. A rod that is too small can deform the soft lead. Next if it's a levergun I use two wooden dowels just smaller than the bore and cut to the cartridge OAL. These are inserted into the chamber end and the action closed. Next the slug is re inserted in the muzzle end and driven to the wood dowel then bumped up so it's now tight. Now, open the action, remove the dowels and gently tap the slug on out. This will give you a really true picture of the bore just in front of the chamber or farther out depending on how many dowels are used.
To measure I like to use a zeroed Starret micrometer. I don't think most dial calipers are accurate enough.

Once you know the correct bore size you can select the correct size bullets. For lead it’s best to use at least bore size to 1 or 2 thousands over. Once you have decided on a bullet size the next step is to open the throats to at least the same size as the bullets or .001 over the bore. What this does is gently funnels the bullet into the bore.
Where you are wrong is the bullet bumps up even before they move out of the case. Your idea of the bullets swedging down in the throats then being bumped up as the enter the bore will result in battered distorted bullet. This distroys accuracy. The ideal setup is a gentle funnel to the bore.

[J Miller]

Steve,

I think I sorta kinda said that, but you said it soooooo much better.

Joe