View Full Version : Working up the nerve to slug my SBH barrel

05-10-2010, 11:19 PM
I wanted to slug my .44 revolver tonight with some stick on wheelweight egg sinkers, but decided to wait till tomorrow. The diameter of the two promising sinkers was about .454 and .441

When I placed the .454 over the cylinder it seems much too large. The .441 diameter sinker looks like it will leave a wide enough spot to measure once it is pushed through.

On the cylinder do I push it through from the back toward the forcing cone? I'll be using a 3/8" aluminum rod -- can I damage the forcing cone if the edge of the rod catches the edge of the cone?

I hear that the most important measurement(s) are the forcing cones, but figure I'll push one through the barrel anyway. I realized tonight that I'll have to remove my UltraDote so I don't shake it to pieces. I just zeroed it this weekend after finding that it had worked loose last weekend [smilie=b:.

I recently acquired a used Starret micrometer, and have figured out how to read it. I'm hoping that it's accurate enough for this purpose, bu don't have a standard to measure to test it.

Any suggestions on alleviating the qualms that I've got about hammering on my revolver's muzzle? I have soft lead, wooden hammer, lots of oil, and a case of the hebegebees.

05-10-2010, 11:38 PM
I'd use pure lead, not the WW sinkers.

05-11-2010, 12:16 AM

Don't bother with a lead slug and a hammer anywhere near your pistol! Use a small-hole gauge and a micrometer for measuring the cylinder throats .. If your 0 - 1 Mike shows "0" when the spindle and anvil meet it is plenty good enough to measure a firearm's bore.

If you want to measure your barrel just load a squib load and shoot it into a heap of rags out in your garage, recover the bullet and measure it. Do not mess with hammers, pounding slugs through expensive holes in your gun!

The most important thing in this process is to verify that the cylinder throats are bigger than the barrel's groove diameter .. lots of other things can go wrong with relatively lessor problems than having a big barrel and small cylinder bores.

Good evening,

05-11-2010, 07:16 AM
Another way to get some base measurements is to measure the internal diameter of a case fired with a full powered load, jacketed is fine. That will give you the max diameter you can work with. Usually you'll end up somewhere near that measurement in the end anyway.

chris in va
05-11-2010, 08:02 AM
I just used a cast boolit and greased the barrel really good. Practically slid through on it's own.

05-12-2010, 09:46 AM

Just yest yesterday I needed to measure the bore of a friend's old M98. He wanted me to check the rifle over and do a little shooting with it. Thus I had occasion to put the squib load measuring technique into operation.

The M98 is an old military item with a semi-good hack-saw sporterizing job on the issue wood. I had on hand some LEE 8mm bullets, as cast at 0.3255 which I loaded over 3 grains 700X. Then I went out to the garage and fired it into my pile of rags.

Too much 700X drove the bullet past the rags into the solid stop and ruined the bullet for measuring purposes. I reloaded with 2.2 grains 700X and a fresh bullet. This time it was just right. I recovered the bullet, measured it and now have a good working basis for coming up with a correct bullet size for the accuracy loading to come.

Good morning,

45 2.1
05-12-2010, 10:36 AM
I reloaded with 2.2 grains 700X and a fresh bullet. This time it was just right. I recovered the bullet, measured it and now have a good working basis for coming up with a correct bullet size for the accuracy loading to come.
Good morning,Forrest

Just a reminder to anyone doing this. This method is fine, provided you start with a boolit larger than what the groove diameter is as this will only give you the smallest major diameter in the barrel. The barrel throat diameter will probably be larger than the diameter found this way or the groove diameter at the muzzle. Accuracy standards are your choice, but most 8mm Mausers can produce some very enlightening accuracy......... moreso than many would have you believe.

05-12-2010, 08:54 PM

Using an aluminum rod and a lead slug (of any allow) you cannot possibly harm your bore or throats.

Compare the forces you would be applying to the bore to what happens when you pull the trigger on a full load.

When you begin to drive a slug through the bore, if it's much oversize whatever is too big to fit into the bore will shear off. I've slugged a 357 bore with a 45 boolit, no problems at all.

As to your mic, when the mic is fully (but gently) closed does it read 0? If it doesn't, round the back of the barrel of the mic you'll see a small, shallow hole. That's where you insert the adjusting wrench that Starrett makes to adjust the zero. As a general rule, any Starrett will be more than accurate enough for what you need.

Good luck!


05-13-2010, 11:01 AM
Yes - slowly close it until the little "clutch" starts clicking, and it's dead on zero.


05-13-2010, 11:23 AM
I too was worried about a hammer and rod on my Super Blackhawk. Then I thought about it; egg sinkers are waaay softer than my .44 Mag. cylinder, the brass rod I used was much softer than the barrel, so I did it. I put the barrel of my Ruger in a leather padded vise, and using a plastic mallet (much softer than Ruger steel) I started the sinker into a lightly lubed barrel. With the sinker still about 1/8" out of the muzzle, I used the brass rod to push the slug through the bbl. For the cylinder, I removed it from the gun and set it on my bench pad, throats up and slugged each bore separately and numbered them.

http://www.lasc.us/IndexBrennan.htm Check this site out for lots of good info. Chapter 2.1 has info on measuring your gun's bbl and cylinder.

05-13-2010, 11:42 AM
Some thoughts on your post...

1. Make sure the contact faces of your Starett are clean and then close the mic It should read 000.

2. Now take a jacketed bullet of known size and mic it. If you get the nominal size, your mic is working well enough.

3. I have sluged hundreds of firearms, and if done right, there is no risk of injury to the gun.

4. Use a soft lead slug. I use swaged bullets or round balls of a larger size.

5. Start the slugs with a rawhide or wood mallet.

6. Seat them an inch or two down from the muzzle with a piece of brass rod.

7. Push them through with a cleaning rod.

8. Make certain the barrel is clean and oiled.

9. Place rags or paper towels at the breech end to catch the slug so it wont be damaged.

Das All..