how-to slug a SAA

Status
Not open for further replies.
D

dashootist

Member
Joined
Feb 8, 2010
Messages
551
I'd like to increase accuracy on my Uberti/Cimarron SAA-clone. I was told to "slug the barrel", to determine the bore diameter. My smokeless reloads are currently using .451 hard-lead bullets. My commercial black powder rounds are using .454 bullets (Buffaloarms brand). So there appears to be a wide range of bullet size for the 45 Colt.

So how do I "slug the barrel" on a SAA?
 
an easy way is to drive a soft lead fishing weight (egg shaped) through the bbl using a wooden dowel, a softer than steel hammer hammer and lots of oil
 
Drive the lead from the muzzle end?

I just stumbled upon the specification table in Cimarron's website. Here are Cimarron's data for the 45 Colt.

CAL. .45 COLT
twist: 16"(406.4) RH
bore: .442(11.23)
groove: .450(11.43)
grooves: 6
wide: .156(3.96)

Assuming these data is accurate, what size bullet should I be using for smokeless and black powder loads?
 
Last edited:
Far as I gather -

For Lead or Lead Alloy Bullets ( not Jacketed ), if the widest diameter of the interior of the Barrel Bore are in fact ".450", then, for Lead Bullets, sizes can be .451 to .453 and all should be well...and even .454 would manage, if less than ideally maybe.

But, depending on the Bullet Alloy and weight, .451 to .453 will have the ideal diameter somewhere between 'em.

Most .45 ACP Bullets seem to be .452...so among those which are Lead, would be some good candidates, easy to get, many variations, Semi Wads and so on.
 
The purpose of slugging a barrel is to find its tightest spot.

My experience is that most .44 and .45 caliber revolvers have a choke point where the barrel screws into the frame. I have two Ruger single actions that had frames choking the barrels down to .448".

The .450" groove number is nominal, most likely accurate until the point where the barrel is inside the frame.

Krochus gave good advice as to the technique.
 
Hi Mifflinkid,


Interesting...


So...how would one relieve the constricted portion of the Barrel? If finding one's Barrel has such a pinch?
 
Oyeboten, you have two choices that I know of.

The easiest, if you reload, is to fire lap the barrel by firing bullets with abrasives embedded into them. The bullets are fired using light charges of a fast powder. The abrasives cut at the tightest point but do nothing in the rest of the barrel as long as the pressure is low. There are several kits available from different companies to help create the lapping bullets. Some kits have bullets with the abrasives already embedded. Others supply abrasives and metal plates you can use to create the bullets for reloading.

The second way is to machine the choke area. This is called Taylor throating as I recall for the person who developed the technique. There are several 'smiths who can do it for you. And I think Brownell's has a kit that we amateurs can use a home.

I've used the fire lapping method. It takes a bit of time, hours for me, as the lapping bullets only take a small amount of metal out per bullet. But, for me, that is good as I could remeasure the frame choke periodically to make sure I hadn't removed too much metal.

It made for an interesting day at the range. I had a audience, with people asking all kinds of questions. As if I had done it before... But it came out well. Both guns no longer have the frame chokes, are more accurate and have barrels that clean up more easily with less leading.
 
For revolvers your main concern is the throats in the cylinders and that is what you should size to. This assumes your throats are larger than your groove size, if they are not you will not have an accurate revolver. You want lead bullets to be a snug fit in the throats or even slightly larger. This prevents gas cutting as the bullet leaves the case which is harmful to accuracy and causes leading. As long as you size for the throats and the throats are larger than groove you should be on your way to finding an accurate load for the gun.
 
Looks like 'Beartoothbullets' has many good things to offer, info wise, and Bullets wise...definitely keeping that Link.
 
You could also use Cerrosafe.

Cerrosafe is the best known material from which to make a casting of the chamber and throat of a firearm - to determine caliber or check the dimensions. It melts at a temperature just above M&M's, so all you need is a propane torch and a bullet casting ladle. It can also be used to make a cast of a dovetail slot or any other hard to measure area. Also, it is great for removing the front half of a case from the chamber, in the event of case head separation; and lots of folks cast a small portion of the barrel to determine bore diameter. For best results, measure the casting one hour after casting.

http://www.midwayusa.com/viewproduct/?productnumber=462291
Click to expand...
 
See post #8.

Fecmech is absolutely correct in that bore diameter is meaningless in picking the most accurate bullet size for a revolver.

The chamber throats are far more critical then the actual bore size.

Slug the cylinder throats and size the bullets to fit.

The bore will take care of itself whatever size it is, unless it is much larger then the throats..

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

This link pretty much covers everything you need to know, even though the guy is talking about a Blackhawk.


http://www.castbullet.com/misc/accrsa.htm <- Different guy, same gun, same problems.

Most revolvers have some barrel shank constriction at one point or another. They also have cylinder chambers that vary in dimension from one to another. The tools used to bore out the chambers don't wear at the same rate, so the chamber size varies by a few thousandths. Every mass-produced revolver should be taken from the store straight to a gunsmith. Have him slug the bore, lap the barrel to relieve constriction, ream the chambers out to a uniform dimension followed by a good honing to smooth 'em up. Then work on the trigger (every new single-action I've ever handled needed a good trigger job).

The guy who worked on the Blackhawk in the first link had clusters that measured around 7" at 25 yards. After reaming out the chambers, firelapping the bore, and a little trigger work it printed one group just shy of 1.5" and two groups under a inch. Ammo used was the same batch he'd handloaded to begin his little odyssey.

Second link's gun started out rougher than the first link's gun. After working on it, the guy fired a group at 25 yds measuring a tick over half an inch.
 
MifflinKid said: revolvers have a choke point where the barrel screws into the frame

Yes, an important point MK, thanks.

The bullet will be sized to this constriction upon firing and "rattle" loosely down the rest of the barrel...not great for accuracy.

The barrel can be lapped to have its largest diameter in the frame area and taper smaller towards the muzzle.

Another critical dimension is the cylinder throat diameter as the bullet will be sized to it before ever getting to the barrel.
It should be at least the same as the bullet diameter.

The accuracy of any revolver can be improved in many ways, depending on how far you want to go.

Just sayin'
Tilos
 
Slug SAA

Contact LBT he will lead you down the right road. Its true the secret is the cylinder throats.
 
Status
Not open for further replies.

Similar threads

J
  • Locked
45 Colt jacketed bullets & Henry Big Boy
Replies
1
Views
419
rcmodel
R
J
  • Locked
Selecting a Bullet
Replies
4
Views
351
243winxb
243winxb
B
  • Locked
Question about slugging a barrel.
Replies
2
Views
538
ReloaderFred
ReloaderFred
M
  • Locked
How do you "slug" a barrel?
Replies
5
Views
1K
David Wile
D
P
  • Locked
"slugging the bore" question
Replies
13
Views
1K
clearcut
C
Back
Top