Bruno2
Member
How do I slug a barrel to find out what size the bore is and what size bullet that I should be using to avoid excessive leading ? 
slugging a barrel ?
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bullseye308
Member
Take a pure lead slug and lightly lube the barrel then push it through. Measure it afterwards and you will know. That is the simplified version.
Bruno2
Member
9mm and 38spl . I ordered some cast bullets 125 tc and 125 RN . The 125 tc 's are for my S&W airweight and the 125 RN are for my 92fs . The tc's are micing out to .357 and the rn's are .356 .
At paper targets .
At paper targets .
Bruno2
Member
How do I push a bullet through the barrel ?
soloban
Member
think you just take a wood dowel or cleaning rod and tap it down the barrel with a hammer.
OK
For your 38SPL, you probably don't need to actually slug your barrel bore (since it's S&W, it's got an odd number of lands which makes measuring groove diameter a bit complicated for shade tree machinists, just like mine!). That dimension is pretty much "standard" for modern firearms. Doesn't vary enough to make measurement worthwhile.
BUT, for a revolver, you should slug each cylinder's throat diameter. That's the critical dimension for bullet sizing for this type gun.
If you have pin gages (they are about $2-3 each from McMaster-Carr, which is a FANTASTIC company to support btw), they're easiest. Find the largest size you can get (+/- 0.0005") which will drop through a given chamber. Number your chambers! If you don't have pin gages, a lead slug (e.g. oversize bullet or fishing sinker) can be driven through the throat and simply mic'd. DO NOT USE CALIPERS! Hopefully, all your chambers will measure the same enough. Otherwise, life gets complicated again and the price to play continues to increase.
For your 9mm (i see it's semiauto), or if you want to measure your revolver's bore "properly", just so you know, you just drive the slug into the barrel with a thick (e.g. 8mm) dowel and a hammer. About .360"+ diameter. "Size 9" quarter oz lead egg sinkers work for me (in 38SPL). Once it's started into the barrel, pushing it out is really not too hard because it will just track the rifling.
For your 38SPL, you probably don't need to actually slug your barrel bore (since it's S&W, it's got an odd number of lands which makes measuring groove diameter a bit complicated for shade tree machinists, just like mine!). That dimension is pretty much "standard" for modern firearms. Doesn't vary enough to make measurement worthwhile.
BUT, for a revolver, you should slug each cylinder's throat diameter. That's the critical dimension for bullet sizing for this type gun.
If you have pin gages (they are about $2-3 each from McMaster-Carr, which is a FANTASTIC company to support btw), they're easiest. Find the largest size you can get (+/- 0.0005") which will drop through a given chamber. Number your chambers! If you don't have pin gages, a lead slug (e.g. oversize bullet or fishing sinker) can be driven through the throat and simply mic'd. DO NOT USE CALIPERS! Hopefully, all your chambers will measure the same enough. Otherwise, life gets complicated again and the price to play continues to increase.
For your 9mm (i see it's semiauto), or if you want to measure your revolver's bore "properly", just so you know, you just drive the slug into the barrel with a thick (e.g. 8mm) dowel and a hammer. About .360"+ diameter. "Size 9" quarter oz lead egg sinkers work for me (in 38SPL). Once it's started into the barrel, pushing it out is really not too hard because it will just track the rifling.
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I used a 3/8" aluminum rod with masking tape wrapped around it and 0.4530" diameter Oregon Trail .45 Colt lead bullets to slug the chambers and bore of my Ruger Redhawk ... and it worked like a charm.
Chamber throats
Average throat diameter based on three bullets per chamber (18 total):
0.4525"
0.4525"
0.4525"
0.4526"
0.4526"
0.4526"
Barrel
Average bore diameter of three bullets each of which was measured in three places 60 degrees apart (six grooves in barrel):
0.4517"
0.4519"
0.4515"
Chamber throats
Average throat diameter based on three bullets per chamber (18 total):
0.4525"
0.4525"
0.4525"
0.4526"
0.4526"
0.4526"
Barrel
Average bore diameter of three bullets each of which was measured in three places 60 degrees apart (six grooves in barrel):
0.4517"
0.4519"
0.4515"
dardascastbullets
Member
Hi Bruno2,
To properly slug your barrel obtain a soft round ball that matches the caliber of your barrel. Also purchase a wood dowel that will have a diameter just a tad smaller than your bore. If this is a rifle, cut the dowel into segments (approx. 6-8 inches).
The round ball will be need to be seated into the barrel's crown only to start it. (Apply a thin film of oil to the bore prior to performing the slugging procedure). Then, the first dowel segment is tapped onto the round ball until it has entered the barrel to the point where the mallet will not strike the barrel. Then the next wood dowel segment is tapped onto the first segment. This process repeats until the round ball exits the chamber end.
Good luck!
To properly slug your barrel obtain a soft round ball that matches the caliber of your barrel. Also purchase a wood dowel that will have a diameter just a tad smaller than your bore. If this is a rifle, cut the dowel into segments (approx. 6-8 inches).
The round ball will be need to be seated into the barrel's crown only to start it. (Apply a thin film of oil to the bore prior to performing the slugging procedure). Then, the first dowel segment is tapped onto the round ball until it has entered the barrel to the point where the mallet will not strike the barrel. Then the next wood dowel segment is tapped onto the first segment. This process repeats until the round ball exits the chamber end.
Good luck!
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