bore slugging question

milsurpaddict · September 20, 2012, 03:53 PM

I am molding my own bullets and I just slugged by latest purchase which is a type 99 Arisaka 7.7 X 58. When I measured the slug it measured .313 at its highest is this common for this rifle? I was told the bore is .311 and that a .312 mold would work. IF indeed it is .313 what size mold should I use ?
Thanks in advance

Jimro · September 20, 2012, 03:56 PM

a .314 is probably the best. Although you aren't telling us if you are going to gas check or patch your bullets in any way.

Jimro

milsurpaddict · September 20, 2012, 04:05 PM

I believe a gas check will be required with most molds I see.

**Unclenick** · September 20, 2012, 04:34 PM

A .314" or even a .315" would be best with a .313" bore. But one question: what did you measure the slug with? If a Caliper, it's not uncommon for them to err by 0.001". You really want to use an OD thimble micrometer with 0.0001" resolution to measure these things. If you do, don't forget to check its zero and subtract what it reads when closed.

Edward429451 · September 20, 2012, 07:30 PM

We load those #311291's with no GC for my friends 30/30 and they shoot fine without leading. Not sizzling loads but good for range ammo. No GC is the poor mans boattail, lol.

hk33ka1 · September 20, 2012, 09:31 PM

Usually a lead boolit should be sized .001-.002" larger than the groove diameter of the rifle. If a .308 Win measures .308", a .309" or .310" boolit will usually be the best choice to prevent leading and promote accuracy. If I had a .313 I wout be looking for a .315 mold/sizer myself. Bigger is usually better with boolits and is more important than lead hardness.

September 20, 2012, 03:53 PM	#1
milsurpaddict Junior Member Join Date: August 17, 2012 Posts: 4	bore slugging question I am molding my own bullets and I just slugged by latest purchase which is a type 99 Arisaka 7.7 X 58. When I measured the slug it measured .313 at its highest is this common for this rifle? I was told the bore is .311 and that a .312 mold would work. IF indeed it is .313 what size mold should I use ? Thanks in advance

September 20, 2012, 03:56 PM	#2
Jimro Senior Member Join Date: October 18, 2006 Posts: 7,097	a .314 is probably the best. Although you aren't telling us if you are going to gas check or patch your bullets in any way. Jimro __________________ Machine guns are awesome until you have to carry one.

September 20, 2012, 04:34 PM	#4
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,062	A .314" or even a .315" would be best with a .313" bore. But one question: what did you measure the slug with? If a Caliper, it's not uncommon for them to err by 0.001". You really want to use an OD thimble micrometer with 0.0001" resolution to measure these things. If you do, don't forget to check its zero and subtract what it reads when closed. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle

September 20, 2012, 04:05 PM	#3
milsurpaddict Junior Member Join Date: August 17, 2012 Posts: 4	I believe a gas check will be required with most molds I see.

September 20, 2012, 07:30 PM	#5
Edward429451 Junior member Join Date: November 12, 2000 Location: Colorado Springs, Colorado Posts: 9,494	We load those #311291's with no GC for my friends 30/30 and they shoot fine without leading. Not sizzling loads but good for range ammo. No GC is the poor mans boattail, lol.

September 20, 2012, 09:31 PM	#6
hk33ka1 Senior Member Join Date: April 20, 2010 Posts: 275	Usually a lead boolit should be sized .001-.002" larger than the groove diameter of the rifle. If a .308 Win measures .308", a .309" or .310" boolit will usually be the best choice to prevent leading and promote accuracy. If I had a .313 I wout be looking for a .315 mold/sizer myself. Bigger is usually better with boolits and is more important than lead hardness.