What is your 45 acp bore diameter

Ed_ · February 27, 2010, 09:38 AM

With all the references to slugging bores, I would be interested in your results after slugging.

mavracer · February 27, 2010, 10:05 AM

I'm not sure exacticly what saami spec is for a 45 acp but any gun made since the '50s will be within .0005 of that. Most people dont have the equipment to measure that close.

Ed_ · February 27, 2010, 10:24 AM

My calipers [Cheap] will measure to .001 but I can guess if if falls between the thousandths ticks. You may be correct if using digital.

Sammi specs I believe are .451 with +.0005 tolerance. [I am probably wrong about this]

But I am interested in what people actually measure after slugging

Ed

freakshow10mm · February 27, 2010, 10:37 AM

The groove diameter is more important than the bore diameter. They are not one in the same.

IllinoisCoyoteHunter · February 27, 2010, 03:14 PM

I am not a fan of checking groove diameter with calipers. I prefer a micrometer and urge anyone who wants to get it down to the gnat's a** to do the same. A micrometer is a wise investment I think every boolit caster should own...but this is my opinion, of course.

Ed_ · February 27, 2010, 04:21 PM

Is the groove diameter the highest points on the lead slug?
If so ,That is what I meant to ask. According to a earlier posts You tube link, the highest points on the lead slug is what needs to be measured. I almost bought a micrometer the other day because I figured that would be the most accurate.

IllinoisCoyoteHunter · February 27, 2010, 06:42 PM

Yes, the groove diameter is the highest spot on the slug. In the barrel, it is the low spot. Micrometers are nice, Ed. I have a 1" Lyman micrometer. http://www.midwayusa.com/viewProduct...tNumber=169644

Measures accurately out to .0001". When using these, make sure that whatever you are measuring is clean and the micrometer does not have any gunk on the part that contacts what you are measuring. If you let stuff build up on there, you will get an innacurate reading (readings will show it being bigger than it really is).

chris in va · March 10, 2010, 01:54 AM

Best I can tell mine checks out at .450...Sig 220. Then again if I apply even the slightest amount of pressure on the caliper it can vary by .002.

That'll Do · April 3, 2010, 05:13 PM

I'd like to say that I've slugged the barrel of my Kimber Custom Target II, but I haven't. However, shooting boolits sized to .452" gives me tight groups (withe the appropriate load; usually a 200gr SWC over 4.2gr of Hodgdon Clays) and no leading, so I feel no need to slug my barrel.

View Poll Results: What is your 45 acp bore diameter
Less than .4510	3	17.65%
.4510 - .4515	6	35.29%
.4515 - .4520	0	0%
.4520 - .4525	1	5.88%
.4525 - .4530	0	0%
Greater than .4530	0	0%
I have never slugged my bore	7	41.18%
Voters: 17. You may not vote on this poll

February 27, 2010, 09:38 AM	#1
Ed_ Member Join Date: January 27, 2009 Location: Southwest Missouri Posts: 96	What is your 45 acp bore diameter With all the references to slugging bores, I would be interested in your results after slugging. Last edited by Ed_; February 27, 2010 at 09:52 AM.

February 27, 2010, 03:14 PM	#5
IllinoisCoyoteHunter Senior Member Join Date: December 23, 2008 Location: Southern Illinois Posts: 1,527	I am not a fan of checking groove diameter with calipers. I prefer a micrometer and urge anyone who wants to get it down to the gnat's a** to do the same. A micrometer is a wise investment I think every boolit caster should own...but this is my opinion, of course. __________________ ~~IllinoisCoyoteHunter~~ ~NRA LIFE MEMBER~ ~NRA CERTIFIED INSTRUCTOR~

February 27, 2010, 06:42 PM	#7
IllinoisCoyoteHunter Senior Member Join Date: December 23, 2008 Location: Southern Illinois Posts: 1,527	Yes, the groove diameter is the highest spot on the slug. In the barrel, it is the low spot. Micrometers are nice, Ed. I have a 1" Lyman micrometer. http://www.midwayusa.com/viewProduct...tNumber=169644 Measures accurately out to .0001". When using these, make sure that whatever you are measuring is clean and the micrometer does not have any gunk on the part that contacts what you are measuring. If you let stuff build up on there, you will get an innacurate reading (readings will show it being bigger than it really is). __________________ ~~IllinoisCoyoteHunter~~ ~NRA LIFE MEMBER~ ~NRA CERTIFIED INSTRUCTOR~

February 27, 2010, 10:24 AM	#3
Ed_ Member Join Date: January 27, 2009 Location: Southwest Missouri Posts: 96	My calipers [Cheap] will measure to .001 but I can guess if if falls between the thousandths ticks. You may be correct if using digital. Sammi specs I believe are .451 with +.0005 tolerance. [I am probably wrong about this] But I am interested in what people actually measure after slugging Ed

February 27, 2010, 10:37 AM	#4
freakshow10mm Junior member Join Date: January 23, 2008 Location: MI Posts: 1,398	The groove diameter is more important than the bore diameter. They are not one in the same.

February 27, 2010, 04:21 PM	#6
Ed_ Member Join Date: January 27, 2009 Location: Southwest Missouri Posts: 96	Is the groove diameter the highest points on the lead slug? If so ,That is what I meant to ask. According to a earlier posts You tube link, the highest points on the lead slug is what needs to be measured. I almost bought a micrometer the other day because I figured that would be the most accurate.

March 10, 2010, 01:54 AM	#8
chris in va Senior Member Join Date: December 26, 2004 Location: Louisville KY Posts: 13,806	Best I can tell mine checks out at .450...Sig 220. Then again if I apply even the slightest amount of pressure on the caliper it can vary by .002.

April 3, 2010, 05:13 PM	#9
That'll Do Senior Member Join Date: October 25, 2008 Location: Pittsburgh, PA Posts: 546	I'd like to say that I've slugged the barrel of my Kimber Custom Target II, but I haven't. However, shooting boolits sized to .452" gives me tight groups (withe the appropriate load; usually a 200gr SWC over 4.2gr of Hodgdon Clays) and no leading, so I feel no need to slug my barrel.