Graf & SonsTitan ReloadingInline FabricationStainLess Steel Media
RotoMetals2MidSouth Shooters SupplyADvertise hereLee Precision

Results 1 to 17 of 17

Thread: Pin gauges : How to use?

  1. #1
    Boolit Master
    Join Date
    Aug 2009
    Location
    SE Michigan
    Posts
    678

    Pin gauges : How to use?

    I got a set of pin gauges and I tried them out on my new Ruger American in 9mm.
    I tried several pins but I am not sure what I should be feeling with different sizes.
    Leadmelter
    MI

  2. #2
    Boolit Master

    Join Date
    Mar 2013
    Location
    Northwest Ohio
    Posts
    7,260
    If .350 goes and .351 dosnt then it .350

  3. #3
    Boolit Master
    Join Date
    Jun 2014
    Location
    Mountains of NC
    Posts
    591
    Been a tool and die maker all my life (48 yrs experience) they are usually -.0002.

  4. #4
    Boolit Master

    DougGuy's Avatar
    Join Date
    Apr 2013
    Location
    just above Raleigh North Carolina
    Posts
    4,493
    Which set did you get? The best for gunsmithing are the minus gages, and as mentioned you want the .0002" under gages.
    Got a .22 .32 .357 .38 .40 .41 .44 .45 .480 or .500 S&W cylinder that needs throat reaming? 9mm, 10mm/40S&W, 45 ACP pistol barrel that won't "plunk" your handloads? Shoot me a PM! Also on Facebook: https://www.facebook.com/Cylinderhone-756429174391912/

  5. #5
    Boolit Master
    Join Date
    Aug 2009
    Location
    SE Michigan
    Posts
    678
    That is what she bought me.
    My dad was a tool and die man at Cadillac Motors for 42 yrs. Every time I see those old Caddies with the big fins I think of him and summers working 12 hours a day/seven a week to get those dies right.
    I never had that talent.
    If one size enters the forcing cone and two later enter the bore, what does that tell me to do with my sizing and setting.
    There is always the plunk test.
    Leadmelter

  6. #6
    Boolit Master

    DougGuy's Avatar
    Join Date
    Apr 2013
    Location
    just above Raleigh North Carolina
    Posts
    4,493
    Quote Originally Posted by Leadmelter View Post
    That is what she bought me.
    My dad was a tool and die man at Cadillac Motors for 42 yrs. Every time I see those old Caddies with the big fins I think of him and summers working 12 hours a day/seven a week to get those dies right.
    I never had that talent.
    If one size enters the forcing cone and two later enter the bore, what does that tell me to do with my sizing and setting.
    There is always the plunk test.
    Leadmelter
    I use two sets of pin gages, one set is marked in thousandths, the other is marked in half thousandths so I am going back and forth between the two sets to find the tightest fit, this is what the hole is that is being measured. .001" increments are okay but when measuring bore and cylinder dimensions, a .001" jump is sorta coarse, not fine enough a reading for accurate work.

    I use the pin gages in a 45ACP barrel for example, to find which one is the most snug fitting pin that will enter the bore riding on the lands, and they can be anywhere from .4415" to .4435" with the majority being .4425" or .443" and once I have that determined, then I know what size pilot to use on a throating reamer, an I keep pilots in half thousandth increments as well.

    For the throat I want to see which pins will go into the freebore and how far they will go and I can detect if the freebore is parallel or tapered by the depth of the pins. When I am finished reaming a barrel I can then use the same pins to "feel" the difference that the reamer made, and I will go and select larger pins to see which ones then fit snug in the freebore so I can measure the diameter of the freebore when it starts, and because it's tapered, I can measure the diameter of it where the leade in to the lands starts. I have done this enough times that now I simply plunk a few of the dummies that customers have sent in and I use this assortment of dummies as a go/no-go gauge so when the barrel plunks the Lee C452-200-RF that is seated out as long as the magazine will allow, I know it is ready to go back and will not present any chambering issues, AS LONG as the boolits are sized below the diameter of the freebore in the throat.

    Usually .452" will give adequate wiggle room and customers that send in dummies that mic more than .452" which is common if they are just dropped from a mold and not sized, I can tell if they will have problems because there will be interference with the freebore if any part of the boolit is greater than .452" so if a .452" pin gage goes .200" into the throat, I know a .452" boolit seated out long will also go into the throat.

    This is what I use pin gages for in an autoloader. With a revolver cylinder, I choose a snug fitting pin or set of pins and get accurate measurements of throat diameters, which also lets me select the correct pilot for the reamer, I don't like using the pins to measure the bore because there are anomalies from barrel to barrel and you CAN get a pin stuck and then you could really have a problem. They are generally too long to measure the forcing cone area unless you cut them shorter which I have never seen the need to do. About the only real purpose in measuring the bore in front of the forcing cone would be to compare it with the bore at the muzzle to check for thread choke, which you can do with a tightly patched cleaning jag. The jag won't give you a decimal reading of the diameter of the choke, but having a numerical value assigned to this serves no real purpose that I have found so I don't bother to try and measure this part. If it's choked enough to stop the jag from moving, it is severe and needs either re-barreling or Taylor throating because the choke is too much to firelap out without damaging the rifling in the good part of the barrel.
    Got a .22 .32 .357 .38 .40 .41 .44 .45 .480 or .500 S&W cylinder that needs throat reaming? 9mm, 10mm/40S&W, 45 ACP pistol barrel that won't "plunk" your handloads? Shoot me a PM! Also on Facebook: https://www.facebook.com/Cylinderhone-756429174391912/

  7. #7
    Boolit Master murf205's Avatar
    Join Date
    Sep 2011
    Location
    middle of Alabama
    Posts
    300
    DougGuy, is spot on, as usual, but don't forget to clean the cylinder throats really good before you start, even if you have been shooting jacketed in it. Scrub them well with a bronze or stiff fiber brush with powder solvent and clean with patches till dry.
    IT AINT what ya shoot--its how ya shoot it

  8. #8
    Boolit Master
    mdi's Avatar
    Join Date
    Jun 2008
    Location
    So. Orygun
    Posts
    4,860
    Simple answer is in post #2 by country gent. It's basically a "go/no go" type of measurement. What are you measuring on your Ruger American with pin gauges?
    My Anchor is holding fast!

  9. #9
    Boolit Master
    Join Date
    Aug 2005
    Location
    South Jersey
    Posts
    4,656
    If .350 goes and .351 dosnt then it .350
    And if measuring bore diameter with over or under 0.002 Go - No Go difference ... what difference does it make respective to reloading?
    Regards
    John

  10. #10
    Boolit Master


    Larry Gibson's Avatar
    Join Date
    Jul 2005
    Location
    Lake Havasu City, Arizona
    Posts
    15,535
    Also pin gauge cylinder throats from chamber end as many are tapered.
    Larry Gibson

    “Deficient observation is merely a form of ignorance and responsible for the many morbid notions and foolish ideas prevailing.”
    ― Nikola Tesla

  11. #11
    Boolit Master
    Join Date
    Aug 2009
    Location
    SE Michigan
    Posts
    678
    mdioading
    I am measuring a 9mm barrel. I have cast several hundred bullets of different type and sized between .356 to .345. I just wanted to make an educated quess before I started loading.
    I guess I will do the drop test and compare to my measurement on the Ruger and my S&W 39 from 1970's.
    Leadmelter
    MI

  12. #12
    Boolit Master
    mdi's Avatar
    Join Date
    Jun 2008
    Location
    So. Orygun
    Posts
    4,860
    Quote Originally Posted by Leadmelter View Post
    mdioading
    I am measuring a 9mm barrel. I have cast several hundred bullets of different type and sized between .356 to .345. I just wanted to make an educated quess before I started loading.
    I guess I will do the drop test and compare to my measurement on the Ruger and my S&W 39 from 1970's.
    Leadmelter
    MI
    Understand, but a much simpler way which give the important info (groove diameter) is simply slugging...
    My Anchor is holding fast!

  13. #13
    Boolit Master

    Join Date
    Mar 2013
    Location
    Northwest Ohio
    Posts
    7,260
    Another use is to find the pin gage the size your making and see what your mics read on it and the part. If the pin gage mics and part all read the same its right. This also will take into account the squareness or wear on the anvils and threads of a mic. Showing it as an off measurement. On gages and High precision parts we did this to insure accuracy on the parts. Pin Gages and gage blocks are your friend. They will show you alot

  14. #14
    Boolit Bub
    Join Date
    Jan 2016
    Location
    Ohio
    Posts
    36
    Pin gauges aren't of much use in determining dimensions on a semi-auto. You need to slug the bore with a piece of soft lead and measure that to know how to size your bullets. Otherwise, you'll be measuring the rifling leade and then the bore diameter (this is the two gauge difference). You need the groove diameter to know what size the bullets should be before the rifling is imprinted on them. The only thing pin gauges would tell you in a barrel is whether you have a constriction of the rifling lands, which might be better determined by slugging or passing a tight patch through the barrel since the grooves might be constricted without affecting the lands.

    On revolvers, where the cylinder throats determine your sizing dimension, pin gauges are much more useful.

  15. #15
    Boolit Master fredj338's Avatar
    Join Date
    Feb 2009
    Location
    kalif.
    Posts
    5,246
    Quote Originally Posted by Leadmelter View Post
    That is what she bought me.
    My dad was a tool and die man at Cadillac Motors for 42 yrs. Every time I see those old Caddies with the big fins I think of him and summers working 12 hours a day/seven a week to get those dies right.
    I never had that talent.
    If one size enters the forcing cone and two later enter the bore, what does that tell me to do with my sizing and setting.
    There is always the plunk test.
    Leadmelter
    A pin gage isn't helping you with bore dia but I sue them to measure cyl throats. If a 0.451" passé thru & a 0.452" sticks, you are 0.4515".
    EVERY GOOD SHOOTER NEEDS TO BE A HANDLOADER.
    NRA Cert. Inst. Met. Reloading & Basic Pistol

  16. #16
    Boolit Master fredj338's Avatar
    Join Date
    Feb 2009
    Location
    kalif.
    Posts
    5,246
    Quote Originally Posted by Leadmelter View Post
    mdioading
    I am measuring a 9mm barrel. I have cast several hundred bullets of different type and sized between .356 to .345. I just wanted to make an educated quess before I started loading.
    I guess I will do the drop test and compare to my measurement on the Ruger and my S&W 39 from 1970's.
    Leadmelter
    MI
    You mean 0.356 to what? Only way to do the bore is slug it & measure the slug. I admit to not slugging my bores, I have too many guns to bother with custom ammo for each. I just load 0.001" larger than jacketed or in some 0.002".
    EVERY GOOD SHOOTER NEEDS TO BE A HANDLOADER.
    NRA Cert. Inst. Met. Reloading & Basic Pistol

  17. #17
    Boolit Master
    jonp's Avatar
    Join Date
    Feb 2013
    Location
    Planet Reality
    Posts
    4,774
    Quote Originally Posted by DougGuy View Post
    I use two sets of pin gages, one set is marked in thousandths, the other is marked in half thousandths so I am going back and forth between the two sets to find the tightest fit, this is what the hole is that is being measured. .001" increments are okay but when measuring bore and cylinder dimensions, a .001" jump is sorta coarse, not fine enough a reading for accurate work.

    I use the pin gages in a 45ACP barrel for example, to find which one is the most snug fitting pin that will enter the bore riding on the lands, and they can be anywhere from .4415" to .4435" with the majority being .4425" or .443" and once I have that determined, then I know what size pilot to use on a throating reamer, an I keep pilots in half thousandth increments as well.

    For the throat I want to see which pins will go into the freebore and how far they will go and I can detect if the freebore is parallel or tapered by the depth of the pins. When I am finished reaming a barrel I can then use the same pins to "feel" the difference that the reamer made, and I will go and select larger pins to see which ones then fit snug in the freebore so I can measure the diameter of the freebore when it starts, and because it's tapered, I can measure the diameter of it where the leade in to the lands starts. I have done this enough times that now I simply plunk a few of the dummies that customers have sent in and I use this assortment of dummies as a go/no-go gauge so when the barrel plunks the Lee C452-200-RF that is seated out as long as the magazine will allow, I know it is ready to go back and will not present any chambering issues, AS LONG as the boolits are sized below the diameter of the freebore in the throat.

    Usually .452" will give adequate wiggle room and customers that send in dummies that mic more than .452" which is common if they are just dropped from a mold and not sized, I can tell if they will have problems because there will be interference with the freebore if any part of the boolit is greater than .452" so if a .452" pin gage goes .200" into the throat, I know a .452" boolit seated out long will also go into the throat.

    This is what I use pin gages for in an autoloader. With a revolver cylinder, I choose a snug fitting pin or set of pins and get accurate measurements of throat diameters, which also lets me select the correct pilot for the reamer, I don't like using the pins to measure the bore because there are anomalies from barrel to barrel and you CAN get a pin stuck and then you could really have a problem. They are generally too long to measure the forcing cone area unless you cut them shorter which I have never seen the need to do. About the only real purpose in measuring the bore in front of the forcing cone would be to compare it with the bore at the muzzle to check for thread choke, which you can do with a tightly patched cleaning jag. The jag won't give you a decimal reading of the diameter of the choke, but having a numerical value assigned to this serves no real purpose that I have found so I don't bother to try and measure this part. If it's choked enough to stop the jag from moving, it is severe and needs either re-barreling or Taylor throating because the choke is too much to firelap out without damaging the rifling in the good part of the barrel.
    ^^^+1 I watched him do my Blackhawk.
    Government is the great fiction, through which everybody endeavors to live at the expense of everybody else.
    Bastiat

    Sic transit gloria mundi

    Non nobis Domine,
    non nobis,
    sed nomini tuo da gloriam

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check