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Thread: Barrel Pin Drill Options

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    Gunco Member akma's Avatar
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    Default Barrel Pin Drill Options

    [FONT='Verdana','sans-serif']Well I was unsatisfied with the results of using a 7mm screw machine drill to drill the barrel pin. Even when you have it perfectly lined up it wants to push off the barrel into the trunnion. Why? Because the drill has a bevel that deflects off the radius of the barrel. Itís designed to be center cutting not edge cutting. So I found this on ebay for $5 it's a 7mm end mill and figured it was worth a shot. http://www.ebay.com/itm/SHARS-7MM-Metric-HSS-FOUR-Flute-Single-End-Mill-NEW-/300725746359?ssPageName=ADME:X:AAQ:US:1123 I tried it and was very satisfied with the results. It cuts cleanly and neatly with no deflection. Give it a try and see for yourself if it isnít an improvement over a drill bit. I used it in a drill press at 250-350 rpm with plenty of cutting oil.[/font]


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    Chief Administrator 7.62x39's Avatar
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    Glad it worked out for you. can't beat the price, that's for sure.
    I use a ream myself. I can't remember the exact size right off the top of my head (17/64 maybe) anyway, I bought the ream and 3 feet of the equivalent size drill rod (enough to keep me in barrel pins for life lol) from Mcmaster-Carr. I don't remember what I spent, but it was a lot more than your solution. nice find.
    .

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    No Hope For Me 1biggun's Avatar
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    ANOTHER WAY IS TO USE A END MILL ( EVEN IN A DRILL PRESS } AN MAKE A FLAT BOTTOM HOLE SO A BIT WILL NOT WALK AN THEN FINISH WITH A 7MM DRILL BIT. THE END MILL DOES NOT NEED TO BE 7MM IT CAN BE SMALLER . I DRILL/MILL FROM BOTH SIDES TO MAKE SURE A TRUNON IS NOT MESSED UP THIS ESPECAILY IMPORTANT IF YOU ARE USING A DRILL PRESS.. I USE A 7MM END MILL MY SELF ON ALL BUILDS.

    MOST HOLES ARE TRUE TOT HE TRUNION SIDES BUT NOT ALWAYS. IT IS ALWAYS A GOOD IDEA TO CLAMP IN THE TRUNION WITH OUT A BARREL AN RUN A BIT OR END MILL THROUGH NOT SPINNING IT AN MAKE SURE IT DOSENT BIND. IF IT DOSENT YOU KNOW ITS TRUE TO THE TRUNION SIDES.

    YOU NEED TO MAKE SURE THE END MILL IS LONG ENOUGH TO GO ALL THE WAY THROUGH BTW MANY STANDARD ENDMILLS ARE NOT LONG ENOUGH.


    THERE HAS BEEN A FEW THREADS ON THIS MATTER OVER THE YEARS.

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    Gunco Member akma's Avatar
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    Quote Originally Posted by 7.62x39 View Post
    Glad it worked out for you. can't beat the price, that's for sure.
    I use a ream myself. I can't remember the exact size right off the top of my head (17/64 maybe) anyway, I bought the ream and 3 feet of the equivalent size drill rod (enough to keep me in barrel pins for life lol) from Mcmaster-Carr. I don't remember what I spent, but it was a lot more than your solution. nice find.
    I was able to use the original pin with no problem.You could try using the 7mm end mill and if you don't like the results you can still ream it to 17/64.


    Quote Originally Posted by 1biggun View Post
    ANOTHER WAY IS TO USE A END MILL ( EVEN IN A DRILL PRESS } AN MAKE A FLAT BOTTOM HOLE SO A BIT WILL NOT WALK AN THEN FINISH WITH A 7MM DRILL BIT. THE END MILL DOES NOT NEED TO BE 7MM IT CAN BE SMALLER . I DRILL/MILL FROM BOTH SIDES TO MAKE SURE A TRUNON IS NOT MESSED UP THIS ESPECAILY IMPORTANT IF YOU ARE USING A DRILL PRESS.. I USE A 7MM END MILL MY SELF ON ALL BUILDS.

    MOST HOLES ARE TRUE TOT HE TRUNION SIDES BUT NOT ALWAYS. IT IS ALWAYS A GOOD IDEA TO CLAMP IN THE TRUNION WITH OUT A BARREL AN RUN A BIT OR END MILL THROUGH NOT SPINNING IT AN MAKE SURE IT DOSENT BIND. IF IT DOSENT YOU KNOW ITS TRUE TO THE TRUNION SIDES.

    YOU NEED TO MAKE SURE THE END MILL IS LONG ENOUGH TO GO ALL THE WAY THROUGH BTW MANY STANDARD ENDMILLS ARE NOT LONG ENOUGH.


    THERE HAS BEEN A FEW THREADS ON THIS MATTER OVER THE YEARS.
    I've seen people use a 1/4" end mill then ream to 7mm.

    I put the assembly in a cross drill vise and put a drill in the trunnion hole and used it like a winding stick to get the hole 90* on both axis. I kept checking to make sure the hole was running true. It cut very good and for me was easier than using a drill bit. For $5 it could be worth trying.

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    No Hope For Me 1biggun's Avatar
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    THE ONLY ISSUE I SEE WITH THE END MILL IN THE LINK IS IT DOSENT LOOK LIKE ITS LONG ENOUGH TO REACH CKLEAR THROUGH. i MAY BE WRONG.

    UNTILL I GOT A LONG 7MM ENDMILL I DID EXACTLY THAT I USED A 1/4" AN THEN OPEND IT UP. i JUST USED A 7MM DRILL BIT AN NEVER HAD A ISSUE. I DOUBT THE THE FACTROY USED A REAMER IM SURE IT WAS JUST A DRILL BIT OF SOME SORT. THIS HOLE DOSENT HAVE TO BE PERFECT IT JUST NEEDS TO BE TIGHT TO KEEP THE PIN IN.

    THOSE END MILLS ARE CHEAPER THAN A DRILL BIT SO WHY NOT???? ITS A GOOD TOOL TO HAVE FOR OTHER THINGS AS WELL. THE PRICE IS RIGHT THATS FOR SURE.

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    Gunco Member akma's Avatar
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    The cutting depth is 3/4" if that helps. I don't think the factory needs to use a reamer if they are doing a virgin build. There is just one clean hole.

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    Chief Administrator 7.62x39's Avatar
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    Quote Originally Posted by akma View Post
    I was able to use the original pin with no problem.You could try using the 7mm end mill and if you don't like the results you can still ream it to 17/64.
    I only use it when I need to adjust the headspace which requires using a larger diameter pin.
    .

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    Gunco Member Jeffaksks's Avatar
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    Great tip guys thanks.

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    I use a 7mm (.2969") bottom cutting reamer. I've sent these to people all over the board. They work great. It's kind of like an end mill and a reamer all in one. I too make my own barrel pins from 7mm drill rod.
    Enforcement, NOT Amnesty!!!!!!

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    I use a end mill to make a undersize cut then follow with a carbide drill these drills are great
    2 NEW SOLID CARBIDE DRILLS 7 MM 140 DEGREE POINT 816 | eBay

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