Drilling and Tapping the Remington 1100/1187/870 for Scope rail

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  • remauto1187

    Shooter
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    Aug 25, 2012
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    Stepping Stone
    Well I finally got my friend talked into getting rid of those ugly loose saddle mounts on his Remington 1100. I just dont understand how it is even possible for those saddle mounts to keep a scope true and never move. You tighten the saddle mount too tight and it squeezes the shotgun receiver and locks the bolt up. You keep the screws loose and it flops the scope all over the place. Simple solution....Drill and Tap the receiver for a weaver rail like you would a rifle. My buddy opted for the high mount see thru rings so he can "see" the sights even though he is blinder than a bat :D and can only physically see the front sight. (the rear is either a blurr or just is not there)

    You will need: #31 carbide drill bit, #6-48 quality plug tap, Weaver #62 rail (comes with the #6-48 screws and is actually for a Remington 742/760) and I used a Williams Scope Mount Drill Fixture. Williams Scope Mount Drill Fixture Great tool and it found center for me perfectly. Comes with drill bushings to keep alignment of drill bit and tap so you can use a cordless drill instead of a drill press.

    Only things to note are that the barrel tang on the 1100/1187 go into the receiver pretty far (3 7/8") so the front 2 rail mounting screws protude too far thru the receiver and would interfere with the barrel tang going all the way into the receiver so they must be ground shorter. The rear 2 are no problem since the receiver is actually almost 2x as thick as the length of the screws. The Remington 870 barrel is substantially shorter so the tang intereference should not exist. You will find on the net that there is supposedly not enough metal toward the front of the receiver where the 2 front rail screws need to be on the 1100/1187. Ive found that not to be true. There is plenty of room to tap enough threads to clamp the scope rail to the receiver.

    Pics coming soon.
     

    DocIndy

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    That fixture can be reused again and again.... until you run out of friends with shotguns needing drilled. A guy I worked with part time, also worked at a gun shop and bought one to make some side money. Shop owner shut him down since he wasn't a licensed smith and if he fubar-ed a gun the shop owner was afraid of being held responsible for the damages.
     

    remauto1187

    Shooter
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    $118.00+Shipping for the drill fixture I hope you charged him to do the job. Seems like a Gunsmith would do the job for less than the fixture cost.
    Actually I wanted the tool in case I decide to start drilling and tapping my own rifles and shotguns but $118 is chump change. Its the miling machine and the building a new house next year thats gonna cost me. :n00b:

    Williams shop (the tool maker) charge around $120 for the job.
    And No I did not "charge him"..... He is a friend, thats what friends do and thats how I roll. :rockwoot:
     

    Zoub

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    May 8, 2008
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    Unless he has a raised comb the high rings will cause him to raise his cheek off the stock. Then again he was doing that with the saddle mount too. FYI but the old Bsquare saddle mounts are rock solid because they are on both sides of the receiver but a rail is better. Nothing wrong with moving him out of the 70's and into the 90's.

    You know in regards to the barrel hood under the screws back when shotgun accuracy became the new "thing" some people pinned their barrels. This gave even more precise return to zero when tossing on the slug barrel and tighter groups. I am sure you can find info on it and it sounds like you might take an interest in it. You may already know this stuff, just sharing in case you don't.
     

    Hookeye

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    armpit of the midwest
    Use a Sportsman 12 auto, they were round top, gets you a couple more threads.

    One a dedicated deer rig, one can use screws and epoxy to secure the base.

    Or go with one that screws in at an angle

    SHOTGUN SCOPE MOUNT | Brownells

    When I did my shotguns I just bought the Weaver base, dimensioned it with a high mag Nikon metrology scope (at work), and then made a drawing, used a milling machine.

    BTW, I know a guy with a mill that does 4 holes for about $50

    (aint me but I'm just saying some guys do good work and don't charge a kidney).

    Hunting season I suppose they might be backlogged and moving ahead in the line with a quicker job might demand a premium.
     
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    baba

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    Aug 24, 2013
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    I have been thinking of doing this forever. I now have access to a milling machine and am thinking about finally actually doing it. How deep did you drill the holes?

    Thanks,
    Brian
     

    BIGE7.62

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    Jul 29, 2010
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    The Hills of Brown
    Back from the dead
    Remauto 1187
    Was looking for some info on drilling/tapping a
    11-87 receiver and this thread came up in my Google search .
    How's the Wheeler jig holding up , still working as it should ?
    Also it's $143.99 now
     

    CampingJosh

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    Hookeye

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    I just bought the scope base on the 870's I did.
    Took the base to work and measured the hole spacing (worked in metallurgy lab so had cool Nikon light table).
    Made a drawing of the spacing.
    Then, put receiver in a mill and made my holes.

    You will need to line up your receiver to run down the center when drilling/milling holes.
    The receiver itself may not have perfectly parallel sides.

    Even if its an old "good one" LOL.

    I suppose one could have a good VR bbl and set up a laser and run from muzzle to back of receiver, check for center and mark accordingly.
    Have seen excellent non drill press D&T.
    Have seen botched machining using a drill press.

    Have also seen guys weld bases onto 1187 receivers.

    Never done an 1100/1187, but would not feel bad using just 3 screws. Full engagement of course. I'd also epoxy the base on.

    Have run clamshell type mounts in the past w OK results.
    There I taped up the sides w Kapton tape so as to not scuff the receiver sides.
    Screw torque was like another posted, too much and you know it.
    Blue Loctite mandatory since torque values not high.

    My preference was for an 870 drilled and tapped, since the mag cap bears on the bbl ring.
    1100/1187 just use the forearm to hold the bbl on.
     

    patience0830

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    Not far from the tree
    Why on God's green earth would you tap a shotgun rcvr unless the bbl was a permanent installation? Pinned or threaded so as not to move.
    Just buy the bbl with the cantelevered scope rail so the relationship of scope to bbl remains consistent.
    Saves buggering up the rcvr and works better. Plus it will be rifled.
     

    Hookeye

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    Cantilevers are too high for me, way too high, even w a high comb stock.
    Had a walnut 870 SP w rifled bore and rifle sights.
    Drilled and tapped the receiver and mounted a 4X Leupold low (high comb stock).
    Did a trigger job on it too. Dedicated deer rig.
    Sub 2" at 100 yards.

    Dedicated deer guns. Serious hunting. Not half arsing it.
    Put it together, zero, clean and then fire a couple foulers, good for the next 10 shots (before clean and foul again).
    Leave the SOB together all season.
    Hell, leave it together all the time.

    The only way a cantilever would be of use, if one has only one gun and is trying to do different hunts.
    But then, they should run a high comb when using the cantilever bbl.
    So there's stock swap back n forth to make it a bird gun, or removal of cheek riser.
    Then there's the trigger thing, want a rifle like trigger on a slug gun.
    Bird gun proly not.

    With PCR and HP now, slug guns are cheap.
    I would not build an 1100 magnum into a deer/turkey rig w D&T of receiver.
    But if doing a reg 1100 or 870.............more common and cheap enough.

    Had two 870's that shot great, D&T receivers.
    Personally I think cantilever bbls to be absolute horse crap.

    IMHO eat PB&J for a while and buy two shotghuns. Don't half arse the deerhunting or wingshooting by playing double duty w one.
     
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    Hookeye

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    The old M500 slug guns used to be D&T receiver on top, even when smooth bore.
    And they shot pretty darn good.
    The prob there was a low scope and that top safety usually meant glove snag LOL.
     

    BIGE7.62

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    Why on God's green earth would you tap a shotgun rcvr unless the bbl was a permanent installation? Pinned or threaded so as not to move.
    Just buy the bbl with the cantelevered scope rail so the relationship of scope to bbl remains consistent.
    Saves buggering up the rcvr and works better. Plus it will be rifled.

    Red dot for coyotes that and I want to .
    I won't be shooting slugs out of this gun only shot shells
     

    BIGE7.62

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    I have a few other shotguns that are used for different things .
    I want to set up my 11-87 sp with a red dot.
    My eyes aren't what they use to be . I'll take every and any advantage I can get .
    I need a chicken defense gun . I can't let the girls free range as much because of the yotes and foxes
    The property behind my coup and run area sold last year.
    Now there is a house about 500 yards away .
    So it's not safe at all to shoot a rifle in that general direction.
    11-87 , #4 shot ,Carlson choke tube and red dot should solve that problem
     

    BIGE7.62

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    I just bought the scope base on the 870's I did.
    Took the base to work and measured the hole spacing (worked in metallurgy lab so had cool Nikon light table).
    Made a drawing of the spacing.
    Then, put receiver in a mill and made my holes.

    You will need to line up your receiver to run down the center when drilling/milling holes.
    The receiver itself may not have perfectly parallel sides.

    Even if its an old "good one" LOL.

    I suppose one could have a good VR bbl and set up a laser and run from muzzle to back of receiver, check for center and mark accordingly.
    Have seen excellent non drill press D&T.
    Have seen botched machining using a drill press.

    Have also seen guys weld bases onto 1187 receivers.

    Never done an 1100/1187, but would not feel bad using just 3 screws. Full engagement of course. I'd also epoxy the base on.

    Have run clamshell type mounts in the past w OK results.
    There I taped up the sides w Kapton tape so as to not scuff the receiver sides.
    Screw torque was like another posted, too much and you know it.
    Blue Loctite mandatory since torque values not high.

    My preference was for an 870 drilled and tapped, since the mag cap bears on the bbl ring.
    1100/1187 just use the forearm to hold the bbl on.

    I could measure everything and lay it out , but the jig will make the task easier . Plus I don't have a mill . The jig can be used with a hand drill
     

    Hookeye

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    armpit of the midwest
    You could mount the red dot on the rib.
    They make a no gunsmithing base for that.
    Also make a lower cantilever base that attaches to rib, but would put the reddot closer to the eye (over receiver).

    If your SP is a rifle sighted choke tube bbl, yeah, diff bbl or do receiver mount.

    Since you are doing shot/ red dot sight..........have you looked at the Weaver clamshell mount?
    It sits low, is plastic.
    Non see through type.

    They work, but IMHO have two problems with that mount.

    1. The nuts fit in pockets and are sloppy. You will need to epoxy them in.
    2. the width of the mount.........at the back it might make hand contact.....just a little clumsy.

    Might be able to bevel here and there for less annoyance.

    The Weaver mount is under 30 bucks. Epoxy the nuts in place and slap a Sig Romeo 5 on it (or 30mm Aimpoint clone like the one from Primary Arms).
    The Sig will turn off and on automatically, so for a grab and go might be the better, but it's a micro sight.

    I find them tolerable closer to the eye.

    IMHO if not shooting slugs, no need to D&T receiver.
     
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