11-87 & 870 drill & tap

[brasskeeper]

I have a 870 and am thinking of buying a 11-87 neither of which are drilled and tapped for a scope mount. I don't like the b-square mount so I wondering how big a deal it is to drill and tap the receiver on these two shotguns? I assume the screws could not protrude through the receiver or they may contact the bolt?

any advice would be helpful.

Thanks

brasskeeper

[Graybeard]

I've had a couple of 870s drilled and tapped for a Weaver base in the past but I can't tell you what base number it was that fit as neither gun is around here any longer. It worked quite well and I'd not hesitate to do it again if I wanted to scope one.

[JoeG52]

I really prefer the cantilever barrels instead of drilling and tapping the receiver.
There is less chance for movement being directly mounted on the barrel.

[Graybeard]

The 870 I set up for me had the rifled barrel and easily shot 2" 100 yard groups using the Remington copper slugs of the day. My wife's had a smooth barrel with screw in rifled choke tube. Hers didn't like the sabots and shot better with the older foster type slugs but hers did about as well at 50-60 yards with them as mine did at 100 with the sabots. I just never found it to be a problem having the scope on the receiver. I've never warmed up to the idea of those cantilevered barrels.

[ScoutMan]

Like GB, I had the receiver drilled and tapped on a Mossberg 500. Having reservations about the strength of the aluminum receiver, I epoxied the base between the screw holes.

Gun has accounted for a number of deer and is still "trucking".

SM

[brasskeeper]

Great replies guys, thanks.

Anybody else know what weaver base to use?

[wink_man]

Brasskeeper,
      870's are easily drilled and tapped, as they have a short barrel sleeve going into the receiver, you just need to drill & tap behind where the barrel sleeve fits into the receiver, and there's plenty of meat on the receiver. 1100's and 11-87's on the other hand, have a long barrel sleeve going into the receiver, and the receiver is to thin, to far back, and while people have drilled & tapped 1100's and 11-87's the receivers are really to thin and you get a minimum number of threads, most gunsmiths won't even do it.

     If you go the 1100/11-87 route, your best bet is a cantilever barrel, and while, like Greybeard, I don't care for them, they do work. The B-Square mount I don't care for either, however, I do like(and use successfully) the Weaver Converta-Mount on several guns. This unit, the whole top is removeable to quickly convert to a bird barrel, and they can be taken on & off and hold zero. Here is a link if you want to check it out:

http://www.weaver-mounts.com/products/shotgunAndPistol.aspx

If you should choose to go the Weaver Converta Mount route, just don't get the 'see under model', as your cheek is to far up and off the stock when looking through the scope.

     I've drilled and tapped 870's since 1980, back before most were doing it, and there was no information to go on. Experimenting on my own, I found that the Weaver base for a Remington 760 rifle was an ideal fit, Weaver part #62, or the pivot mount version, part #162, however, the #162 isn't made anymore. This base utilizes 6X48 threads, and can be mounted behind the thin part of the receiver where the barrel sleeve fits in no problem. Incidentally, I've always drilled straight through the reciever, and have never had a problem. And the screws that come with the base do not protrude through the receiver.

    Here's a few pics of the first 870 I drilled and tapped back in 1980. This one utilizes the Weaver #162 Pivot mount, the pics will give you an approximate idea of where the holes should be drilled and tapped if you're going to attempt it yourself. Good luck.

[brasskeeper]

Thanks wink_man great information.

[brasskeeper]

wink-man I've been looking at the Weaver Converta-Mount what holds it on? Looks like you replace the pins in the receiver, if so does it come with the bolts to go through the pin holes?  If you don't mind and have one available could you post a picture of a  Converta-Mount on a shotgun.


As far as the base, Weaver part #62, do you use a fixture to drill the receiver or do you use the mount to mark the bolt pattern?

[wink_man]

Here's a few pics of the Converta-Mount on my daughters 1100.

Picture 1 Shows the base permanently affixed to the receiver. It's a very simple operation, just remove the 2 trigger pins, put a little loc-tite on the threads of the screws that come with the Converta-Mount which replace the trigger pins, push them through the trigger pin holes, and tighten them up on the base(don't overdue the tightening). The base is then permanently affixed to the gun and doesn't come off. Then the top bracket attaches to the base via the 2 thumb screws shown on the bracket. The bracket lines up with the machined groove in the base, and thats how it holds zero, even taking it on and off. Nice part about it also is that you can have multiple top bracket/scope combinations for the same gun, such as one for foster slugs with a smooth bore barrel, and another for a rifled barrel and sabot slugs. Thumb screws on the top bracket only need to be finger tight, even if they are loose, as long as they are not loose enough for the bracket to wobble, it holds zero. I was very leery of ths setup when it came out years ago, but bought one, and tested it thoroughly, every way I could, and they do hold zero. Far as I am concerned, if you're going the saddle mount route, the Converta-Mount is the ONLY way to fly. Nice part about it is, that you can take the top mount right off, throw on a bird barrel, and you're good to go to shoot a few pheasants. Like this year, for example, my son has the Converta-Mount on his Ithaca 37(they don't make it for the Ithaca anymore). Anyways, he hunted pheasants all through November with the Ithaca, and the Sunday night before deer season opnend the next day, I asked him if he was going to put the slug barrel and scope on the gun tonight, or wait till we were ready to leave in the morning to do it. He put the slug barrel on, and the top bracket of the Converta-Mount and the following Thursday shot a nice buck, 50 yards away, right through the lungs. What more can you ask for of a mount?



  Picture 2 shows the top bracket/scope mounted on the gun from the same side:



And picture 3 Shows it from the opposite side:



As far as drilling and tapping the receiver on an 870, the first time I did it, I put the base on the receiver with a bunch of elastic bands, gently put the rings/scope on the base, and moved it up and down the receiver till I had the location I wanted it. took the scope off(being careful not to move the base) marked the holes, removed the base, centerpunched the holes and then drilled and tapped them. Now I just take the measurement off that first gun to the first hole, put the base on, and mark the 4 holes and proceed as above. Make sure you centerpunch the holes all straight and in line, because once you drill holes, they are very permanent. Hope this helped.

[brasskeeper]

Thanks again wink_man great information you have given me alot of great ideas.

[Phoneman]

Just got in my new jig from williams to drill and tap receivers It has a note in the instructions that advises against using it on the 1100 and 11/87 because of the thin receivers. Thought you should know.

[brasskeeper]

I appreciate the info but I wonder why the Remington 11-87 SP-T comes from the factory drill/tapped if its to thin?

[Phoneman]

Maybe it is thicker that the old ones. Stronger metal?  Don't know.