Gunsmithing Rem 700 dbm install

[DaveinCO]

Bringing this over cause it helped me a lot and is too good to lose.



DaveinCO
Pillar height for PTG bottom metal?
01/18/2016

I am getting ready to inlet the stock on my 700 and was checking the pillar heights in the stock vs the ones that came with the bottom metal. In the stock the rear pillar is .001" longer and the front is.016" longer than the ones that came with the PTG bottom metal.

Should I mill .015" off of bottom of the front pillar or not worry about it? I will have the stock in the mill to inlet it anyway and i really don't want to pull the old pillars and start over. I am not sure how critical the alignment is to proper feeding from the magazine and i don't want to screw this up and have to tear it all apart and rebed later anyway.

Thanks guys,
Dave

LongRiflesInc
Re: Pillar height for PTG bottom metal?
01/20/2016 Last edited 01/20/2016 by LongRiflesInc

.725" on the front and 1.075" on the rear if I'm not mistaken. (still at home presently)



You have some degree of wiggle room. What your ultimately after are the following:



1. Sufficient cartridge case overlap with the bolt face. The shorter the cartridge, generally the more you are going to want. Reason is the entry angle into the breech is increased with a shorter case. Having more overlap prevents the rim from slipping under the bolt body. The limiting factor is when the feedlips start riding on the bolt body. Then you've gone too far.

2. Sufficient seating depth of the floor metal so that the magazine is captivated in both directions. -Meaning it doesn't rattle up/down like a marble in a tin can. It should slide in and click, and maybe have an extra .01-.03 of additional room.

3. Nice presentation with the bottom of the stock. Having a floormetal sunk in the stock just looks poor. Likewise having sitting above the bellyline is also an eyesore. It's fairly common for us to fit the floor metal flush and negotiate the magazine function by working on the release lever. Sometimes I have to zap the release lever with a TIG welder and a bead of maintenance rod to build it up. The room to play here isn't huge as most DBM's restrict how far the magazine can penetrate the well. This is governed by tab on the back of the magazine and how it contacts the backside of the well directly above the release lever. There is room typically, but not a whole lot.

4. Last-When you get this all put together and your checking it out: IF your magazine isn't seating fully in the DBM (you'll know cause the "click" won't be there) you want to check to see if the backside edge of the magazine (directly between the feed lips) is catching on the little tab/boss that's present on an M700 receiver at the rear of the magazine/feed lip mortise. It's the little peninsula looking thing that juts out in front of the trigger well features in the action.

I have had my nuts kicked by a gun more times than I care to admit by that damn thing. I always seem to forget about it until AFTER I get jiggy with the release lever. Then I go to the mill cussing a storm because I ruined the release lever and have to machine one from scratch. If that little boss invades the magazine well by even the slightest amount, the magazine function will be horrible. It will be reluctant to register and it won't fall out when you hit the lever. Buzzing the face so that it is behind the footprint of the well makes everything nice and happy.

So, check that AS SOON AS YOU GET THE DBM IN THE STOCK and save yourself the ruckus I often fall into.



Hope this helps.



C.

dinc2
Re: Pillar height for PTG bottom metal?
01/20/2016

What Chad said. Rear pillar 1.07", Front 0.72". A couple of thousandths won't kill you but a hundred and a half will. Mill it down.

DaveinCO
Re: Pillar height for PTG bottom metal?
01/25/2016

Thanks for the help guys.
With your input I got most of it right, but I did sink the bottom metal too deep to the rear of the trigger. There is definitely a lot to keep track of when you are setting up to mill it. I think it turned out ok, and I would probably do better next time.
Function is fantastic though and with the bedding job i did at the same time it is now sub moa even before any load development.
Bottom line is I would do this on a factory stock on a working rifle, but for a nicer stock I would probably order a stock pre-fit or send it to a pro.
LongRiflesInc
Re: Pillar height for PTG bottom metal?
01/25/2016

Here's a tip if you do these more than a few times.



Build a fixture that holds the front of the stock down and secures the sides. Leave the receiver inlet area free of any down or side pressure as it will distort the inlet. (squeeze it and it'll spring back once popped out of the fixture, you'll have gaps)

Next, set your tool length off the base the fixture and work in a positive Z direction. If showline is zero and the action is 1.350" OD then you move up .675" (radius) and add your pillar lengths.



.675+.725=1.4" installed height for front

.675+1.075"=1.75 installed height for rear



Going this route makes it easier to set your positions.



C.


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