RT pro rail foregrip

[Tym]

Hey guys, So I have this RT pro rail.. I like the way it looks and I want to use it, but I don't want to get/attach that stupid bracket that the asa bolts into.

My question is simple, If I drill out the rail to accept the 2 bolt style ASA, What size bit should I use? And what side counter sink bit? Also how deep on the countersink?

Has anyone done this before? if so any tips? Thanks guys!

[Guardian]

Here you go , screw size is 10-32 . clearance drill size for a 10-32 is #9 (for a tight fit) or #7 (for a looser fit) :

http://www.shender4.com/thread_chart.htm

What type of screw are you going to be using ; machine screw (also called socket head cap screws) , flat head or button (round head) screws ? Machine and button screws will require a counter bore (using a larger drill is a quick & dirty way for a counterbore which will work for what you are wanting to do), the proper way is to use an actual counterbore drill .

http://www.use-enco.com/CGI/INSRIT?P...&PARTPG=INLMK3

flat head screw will need a countersink . This one will work .

http://www.use-enco.com/CGI/INSRIT?P...PARTPG=INLMK32

Size of the countersink really doesn't matter just as long as it is capable of producing a chamfer diameter larger than the screw head . Just about any countersink will work for the size of screw you will be using . Just make sure you go deep enough to completely recess the screw head into the rail .

How are you going to center the ASA on the rail ?

[Tym]

Hey man, the rail already has a pre drilled and pre countersunk hole for the asa, But I need two. I was going to wait till my asa shows up (ordered from KC) Then measure the asa bolt pattern and copy it to the rail, use a drillpress, drill the other hole, countersink it and try that.. As far as centering the asa, I'll measure the predrilled hole to center the next hole.

Thanks for the info man!

Have you any Ideas? I would love to hear from someone who's done this or knows how to do this.. I'm sure I won't have any problems, but I would like to know how others have done this.

[Guardian]

I took a look at my RT Pro rail , I assume you will be using the hole at the very end as the only other hole is for the barrel twist lock . On my rail , the hole is not drilled completely through , It's diameter is 1/4" with a 3/8" counterbore . A little big for a 10-32 but not a problem ; will still work with a 10-32 bolt .

One option for copying bolt pattern is to use transfer screws . The link below is not a good picture as it only shows the case they come in . But it's a set of 6 screws , each has a sharp point to mark the hole location on an adjoining part .

http://www.use-enco.com/CGI/INSRIT?P...PARTPG=INLMK32

Since you have one hole , finish drilling that out if needed . Scribe a line to mark the center of the rail . Then screw one of the transfer screws into the ASA , use the existing hole to bolt the asa to the rail , keep the point of the transfer screw lined up with the scribed centerline , tighten asa down , then take it off . You should then have your hole location marked .


Another option for the hole location would be to just use a steel rule , preferably with 1/64" or .1mm graduations(if american standard measuring tools are hard to come by up north) , a scribe and centerpunch to lay out the location . To do that :

Find center of rail , scribe line . Measure the center of bolt hole to center of bolt hole distance of the asa . Scribe another line across the first scribed line at the same distance as the measurement you just took from the asa . Mark the cross of the scribed lines with a centerpunch . Then drill .


Hopefully you understand that wall of text , which it sounds like you'll be doing option 2 anyway . One of those two methods would be how I'd do it without a milling maching , micrometers , granite block , and a height gage and other necessary precision tools . While I've never done this mod , I do have a few years machine shop/tool making experience .

[Tym]

I took a look at my RT Pro rail , I assume you will be using the hole at the very end as the only other hole is for the barrel twist lock . On my rail , the hole is not drilled completely through , It's diameter is 1/4" with a 3/8" counterbore . A little big for a 10-32 but not a problem ; will still work with a 10-32 bolt .

One option for copying bolt pattern is to use transfer screws . The link below is not a good picture as it only shows the case they come in . But it's a set of 6 screws , each has a sharp point to mark the hole location on an adjoining part .

http://www.use-enco.com/CGI/INSRIT?P...PARTPG=INLMK32

Since you have one hole , finish drilling that out if needed . Scribe a line to mark the center of the rail . Then screw one of the transfer screws into the ASA , use the existing hole to bolt the asa to the rail , keep the point of the transfer screw lined up with the scribed centerline , tighten asa down , then take it off . You should then have your hole location marked .


Another option for the hole location would be to just use a steel rule , preferably with 1/64" or .1mm graduations(if american standard measuring tools are hard to come by up north) , a scribe and centerpunch to lay out the location . To do that :

Find center of rail , scribe line . Measure the center of bolt hole to center of bolt hole distance of the asa . Scribe another line across the first scribed line at the same distance as the measurement you just took from the asa . Mark the cross of the scribed lines with a centerpunch . Then drill .


Hopefully you understand that wall of text , which it sounds like you'll be doing option 2 anyway . One of those two methods would be how I'd do it without a milling maching , micrometers , granite block , and a height gage and other necessary precision tools . While I've never done this mod , I do have a few years machine shop/tool making experience .

Yeah, I"ve done quite a bit of machining, I've got full shop almost, (just no milling machine) do have a lathe and drillpress tho.. I was for sure going to use my metal rule, I've got a few, but one brand spankin new, as the old ones have a few nicks in em.. And yeah a center punch.. I've done many things like this before, I was just hoping someone would offer something I didn't think of :)

I was SO hoping for the bolt spacing for the foregrip.. Oh well Looks like I'll have to figure it out, I will of course drill a test piece before I drill the actual rail.. That way I can get a pattern and even set stops etc..

Thanks for all the help man