Gunsmithing Yes, Another Damn question about Flush Cups

[Ballistic Artist]

Hey all,
Installing flush cup swivels on a 17Lb rifle. Ive got the HD outside threaded cups I believe they're Grovetech. Ive heard various ways to install them. One was to cut threads in your stock then epoxy the cup and thread it in. Another one said to just drill the stock a bit over size and epoxy it in.
What is the strongest way to install flush cups on a Mcmillan stock? Thanks for the input.

 

[Sean the Nailer]

Re: Yes, Another Damn question about Flush Cups

Contact McMillan?

I dunno, but I'm thinking some sort of 'backing-plate' that this flush-cup would thread into, would be better.

 

[PCR]

Re: Yes, Another Damn question about Flush Cups

We run a 1/2" endmill, then tap 9/16X18, coat the insert with Devcon and screw it in. Our tap is ground so the threads reach the bottom. Easy to set depth and run the tap straight with a manual mill and no worries of the gelcoat chipping. Chamfer the leading edge of the hole to keep things neat. We actually do this with another endmill.

If using a hand drill, put masking tape on the stock first and be careful not to cut an oversize hole or chip the gelcoat. Use a smaller drill bit for a starter hole. You might want to break the leading edge with a round file so that the tap doesn't chip the gelcoat. Apply a small amount of Devcon to the threads and make sure to clean up the excess or you won't get the swivel insert to go in or lock.

 

[coldboremiracle]

Re: Yes, Another Damn question about Flush Cups

^this. Though I dont have a mill, I did it the same way with poor boy tools in the garage.

 

[p3ripperfw]

Re: Yes, Another Damn question about Flush Cups

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ColdBoreMiracle</div><div class="ubbcode-body">^this. Though I dont have a mill, I did it the same way with poor boy tools in the garage.</div></div>

Exactly how I did mine as well. I wished I would have ground the tap down so the threads would have reaches ther very bottom of the hole though. Either way just take your time and go up a couple drill bit sizes per time and youll get up to the 1/2" and be ready to tap it. Hardest part for me was finding a 9/16 tap but eventually I did find it. I just used standard 30 minute epoxy on the threads. The Grovtech cups are very nice quality.

 

[Ballistic Artist]

Re: Yes, Another Damn question about Flush Cups

Thanks for the input. How about on the forearm of the A5 McMillan? How its not very flat? Dow you first mill a flat on it or just mount it? It looks as if it might have the top thread exposed on 2 sides to be able to have the flush cup up far enough to work properly. Thanks again,

 

[Sonic Crack]

Re: Yes, Another Damn question about Flush Cups

I would say the absolute strongest way would to be use the threaded inserts used to install bipod rails and epoxy in the flush cup in. Use a button head screw to hold the flush cup into the threaded insert.