Marlin Firearms Forum banner

How To Enlarge The I.D of a Rear B.U.S. Aperture I.D. Properly ??

633 views 9 replies 5 participants last post by  MidBigWest 
#1 ·
My Ruger rear BUS's aperture is the small ID hole for long distance use. I wish to enlarge the aperture hole to my personal tastes. If I can... I'll save @ $110.00 and be able buy a Mission 1st Minimalist buttstock so my nifty ALG QD 7075 T-6 Forged aluminum sling swivel will have a place to attach my buttstock and money left over.. That way the other end of the sling will match..LOL.

Anyone else ever attempt this stunt? Any tips? Impossible ? Maybe a Good Luck ?
 
  • Like
Reactions: flatsneck
#2 ·
its not too difficult to do if you have a good set of small, sharp, precision, numbered drill bits.
Ive done it on a few occasions in the past. My recommendation is to find a bit that matches, then go up one size (number), check to see if that will work. Drill thru, visually inspect. Repeat until you find the diameter what you want.

Remember, you can take metal off pretty easy, just a LOT harder to put it back if you go too much.

Finish off the exposed, shiny metal with your favorite cold bluing and youre done..

Dont turn the drill bits a high RPM. slow and steady is better, and tapping fluid is a big help with those tiny drill bits. let the tools do the work.

to clean up any burrs you will probably get coming out the back side, just get a drill bit 5 or 6 times larger. turn by hand on the hole to gently remove the burr and give the hole a very slight champher.
 
#3 · (Edited)
Well what worries me is these Ruger brand B.U. sights appear to be 100% plastic, not the IM metal the magpuls are. I tested them with a magnet. Only metal i the fasteners. I figure the bit might walk/not stay on center of hole due to this.

Guess I'll give it a try though. I just hope the bit doesn't snag and break off the aperture "ear".

I've had good luck "drilling" car interior plastic panels (to mount accessories and additional lighting etc) with a drill bit , just turning it with my hand. I figure that might be the way to go here. Luckily I have letter sized, number sized and fractional sized drill bits.

Can anyone measure their Magpul MBUS rear sight's LARGER aperture's inside diameter and post it here, so I have a size to sorta go by..........

I'll report back with my success or failure......
 
#5 ·
Thanks Scorpiusb. Time to hunt down my number and letter drill bits...........
 
#6 ·
I enlarge aperatures all the time. The biggest part of my rifles have reciever or tang sights. You can use drill bits but I fool with them so much I invested in some small tapered reamers. Turned by hand you can control the size hole you want as you go. I have a 22 rifle that is my main Turkey Shoot gun and my aperature is tuned with a aperature front to perfectly bracket the bullseye they use at the 100' distance. Trail & error, a bit at a time you can tailor your aperature for your needs with tapered reamers.
 
#7 ·
Well, cannot find my number bit set. Started with a 9/64th bit. Chucked the bit in lathe, started the bit into aperture and turned chuck by hand. Guess I'll take the sight with me, and go find a number bit @ .015 larger than this .130" hole later this evening. Trying to get a wide field of vision as possible. FWIW this 9/64" hole is a huge improvement over what it was.







I did find this wrench though.......maybe that's why I can't find the number drill bit set....read the name of the tool company and it's metric size..........




 
#8 ·
FWIW I went ahead and opened up the aperture to 5/32". There's still a 1/16th" of aperture material left before the "aperture tab" would be too thin at it's top.

I'm gonna stop at 5/32" and shoot it some tomorrow and see how I like it now.

I pulled "yard duty" today, instead of sighting in my Ruger. And today was a perfect day here in NC to sight in a rifle....no wind/breeze all day . Hopefully tomorrow will be the same.....

Thanks for the encouragement and needed info guys ! BTW, I'm going to frame the Murphy's 13mm wrench and hang it on my garage wall soon.
 
  • Like
Reactions: Scorpiusb
#9 · (Edited)
UPDATE: I went ahead & opened it up some more with a 3/16th"drill bit. Or .185" as the dial calipers indicate.

I hope to sight it in tomorrow (Wednesday) if all goes as planned and weather permitting.

If I can find my number drills I'd like to take it to .195".
 
#10 ·
They sell taper bits for metal.
Gets you a real easy way to enlarge and debur at the same time.
If you leave enough material to add back is easier than you think.
You can tap the hole fill with a filler plug then re-drill to the size you want.

I have repaired moulding presses this way and have never had a problem.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top