Bolt mod or "Drop Free" bolt modification.

[czgunner]

Anybody try to modify a bolt carrier so that mags can be inserted/removed w/out the bolt open? Is it possible.



 **Edit: There seems to be renewed interest in this mod since the advent of the Tapco 20rd mag,
             so I moved this to the top and made it a sticky . 

             Remember, All 922(r) laws apply.

BB

[cvasqu03]

There is no need to modify the bolt carrier at all.  You do, however need to modify the bolt itself by removing the extentions that slip under the feed lips of the mag and mechanically lock it into the magazine.  Basically, you have to make it match the bolt on an SKS-M, Many people have successfully done it. I'd recommend starting with a Dremel tool and finishing up with a file.

Heres' a picture of one I did.  The bolt to the left is an unmodified SKS bolt.  The middle is the one I modified, and the one to the right is the bolt from an SKS-M.  The one in the middle is kind of hard to see becasuse it was very shiny so it kept reflecting everything, but you should be able to get the idea from this picture. You don't have to go back as far as they did on the SKS-M either. 

This mod is relatively safe and will even allow you to continue using the standard fixed magazine.  Just don't damage the bolt face.

[Lollygagger]

Some more pics, bottom one is modified...





Lollygagger 

P.S -FWIW, this duplicates the bolts in the SKS "D"/"M" firearms.

[Lollygagger]

Here is a pic thru the mag well ("cleaned up") of one modified...



Note that the modified bolt is narrowed in width for almost the full length of the mag well opening, just starting to "flare" towards the original wide width before it is covered at it's rear by the action.

This is what is required in order to gain a ability to use a detachable mag that CAN BE PLACED/REMOVED IN ANY CONDITION (loaded or unloaded) -as with anyother modern detachable magazine accepting weapon.

This is major SKS magic that I can't understand why anyone capable would not do, except the most dyed in the wool "purist" types. I would not use detachables without doing do, as w/o such, they are a PITA & have less reliability ('cause they get their flimsey selves bashed around too much in use).

Since it has no effect on use of the standard factory 10 round fixed box mag -it all come under the "Why not...duh!" catagory. Of course, screwing the bolt up if not done with care *is* not good.

Lollygagger 

[Lollygagger]

Damn Lollygagger, you really took a mill to that bolt.  I assume you used more than just a file right?

A file takes too long by itself...

I used a bench grinder with a fine wheel (with care!) to rough it out -and finish with a Dremel & stone, file & polish wheel on the Dremel with diamond grit (great stuff, but major danger to the eyes).

While maybe not required, I pretty well profile them to the ones in my SKS "D"/"M" firearms. I doubt that the "step" made on the bolts underside is actually needed for use in a standard SKS (does not hurt).

Lollygagger 

[Lollygagger]

Ha! The SKS bolt mod EVILNESS grows!



Who will save you now, SKS "purists"?

Lollygagger 

[Lollygagger]

One thing I'm wondering about this bolt mod. Do you need to reharden the bolt ?

No.

LG 

[Trev]

I went ahead and did mine last night with a dermal tool.  Went slow and it only took me 20 minuets to finish.  I would definitely not hesitate to do this modification again.   

  Now, I have an unknown brand five round magazine and everywhere from 3 rounds to empty it works fantastically.  The forth and fifth rounds on the other hand are no goes with the bolt shut.  Has anyone tried this mod with the five round Tapco magazines?   People say the Tapco 20 rounders work fine butt I really prefer the looks of the smaller five round magazines.  I really don’t want to relive the bottom of the bolt if I don’t have to.


(Click on pic's to make bigger)
Before


After


The black bolt is the modified one
 

PS: If anyone wants more pics just let me know.

                                            Trev

                                       

[milsurpcop]

Ok, I did it today.  Fortunately I have an M so I had a perfect template to go by.  I took my time and would remove a little, reassemble and test.  Remove a little more....ect. you get the picture.  I didn't remove as much as others have in the pics I've seen.  I used a dremmel with the conical stone & cutting oil.  I tried the sanding wheel as others used, but it didn't seem to work well for me.  I did try my bench grinder, but I didn't seem to have the control I wanted.  It took me about an hour, but I'm pleased with the results.  When I finished with the grinding, I used 600 grit sandpaper and polished it up.  I then used a polishing wheel w/compound with the dremmel and shined it up.  I didn't remove material from the bottom, but I did lightly polish it with the polishing wheel.  In the pics the M bolt is on top and the modified Chinese is on the bottom.  The last pic shows the bottom view, the modified bolt is more even than it looks, must be the camera angle.  I may take another look at it and see if it needs a little evening up. 

[Sabre]

Thanks to LG I did mine. It was no problem and works great with the TAPCO mag.

{broken pic links removed BB/Mod}

[BillyBang]

I'll post this pic up here for a while (best my cam can do).
Hope it helps to explain what is done to make a standard bolt "Drop Free".

Note on the extractor side (left pic), the ledge ground flush to the bottom of the "slot" (slight trace of ledge left on mine).
The other side is ground down an equal amount but the slot is deeper so you still have some slot/ledge left.
Only the side ledges are ground on this one, none is taken off the bottom of the bolt.
If you want clearance for that "last round" for a detachable,
I would look at trimming the follower, not the bolt. IMHO.

{pic removed}


BB