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Durkin Tactical Franklin Armory
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Posted: 8/4/2009 1:27:04 AM EDT
Tried knocking out the taper pins on my FSB  (Bushy M4)  All I'm doing is leaving brass marks all over the FSB and deforming my brass punches.  Should I move up to a metal punch or will that just mushroom the taper pin heads?
Link Posted: 8/4/2009 2:05:20 AM EDT
Steel 'starter' punch and at least a 24oz hammer - Left to Right.

Link Posted: 8/4/2009 2:46:23 PM EDT
Got it!  Used the buddy method and got the pins out. (My buddy had the steel punches )  Once they broke loose they were easy
Link Posted: 11/1/2009 8:56:21 PM EDT
anybody have a jig or fixture that is used to hold the barrel assembly while you are trying to drive out the pins?  I tried the one from Brownells and it allows the barrel to rotate when you whack it...

I have some very very stubborn pins that won't budge.
Link Posted: 11/1/2009 9:19:25 PM EDT
Link Posted: 11/1/2009 9:26:43 PM EDT
I'm driving them the right way....sure about that and I have the correct punch, even tried the cup tip one from Brownells that they say is for this exact issue.  Whacked it hard with a 32 ounce hammer...no joy.  

It is soaking in penetrating oil right now.  I will attack it again shortly...
Link Posted: 11/1/2009 9:41:38 PM EDT
Link Posted: 11/2/2009 6:31:28 PM EDT
Well....good news, I used the BFH on it and it is done...for better or worse.  

Broke or bent 5 punches (good punches) and distorted the cup tips on 3 cup tip punches from Brownells.  The FSB is pretty beat up around the hole.  It was ugly...froze it...didn't help.  Soaked it in penetrating oil overnight...didn't help much.  Got the first pin out that way.  

Second pin was the stuborn one.  Finally used heat and got it to move flush with the surface but was stuck from there.  This was strange since usually taper pins are easy once they move but not these.  Had to drive them hard the whole way out.  After I heated it a LOT with a torch the second time, I whacked it with my last (4th) cup tip punch and it finally drove out.  

All in all...this was strange.  I have done several uppers prior to this and the pins came out without too much trouble...but not this one.  

It was almost as if the hole wasn't nearly as tapered as the pin.  

There has to be a better way.  How is this done at the factory when they have to remove an FSB?  I assume there must be a fixture of some sort and a press?  There has to be something better than the BFH and punches
Link Posted: 11/2/2009 10:12:36 PM EDT
Link Posted: 11/2/2009 10:33:09 PM EDT
Arbor press.

Available from Northern Tool, Harbor Freight, etc.

And if you really want to do it right, get one of these:

Available from Brownell's: http://www.brownells.com/.aspx/pid=20727/Product/AR_15_FRONT_SIGHT_BENCH_BLOCK

[ETA:] To prevent marring, put a piece of hardwood, leather or something else that's not quite as hard as the pins between the press and the pins.

Link Posted: 11/2/2009 10:58:59 PM EDT
Yes, backer plate and a press make short/easy work out of removing the pins, but as stated, the Bushmaster pins are parkerized in place, so you do slightly mar them even this way, and end up using new taper pins to reinstall the FSB (read customer is not going to like his rifle handed back to him with the taper pins mar'd up at all, hence the reason that removing a FSB in a shop is going to cost you more than just labor alone).

This was a BCM and I belive the issue was that the holes didn't really "taper" all that much...  I am guessing here but the pins were far tighter going back in than any I have seen before including other BCM uppers.  

I have done this on Bushmasters, Colts, and BCM uppers...this one was nuts.  

Its done and I will NEVAR NEVAR NEVAR install another Daniel Defense FSP rail.  It is a great rail but it takes about 4 hands to do it all and keep everything lined up.  Nice rail...but damn.  

If I were doing it again, I would get the rail that is solid and just uses a rail mounted front sight.  Trying to drive the taper pins back in with the rail on there was a PITA.  

I am going to look into that press.  It has to be better than the BFH method that I just used.  That block from Brownells sucks.  It is flat and the barrel is round...it allows the barrel and front sight assy to tilt and the punch to slide off.  Not a great design.  They need to make it round to match the profile of the upper.  

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