AR Front post removal
I have a DPMS lite and want to remove the front post and replace it with a flip up site. Is this hard to do?
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Jerecole,
If you have the standard front post it's not all that hard but you have to have a couple of the RIGHT pin punches. You punch out the (usually two) pins holding the sight on. Then, you need a really small roll pin punch to push out the roll pin holding the gas tube.
That's pretty much it. A good vise with wood or soft blocks that won't damage your rifle.
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My pins weren't tapered either. But, that fixture would be a very nice addition to have. I usually set my uppoer in the vise and turn it to the front sight is over the workbench. I then put my steel bucking bar under it and drive the pins out. As noted make sure you're driving them not just flattening them out.0 -
You have to remove the sight assy. and replace the gas block with one that has a rail on top. Use the directions above. Remember the two pins mentioned are tapered and very tight. 0 -
One of these fixtures comes in very handy and it tells you which way the pins go. How ever in this case a 4 lb. dead blow hammer wasn't enough to remove the pins on this CMMG ftont sight base. The pins had to be drilled out. They can be some what easy to remove or they can be very difficult
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quote:One of these fixtures comes in very handy and it tells you which way the pins go. How ever in this case a 4 lb. dead blow hammer wasn't enough to remove the pins on this CMMG ftont sight base. The pins had to be drilled out. They can be some what easy to remove or they can be very difficult
Be sure to pay attention to the quote and the pictures. If you screw up and try to push the large end of the pin through the small end of the tapered hole, well, you have damaged the sight tower or made things ugly, at least.
If the pins have never been removed, they're probably extremely tight. Be sure to use the correct size punch, preferably a "starting punch" (one that is short and won't bend over when struck). In this case, it is worth it, if you don't have a starting punch of the correct size, to take a regular punch of the correct size and cut it off to the shortest usable length for this job. You can order a specialty punch from Brownells and others that is short and cupped, since most of these pins have slightly rounded heads, but it's not absolutely necessary. Once you get it started, use a regular length punch to finish the job of punching out the pins.
You don't absolutely need the fixture, either, but it sure helps. The trick is to not soften your hammer blows. You can secure the gun barrel on pieces of wood, brass or aluminum, but not on a cloth or a pad. Practice first on a piece of wood, then place your punch, keep your eye on the impact point and hit it hard. The shock is what will loosen these pins, so use a good, 8 oz. or 12 oz. or even a 1 lb. STEEL ball peen hammer and strike a sharp, solid, heavy blow, otherwise the pins will be peened all to heck.0 -
quote:Originally posted by armilite1015
One of these fixtures comes in very handy and it tells you which way the pins go. How ever in this case a 4 lb. dead blow hammer wasn't enough to remove the pins on this CMMG ftont sight base. The pins had to be drilled out. They can be some what easy to remove or they can be very difficult
[img][/img]
The last two CCMG's I removed had straight pins, not taper. Both pins were both broken on both guns.
An 8-12 oz steel hammer swung sharply will work much better than a dead blow of any sort.0 -
The harder you swing the hammer the louder you have to swear - that's the secret. [;)]
I've encountered tapered and straight, the tapered was easier to drift. One thing that helps is to use a very short stemmed steel punch. If you use the typical long nosed type they can bend or break and IMO don't seem to transfer the full blow to the pins.
Also, on the tapered type, once you get any movement hold off on the heavy hits, just try & push it out. The tapered gives way very quickly, if the first hit moves it your second whack will encounter no real resistance - unless you count your thumb being squashed between the hammer and barrel as resistance.0 -
A starting punch can be made by grinding the point off a tapered center punch. Switch to a pin punch after the pins start moving.
You need to deliver some heavy, controlled blows to start the pins moving.0 -
Another option for a starter punch is to use a proper sized nail set. Has always worked well for me. Use the nail set to get the pin started and then the pin punch to remove.
If that rifle has a 14.5 inch barrel with the flash hider to bring it to the 16 inches legal length it will be pinned and welded. That is not so easy to remove. If you have no experience that step is the hard one. Might be worthwhile to let a smith do that.0 -
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The last two CCMG's I removed had straight pins, not taper. Both pins were both broken on both guns.
An 8-12 oz steel hammer swung sharply will work much better than a dead blow of any sort.
I used steel hammers up to 2lbs and those pins did not budge. It was recommended by 2 different people in this forum to use a dead blow hammer. There is no rebound of a dead blow hammer like there is on a conventional steel hammer. Thus all the force that the hammer develops goes right to the item being pounded making it more efficient then a conventional steel hammer.0
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