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Posted: 12/27/2014 5:19:41 PM EDT
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My A1 front sight base for some reason won't let the tapered pins go through all the way. The pins are in, but are not sticking out from the other side. I put in pins in small side first. In addition, the front sight base wobbles from left to right with a small amount of gap between the FSB and the handguard cap.
Any suggestions/fixes? |
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Are you trying to re-install the original FSB or replacing with a different FSB? FSB's are NOT drop in parts. If your replacing the FSB the holes must be reamed after the FSB is installed on the barrel. There will be a gap between the barrel shoulder and FSB if you don't install a handguard cap Some manufacturers use straight pins instead of tapered pins. |
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Quoted:
Are you trying to re-install the original FSB or replacing with a different FSB? FSB's are NOT drop in parts. If your replacing the FSB the holes must be reamed after the FSB is installed on the barrel. There will be a gap between the barrel shoulder and FSB if you don't install a handguard cap Some manufacturers use straight pins instead of tapered pins. Thank you. I will do this. |
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Can you provide us some info on the barrel, maker, and did it come mounted with a front sight base or is it something you are trying to add? Is this on a barrel where it came mounted with a front sight base that you removed, now have reinstalled it and its loose? If so then you need to make sure what type of the pins you have (taper, dowel, or roll pin), as this will determine how the pins hold things. Some front sight bases have been mounted using 1/8" roll pins (these are called different names like coil pins, slotted pins, slotted spring pins, spring pins, etc), and these can usually be put in from either direction. Dowel pins are used by quite a few barrel makers, these are generally 1/8" in diameter, and are a solid pin (same diameter all the way across), and generally flat on the heads. dowels can generally go in/out either direction. Taper pins are the most common, these are smaller on one side and larger on the other, most common is a 2/0 taper pin, and these are generally convex (domed or protruding outward) on the heads. The taper pins basically wedge things into place, and do a nice job at taking any play out so there is no wobble. Taper pins on most barrels are put in from right to left (large side on the right and small side on the left), some makers will put them in the opposite direction, so you need to be careful to make sure you are removing and reinstalling them the way the holes were machined/reamed. When using a taper pin, you need to make sure you firmly seat it upon installation so it wedges things into place.
CY6 Greg Sullivan "Sully" SLR15 Rifles TheDefensiveEdge.com (763) 712-0123 |
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Quoted:
Can you provide us some info on the barrel, maker, and did it come mounted with a front sight base or is it something you are trying to add? Is this on a barrel where it came mounted with a front sight base that you removed, now have reinstalled it and its loose? If so then you need to make sure what type of the pins you have (taper, dowel, or roll pin), as this will determine how the pins hold things. Some front sight bases have been mounted using 1/8" roll pins (these are called different names like coil pins, slotted pins, slotted spring pins, spring pins, etc), and these can usually be put in from either direction. Dowel pins are used by quite a few barrel makers, these are generally 1/8" in diameter, and are a solid pin (same diameter all the way across), and generally flat on the heads. dowels can generally go in/out either direction. Taper pins are the most common, these are smaller on one side and larger on the other, most common is a 2/0 taper pin, and these are generally convex (domed or protruding outward) on the heads. The taper pins basically wedge things into place, and do a nice job at taking any play out so there is no wobble. Taper pins on most barrels are put in from right to left (large side on the right and small side on the left), some makers will put them in the opposite direction, so you need to be careful to make sure you are removing and reinstalling them the way the holes were machined/reamed. When using a taper pin, you need to make sure you firmly seat it upon installation so it wedges things into place. CY6 Greg Sullivan "Sully" SLR15 Rifles TheDefensiveEdge.com (763) 712-0123 The barrel is an 11.5" Colt commando barrel, the FSB is from a Colt XM177. The pins are tapered and even though i'm putting them in correctly, they won't go all the way in. I am assuming that I will need to ream and re-machine the FSB onto the new barrel in order to allow for a good fit? |
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Yes, FSB's are individually installed/ drilled to the barrel that they are being mounted to, and not a consistent fit through out the batch of barrels.
If you are trying to mount a FSB that was mounted on one barrel to another barrel, best of luck since your semi fighting a lost cause (depends on how close the channels mate up between the two to begin with). As for if the channels are close to each other, then reaming slightly over size with a over sizer taper reamer with the FSB jigged up to hold it TDC/ indexed with the barrel extension, then using over side taper pins is an option. |
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Quoted:
Yes, FSB's are individually installed/ drilled to the barrel that they are being mounted to, and not a consistent fit through out the batch of barrels. If you are trying to mount a FSB that was mounted on one barrel to another barrel, best of luck since your semi fighting a lost cause (depends on how close the channels mate up between the two to begin with). As for if the channels are close to each other, then reaming slightly over size with a over sizer taper reamer with the FSB jigged up to hold it TDC/ indexed with the barrel extension, then using over side taper pins is an option. Would you recommend sending it off to ADCO for work or do-it-yourself? |
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Would you recommend sending it off to ADCO for work or do-it-yourself? Quoted:
Quoted:
Yes, FSB's are individually installed/ drilled to the barrel that they are being mounted to, and not a consistent fit through out the batch of barrels. If you are trying to mount a FSB that was mounted on one barrel to another barrel, best of luck since your semi fighting a lost cause (depends on how close the channels mate up between the two to begin with). As for if the channels are close to each other, then reaming slightly over size with a over sizer taper reamer with the FSB jigged up to hold it TDC/ indexed with the barrel extension, then using over side taper pins is an option. Would you recommend sending it off to ADCO for work or do-it-yourself? If you must use a pinned FSB I'd send it off to ADCO. Pinned FSBs are not really "replaceable"; the FSB and barrel is drilled as a unit for the pins and one FSB is not generally usable on another barrel. What's going to end up happening, assuming you have an existing drilled barrel and a new, undrilled FSB, is that the barrel will have two sets of pin holes. If the FSB has already been drilled I gotta say it's probably never going to work out. You MAY be able to get it pinned somehow, but it's going to be a shit job and it'll never be as good as a virgin barrel and a virgin FSB. |
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Would you recommend sending it off to ADCO for work or do-it-yourself? Call Adco and see if they will do it for you, but chance are, it will be a lot cheaper to use a clamp on style FSB, instead of trying to fit a new FSB with taper pins to the barrel instead (using the channels in the barrel already drilled). As for doing it yourself, do you have a full machine shop, the need jig to hold the FSB indexed correctly on the barrel while you over size machine ream the channels to remove any voids, and even a lathe to make over size pins out of tool stock to make the new over sized taper pins? Also, a bead blast cabinet and a way to parkerize the new pins before you install them? |
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