User Panel
User Panel
User Panel
|
Posted: 3/31/2017 4:29:25 PM EDT
I'm in the middle of changing my HBAR 16" carbine from standard handguards to free float. Part of the change-over requires removing the FSB and replacing with a low profile gas block.
I drove out the FSB pins with any problems and found that both of them had cracked cleanly in half! 
Has anyone a clue as to why this may have happened? Seems pretty odd to me but I can't figure out why it might be. 
|
|
|
|
Posted: 3/31/2017 5:29:28 PM EDT
[#1]
May have went in broken.
|
|
|
|
Posted: 3/31/2017 7:55:00 PM EDT
[#2]
Maybe at some point in your rifle's life the FSB was struck or experienced some sort of impact that sheared the pins?
Maybe the FSB installer tried to correct a canted installation by slightly "tweaking" it straight ? |
|
|
|
Posted: 4/1/2017 12:49:42 PM EDT
[#3]
Odd thing is, I had that FSB off in 2005 when I threaded and crowned the barrel. I don't recall any issues then getting it off or on. The pins were in good shape then.
I don't recall any impacts either. I have an aimpoint and a rear BUIS so once the iron sights were sighted in, I never much looked at them. |
|
|
|
Posted: 4/1/2017 1:49:06 PM EDT
[#4]
Taper-pins are designed to take up any slack between the top of the barrel & the underside of the gas port on the front sight base. Sometimes, when the barrel heats up really fast, or the front sight base cools off really fast, the pins can snap. It's rare, but seems to happen more if the front sight base pins have been removed & reinstalled once before..
|
|
|
|
Posted: 4/1/2017 2:08:37 PM EDT
[#5]
Not going to call it normal for the taper pins to snap, but it does happen once in a while.
The pins are hardened, and if they are not tempered correctly afterwards, it does leave them on the brittle side. When the pins are installed, they are not pounded in, but pressed in. Guessing that when you removed the pins, a punch and hammer was used (not a arbor press) and the jolting on the more brittle type pins will cause them to snap. As for the pins, just get replacement taper pins, and all should be fine with the world again to reinstall the FSB. Note, make sure you are driving the pins in the correct way, since both the pins and the channels are taper reamed one direction only. |
|
|
|
Posted: 4/3/2017 2:56:01 PM EDT
[#6]
Quote HistoryQuoted:
Not going to call it normal for the taper pins to snap, but it does happen once in a while. The pins are hardened, and if they are not tempered correctly afterwards, it does leave them on the brittle side. When the pins are installed, they are not pounded in, but pressed in. Guessing that when you removed the pins, a punch and hammer was used (not a arbor press) and the jolting on the more brittle type pins will cause them to snap. As for the pins, just get replacement taper pins, and all should be fine with the world again to reinstall the FSB. Note, make sure you are driving the pins in the correct way, since both the pins and the channels are taper reamed one direction only. Driven out then pressed in once before. Since this doesn't point to something terribly wrong with the barrel, I will go ahead with my plans and install the low pro gas block and FF handguard. Thanks all. |
|
|
|
Posted: 4/3/2017 3:16:51 PM EDT
[#7]
That's some outstanding bayonet drill. Post pics of dummy.
|
|
|
Win a FREE Membership!
Sign up for the ARFCOM weekly newsletter and be entered to win a free ARFCOM membership. One new winner* is announced every week!
You will receive an email every Friday morning featuring the latest chatter from the hottest topics, breaking news surrounding legislation, as well as exclusive deals only available to ARFCOM email subscribers.
AR15.COM is the world's largest firearm community and is a gathering place for firearm enthusiasts of all types.
From hunters and military members, to competition shooters and general firearm enthusiasts, we welcome anyone who values and respects the way of the firearm.
Subscribe to our monthly Newsletter to receive firearm news, product discounts from your favorite Industry Partners, and more.
Copyright © 1996-2024 AR15.COM LLC. All Rights Reserved.
Any use of this content without express written consent is prohibited.
AR15.Com reserves the right to overwrite or replace any affiliate, commercial, or monetizable links, posted by users, with our own.
