Breech Plug problem on GM IBS LRG Barrel

I know that several of you own TC Renegade or Hawken with installed Green Mountain Hawken IBS system Octagon 1 in 28" twist barrels.
I have had one in my Renegade since 2009. I have also been using a scope on the Renegade for several years and have been unable to remove the barrel. I recently took the scope off and wanted to do a thorough cleaning, but was unable to remove the screw on the outside of the breach plug that came with the Green Mountain IBS barrel. It is set up for an extremely small Allen screw which provides insufficient torque to remove the screw.

I'm wondering if anyone has tips on how to deal with this situation? I want to replace the breach plug, can I use an aftermarket Thompson Center replacement? Do you know if Green Mountain provides replacements?'

It is also very possible that I am missing something easy. I still consider myself somewhat of a newbie with this gun, even though I have over 200 rounds or more through this otherwise awesome barrel.

Thanks, in advance for your help. OEH2

what/where is this "breech plug screw". is this a caplock or flintlock? if caplock, there is a bolster, nipple and clean out screw, fitted to the breech plug. if a flintlock, there is a vent/touch hole either before or on the breech plug. there are some specific considerations about removing the breech plug on a side lock. anyhoo, a pix would help.

I think he's talking the bolster clean out screw. Just leave it alone if it will not come out. A good water bath can flush clean the bolster. As for the breech plug bolt/hook leave that alone too. Many of them are welded and you'll only make a mess of things.

the clean out screw was meant to come, else why have it in the first place. this is why it is SO IMPORTANT to anti-seize lube breech plugs, touch hole liners, bolsters, nipples and clean out screws from the get-to, so future removal will be easy. that clean out screw could be "welded in" by the bp fouling residue that will invade all threaded fixtures that are next to the combustion chamber. i'd dip the whole assembling in liquid wrench for a day or so and give it a go to remove.

It is an amazingly small allen screw for its function. Any amount of BP buildup would make it impossible to unscrew, regardless of the anti-seize used. I have a call into Green Mountain to see what they have to suggest.

Most likely, Cayuga, is right (as usual). I should just leave it alone at this stage. I will post a pic after work tonight.
Thanks OEH2

caplock "clean out" screws are really relief "valves" where if there was too much pressure build up on detonation (post ignition) that screw would blow. while it's true that it doesn't need to be removed, using it is a great way to clean out the flue to chamber. i'd still give it a liquid wrench soak and if the socket head is reasonably firm with the key installed, add some length to the key for leverage and maybe she'll budge for ya.

I will definitely give it a try. Thx!

I have 6 of those barrels. I took the screws out a couple times. Now I don't bother with it. Washing them out with soapy water will get them as clean as you need them. I promise!

yep, for the most part the clean out screw doesn't need to be removed. neither does the breech plug, or a flinter's vent liner (well, maybe for that), or a caplock's bolster (but its nipple is a mandatory removable part). anything that screws into the barrel should be properly lubed with anti-seize so they can all be relatively easily removed somewhere in the future, else you may end up with a wall hanger. why most of these commercial sidelocks don't have properly lubed barrel components must either be built in obsolescence, don't-give-a-krap, or plain stupidity. which is why it's smart for the consumer to do what the manufacturer hasn't done, and do it from the get-go before the bp crud starts invading the threads. well, 'cept for all the spanish built ml's (traditions, cva, etc) where you can NOT remove any of the barrel parts without buggering the barrel itself. to me, those are the cheap sidelocks to avoid as there's no long term value happening there.

here's a brand new, never fired investarms patent breech plug. yeah, lotsa crud, unbelievable ...


here's the chamber area, also fulla crud ...


here's a solid reason for the need to pull a breech plug ... no, not to clean the crud on the breech plug face ...


to push out the patched ball that REFUSED to get pulled out with a screw worm
(what idiot dry balled that barrel??? oh, right, that was me, doh!) ...






one of the better tools for removing breech plugs, the reed corp 18" wrench and worth every penny ...

Green Mountain does have replacement clean out screws available. Call them to order. PM me if you need the order # and contact info.
Thanks again for your help. OEH2