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Bushmaster ORC for 3 gun.


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Ok, guys I have another of my "why would you want to do that" questions for y'all.

I have a 308 Bushmanster  ORC that I want to convert to an iron sight gun.  In normal times, I might just sell it and buy the gun I want, but I haven't seen the exact configuration I want for sale anywhere, even before the panic.  So I think my best option is to change what I have to what I want.


  My first and most pressing question is what to do about a free float tube.  When I search on 308 free float tubes for Bushmaster I get some conflicting information on what will fit, and whether a standard AR tube will fit or if I need a special adapter.  My gun looks exactly like this, except I have MOE hand guards on it.  Since I was able to replace the hand guards with standard AR furniture, it stands to reason the mounting for free float tubes might also be the same.  If I understand the difference, I only have to worry about the odd size free float tube/adapter if my rifle came with a FF tube from the factory, which mine did not.




What I think I want is to run a free float out to the brake, and use a standard AR fixed Rear sight.  Where I am on the fence is with the front sight. 

First option is to clamp a normal front sight [or a folding one] to the barrel, butted up against the back of the brake, and stop the free float tube just before it.  I want to clamp because I don't want to mill for pins and I am not going to jack with the gas system.  My objective is to get the longest sight radius I can.

Second option is to go with a longer tube, and attach the FS to the tube.  This has the advantage of seeming simpler but since the front sight is going to take some abuse [this s going to be a 3 gun rifle] going into barricades and dump barrels I would want to be sure it was going to stay put.

It seems clamped to the barrel might be strongest and most durable, but the least elegant, and in the way if I decide to clamp on a scope for load testing.  A folding clamp on like an ARMS #41 or the YHM 9394 would solve the "in the way" part but be less durable.  The unknown [by me] is where a free float mounted front sight fits in.

If it makes a difference I am considering an AP Carbon fiber tube to save some weight.


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So, I mentioned my plan to my LGS, and he says, "Come on over, we got you covered."  I said "Really?"  "Oh yeah, no problem, come over after work, and we will hook you up."  icon_smile_big.gif

So, over I go, after work, to be hooked up...  Disassembly went about like you would expect, with much pounding and cussing and gnashing of teeth, then was heard the utterance: "OH."  icon_smile_shock.gif

This was not a good sound.  "Wow, that's ALOT bigger than I thought."  That was a worse sound.  So we march in from the shop to look at the available parts..."Nope, nope, nope, nope and nope." smiley_abused.gif

Friends, romans and fellow wrench turners, I have completed the walk of shame, with a bag full of rifle parts and shattered dreams.icon_smile_dissapprove.gif

My plan not to jack with the gas-block - Gone! 

So, this has gone from a rescue operation to a salvage operation.  smiley_confused.gif  I have no words for the despair in my heart right now...icon_smile_dissapprove.gif



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OK, don't panic. First off, no AR15 parts for free float tubes will fit. ZERO. Free floats mount using the barrel nut and the nut on 308ar's are way bigger. You mentioned carbon fiber…. you mentioned longest sight radius…. here is my plan for you, no holds barred, for a competition 3gun rifle.


Here is your carbon fiber handguard, that will cover the lo profile adjustable gas block you should buy to replace the one that you had. This will :

Allow you to put a rail at the end of the guard to mount a rail mounted ft sight, giving you the longest sight radius possible.

Also give you gas adjustability to fine tune you rifle for the rounds you are using for 3gun.

Buy a heavy buffer from Heavybuffers.com, which will reduce recoil and improve your ability to keep your eyes on the targets in transition.

Get a Geiselle 3gun trigger. Fastest reset out there. It's a two stage that feels like a single. It's slick as bat shit!

Ask and ye shall receive. If this is truly going to be a 3 gun rifle, you will need to update some parts to really get her going, and per your specs this how I'd go. Also consider doing the work yourself, if you have any mechanical ability, doing the work is easy and will allow you to be more familiar with your rifle, and allow to change out parts to tailor it to your desire without paying a shop, or letting them butcher it and say "uh-oh". DUMBASSES.

Edited by edgecrusher
added comment for your gun shop
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Edge is on the mark here...


Since you are already into the wrenching... Get rid of that flashhider and get yourself a BABC. You will need a BABC (or similar) for that fast follow-up shot.


The stock you have on there is already super lightweight, save yourself some $$ by keeping the stock and adding a "limbsaver"


The Magpul MOE+ is great (inexpensive) option for the guys that have to hold their rifles for extended periods.

Edited by Robocop1051
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Ok, breath(s) taken.


Easy stuff first, I already have a SJC titan comp on it, so that end of the barrel is squared away. Or rather, I HAD a SJC titan comp on it until LGS decided to stick a screwdriver through it to remove it instead of grabbing the wrench that was right there on the bench..  [sorry, Traumatic events take a moment to fade.] 


I also already have a couple of Magpul stocks to swap out  [MOE and a ACS] depending on weather I want to carry a battery.  I also already have a match trigger in it.  it's not a Geiselle but it will work, and it's not on backorder, it's in the gun..  ;-)


I am going to look at that lancer, it might be the ticket.  [HOLY CRAP, $350 AND a month's wait??? This better be the hottest thing since Jessica Alba]  Anyone happen to have a used one laying around?


Then I have to come up with some sights.  With 3 different DPMS rail heights [miner is the new short] that ought to be interesting..


I never thought about an adjustable gas system, but I love the one on my FAL, so that might be something...

Edited by barrysuperhawk
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Ok, I was about to pull the trigger on the Lancer and I noticed this on their site:

No rails – This is the lightest of all options. The handguard tube is supplied with cooling slots but have no attachment points for sight rails. Handguards with no sight rails cannot be user modified to accept sight rails.



This means I get to instantly void my warranty and learn how to drill CF and figure out how to match up Front Sights, yes?

Edited by barrysuperhawk
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The 7.62 version doesn't have the top mounts. Lancer is all butt sore about the varying rail height and made their handguard incompatible.

You'd be better off doing a flip up tower sight (or similar) at the gas block. Or mock up an extended faux-gas block, and secure the sight at the end of your handguard.

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The 7.62 version doesn't have the top mounts. Lancer is all butt sore about the varying rail height and made their handguard incompatible.

You'd be better off doing a flip up tower sight (or similar) at the gas block. Or mock up an extended faux-gas block, and secure the sight at the end of your handguard.


But certainly, I can make something work, can't I?  it seems I just figure out how tall the parts are and adjust with shims or Dremel, right?

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  • 7 years later...
14 hours ago, Brickdude said:

So my bushmaster has a broken extractor. Is there anything compatible out there currently being manufactured?

What model of Bushmaster?   Need to at least know that part. 

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Ok, This is resurrecting an 8 year old thread, but I will try to help.  I assume that @Brickdude also has a Bushmaster ORC in 308, found my thread via a search, then joined just to reply.  

In my experience, I have not found any incompatibilities in .308 extractors.  In the ORC in this thread, I currently have an APCustom extractor in my stock bolt. and it fits perfectly.  That doesent do you much good, because AP is also out of bizznas.  But Wilson Combat still makes and sells .308 extractors and they are even available on ebay as of this posting:

Wilson .308 extractor

Some guys double o-ring their extractor, but I personally don't because it pretty much guarantees if the rim fails, it takes such a big bite that you have to pound the brass out with a rod.  With a single, it's not quite as aggressive and you can still get in there with a little hook and pull it out if you need to.  


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  • 1 month later...

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