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Posted: 7/26/2012 7:02:57 AM EDT
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Greetings all,
I am in the mood to build myself a 605 A1 "Carbine". My question is regarding barrel length. I know once cut down to the FSP the barrel measures 15". Can anyone tell me if permanently fixing a 3 prong FH will bring it to the non-NFA 16"? Im not sure that i want to go through the trouble of adding this to my trust as an SBR and paying the $200 tax. Thanks all. Kasey |
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If you have a threaded 15" barrel, and attach an original or clone 3-prong FH, it will bring the length to 16" or a little over. If you pin and weld or silver solder it, so it is permanent, you're GTG.
Problem is, if you have gas system issues, you will have to undo the pin and weld, have the gas port tweaked, and re-do the pin and weld. This is why I think it's better to go with a CLGS or MLGS on the 15" 605, and would have made it a viable production gun back in the 1960's if they had just done that then. It chokes in cold weather, since not enough dwell time and gas port pressure combine to short-stroke the action. This is what killed it militarily, and members here have experienced the same issue with 605 clones using a RLGS. You have to decide if replication or function are more important to you. |
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Quoted:
If you have a threaded 15" barrel, and attach an original or clone 3-prong FH, it will bring the length to 16" or a little over. If you pin and weld or silver solder it, so it is permanent, you're GTG. Problem is, if you have gas system issues, you will have to undo the pin and weld, have the gas port tweaked, and re-do the pin and weld. This is why I think it's better to go with a CLGS or MLGS on the 15" 605, and would have made it a viable production gun back in the 1960's if they had just done that then. It chokes in cold weather, since not enough dwell time and gas port pressure combine to short-stroke the action. This is what killed it militarily, and members here have experienced the same issue with 605 clones using a RLGS. You have to decide if replication or function are more important to you. Actually, you can just remove the gas tube, then the fsb pins and rotate the FSB 180 degrees and there's a hole under the slimg attachment point where they drilled the gas port that allows you to get to the gas hole. I think m1sniper told me that one. Brent |
| Good point gents! You learn something new every day. I thought it was deja-vu when one of the guys here who lives up north report that his 605 clone had run 100% until his post about it not running anymore. We looked at the date (Oct or Nov IIRC), and his State, put 2 and 2 together, and guessed that was the likely culprit. |
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LRRPF52, I thought you would be along shortly! I always enjoy your thoughts on the 605 and the barrel / gas system of this most cool carbine.
Question: is a carbine or mid length gas system preferable with a 15" barrel? I have read carbine works best for the 14.5" and mid length works best for the 16" barrels. One of these days, I am going to build a 605. I think this model carbine has probably been in every retro-heads bucket list at some point in time. |
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I've heard the argument that 14.5" with CLGS is best for reliability. I have several different configurations among my carbines, and I really like both 14.5" and 16" with MLGS for the smoothness of the cycling. I usually put at least an H2 or H3 or MGI buffer in a 16" CLGS carbine, as that set-up is strictly derived from adherence to the 1934 GCA, not optimum cycling of the action. The pinned 14.5" MLGS BCM carbine we have runs 100% so far, and I shoot no less than 350 rounds per range session with it. I've only fed it American Eagle 55gr FMJBT, Federal XM193F, and Winchester White Box 55gr so far.
After I burn my 605's re-contoured Bushampster CLGS barrel, I will most likely use a MLGS pipe in it, cut to 15" again, pinned & welded. |
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OP I have 2 605 builds.
As others have stated make sure to open the gas port to .110 before pinning the flash on. That should allow it to function with out issues, but if you do need to open it up more you can do as also stated and rotate the fsb and drill it out some more. |
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If you have a threaded 15" barrel, and attach an original or clone 3-prong FH, it will bring the length to 16" or a little over. If you pin and weld or silver solder it, so it is permanent, you're GTG. Problem is, if you have gas system issues, you will have to undo the pin and weld, have the gas port tweaked, and re-do the pin and weld. This is why I think it's better to go with a CLGS or MLGS on the 15" 605, and would have made it a viable production gun back in the 1960's if they had just done that then. It chokes in cold weather, since not enough dwell time and gas port pressure combine to short-stroke the action. This is what killed it militarily, and members here have experienced the same issue with 605 clones using a RLGS. You have to decide if replication or function are more important to you. Actually, you can just remove the gas tube, then the fsb pins and rotate the FSB 180 degrees and there's a hole under the slimg attachment point where they drilled the gas port that allows you to get to the gas hole. I think m1sniper told me that one. Brent This ^^^^^is correct and the info came from Heatnbeat.Just to add,,you need to remove the sling swivel to access the hole.Soo,,remove swivel,remove 2 taper pins,rotate the FSB 180 degress and there you have it. |
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Quoted:
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Quoted:
If you have a threaded 15" barrel, and attach an original or clone 3-prong FH, it will bring the length to 16" or a little over. If you pin and weld or silver solder it, so it is permanent, you're GTG. Problem is, if you have gas system issues, you will have to undo the pin and weld, have the gas port tweaked, and re-do the pin and weld. This is why I think it's better to go with a CLGS or MLGS on the 15" 605, and would have made it a viable production gun back in the 1960's if they had just done that then. It chokes in cold weather, since not enough dwell time and gas port pressure combine to short-stroke the action. This is what killed it militarily, and members here have experienced the same issue with 605 clones using a RLGS. You have to decide if replication or function are more important to you. Actually, you can just remove the gas tube, then the fsb pins and rotate the FSB 180 degrees and there's a hole under the slimg attachment point where they drilled the gas port that allows you to get to the gas hole. I think m1sniper told me that one. Brent This ^^^^^is correct and the info came from Heatnbeat.Just to add,,you need to remove the sling swivel to access the hole.Soo,,remove swivel,remove 2 taper pins,rotate the FSB 180 degress and there you have it. Would this work on an A2 fsb? Ie one of those seen towards the bottom of the page here? http://www.ohioordnanceworks.com/Parts/Barrels.cat I wanted to do a cheap A2 themed 605/dissipator rifle for my car, and if i can open it up and cut down the barrel myself, I could save significant money. |
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Thanks for all the feedback guys. I'll make sure to have the port opened to .110" before pinning and will work on it from there. Very excited for this build. Kasey it's a winner in my book. balances well, fixed stock, carbine length barrel w/ rifle sight radius. hard to beat all those pros. |
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tag for more input.  I'm pretty sure all fsb have this, at least the five I have all do. That barrel would work, it's the wrong profile to be "correct" , but would work fine. The carbine gas system hidden under the HG would be a more reliable option, but as you see lots of folks pull it off with a rifle system. |
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tag for more input. I'm pretty sure all fsb have this, at least the five I have all do. That barrel would work, it's the wrong profile to be "correct" , but would work fine. The carbine gas system hidden under the HG would be a more reliable option, but as you see lots of folks pull it off with a rifle system. Thanks, I'll just have to try it and see. I have a rifle gas lightweight dissipator, but getting it reprofiled and the fsb pinned cost me a mint. 
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tag for more input. I'm pretty sure all fsb have this, at least the five I have all do. That barrel would work, it's the wrong profile to be "correct" , but would work fine. The carbine gas system hidden under the HG would be a more reliable option, but as you see lots of folks pull it off with a rifle system. Thanks again, and just to reiterate, should be able to drift out the taper pins, rotate fsb 180, drill, rotate back, then repin? How hard is it to cut a barrel down and recrown? |
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i bought these two cut down A2 barrels that run the standard rifle length gas system from the EE a few years ago...they're cut to 16" and run old RRA's A2 style muzzle brakes, but the gas ports are the factory sizes and they run just fine. I don't know what, if any, effect cutting them back another inch to 15" and running flash hiders would have on the reliability though
top is a Colt 1/7 and the bottom one is a Bushy 1/9 (which lost it's bayo lug immediately after this pic was taken) both chrome lined 
and I don't really consider a 16" barrel with a rifle gas a "dissipator". To me that describes the barrels running carbine/mid length gas under rifle length HG's with a non-functioning fsb holding them on, as the ones that have been sold by Bushmaster for many years now. 
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