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Posted: 11/15/2006 8:12:19 AM EDT
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teh slipover from bushmaster would not work with a barrel that short. it would need to be longer. the treads are pretty far up in the slipover. any of tthe bushmasters will need some work to make it look correct. they have a little ridge at the botom and no wrench flats. there flash ports are a little long also. get with randal at ar15 barrels.com. he can modify the bushy to make it look almost correct on the end. he cant do anything to the ports though. if you wanted reliability without a bunch of doodads just get a slipover and run a longer barrel iside of it. randal can cut the barrel to work with it and butt up against the FSP. remember that they ran a a1 split lockwasher with both of those models so have that too. this will give you something like a 12.5" barrel or so, off the top of my head. it would be more of a finished looking product. there are several ways to go about running a longer barrel with a flashider. get a regular bushy FH and thread whatever length barrel you want ans screw the FH down to the FSB. this would leave you with a barel stub if you look down through the flashider. doing any of these will leave you with a longer barrel and if you get tired of it will require work if you want to run an A1 FH at a later date both of these models came with a lightweight .625 barrel without a bayo lug slip rings and delta rings both use the same spring and retainer and are interchangable. i hope this made a little sense. someone will come along and clean it up for me  |
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Okay, 10.02" barrel, open gas port for proper functioning. My gas port is 0.093". Total Silence, Inc. XM177 moderator I run an "H"-buffer and M16 carrier in mine. I am using the Crane "O"-ring and an extra-strength Wolff extractor spring and have no reliability issues using a standard gas tube. The straight handguard slip rings will work with the current spring and ring kit. You can also do the extended barrel within the flash suppressor. I do not know the length/gas port size combination to work for you. Also, the Total Silence, Inc. moderators are not threaded all the way through since they are blank adapter-compatible. Here is my 10.02" Colt barrel with a Total Silence, Inc. moderator shown closest to camera...  |
Wow you suck!! Where'd you get a Colt 10" barrel?? I'm probably just gonna have to settle for a Bushy superlight cut down to 10". Workin on my E2 right now, though. Scored a real Colt 733 barrel on a trade so thats what decided for me. The E1 project is a lil far off. Need to get my E2 and 601 more into action first. ETA: Does the barrel measure 10" from the chamber to the end of the threads or from the barrel extention to the beginning of the threads? |
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Wait a minute. Last time I looked, the moderator on the XM177 did not have wrench flats. They didn't appear until the collared type fouind on the E2. So far as I can tell from the pics, the Bushie dup is, in fact an accurate rendering of the first issue moderator of the first 177s. Or are the photos in WHB Smith's "Small Arms of the World" incoorect? 
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Look at the pics in my post on page 1 of the tacked Real Deal pics thread. All of the XM177E1s (including the one the guy in the field is holding and the export model) have the wrench flats. |
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I am not so much worried about accuracy as I am cycling, functioning, and jamming. I would like to run a compact 2X ACOG with it. As long as I can pick shots from 50 to 75 yards, I will be happy. Sounds like just getting the original Moderator is the way to go and just get the gas port bored out a little. As far as the buffer do I want the H, H2, or H3? I thought the whole idea here was to have weight, but I read that the H2 and H3 buffers are condiderably more heavy. |
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The Colt barrel was a lightweight post-ban. After the ban, lots of people were replacing them with M4 barrels that had evil bayonet lugs and had threads and flash suppressors, etc... This was desirable as there was no bayonet lug to start with, so that was one less thing to worry about. 234747, I think the "H" buffer is fine and I'm running an "H2" in my Mike Rock 7.5" upper. I don't think there is any extra benefit for an XM177E1 by going to an "H2" or "H3" buffer... |
Sorry BD. Your pics don't come up on my ancient computer, but of the 177 pics that do come up, most are distant and/or fuzzy enough that you can't tell if the moderator hss flats or not. Of the few that that you can see the area well enough, there is only one, of a 101st trooper, that MIGHT be a moderater with flats. On the other hand, further down, there's a very clear pic of a trooper w/an early 177, that shows NO flutes, and even shows the little secondary rebate right at the very edge of the threaded portion. just like the Bushie copy.  I stand by my first post. The first issue moderators were without takedown flats, and the Bushie piece is a good copy. What would have been the point of the flats? The rifle flash suppressors were still the three prong type, and the takedown tool didn't have the wrench cutout for the suppressor yet. By the time the E2 piece was introduced, the TD tools had the wrench for the flats, because the birdcage rifle suppressor was standard. |
here is a pic fron the tacked thread. from BD clearly shows the flats with a lock washer. i can make out wrench flats on many of the pics. in the tacked thread. there was debate before if the e1 had flats or not a while back. i dont remember the outcome of it though. if it did not have flats how would it be torqued down, would they rely on a strap wrench? in the builders case he stated he really dont care about historical accuracy as much as function so it may be a mute point. |
I like the retro look and it is important, but I want a really light, compact, tool for my toolbox. I am willing to sacrifice the proper part, or accept my fenced modern lower, or a shell deflector for something that is close enough and eats brass consistently. |
If you are going to SBR it you might as well go all the way and stay with the 10 inch barrel. They will usually run with a .093 gas port and can be tuned to run without resorting to a real moderator (another tax stamp!) or special gas tubes.
As mentioned, you must have enough barrel to work with a slipover. At least 14.5 inches for most in order to engage the threads. You could have it shortened back to 12 or 13 inches but that would require a bit more work.
You don't need a buffer of additional weight in it if you are just going to shoot semi auto. The heavier buffers prevent bolt bounce for full auto guns and control the rate of fire. They do nothing for the semi auto. If you increase the weight of the bolt group and buffer too much you may find that the action will short stroke due to the dwell time of the carbine gas system. You'd be creating a problem rather than solving one. An M16 bolt group probably won't affect reliability one way or another but it might make an ATF agent look at it in a suspicious manner since it is a machine gun part. Adding the O ring would probably do more than anything else. No need to resort to a PRI gas tube unless you are using a crappy aftermarket barrel and not something from Colt or Bushmaster.
The straight ring is a "slipring" and the new angled ring is a "delta ring." The delta ring is correct for the XM177E2 but the slipring would be correct for the 609 or 619 which are earlier guns than the 639. The delta ring is much more finger friendly though and much easier to use should you want to actually remove your handgaurds.
This is probably the best way to end up with a reliably functioning upper assembly. The more barrel you have in front of the gas port the better it will run. Installing a slipover on a 12 or 13 inch barrel will be a much easier way to avoid problems. |
When you say "tuned to run", what would you need to do other than open the gas port? I can run my existing buffer and RRA Enhanced bolt and carrier. Like you said, I could beef up the extractor and use a crane ring. |
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You read and understood correctly. Tuning usually means opening up the port a bit. I have two 11.5 inch uppers for my M16 and both run flawlessly. One is a lightweight postban Colt 16 inch 1/7 that was cut down. The original .0635 port wouldn't cycle but when I got it to .0730 it worked like a charm. The second upper is from a Colt 16 inch 1/9H-Bar and I bought it from a friend who had it cut down. It's port was reamed to .0830 and works perfectly but strange enough has a lower cyclic rate than the other barrel, and this is on the same lower using the same M4 H buffer! Weird. While both of these work fine with the standard extractor and spring it would never hurt to install an O ring as the working pressures are much higher with short barrels and the shell casing sometimes needs a little help getting out of the chamber. There is usually plenty of pressure to drive the bolt group rearward but that same pressure can cause the case to adhere to the chamber. You don't have to go all the way to .090 or more, just go a little at a time until it works reliably. Too much gas is worse than not enough. It can batter and break parts. Trouble shooting shorties is a fine art that takes years to develop. I've seen all sorts of fixes for all sorts of problems created by individuals who lacked the knowledge they needed to proceed with the project. Their first mistake was not consulting a single relatively knowledgeable individual. It is only after great expense and frustration that they relinquish their pride and ask for help. My advice is pretty simple... First, use quality parts. Colt, Bushmaster, or something with a 5.56 NATO cut chamber and chrome lined. Don't try to go cheap with a shorty. It won't work. Second, go slow. If you have to increase the port size don't over do it. Just enough is just enough. Take care with the parts as you remove and install them. Third, if you don't have the proper tools or jigs, have it done by someone that knows what they are doing. Don't try to do it in your kitchen with a hand drill and a large hammer. |
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