View Full Version : Considering a Barrel Swap and Free-Float Install
I've been contemplating these mods to my so-far stock M&P15 (flattop receiver, M4 barrel, fixed front site).
I've never monkeyed to this extent on an AR (although I used to do all kinds of things to 1911's, and I'm not too idiotic with tools in general). A few discussion threads and web videos have me believing it's within my ability, although I'd definitely like to know of any fine points to look out for. Appears to mostly be a matter of getting the right tools.
Mostly though, I'd like some direction on which components to choose from. I'd like to change the M4 barrel for one of the lightweight "pencil" type, but I have no knowledge of variations in quality among the different makers.
While I'm at it, I'd like to install one of the smooth type (non quad rail) free-float handguards. Just the single rail across the top is all I should need. I'd also like as good of ventilation/cooling as possible, and a small outside diameter of the tube. Again, I have no knowledge of quality among current offerings.
I'm assuming I'd be replacing the current fixed-sight gas block with a low-profile type under the handguard, and then installing a flipdown front sight on the handguard rail.
So, that's the vision. Any input, direction, advice, etc. is appreciated.
My advice would be to keep the barrel you have. I'm running a BCM lightweight profile and while the weight savings is nice, I definitely like a standard or government profile barrel just as much. You should seriously consider sticking with the barrel you have. Put the money saved towards ammo, training, and perhaps the free float rail.
If you're not looking for a quad rail then I'd recommend the Troy Alpha Rail, which is also what I'm running on my BCM. It's basically an updated version of the Troy TRX. It's a rather great modular, free float rail that is very, very light and extremely durable. It's also extremely easy to install. It comes with rail sections so if you ever decide you want more rails or the quad-rail look then you can easily install them.
Depending on the length of the rail, you may or may not be replacing or cutting down your FSB. If you want a longer one then I'd recommend just chopping your FSB and calling it good -- why waste the money on a new low profile gas block? Pointless, IMO.
You'd also do good to look into Centurion's rails but I mention the Troy TRX Alpha Rail because you said you aren't into quad-rails; not sure if Centurion offers a FF handguard/tube these days or not. Honestly if you're looking for a no frills, free floating hand guard that is not a quad-rail then you can't do much better than the Alpha Rail.
Thanks. The Troy Alpha looks real good, and I like that it comes in FDE. Price is not bad either.
I forgot about the option to just chop the fixed-site gas block. Of course that makes perfect sense.
Why not the pencil barrel? Just the added expense?
Looks like the Troy Alpha mounts with set-screws instead of threads. Any compromise on strength there?
Why not the pencil barrel? Just the added expense?
Yes, I think djmorris suggested keeping your current barrel as a means of saving some money, and perhaps a little hassle. Plus, if you're rifle shoots well and functions fine, why not just keep it intact? Adding only the freefloat handguard would be an upgrade to your already reliable rifle.
If it were me, I'd shelve the LW barrel swap idea and proceed with the handguard swap now. At a later time, I'd build an upper with a LW barrel. And then I'd assemble another lower to go with that upper. Ta-da! Another complete rifle.
As for the Troy Alpha strength question, I don't know. I think the Alpha might install in a similar manner to the Ranier/Samson Evolution, in that it has alignment tabs on each side of the handguard to eliminate rotation, and pinch bolts that clamp the handguard onto a compression bushing to lock it onto the barrel nut and prevent it from being pulled off. I have two Ranier Evolution HGs, and they seem solid to me.
.....I'd shelve the LW barrel swap idea and proceed with the handguard swap now.....
I'm leaning that way -- separate the apples from the oranges. Although I might still put a LW barrel on this same gun, it might be better to keep that as a later job and just stick with figuring out a good HG solution for now.
I've experienced no issues with the Alpha Rail, and I have not really heard of others experiencing any issues either. They really are great rails, easily the best in their price range. The lockup is very simple and extremely sturdy; the screws are definitely not an issue.
Some people don't like the standard TRX look with the "cheese grater" holes but they are actually better than the VTAC Alpha Rail version in some ways, mainly because you can mount a QD in any of the holes -- this is how I'm running my Vickers sling. Plus, as with all of the Alpha Rails, there is an extra spot for QD attachment in the optional rail section(s) that are included.
Another thing, the Alpha Rail was very easy to install. I did it on my kitchen table with a few allen wrenches and a good pair of vice plyer thingies to get the flash hider off. After getting the flash hider off, it takes about five minutes. All in all, the Alpha Rail is very badass and the modular features are great.
So yeah, definitely should reconsider the keeping barrel you have for the time being and putting an Alpha Rail on it. Smith & Wesson doesn't make the best AR's out there and they definitely are not up to the standard of the big boys, BUT they are way better than a lot of the junk out there such as Bushmaster and Rock River. If you're going to 'upgrade' your rifle (other than a FF rail), swap out your barrel, or replace major parts on it then you'd honestly be much better off just selling it and getting something up to spec like BCM, Colt, DD, LMT.. I say install the Alpha Rail, shoot the shit out of the gun and get some training in, then you'll know what you want/need from there.
Instead of swapping for a LW barrel, I'd just get a complete LW upper from BCM or similar, because then you can add a lower receiver later on and have two AR's. LW barrel profile is nice and if I'm doing a new custom build then I prefer it to the standard profile for the weight savings but it's really not worth swapping a brand new barrel out.
here's a crappy pic of my BCM LW middy wearing the 9" Alpha Rail, retaining the FSB and all.
....Smith & Wesson doesn't make the best AR's out there....you'd honestly be much better off just selling it and getting something up to spec......
.....it's really not worth swapping a brand new barrel out.
Thanks for the further input.
For the record though, this M&P15 was bought in 2007 and has over 7000 round through it -- original barrel and all other parts -- with zero problems. So I have no complaints with the current gun, just looking for ways to make it a little easier handling, and not in replacing or augmenting it with a second rifle.
Thanks for the further input.
For the record though, this M&P15 was bought in 2007 and has over 7000 round through it -- original barrel and all other parts -- with zero problems. So I have no complaints with the current gun, just looking for ways to make it a little easier handling, and not in replacing or augmenting it with a second rifle.
Right. I wasn't meaning to put down the rifle in any way. Simply stating though with the money you'll put down towards a LW barrel and more importantly, the installation of the barrel, you could almost buy a quality upper that you won't have to pay somebody to install.
(this is assuming you've never done a barrel swap -- it's one of the only things you might actually want to pay somebody to do with your AR)
.....with the money you'll put down towards a LW barrel and more importantly, the installation of the barrel, you could almost buy a quality upper that you won't have to pay somebody to install.....
OK, I'm with you. I should also be looking at complete uppers.
I've been reading good things elsewhere about the Troy Alpha HG.
Q2arrowhunter
04-26-12, 12:48
I am pretty active on other forums and usually just read here but here is my 2 cents. I agree with everyone else - keep your current barrel. There really is not much of a weight savings (at least from my point of view). Here is where I slightly differ. Find an inexpensive round free float tube (choose your length - carbine, mid, or rifle - I like the mid). Cut down your front sight to make it a low profile gas block, Install the free float tube, mark the top dead center and bottom and just install your own rails in the positions you want by drilling and tapping. Saves you $.
.....I agree with everyone else - keep your current barrel......
......Find an inexpensive round free float tube......Cut down your front sight.....and just install your own rails in the positions you want.....
Thanks for your perspective. I've pretty much decided to hold off on the barrel, and I'll definitely just be chopping the FS. I'll need to decide whether it is worth the extra $ to me to have the full-length top rail -- it will need to hold an X300 as well as a flip-up FS.
Unrelatedly, entire replacement uppers seem to be well over $1K, whereas Brownells is listing DD lighweight barrels for $260. Just so's I'm clear on this, you do have to remove the barrel to install the FF HG anyway, right?
Thanks for your perspective. I've pretty much decided to hold off on the barrel, and I'll definitely just be chopping the FS. I'll need to decide whether it is worth the extra $ to me to have the full-length top rail -- it will need to hold an X300 as well as a flip-up FS.
Unrelatedly, entire replacement uppers seem to be well over $1K, whereas Brownells is listing DD lighweight barrels for $260. Just so's I'm clear on this, you do have to remove the barrel to install the FF HG anyway, right?
What are you talking about, bro? $1,000 could buy you a whole new BCM or Colt -- upper and lower, assembled.
And it depends on what rail/hand guard you decide to use. If you go with the Alpha Rail, you do not have to remove the barrel because it uses the stock barrel nut. Some you do, some you don't.
BCM sells uppers without the BCG/CH (which you already have) for like $389. If you want a BCG/CH then you can find deals on Gandrtactical.com and here on the Equipment Exchange for a bit more. I know Grant sells complete Colt uppers with the BCG, CH, Magpul sights, Magpul MOE Handguards, etc for $550 but he is currently out of stock. All you'd need for a complete rifle for that would be any $150 lower you can scrounge up.. and it'd be a damn fine gun too... but this is a little irrelevant.....
What are you talking about, bro? $1,000 could buy you a whole new BCM or Colt -- upper and lower, assembled......
I was looking at this kind of stuff:
https://danieldefense.com/upper-receiver-groups.html
http://www.laruetactical.com/larue-tactical-stealth-sniper-system-lt011
.....And it depends on what rail/hand guard you decide to use. If you go with the Alpha Rail, you do not have to remove the barrel because it uses the stock barrel nut. Some you do, some you don't......
Sorry, I've never disassembled this part of the gun before. I must be getting confused with having to remove just the Delta ring and gas block, which all FF installs require?
dunno if you'll find this (https://docs.google.com/spreadsheet/ccc?key=0Ajl2UPK0UHPsdGlBeGN1eERSWHVhaHRHejVRMURKUmc) helpful in your barrel decision.
ETA:
I probably wouldn't bother removing the barrel on a gun that's shooting well either, but if fiddle-****-itis has got you (and it gets all of us from time to time) I'd look into the Daniel Defense lightweight midlength. I think it's enough of a departure from what you have M4->A1, button-rifled->hammer-forged, carbine-length->mid-length) that you might actually notice. But you'll get more use out of the longer handguard and save money just shaving the FSB down.
dunno if you'll find this (https://docs.google.com/spreadsheet/ccc?key=0Ajl2UPK0UHPsdGlBeGN1eERSWHVhaHRHejVRMURKUmc) helpful in your barrel decision......
Thanks. I was wondering how big a weight difference there was M4 barrel vs pencil, but wasn't finding much info on it anywhere. From this, it looks like 2-3 oz.s is hardly worth the trouble/$.
Robb Jensen
04-27-12, 07:26
I'd use a Troy Alpha rail in 11" or 13". I'd also shave the FSB down into a low pro gas block.
If you tackle this yourself remember S&W taper pins just like Stag come out the shooters left side. Colt and everyone else has them come out the shooters right side.
I'd use a Troy Alpha rail in 11" or 13". I'd also shave the FSB down into a low pro gas block.
If you tackle this yourself remember S&W taper pins just like Stag come out the shooters left side. Colt and everyone else has them come out the shooters right side.
Thanks for chiming in Robb. Your perspective is like money-in-the-bank. :happy:
A 13-inch Troy Alpha it is then, with existing FSB trimmed to-fit. Also, thanks for the reminder on the pins direction -- I recall you pointing this out to me some time ago.
The only remaining point-of-confusion: Don't I need to remove the barrel nut to remove the Delta ring?
Now I just need to decide on black or FDE. Anybody know how well Troy's FDE matches Magpul stuff? (I'd be using their CTR stock and MOE PG.)
I was looking at this kind of stuff:
https://danieldefense.com/upper-receiver-groups.html
http://www.laruetactical.com/larue-tactical-stealth-sniper-system-lt011
Sorry, I've never disassembled this part of the gun before. I must be getting confused with having to remove just the Delta ring and gas block, which all FF installs require?
Right, it's all good. Those uppers cost so much because they are complete uppers with the BCG and wearing $400 - $500 rails plus grips, sights, etc.
I was referring to something more along the lines of this: http://www.bravocompanyusa.com/BCM-16-Mid-Length-LIGHT-WEIGHT-Upper-Receiver-p/bcm-urg-mid-16lw.htm
Although BCM has gone up in price a little bit, you can find a really good deal on a barely used upper like the one above on the Equipment Exchange here.
There's a number of high quality free floating rails out there that actually do utilize the delta ring. So no, you don't always have to remove the delta ring either. You will need to remove the delta ring if you decide to run an Alpha Rail, however.
As far as the FSB goes, you've always got the option to shave it, swap it for a low-pro gas block, or keep it as is and run a short enough rail. As mentioned before, I kept my FSB intact and am running a 9" Alpha Rail on my mid-length.
The LW profile is typically a few oz's lighter. It's a noticeable difference for sure, but you're better off cutting the weight in other areas that would be easier (read: cheaper) ...
Thanks for chiming in Robb. Your perspective is like money-in-the-bank. :happy:
A 13-inch Troy Alpha it is then, with existing FSB trimmed to-fit. Also, thanks for the reminder on the pins direction -- I recall you pointing this out to me some time ago.
The only remaining point-of-confusion: Don't I need to remove the barrel nut to remove the Delta ring?
Now I just need to decide on black or FDE. Anybody know how well Troy's FDE matches Magpul stuff? (I'd be using their CTR stock and MOE PG.)
If you cut the delta ring off with a dremel, you don't need to remove the barrel nut. Otherwise you do.
If you cut the delta ring off with a dremel, you don't need to remove the barrel nut. Otherwise you do.
Thanks. I've seen some web posts and youtubes on cutting it off. I don't own a Dremel (I know -- sacrilege), but I wonder if getting a receiver vice block and barrel-nut wrench would be any cheaper.
I picked up a Dremel at Wal-Mart for like $30 or so to cut my delta ring off. It came with accessories for all kind of other useful shit. I can use it to polish feed ramps if the need ever be, cut shit, sand shit, make shit shine.... you name it!
I pretty much figured for $30'ish and all the uses I can get out of a Dremel it'd be better than having to mess with the barrel and barrel nut torque, etc. Also, delta rings are cheap enough to replace at $5 - $10 so I wouldn't sweat cutting the lil' bastard off.
So I wouldn't need a nut wrench then, and the vice block isn't really needed just to get the flash hider and gas block off.
Q2arrowhunter
04-27-12, 12:29
Thanks for your perspective. I've pretty much decided to hold off on the barrel, and I'll definitely just be chopping the FS. I'll need to decide whether it is worth the extra $ to me to have the full-length top rail -- it will need to hold an X300 as well as a flip-up FS.
Unrelatedly, entire replacement uppers seem to be well over $1K, whereas Brownells is listing DD lighweight barrels for $260. Just so's I'm clear on this, you do have to remove the barrel to install the FF HG anyway, right?
Shoot I built a complete flattop upper, M4 clone barrel, gas tube, and a round free float tube including the bolt and carrier group for $300. Barrel was new blem, used bolt/carrier group and new receiver. Just look around for parts. Find a good price and buy it then wait until you have everything. At least it worked for me.
Yes you will need a barrel wrench (with the prongs) to install the free float tube barrel nut. I just cut two pieces of furniture grade plywood to place between the top of my receiver and the bottom (between the lugs) and lightly clamped it into my vise to tightenthe nut. Worked like a champ. Do not over tighten the vice, just enough to hold the receiver as you turn the nut.
Thanks. I've seen some web posts and youtubes on cutting it off. I don't own a Dremel (I know -- sacrilege), but I wonder if getting a receiver vice block and barrel-nut wrench would be any cheaper.
If you plan on buying/working on more ARs in the future, it would not hurt to invest in a barrel nut wrench and clamshell-style upper receiver vise block.
So I wouldn't need a nut wrench then, and the vice block isn't really needed just to get the flash hider and gas block off.
To (properly) remove the flash hider, you should have a set of barrel vise blocks:
The vice block isn't needed to remove the front sight post/gas block. You do need a front sight post bench block to remove the front sight (at least to do so without loosing your sanity and/or breaking fingers). Link to the block I'm talking about: http://www.brownells.com/.aspx/pid=20727/avs|Make_3=AR-15zz1zzM4/Product/AR-15-FRONT-SIGHT-BENCH-BLOCK
And if you're gonna buy that, then you should get this also (punch for front sight pins, makes it easier to keep punch on the pins): http://www.brownells.com/.aspx/pid=26485/Product/TAPER-PIN-STARTER
To properly remove the flash hider, you should have barrel vise blocks: (http://www.brownells.com/.aspx/pid=12799/Product/SCG-AR-15-M16-ACCU-GRIP-BARREL-VISE-JAWS), but plenty of folks use the regular upper receiver vise block. Just be careful with how much force you apply.
Long story short: To do it right will cost some money, there is usually nothing "cheap" about doing it right.
Thanks. I was wondering how big a weight difference there was M4 barrel vs pencil, but wasn't finding much info on it anywhere. From this, it looks like 2-3 oz.s is hardly worth the trouble/$.
It matters where that weight is, remember. On an M4 or A2 barrel, the barrel diameter from chamber to FSB is the same as an A1 barrel. So that 2-3 oz is all at the muzzle end, making it feel heavier and harder to drive target-to-target.
.....The vice block isn't needed to remove the front sight post/gas block. You do need a front sight post bench block to remove the front sight (at least to do so without loosing your sanity.....
I managed over the weekend to remove the FSB pins (right-to-left on this M&P/Stag, as Good Robb advised) but only after some WD-40 followed by heat. Man were they tight! Nearly did cost my sanity.
.....To (properly) remove the flash hider, you should have a set of barrel vise blocks.....plenty of folks use the regular upper receiver vise block. Just be careful with how much force you apply
I was profoundly unable, however, to get the slightest budge out of the flash hider. Some major torque is going to be needed, possibly beyond the safe-limit of the reciever block, so looks like the barrel block will be needed instead.
Having a barrel block though, won't that also let me loosen the barrel nut, without having to use use a receiver block?
I'm planning to order all this stuff this morning, so need to complete the list ASAP.
Having a barrel block though, won't that also let me loosen the barrel nut, without having to use use a receiver block?
allow maybe, but not done correctly.
allow maybe, but not done correctly.
Can you elaborate? As long as I have either the receiver or barrel secured, what else is needed to loosen the barrel nut?
I'm willing to buy whatever is needed to not screw anything up, but likewise would prefer to not end up with tools that I didn't really need.
Can you elaborate? As long as I have either the receiver or barrel secured, what else is needed to loosen the barrel nut?
I'm willing to buy whatever is needed to not screw anything up, but likewise would prefer to not end up with tools that I didn't really need.
Using a receiver block is the correct way to remove the barrel nut. You're better off spending $40 for the receiver block, then winging it with the barrel block. Different tasks require different tools to be done correctly. And you could always sell the receiver or barrel block on the equipment exchange here.
Can you elaborate? As long as I have either the receiver or barrel secured, what else is needed to loosen the barrel nut?
I'm willing to buy whatever is needed to not screw anything up, but likewise would prefer to not end up with tools that I didn't really need.
The barrel is not part of the threaded system. Just like turning on the FH with only the upper secured, turning on the nut with only the barrel secured could cause you to enlarge the index pin notch.
It's just the right way to separate two threaded halves: hold one half, turn the other. In the case of the barrel nut and the upper receiver the barrel itself is not one of those halves.
Or, do it your own way. It's been awhile since we had one of those "hey, I tried to build a gun with a bent butter knife and a 2x4 and now it's ****ed up" kinds of threads.
:D
The barrel is not part of the threaded system. Just like turning on the FH with only the upper secured, turning on the nut with only the barrel secured could cause you to enlarge the index pin notch.
It's just the right way to separate two threaded halves: hold one half, turn the other. In the case of the barrel nut and the upper receiver the barrel itself is not one of those halves......
Now I understand.....need to see if Brownells can update my order with addition of the receiver block.
Well I caught Brownells in time to add the receiver block to the order.
I'll need the receiver block because I decided to remove the Delta ring by taking off the barrel instead of cutting the ring. I want to have the option of returning the gun to the original non-FF-handguard configuration.
For the same reason, I also am ordering a low-profile gas block instead of cutting down the existing FSB, which I want to leave intact. Since this M&P/Stag has the unique in-to-the-right pins, I'm not sure that I would be able to find a new FSB with the large and small holes on the correct sides to correspond with the taper direction of the pin holes on the barrel. Also, the $35 for the new gas block seems worth not having to take on the extra work of cutting and grinding the old FSB.
And I still haven't ruled out eventually trying a pencil barrel, although I am going to complete the FF-handguard install as a separate project first. Obviously I'd need the receiver block to replace the barrel. Also, if I were to end up liking the pencil barrel well enough, I'd want the option to sell the old barrel which I would include the pinned FSB with.
So everything needed is hopefully on its way. Thanks everyone for all the info. I'll post before/after pics in a separate thread once complete.
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