View Full Version : Anyway to mount a fixed front sight to this barrel with this hand-guard?
BCM barrel and 13 inch V-tac guard. By the way I know the crush washer is back wards, it's temporary and I reused it. ( I know someone would notice :p)
http://i85.photobucket.com/albums/k45/PRODGI/guns061.jpg
Length from guard to to step, 1.60, OD goes from .740 to .720. Problem is the two sights I have here are measuring 1.80 in length. This would cause half of the front mounting band to have no contact with the barrel at all. Any Ideas?
Should I just go with a rail mounted front sight? I'm worried about a zero shift with a hasty sling. I like the simplicity of the rail mounted front sight but not willing to trade durability and or function for a simple solution. If most guys think a rail mounted sight is go to go I'll explore that option.
Thanks
An Undocumented Worker
03-13-11, 23:27
BCM barrel and 13 inch V-tac guard. By the way I know the crush washer is back wards, it's temporary and I reused it. ( I know someone would notice :p)
http://i85.photobucket.com/albums/k45/PRODGI/guns061.jpg
Length from guard to to step, 1.60, OD goes from .740 to .720. Problem is the two sights I have here are measuring 1.80 in length. This would cause half of the front mounting band to have no contact with the barrel at all. Any Ideas?
Should I just go with a rail mounted front sight? I'm worried about a zero shift with a hasty sling. I like the simplicity of the rail mounted front sight but not willing to trade durability and or function for a simple solution. If most guys think a rail mounted sight is go to go I'll explore that option.
Thanks
JP enterprises may have a mounting block that will fit on your barrel.
If you have any questions regarding what they have, don't hesistate to call them as I have found them to be very responsive and informative regarding inquiries.
http://www.jprifles.com/1.6.4.php
You do realize that lots of people use rail mounted sights correct?
BCM barrel and 13 inch V-tac guard. By the way I know the crush washer is back wards, it's temporary and I reused it. ( I know someone would notice :p)
http://i85.photobucket.com/albums/k45/PRODGI/guns061.jpg
Length from guard to to step, 1.60, OD goes from .740 to .720. Problem is the two sights I have here are measuring 1.80 in length. This would cause half of the front mounting band to have no contact with the barrel at all. Any Ideas?
Should I just go with a rail mounted front sight? I'm worried about a zero shift with a hasty sling. I like the simplicity of the rail mounted front sight but not willing to trade durability and or function for a simple solution. If most guys think a rail mounted sight is go to go I'll explore that option.
Thanks
Get the front of the barrel turned down to .625" and a .625" FSB pinned on it.
If you have the vtac installed and torqued correctly it shouldn't be going anywhere....nothing wrong with a rail mounted sight
I would simply use your rail to mount your BUIS. If you want a fixed both DD and LMT make good ones.
I use a folding Troy on a 13" TRX, works just fine. It is also a popular set up.
I have always wondered or worried rather that the tube can flex when slung up tightly as in the hasty sling method. In the past I have steered clear of rail mounted front sights. This is the first time I had considered it and then I see this.... http://m4carbine.net/showthread.php?p=902315#post902315
If indeed the rail mounted sight works well and your zero is not effected I'll give it a try.
I would however prefer to find a fixed front sight that can be mounted to the barrel. Obviously it will have to be a bolt on type unless I want to pay a smith to do that is.
OK something like this. I do need the proper height as to match my LMT rear sight.
http://www.bravocompanyusa.com/JP-Adjustable-Gas-Block-Front-Sight-Base-p/jpgs-2fs.htm
Although this sight is a lot more than a standard pin on type. I wonder what a smith would charge to cross drill and install a pin on type?? Hmmm.
You're overthinking this issue with rail flex.
Anyway, if you're dead-set on this, you should follow this advice:
Get the front of the barrel turned down to .625" and a .625" FSB pinned on it.
Armalite makes a standard looking front sight that clamps with cross bolts.
http://www.armalite.com/ItemForm.aspx?item=EU0240MPKIT&Category=07033031-2a2e-439c-a701-edf0d7327c93
I don't think I would trust it clamped to a .740" and .725" sized barrel.
lethal dose
03-15-11, 10:22
if there is enough room from the end of your rail to the barrel threads, just email dave or steve at adco. they WILL be able to set you up. they contour barrels and everything. adco does amazing work and they can PIN a new fsb in front of that rail, granted there is enough room.
lethal dose
03-15-11, 10:24
to add... if i wasn't going to run a standard fsb that was PINNED, i would run a rail mounted sight... no way will you catch me running a fsb clamped to the barrel... same goes for a gb. i say pin or nothing. that way, you KNOW it isn't going to move.
I personally would advise against what you are doing. If you are going for a longer site radius, maybe. But what are you gaining, an inch? The main reason I bring this up is cost. The cost of the sight, the cost of turning down the barrel, the cost of properly mounting it..... and I am sure there is something I am missing. I would wager to say, this will cost you about 250+ in the end. So now you have consider the costs of this vs a BUIS that clamps to your rail. The BUIS might cost 100. However, if you are willing to spend that 250+ would you be better served to sell your barrel, take that money, roll with the 250 onto this Noveske 18" Irons 5.56mm Stainless Barrel (http://noveskerifleworks.com/cgi-bin/imcart/display.cgi?item_id=b-18i-556&cat=147&page=1&search=&since=&status=)
I bring this up because why spend 250 on a crap barrel?
Take my advice for what its worth. Which might be crap. But I think a BUIS attached to a rail is very accurate.
Cesiumsponge
03-15-11, 21:14
There was a thread not long ago discussing rail flex and touched on BUIS POA/POI. I made some actual measurements and found there was indeed rail flex through a measurable means from gravity, bipod, and sling use. I was hoping for more discussion after getting some actual numbers but that never materialized. Whether the flex is enough to bother or not bother you is a decision you'll have to make.
Anything custom with the barrel can be done through Adco if it's physically possible. I've been talking to Dave there for a special barrel contour project and as soon as their barrels are back in stock, I'm going to pull the trigger.
The specific post in question:
https://www.m4carbine.net/showpost.php?p=924812&postcount=32
The original thread:
https://www.m4carbine.net/showthread.php?t=73401
I personally would advise against what you are doing. If you are going for a longer site radius, maybe. But what are you gaining, an inch? The main reason I bring this up is cost. The cost of the sight, the cost of turning down the barrel, the cost of properly mounting it..... and I am sure there is something I am missing. I would wager to say, this will cost you about 250+ in the end. So now you have consider the costs of this vs a BUIS that clamps to your rail. The BUIS might cost 100. However, if you are willing to spend that 250+ would you be better served to sell your barrel, take that money, roll with the 250 onto this Noveske 18" Irons 5.56mm Stainless Barrel (http://noveskerifleworks.com/cgi-bin/imcart/display.cgi?item_id=b-18i-556&cat=147&page=1&search=&since=&status=)
I bring this up because why spend 250 on a crap barrel?
Take my advice for what its worth. Which might be crap. But I think a BUIS attached to a rail is very accurate.
Not so sure a BCM BFH barrel is crap. :no: Neither do I think you advise is. ;)
I'm very surprised actually that some are against a clamp on sight when they feel it acceptable to clamp a rail on, have 13 inches of leverage against it all to have a sight clamped on to that rail. We trust gas blocks to be pinched and or clamped right?
So here's what I went and did. I had an old FSB laying around cut off the sling mount and bayo lug. Polished all the casting marks off, drilled and tapped for a 8-32 stainless set screw, painted it and installed with thread locker. It's a trial as of right now. It's definitely secure and won't budge at all. I think It will hold just find but I'll keep an open eye for something better or keep it until it fails.
Now I'm just waiting for my LMT rear sight to show up so I can head to the range.
http://i85.photobucket.com/albums/k45/PRODGI/guns065.jpg
http://i85.photobucket.com/albums/k45/PRODGI/guns066.jpg
So what ya'll think bad idea?
I'd suggest using a transfer punch to mark the barrel, and then use a drill bit to dimple it where the set screw sits. The dimple in the barrel will make sure that the set screw never moves in relation to the barrel, some locktite and it's a done deal.
I had to do this for the railed gasblock I used on my first build and it made a world of difference.
We trust gas blocks to be pinched and or clamped right?
A large percentage of those here don't. The most rugged method is having whatever gas block you're using pinned into place.
I'd suggest using a transfer punch to mark the barrel, and then use a drill bit to dimple it where the set screw sits. The dimple in the barrel will make sure that the set screw never moves in relation to the barrel, some locktite and it's a done deal.
I had to do this for the railed gasblock I used on my first build and it made a world of difference.
Yea I may do that after I shoot it, just to make sure the sight is as straight as I think it is.
There was a thread not long ago discussing rail flex and touched on BUIS POA/POI. I made some actual measurements and found there was indeed rail flex through a measurable means from gravity, bipod, and sling use. I was hoping for more discussion after getting some actual numbers but that never materialized. Whether the flex is enough to bother or not bother you is a decision you'll have to make.
Anything custom with the barrel can be done through Adco if it's physically possible. I've been talking to Dave there for a special barrel contour project and as soon as their barrels are back in stock, I'm going to pull the trigger.
The specific post in question:
https://www.m4carbine.net/showpost.php?p=924812&postcount=32
The original thread:
https://www.m4carbine.net/showthread.php?t=73401
Yea that's why I'm back to not liking the idea of a rail mounted sight. Not to argue with anyone or to say that they are wrong, I feel that rail flex is unavoidable when using a hasty sling. Believe me I think Troy makes good stuff but I'm not left with a great deal of confidence that there is not a fair amount of flex.
Thanks for all the work you did there is was most helpful.
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