PDA

View Full Version : v-tac freefloat tube question


chunger
07-18-2007, 4:31 PM
Got a V-tac tube in the mail and I have an installation question.

I do not plan on attatching anything to the tube, but I'm wanting to install it properly aligned "just in case" I decide to mount something later. You never know.

How do you line it up with the upper receiver? . . . that is, without spending another $60 on a top rail I'm not going to use.

mltrading
07-18-2007, 4:33 PM
Use a detachable carry handle.

BTW, the top rails of VTAC HG is very close to the rails of upper receiver. You should be able to do it by eyeballing.


EDIT: Almost forgot, there's no top rail of basic VTAC HG. If you want to use a detachable carry handle, you need to install top rail temporarily.

ar15barrels
07-18-2007, 5:19 PM
I can temporarily install a top rail for purposes of alignment and then remove it afterwards.
I have the rails in-stock.

Technical Ted
07-18-2007, 5:55 PM
I can temporarily install a top rail for purposes of alignment and then remove it afterwards.
I have the rails in-stock.
Also do a test fit before final assembly. Sometimes it's necessary to pull the ejection port hinge pin, file it down and touch it up with Birchwood Casey cold blue to get the outer barrel nut to fit snug against the upper receiver.

I got a top rail with mine even though I wasn't intending to leave it on. Wound up leaving it in place in case I went with a longer scope, or needed the extra real estate to mount the scope forward for proper eye relief.
http://www.hunt101.com/img/398963.jpg
http://www.hunt101.com/img/398965.jpg

C.G.
07-18-2007, 8:11 PM
Looks good, Ted. I decided to put one on my Grendel a while back, but still haven't got all the parts.

blacklisted
07-18-2007, 8:29 PM
Hey, an excuse to post pics!

I just finished putting one on mine. It's easy as long as you remember to not disturb the threaded parts while the loctite is curing ;)

http://i22.photobucket.com/albums/b343/ebolamonkey/complete003.jpg

ar15barrels
07-18-2007, 11:42 PM
Also do a test fit before final assembly. Sometimes it's necessary to pull the ejection port hinge pin, file it down and touch it up with Birchwood Casey cold blue to get the outer barrel nut to fit snug against the upper receiver.

I have done a few dozen of these so I assume the "heads up" was not for me, but you are certainly correct that many uppers will need the ejection port door hinge pin to be shortened.

chunger
07-19-2007, 12:10 AM
So,

After you locktite this guy on there, can you install/uninstall the ejection port cover assembly without burning the outer nut off?

I'm thinking it's possible, but getting that tiny "pinch washer" on and off of the ejection port pin's going to be a bit of a hassle.

ar15barrels
07-19-2007, 12:21 AM
After you locktite this guy on there, can you install/uninstall the ejection port cover assembly without burning the outer nut off?

Not easily.

Heat breaks down loctite.
You only need about 400 degrees to do it.

How often have you changed the ejection port doors on other rifles?

I would not worry too much about it.

ar15barrels
07-19-2007, 12:28 AM
My installation tips on JP Vtacs:


Trial fit everything dry and clearance hinge pin as required.
Apply loctite to receiver threads only, not into the barrel nut or on the sleeve.
Spin the barrel nut into place.
Install a 0.180" drill blank in the barrel nut to verify alignment with the receiver.
Spin the sleeve down finger tight against the receiver face to force the barrel nut forwards.
This causes all the loctite to shift to the trailing edges of the threads.
This will make for a more solid barrel installation because you will be metal-metal in all places rather than compressing against cured loctite if you did NOT install the sleeve snugly during loctite cure.
Be careful that excess loctite does not get on the sleeve or you will have to take it all apart and start over after cleaning off the loctite.
Let the loctite cure overnight.
The 1-2 hours it says on the bottle is not enough.
You want a good strong cure to torque against.

Technical Ted
07-19-2007, 12:35 AM
The 1-2 hours it says on the bottle is not enough. You want a good strong cure to torque against.
Despite the temptation to get the assembly done ASAP, I actually let both of mine cure for 24 hours.

chunger
07-19-2007, 2:48 AM
Is this the correct size drill blank? I'm finding #15 to be .18 inches. That drill blank sure is cheaper than a top rail :)

http://www.wttool.com/product-exec/product_id/22862/nm/Drill_Blanks_Number_Size


My installation tips on JP Vtacs:


Trial fit everything dry and clearance hinge pin as required.
Apply loctite to receiver threads only, not into the barrel nut or on the sleeve.
Spin the barrel nut into place.
Install a 0.180" drill blank in the barrel nut to verify alignment with the receiver.
Spin the sleeve down finger tight against the receiver face to force the barrel nut forwards.
This causes all the loctite to shift to the trailing edges of the threads.
This will make for a more solid barrel installation because you will be metal-metal in all places rather than compressing against cured loctite if you did NOT install the sleeve snugly during loctite cure.
Be careful that excess loctite does not get on the sleeve or you will have to take it all apart and start over after cleaning off the loctite.
Let the loctite cure overnight.
The 1-2 hours it says on the bottle is not enough.
You want a good strong cure to torque against.

ar15barrels
07-19-2007, 8:50 AM
Is this the correct size drill blank? I'm finding #15 to be .18 inches. That drill blank sure is cheaper than a top rail :)

http://www.wttool.com/product-exec/product_id/22862/nm/Drill_Blanks_Number_Size

That looks like the one I use.
Remember that the drill blank should fit freely through the barrel nut and receiver.
You can't use the blank to hold the two in alignment.
It's just to check alignment.
If you twist against it, it will just go crooked on you.

Technical Ted
07-19-2007, 1:27 PM
Is this the correct size drill blank? I'm finding #15 to be .18 inches. That drill blank sure is cheaper than a top rail :)
A #15 Drill or drill blank is used to make sure the gas tube hole and barrel nut (standard notched or free float bored) are aligned to pass a gas tube without contact.

You can use a gas tube for this as well.

If you're not going to mount a rail on the tube, just align it by eyeball: TDC of the barrel shroud with the centerline of the receiver rail (As long as the gas tube can pass freely).

ar15barrels
07-19-2007, 1:38 PM
You can use a gas tube for this as well.

Just make sure you use the LARGE part of the gas tube, not the reduced section.
I align all mine by eye.
It's MUCH more accurate than relying on a pin.

I use the pin to verify that my eye is correct.



Here's a neat trick you can do with regular barrel nuts and a #15 drill blank...
Install the barrel nut on the barrel and receiver.
Torque it so it's most of the way into proper alignment, but just a couple degrees shy.
Set the pin through the top notch of the barrel nut and just into the cloverleaf cut.
The pin will be pointing slightly to the right (when looking from behind the receiver).
As you put final alignment torque on the nut, the pin swings over to top of the barrel like the needle on a gauge.
When the pin lines up with the barrel, the barrel nut is perfect.