Front sight block removal

[ckyllo]

Come September ( with any luck ) I plan on putting a flash suppressor on a pair of bushie ar's. the question is does the front sight block need to be removed in order to turn the barrel? I have access to a metal shop and a metal lathe but dont want to have to take the FSB off of it ( since I most likely not line it up correctly on reinstall.I have heard that bushmaster finishes the barrel and fsb as one piece and dont come off easy.)

specs ( correct me if I am wrong )

barrel end turned to .505"
5/8" length of turn
1/2 x 28 tpi
seporate upper and lower reciever
remove grips
remove gas tube pin from fsb
remove gas tube
remove upper reciever from barrel
remove delta ring
turn and thread
put all back to one piece


will headspace be effected by the barrel removal and reinstall?

if I am lazy how much is it to have a smith perform the task?

thanks in advance

 

[usp_fan]

I'm looking at doing the same thing. I recently talked to a smith that quoted me $40.00. This seemed cheap so I asked around and got other quotes btwn $60 and $90. From what I understand, the FSB shouldn't need to be removed.

Also, headspace shouldn't be impacted. Just reinstall to the correct tourque spec and all should be fine. On the AR, the HS is set by the bolt and barrel extension interaction, installing loose or tight shouldn't make any different on HS.

Remember to tighten, loosen, tighten, loosen, and Tighten to hit the proper tourque. This helps keep things straight and diminishes stress in the system.

Good luck,

--usp_fan

 

[Badger Arms]

You can keep the FSB in place, but you might want to buy an FSB with a bayonet lug if you so desire.

 

[ckyllo]

I have the bayo lug figured out. DPMS has bolt on lugs for $20. since I have no plan to use a bayonet on it, for show only. thanks for the info. might have to see what a local 'smith wants for the whole thing. I am also gonna check to see to have him tear it down, I'll turn it, have him put it back in one piece. I checked the tap and die set and it didnt have a 1/2"x28tpi in it so i will have to see what that will cost.

 

[yankytrash]

You know how many people are going to want that service? Heck, buy the die set and get a few friends to chip in who want their AR's turned.

 

[Don of Kalifornia]

Don't use a die to try to cut the threads on the end of your barrel, most dies only clean up bend threads. have the machinist when he turns the barrel single point the threads on in the lathe, you'll get a much better job done, and you'll have your threads to the full depth and properly relieved.

If your gunsmith/machinist can not single point the threads, fine a new one, single pointing threads is one of the basic skills all machinists should know.

 

[ckyllo]

I am leaning to having it done by a machinest. called a gunshop that has machineing ability and was quoted $150 per gun????? I dont know if he didnt know AR rifles or what. another gun shop said he would tear down and reassemble for $40 to $50 a gun but than still have to have it turned and threads cut. I do have access to a lathe but I have not ran one in a very long time and than it was very basic operation. I am not about to risk a set of bushmaster barrels on my thread cutting ability.

 

[Redlg155]

I'd also look at ADCO Firearms . They have a pretty good reputation with the AR-15 guys. $56.00 for a cut and thread job isn't bad at all. The last I checked the turnaround was less than a week, but I'm sure their turnaround time will increase once the ban sunsets.

Good Shooting
Red

 

[BillL223]

Its not that difficult to remove the sight base, I just did it when I replaced the base with a JP gas system. Knock the pins out from the left side. Then pull the base with gas tube out. Its probably easier to remove the gas tube with the base off the barrel. If you want to send it to a smith, consider EGW, they make a muzzel brake that looks like a standard flash-hider except no slots on the bottom.

 

[Harry Tuttle]

for one fifty, i would consider a bushmaster barrell assembly for $219

http://www.bushmaster.com/shopping/barrel-assemblies/abbl-20a2.asp