Gunsmithing turning a blank or barrel for an AR rifle...

[AXEMAN]

i am trying to get everything together for a 308 upper for my DPMS. nothing too fancy, im not going to enter any contests or anything. but in my search, i have had it suggested that a rem 700 take off or new barrel could be used. i am not sure we have smiths that will or can do that here. i know a few journeyman machinists and would trust them to do the work, but its the never having done it before that concerns me. drilling the gas port being one thing i worry about. it may be a simple operation, i dont know whats involved. i have heard there are a few smiths here that can do this. whats involved? whats needed? how much and who does this? its a 308 so im not really worried about a shot out barrel so much, but i imagine there would be a minimum contour required. ill search for specs too, but does anyone have them or can you link me to them? thanks

 

[wnroscoe]

Re: turning a blank or barrel for an AR rifle...

Spend the money and buy a Krieger, they'll do the whole thing.

 

[AXEMAN]

Re: turning a blank or barrel for an AR rifle...

cool. just an option i was looking into. buy ready made from someone seemed easiest. but the other option was something i had no knowlege of. thanks

 

[Wild_Bill]

Re: turning a blank or barrel for an AR rifle...

you could re profile a take out barrel or a blank but you realy have to then have it re heat treated and lapped after the machining as the dimensions ans stress will change when re profiling buy a pre made one finished at the shop that manufacturers the barrels if Krieger make them get one and start shooting. you will end up with more in a barrel you do the work on than a match barrel from the start.

 

[AXEMAN]

Re: turning a blank or barrel for an AR rifle...

cool, thanks again. i know someone here did it with success, it was final cost that i was trying to figure out. plus finding a smith to do it.

 

[bohem]

Re: turning a blank or barrel for an AR rifle...

Bill, rifle barrels are not heat treated because the hoop stress induced during firing will cause it to burst.

Axe- the krueger route is the easiest wayto go for a good barrel. I do have a factory unfired armalite barrel that is sitting on the shelf. It is a cheaper route but the krueger will be a much better barrel

 

[toolmaker]

Re: turning a blank or barrel for an AR rifle...

Since when are rifle barrels not heat treated?

 

[AXEMAN]

Re: turning a blank or barrel for an AR rifle...

thanks guys. im still tryiing to sell some ar15 stuff to finance the upper. ive had a few offers of new as well as used dpms barrels and actually found an ap4 upper, which i would be ok with. i just need $$ to get it done.

 

[bohem]

Re: turning a blank or barrel for an AR rifle...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: toolmaker64</div><div class="ubbcode-body">Since when are rifle barrels not heat treated? </div></div>

Never, they may be forged, but the standard heat treating process is not used for burst safety reasons.

If you don't believe me go do a hardness test on a barrel stub leftover from a job, the 4000 series CM barrels test out in the low 30's Rc, they're not hardened. If they were, it'd be high 30's to low 40's at least.

Receivers on the other hand, are heat treated.

 

[Wild_Bill]

Re: turning a blank or barrel for an AR rifle...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bohem</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: toolmaker64</div><div class="ubbcode-body">Since when are rifle barrels not heat treated? </div></div>

Never, they may be forged, but the standard heat treating process is not used for burst safety reasons.

If you don't believe me go do a hardness test on a barrel stub leftover from a job, the 4000 series CM barrels test out in the low 30's Rc, they're not hardened. If they were, it'd be high 30's to low 40's at least.

Receivers on the other hand, are heat treated. </div></div>

Sorry they are heat treated i did not say hardened they are stress relieved and some use a heat treating process where the barrel is brought to a certain temp then slowly reduced back to room temp others use cryo treating to relieve the stresses in the blank after machining and then others use a diferent process using vibration.

Yes most barrels are heat treated cal and ask any barrel maker how they stress relieve their barrels and it is by heat treating that most achieve this.

 

[toolmaker]

Re: turning a blank or barrel for an AR rifle...

So rifle barrels were never heat treated? Someone should contact the U.S. Government and tell them the millions of rifle barrels produce for them by Springfield Armory, Winchester, H&R,TRW,and other contractors were all improperly made.BTW You better tell the Germans all their Mauser barrels were made wrong also.

 

[bohem]

Re: turning a blank or barrel for an AR rifle...

Heat treated (as in hardened) is what I thought you were talking about. Heat treating to stress relieve and then cryo treating is completely different from what I was refering to.

In that regard, I agree with you, I thought you were referring to a hardening process for strength reasons.

Heating to a hold point adn then slowly cooling is more commonly called annealing to be more specific. Cryo treatment is referred to in a similar manner to avoid confusion.

My apologies for the mixup, in that regard, you are both correct and my assumptions have opened my mouth good and wide for foot insertion.

TM64- Are you sure about the stress relieved government production barrels? The heat treating processes on the mausers was rarely stress relieving, they were much more commonly hammer forged to help straighten the barrels after rifling in military production grade barrel steel.

I have seen a number of mauser barrels visibly warp when they're cold vs. hot and then rolled over a granite table. They're far from "stress relieved"

 

[toolmaker]

Re: turning a blank or barrel for an AR rifle...

Most rifle barrels are hardend to some degree. Just one example, ''Smith Enterprise Inc.M14SE 22''and Mk 14 SEI 18''chromium plated barrels are hardened to 35HRC.This leaves the barrel strong enough to handle the chamber pressure with a comfortable safety factor yet tough enough to resist substantial impact.'' This info was taken from Lee Emerson's book,''M14 Rifle history and development'' Pg.221 While 35 RC may not be ''hard'' in comparison to other heat treated components it is indeed hardened and is harder than the raw material. One more example,more than 1,200 NM M-14 barrels made by SGW were rejected by Rock Island Arsenal because the barrels were too soft and considered unsafe for use.

 

[AXEMAN]

Re: turning a blank or barrel for an AR rifle...

back on the turning from a blank or take off... how much are we looking at as far as machine work? who here has a lathe and the desire to give this a shot if i go this way? ive seen specs for the 223/556 profiles, not too many for the 308/762 barrels.

one thing im looking at is a 16" with rifle gas port location. i would think mid would be needed but fulton sells a 16" with rifle so its possible. anyway, im kinda just gathering info and still exploring stuff.

 

[300sniper]

Re: turning a blank or barrel for an AR rifle...

i have seen take off 700 barrels used on an ar platform so it can be done. the ones i have seen were done by the owner that happened to have the equipment to do so. my guess is they did it more because they could, not to save time or money.

if you are having to pay for the take off barrel and machine work, you will probably be money and time ahead by ordering a new barrel already contoured and the gas port drilled correctly.

 

[AXEMAN]

Re: turning a blank or barrel for an AR rifle...

i am trying to get some idea what that figure would be. i saw a m70 varmint contour with a .774" muzzle i thought, in the white for $75. i know id need a barrel extension and gas block and tube. im just still trying to see what a price would be since i know what a kreiger is, $320 and dpms 24" are $229 and would require lathe work making it shorter. the sass is only $180 when i catch it in stock. but needs a special gas block ($90 from dpms) so $270ish. its not a money saving thing, ill pop for the kreiger most likely. but if id still like to know what the shop work would be roughly.

 

[skinnj1]

Re: turning a blank or barrel for an AR rifle...

Gunsmithing =Roughly what ever a shop charges for doing a chamber job and getting a muzzle threaded. $200-$450 depending upon their specifics. You will be paying a gunsmith the same for labor and capital investment dosen't matter if it is a take-off, or a douglas, or a krieger

It only makes sense if: you do your own work, know someone who will work cheap, or you need something custom but the budget will not allow a better tube.

If you are looking at the cheapest way to get into a .308, get a factory barrel, it will be cheaper (midway has a 24" heavy stainless for 219 retail, and carbine for same price, Heavy barrel will need a .933" AR gas block, carbine has FSB both in stock)

 

[AKA-Spook]

Re: turning a blank or barrel for an AR rifle...

I made the barrel for my IRA project out of a new Howa ,SS, .308 barrel.
It shoots really well. Gas block in the rifle position, factory taper under the hand guard. Going to try a 338 Whisper next.

 

[AXEMAN]

Re: turning a blank or barrel for an AR rifle...

well i want a 16" barrel when its all over. i could get the midway for $220 and then some machine work. i could get the $320 kreiger. i could start with a blank... AKA- id like my barrel to be basically the gas block & your flash supressor. short like the 338 fed that dpms offers. there dont seem to be an easy way to get to 16" other than the AP4 barrel or a 18" cut down bull. they are within $100 of the kreiger. all roads point to kreiger huh?

 

[jwSubMOA]

Re: turning a blank or barrel for an AR rifle...

A quality gunsmith and the cost of a blank or even a takeoff will likely be as much or more than a Kreiger ready to go.Most of us that can do this type of work do it more so we can say we did than to save a massive amount of money.That being said we can consider our time involved as recreation and feel that we've saved a bit and have somrthing unique.I have done similar setups using Israeli 1919 machinegun barrels that have chrome lined chamber and bores.They work great for 16" M1A/M14 barrels and would be perfect for your project if you can get someone to do it cheap.

 

[AXEMAN]

Re: turning a blank or barrel for an AR rifle...

well i just picked one for sale ad and used that. it was a mod 70 varmint. i fugured it had enough meat on it. found a guy that does ar15 anything. it was his site that gave me the idea of the 16.1" with the YHM supressor QD mount pinned. but mid or carbine gas port. ive got time. i should get the barrel block and charge handle this week, buffer and port cover stuff and BCG next week. then i need to get serious about a barrel.