AR School 102

[Skribs]

Like I said, it's not about knowing how to do it or not. If it involves a punch, I take it to someone who can do it properly. I tend to miss the punch...every time...and put a hole where I shouldn't.

 

[Ramone]

I tried to put in a drop-in trigger kit into a M&P pistol, and I ended up putting a hole in the trigger and ruining the safety return spring, requiring about a half an hour of a gunsmith's time to fix before he finished the kit for me. Please don't tell me that I'm less intelligent than an idiot because I am not mechanically savvy, and understand my limitations as far as building things is concerned.

Regarding the gas tube, so if I bought a complete 16" carbine, and wanted a 16" mid-length gas system (for whatever reason), I'd have to buy a new barrel as well as the gas system?

Point taken. Still, it is pretty easy.

Yes, you would need a new barrel* along with a gas tube of the right length.

*though in theory one could weld the old port shut, drill a new port in the right place, and machine the barrel and gas block to meet at the new location, it'd be a lot easier to just get a new barrel

 

[ExAgoradzo]

Respectfully, I don't know why you guys keep saying that I want to mix AR-10 with AR-15. I understand that difference (that's why I said 102).

I've started to get an answer now: if I buy DPMS I need to buy DPMS mags etc. Armalite has a couple of aftermarket compatibility companies, Bushmaster?, Colt?...what else is there, and what are the companies that build AR-10 style ARs.

Armalite has a 45 degree back side of the upper and there's another company that has more of a swoop. What manufacturers make the swoop and what manufacturers make the 45 degree backside of the upper?

 

[MachIVshooter]

Regarding the gas tube, so if I bought a complete 16" carbine, and wanted a 16" mid-length gas system (for whatever reason), I'd have to buy a new barrel as well as the gas system?

The "gas system" you're referring to is simply the tube, about $15. The expensive part of this swap will be the barrel. So long as both barrels have the same OD at the gas port, everything else is interchangeable.

Changing a barrel is not difficult. You just need a small hammer, a couple of punches (1/16" and 3/32"), a vice, an action block (or some soft pieces of wood, and an armorer's wrench (about $25, unless you're going to use it a ton; That would warrant a more expensive one).

1) Remove handguards
2) remove flash hider/brake/compensator
3) drive gas tube pin out of front sight base or gas block
4) drive out pins holding front sight base/gas block to barrel (unless you have a set screw fastened low profile gas block) and remove FSB/GB
5) Secure recevier in vice and loosen barrel nut. Unscrew and remove barrel

The only part that can be trying is getting the barrel nut aligned with the gas tube hole in the receiver. The amount of torque required to go from minimum and "oh, I just passed the last notch" to lining up the next notch can be A LOT. This step becomes even more tedious if installing a free float quad rail or drop in quad rail handguards that align on the barrel nut, as being off by the tiniest amount will be noticeable in the rail alignment.

 

[Skribs]

Mach4, as mentioned above: if it involves punches, I don't do it.

 

[madcratebuilder]

Respectfully, I don't know why you guys keep saying that I want to mix AR-10 with AR-15. I understand that difference (that's why I said 102).

I've started to get an answer now: if I buy DPMS I need to buy DPMS mags etc. Armalite has a couple of aftermarket compatibility companies, Bushmaster?, Colt?...what else is there, and what are the companies that build AR-10 style ARs.

Armalite has a 45 degree back side of the upper and there's another company that has more of a swoop. What manufacturers make the swoop and what manufacturers make the 45 degree backside of the upper?

The DPMS LR-308 uses SR-25 style magazines. The popular .308 Pmags are SR-25 style.

ArmaLite, LMT, Kac and CMMG also use SR-25 style mags. ArmaLite also has the AR-10B that uses converted M14 mags. This is the model ArmaLite has been building for years. ArmaLites newer model, the AR-10A uses the SR-25 mag. The SR-25 mag has become the defacto standard.

One plus for the AR-10B and M14 style mags is they are available in 10 rd, 15rd, 20rd, 25 rd and I think even 5rd. The first or GenI AR-10B mags were actual modified M14 mags. The later GenII AR-10B ,mags are built new. These mags are about 8-10 dollars more each then Pmags. ArmaLite went with the M14 mags because of the AWB in effect at the time they released the rifle.

This FAQ well really help understand the differences between manufacturers.

About the only AR-15 part used in the 7.62 AR's, that is common across all manufacturers is the FCG and safety selector, and of course some of the pins, springs and detents.

I would recommend the ArmaLite AR-10, they are the only 7.62 AR with a life time warranty. Choices of mag style, several models to choose from. Great support from the manufacturer. With the release of the new AR-10A there are good buys on used AR-10B's, check out Gunbroker.com.

 

[ExAgoradzo]

Thanks madcratebuilder.
Greg

 

[MachIVshooter]

ArmaLite went with the M14 mags because of the AWB in effect at the time they released the rifle.

And because they were the most suitable existing design offering >10 round capacity during that period, since no new mag could be produced with >10 round capacity.

It's in their FAQ why they chose the M14 mag over the common and cheap CETME/G3 mag and FAL mag.

The Gen I mags did have a flaw (one that would not have been avoidable with other designs); To make the BHO operate, the follwer had a spring-loaded plunger at the rear. This plunger increased follower friction, and ocasionally led to feeding failures. The Gen II post-AWB mags use an AR-15 style follower with a fixed BHO catch that rides in a channel at the rear of the magazine. I have never had a failure with a Gen II mag.

RRA chose the FAL mag, and they have experienced problems with the design. Maybe they finally have the kinks worked out? I dunno, I just recall that the rifle had a lot of teething problems that caused delays and cancelled production runs.

The Pmag compatible AR-10A will no doubt have a following. Me? Even if I were buying today with that option, I'd still choose the B model. The Gen II mags aren't much more than Pmags, are very high quality, and offer 25 round capacity instead of 20 (they also look better, IMO, protruding below the grip). Of course, gen IIs are available in 5, 10, 15 and 20 round capacity as well.