Can't figure out why the price difference in barrels

[RK1717]

So Im looking to do a budget build for an ar-15 upper. And I missed the group buy. So Im on green mountain rifle and I can't figure out the difference in these barrels.

Other than 1:8 twist vs 1:9 but why the $50 price difference? The $100 has a parkerized finish and the $150 doesnt say. Is it just a sale? Im not an expert on barrels. Thank you for your help

http://www.gmriflebarrel.com/16-m4-for-mid-length-gas-system-5-56-nato-chromed-bore-chamber/

http://www.gmriflebarrel.com/gm-m9-1-9-twist-16-m4-barrel-chromed-and-parkerized-41v50/

$99 is GM-M9 / $149 is GM-M8

 

[7.62x39]

The more expensive one has been air gauged. They are also two different gas systems, which are you looking for CAR or Mid length?

 

[RK1717]

The more expensive one has been air gauged. They are also two different gas systems, which are you looking for CAR or Mid length?

I was going to buy what ever was cheaper, but within reason (no dpms barrels). If I bought any barrel I'd buy any gas tube to go with it, I think that's how it goes. The difference between Carbine and Mid-length never concerned me.
After searching "air gauge" I think Im just gonna grab the $99 barrel. It seems like a good deal from a good company.

Thank you for you help. correct me if Im wrong on my decision to buy the $99 barrel

 

[noxin]

If you're looking for dirt cheap barrels, Classic Firearms has some 16" Carbines for $70. They look decent, but I haven't shot them yet.

http://www.classicfirearms.com/arbarrel16parkerizedm4contour

 

[mac1911]

Just be warned some of these cheap barrels do not come with front sight cuts for the front sight base pins if your going ghat route. I did a few cheap builds several yrs ago. If I didnt find all the other parts used or cheap I would have spent more on barrels.....I got 3 barrels from s co Inc they where in the white and shot 55 gn bulk around 2moa ish for a sub 400$ build at the time they where fine barrels.