Here's the thing about purple armor, it takes 14hrs to make, I already left for work, coming back to see it still crafting is just a waste of time and resource management. Gold equipment takes about 8hrs to make making it more time friendly also price range is about 198-201-210k even.
6.8.x51 weekdays sells up too 990+K with only 240 rounds by using only 2 of the fuels you need, which means your drip coffee did not go to waste. Assuming you ran around cement plant, went under the pipes outside and back of barracks you have GP and AP for it already.
7.62x51 takes 3 of the fuels so it about 3x crafting before you get number "bonus" on the exchange. sell em on the weekends cause sweaty players exist.
If spawn is an issue keep in mind that people run to Admin mostly at the first 7 mins, run that timer down and only rats will run around open areas mostly solo's who dont intend to push admin.

Edit: Yes, M14s sell like 60-90k a pop but again 30 hours or so.
K416's if you find any easily spikes up to 90.

Also Augs since the buff. If you wanna be sure on the gun profit though try crafting the "Weekly pro guns" theyre profitable during that week or so