Harbor Freight 90 Amp Flux Wire Welder

[general_disarray_prk]

Suggestion to a trouble-free build - but as always - YMMV.
Buy a 110 volt HF spot welder (as opposed to a 220 volt version), and the "arms" from Curtis/AK Builder.
NOTE: HF Spot Welder is on sale for $169 & use a HF 20% off cupon to bring the price down.
Practice spot welding together some of the de-mill front/rear flat sections your kit came with.
Then, when you feel up to it, use the spot welder/arms to do weld in your rails.
Sell the HF Spot Welder and AK Builder Arms on Calguns Classifieds - there's always a buyer out there looking for one.
Whenever this combo is offered on the classifieds, it's snapped up pretty damn quick. Use the search function to verify & HTH.

[BomarFab]

My offer still stands to do the welding, for free, if you want to come down this way. It hardly costs me anything in materials to do a few spot welds. And I can do it in 312 rod.