To do Gunsmith Part 6 this way, you'll need Peacekeeper 3, and having Jaeger 2 makes it about 15k cheaper. With some planning, you can follow this guide as soon as Gunsmith Part 6 becomes available at level 18.
Note that people buying Leupold Mark 4 scopes and 18" barrels may cause the price to rise on flea market (but is unlikely to affect the price of the SDN-6 significantly). This is simply the cheapest build currently available. I have provided some alternatives at the end of the post.
After you've done the 20 level 15+ dogtags trade:
From Peacekeeper, buy:
- a Colt buffer tube, 12$, 1512 roubles
- an MOE Carbine stock OD, 62$, 7812 roubles
From Jaeger, buy:
- a 30mm Scope mount, 4291 roubles
From flea, buy:
- an 18" barrel for an AR-10 and compatible 7.62×51 NATO, ~20,000 roubles
- an AAC SDN-6 7.62×51 Sound Suppressor, ~40,000 roubles
- a Leupold Mark 4 LR 6.5-20×50 Scope, ~40,000 roubles
- if necessary, a 30mm Scope mount, ~20,000 roubles
Finally, strip the stock 20" barrel and sell it to mechanic for 26,787 roubles
The final build should look like this:
It's important to remember to remove the magazine, as that's not necessary for the quest and subtracts 2 ergonomics.
Finally, alternatives in case of flea price increases:
If the Leupold Mark 4 LR rises to 50k roubles, the VUDU 1-6 riflescope available from Jaeger 3 or Flea works as an alternative.
If the 18" barrel rises over 35k, instead of replacing the default barrel, add a Magpul M-LOK AFG and either add KRISS "Defiance Low Profile Flip Up" front and back iron sights from Skier II or replace the MOE Carbine Stock with a Fab Defence GLR-16-S stock from Skier III or Flea.
While unlikely, in the event that the SDN-6 rises to 50k roubles, the KAC QD suppressor is available for 412$ + 60$ from Peacekeeper 3, and even has 1 better ergo.