Reference

Also see notes below tables...

Weapon + Magazines			Ammo					Notes
Weapon + Magazines			#	Round	Cost	Pen	Dmg
Cost	Setup	Details	#	Round	Cost	Pen	Dmg
15-30k		inspect	30	PS	3k	32	57	Nothing wrong with iron sights and 10-rounders at low level. All mods optional, better than SKS even stock.
30-40k		inspect EKP	60	M855	11k	32	57	Use battery trade. EKP is slightly taller than front sight; +5k to remove it. Usually used for its good handling, cheap mid tier ammo and good silencer options. Can put on PWS compensator (10k), but anything past muzzle mods needs full-auto to be worthwhile.
30-40k		inspect EKP	60	M855A1	15k	43	45
45-55k		inspect ~85k_alternative	60	PS	6k	32	57	Generally better platform than OP-SKS. A more exepensive build only makes sense if you prefer handling/mag size over 7.62x51 damage.
45-55k		inspect ~85k_alternative	60	BP	45k	47	58
45-55k		inspect	60	AP	24k	42	90	Very high recoil (including horizontal), high damage, okay accuracy, cheap silencer. The fact that you can black limbs in a single hit and one-hit-to-torso people with no or damaged armor gives this a slight edge over the VPO-136 or Hunter in certain situations.
45-70k		inspect OKP	30	M80	6k	41	80	The Hunter is primarily dragged down by the size and cost/rarity of its magazines. If you can work with small magazines (and buy them from Jaeger), its price-performance ratio is hard to beat. The OKP works well with the high mount point.
45-70k		inspect OKP	30	M62	14k	54	79
70-80k		inspect	60	M80	12k	41	80	Handles like a Hunter, except with larger mags and better mounting points. Use it once trader unlocks (mags/optic mounts) allow. Archangel/ALCS stocks are too expensive for what they offer.
70-80k		inspect	60	M62	28k	54	79
100-115k		inspect	60	M80	12k	41	80	Short, high ergo and full-auto but only 20-round mags. Good base stats, but low mod scaling (-> good for cheap silencers). Can't take backup sight. Horizontal recoil seems higher than comparable M1A.
100-115k		inspect	60	M62	28k	54	79
90-165k*		inspect stage2 stage1	90	M80	18k	41	80	Use any variant on this upgrade path: S.A.S.S. -> long barrel -> BMD Combo -> w/e. For the better variants, the recoil is also good enough to play much more aggressively so I prefer to have some extra ammo ready. Cheap drum mags via Mechanic LL4 barter (GM Counter).
90-165k*		inspect stage2 stage1	90	M62	42k	54	79
170-180k		inspect alternative	90	M80	18k	41	80	Full-auto and high base recoil but very strong mods that require at least Mechanic LL3 to get for reasonable prices. Marginally worse recoil than a full M1A build at similar cost - no noticeable ergo difference. Budget or improvised flea market builds are only good if you want large mag full-auto, otherwise an M1A/MDR will handle better for similar or lower cost. Cheap drum mags via Mechanic LL4 barter (GPhone).
170-180k		inspect alternative	90	M62	42k	54	79

Situational/meme guns

Weapon + Magazines			Ammo					Notes
Weapon + Magazines			#	Round	Cost	Pen	Dmg
Cost	Setup	Details	#	Round	Cost	Pen	Dmg
30-50k		inspect	20	AP-20	4k	37	164	Carried by AP-20. Low accuracy, low muzzle velocity,small mags. Decent budget option at higher levels. Mp-153 if you also want to run a cheap vest.
35-45k		inspect ~70k_trade backup_sight	30	PS	3k	32	57	Janky recoil, but low horizontal component. PSO makes for an acceptable low level/budget setup. Top loading needs less rig space and risks less ammo, without being too clunky. Depending on prices and your trader levels, the Mechanic LL2 trades (SKS, OP-SKS) are decent alternatives to the otherwise better VPO-136.
35-45k		inspect ~70k_trade backup_sight	30	BP	22k	47	58
80-90k		inspect	60	M80	12k	41	80	Low level gun, large mag alternative to Hunter. Recoil is fairly high and fast, making it hard to compensate manually, similar to SKS. When firing quickly, shots seem to land low, similar to pistols. Very easy to mod, but ultimately worse than a stock M1A or MDR depending on use case, while being more expensive.
80-90k		inspect	60	M62	28k	54	79
90-110k		inspect	40	7N1	29k	45	86	Not great, not terrible. Best part is the price of SNB, if you expect to meet enemies wearing level 6 armor (or 5 if you don't have M62 yet). Example mount has best ergo. Dumping another 20-30k into this just for ergo is sadly not worth it.
90-110k		inspect	40	SNB	21k	62	75

General notes

This is primarily an overview of cost-efficient reference builds for semi-auto play styles.
Recoil/ergo can't be compared across different guns. Only useful to compare different builds on the same gun.
Armor reduces damage if penetration not much higher than effective armor (pen - eff.armor < 12). In practice only 5.56 rounds and 7.62x39 PS actually get their hits to kill reduced by this. Others either don't pen or do > 42.5 damage.
1 MOA is roughly 2.9cm of spread (cone diameter) per 100m. Anything below 3MOA is good for general use. For high tier guns the differences are too small to consider even for 400m headshots.
The lesson here should be that for semi-auto you should switch to a bigger caliber before getting into expensive mods.
Prices are estimates including common flea market fluctuation for guns and some minor options where noted.
EKP is used as a reference sight because it is cheap(10k), available early, fits on all guns and makes prices a bit more representative.
There is no fix for level 1-9. Get Peacekeeper LL2 for M80 and M855A1 when behind the curve.

Sights

Scopes are mostly preference, but I find high FOV helps a lot. Strongly recommend low zoom, a laser or an additional red dot for short range fights.
Some also have a 1x mode, which i find awkward, but could work for you. ADAR can mount some scopes on the carry handle off which you can remove scopes in raid to use its decent iron sights.

My favorites

EKP - 10k: cheap, good reticule choices, -1 recoil. Available immediately.
FastFire 3 - 20k: Big dot is easy to track during recoil, fits on backup mount. Available very early.
Prism 2.5 - 20k: high FOV, good ergo, usable at fairly close ranges. Fits on small mounts and on carry handle. Available very early.
TAC 30 - 20-30k: high FOV, good ergo, enough zoom for most ranges, size/shape works well with canted+FF3
PSO - 12-20k: Decent FOV/zoom, occasionally makes for very cheap setups (e.g. headshot tasks).

Getting a scope + compact red dot:

Silencers

go to https://tarkov-market.com/tag/suppressors and look for the cheapest option

Consider a suppressed pistol as secondary for scavs instead. They're quieter and at ~25k with ammo cheaper to buy and shoot.
For shorter ranges (e.g. customs), consider a VSS. It works just fine in semi auto (and thus with small mags), because of the high flesh and armor damage (sp5 usually 3-hits cheap lvl 4; 2-hits with SP-6)
Shotgun and .366 suppressors are comparatively cheap for already cheap and high damage weapons.

Examples

Some opinionated, ready examples. Note that for a "full DMR setup" silencers and optics are expensive enough to not really bother with cheap weapons.

Weapon + Magazines			Ammo					Notes
Weapon + Magazines			#	Round	Cost	Pen	Dmg
Cost	Setup	Details	#	Round	Cost	Pen	Dmg
80-90k		inspect	60	M855A1	15k	43	45	Reasonable for its price and overall feature set (silencer, variable zoom scope). Trying to fix the ergo or recoil is a waste of money.
95-105k		inspect	60	AP	24k	42	90	Low level/memes only. Low zoom/high FoV and a laser replace backup sight. Reference stock is 14k cheaper.
120-130k		inspect	60	M80	12k	41	80	Cheapest serious dual optic setup.
145-165k		inspect	60	M62	28k	54	79	Short and good ergo despite silencer.
160-190k		inspect	90	M62	42k	54	79	Best price-performance ratio.
200-210k		inspect	90	M62	42k	54	79	Short M1A, literally only good if you want to enter buildings.
235-245k		inspect	90	M62	42k	54	79	Close enough to minimum recoil without sacrificing features or usable ergonomics.
240-260k		inspect	90	M62	42k	54	79	Low recoil without dragging ergo into uncomfortable levels.

"But what about ... ?"

TX-15: in semi auto/at range 5.56 stops being a good caliber past a ~50-70k budget, which is where this gun starts.
AK-74M: Held back by high ammo costs and worse ergo than an ADAR. If you really want that full-auto option, laser + PSO with light ergo mods is a decent approach - for anything else, you're looking at the wrong guide.
SR-25: bad base stats, bad mod options, high price.
R11 RSASS: base price almost exceeds a fully built M1A and can't get any advantages over it.
Ash-12: The only reliable OHK through lvl 4 armor in the game - sounds really good but for ~100k total and with low velocity and huge recoil not that great overall. Cool concept though.
Bolt-action rifles: No.
ADAR->M4, VPO-136->AKM: Sure, wrong guide, tho. I prefer specialized weapons, so would pick an SMG (mp7/VSS currently) for buildings, get the task done and piss off.