Gun Research Notes

Concepts

MOA (Minute of Angle)

Angular measurement = 1/60th of a degree. Practical rule: 1 MOA ≈ 1 inch at 100 yards.

Distance	1 MOA
100 yards	1.047”
200 yards	~2”
500 yards	~5”
1000 yards	~10.5”

Roller-Delayed Blowback

Delays bolt opening until chamber pressure drops to safe levels. Two small rollers cam outward into receiver recesses, creating mechanical disadvantage that slows bolt movement. Not a true lock — delays rather than locks.

Famous roller-delayed guns: - HK G3 / HK91 — .308, West German military rifle - HK MP5 — 9mm, definitive SMG - HK33 / HK53 — 5.56 variants - CETME — Spanish, inspired the G3 - CZ Scorpion EVO — modern pistol/carbine - PTR 91 — US-made G3 clone, ~$900–1,100

Advantages: Mechanically simple, reliable, handles high-pressure cartridges well, smooth cycling Disadvantages: Requires fluted chamber (marks brass — bad for reloading), harder to suppress than gas-piston designs

FAL Metric vs Inch Pattern

Metric (dominant standard, most parts/aftermarket): - Original FN FAL (Belgian), Imbel (Brazilian), DSA SA58, most military surplus (Israeli, Austrian, Argentine)

Inch pattern (Commonwealth only, niche): - L1A1 (British), C1A1 (Canadian), Australian L1A1

Metric and inch parts are not interchangeable — magazines, small parts, and threading differ. Stick to metric for parts availability and DSA compatibility.

Pistols

Glock Reliability Benchmark

Glock’s reputation comes from simplicity (fewer parts) and loose tolerances that keep cycling even dirty. Competitors that match it:

Platform	Notes
SIG P320 / P226 / P229	Military adopted, decades of special forces use
S&W M&P series	Extensive law enforcement adoption
CZ P-10 series	Czech military/police, often more accurate out of box

Revolvers (nearly indestructible): Ruger GP100 / SP101 > S&W 686

SIG P226 / P229 / P320 Compared

	P226	P229	P320
Frame	Aluminum	Aluminum	Polymer
Action	DA/SA	DA/SA	Striker
Weight	34 oz	32 oz	29 oz
Capacity (9mm)	15+1	15+1	17+1
Era	1983	1992	2014
Modularity	None	None	High

P226: Full-size, US Navy SEALs carried for decades
P229: Compact P226 (shorter barrel/slide, same frame width), FBI/Secret Service/DEA standard issue
P320: Modern striker-fired, US Army M17/M18 — choose this for a modern Glock alternative; choose P226/P229 for traditional hammer-fired metal pistol

SIG P365XL (Micro-Compact Carry)

Early P365 (2018) had striker/trigger issues — resolved mid-2018. XL (2019+) launched with fixes incorporated.

	P365XL	Glock 43X
Capacity	12+1	10+1
Trigger	Better out of box	Glock standard
Reliability	Excellent	Excellent
Street price	$550–620	~$500

Glock advantage only appears under extreme neglect/abuse. Equivalent for practical carry.

Glock 19 vs G26

	G19	G26
Size	Compact	Subcompact
Barrel	4.02”	3.43”
Height	5.04”	4.17”
Capacity	15+1	10+1
Price	~$500–550	~$500–550

G19: “Goldilocks” — most popular handgun in the US, full grip, best balance of concealability and shootability
G26: Deep concealment; pinky hangs off for most hands (fixed with G19 mag). G26 accepts G17/G19 mags — capacity disadvantage largely eliminated

Glock Clones & Alternatives

True drop-in Glock compatible (accepts Glock internals/mags): - PSA Dagger (~$300–350) — Glock 17 clone, barrels/slides/triggers/sights all interchangeable, best value Glock clone - Lone Wolf / Timberwolf (~$120–150 frame only, $600–900+ complete) — improved grip ergonomics, accepts Glock internals - Polymer80 — 80% frames, DIY build, no serial number (heavily regulated)

Glock-pattern (same operating system, proprietary parts): - Canik TP9 Elite SC (~$350) — exceptional trigger, comes with mags/holster/kit, feels like a $600 gun - Springfield Hellcat (~$450) — 11+1 / 13+1 extended, closest P365XL competitor - Taurus G3C (~$250) — 12+1, best pure value, mediocre trigger - Ruger Security-9 Compact (~$300) — 10+1, above-average build quality for price

Magazine availability ranking (most → least common in stores): 1. Glock — everywhere, including rural stores, OEM + Magpul/ETS/KCI aftermarket 2. Ruger — strong US retail presence 3. S&W M&P — second only to Glock in LE adoption 4. SIG P365 — now widely stocked 5. Springfield Hellcat — easy online, good at dealers 6. Taurus G3C — improving, hit-or-miss in stores 7. Canik — easy online, rarely in physical stores

Note: Extar EP9 (pistol-caliber carbine) accepts Glock 17/19 mags natively.

Budget P365XL Alternatives (9mm Compact Carry)

	P365XL	Taurus G3C	Canik SC	Ruger Sec-9	Hellcat
Capacity	12+1	12+1	12+1	10+1	11+1
Price	~$580	~$250	~$350	~$300	~$450
Trigger	Good	Mediocre	Excellent	OK	Good
Reliability	Excellent	Good	Good	Excellent	Good

Tightest budget: Taurus G3C
Best value overall: Canik TP9 Elite SC
Most rugged: Ruger Security-9
Closest P365XL feel: Springfield Hellcat

Shotguns

Mag-Fed 12 Gauge — Most Reliable

Mag-fed shotguns are inherently harder to make reliable than tube-fed due to shell taper and rim geometry.

	Mossberg 590M	Panzer BP-12	Rock Island VR80
Action	Pump	Semi-auto	Semi-auto (gas)
Reliability	Best	Moderate	Good
Price	~$650	~$500	~$500
Ammo sensitivity	Low	Moderate	Moderate

Mossberg 590M: Purpose-built (not a conversion), double-stack proprietary mags (5/10/15-round), gold standard for reliability
VR80: Gas-operated reduces felt recoil, better for high-volume shooting, improving reliability
BP-12: Needs break-in, picky about ammo

Rifles

Caliber Comparison: .308 / 7.62×51 vs 7.62×39 vs 5.56

	.308 Win	7.62×39	5.56 NATO
Bullet	147–175gr	123gr	55–77gr
Energy	~2,600 ft-lbs	~1,500 ft-lbs	~1,300 ft-lbs
Effective range	800–1000+ yards	~300 yards	~500 yards
Barrier penetration	Excellent	Good	Moderate
Ammo cost	~$1–2/round	Cheap (surplus)	Cheap
Recoil	Significant	Moderate	Light

.308 for long range and anti-materiel. 7.62×39 for short range, barrier penetration, reliability under neglect. 5.56 for volume, light carry, longer range than AK.

7.62×39 Platforms (AK Cartridge)

Rifles: - AK-47 / AKM variants — Zastava M70 = best quality currently importable to US - SKS — fixed 10-round mag, predates AK, very common and affordable - Ruger American Ranch Rifle — bolt action, takes AK mags (~$500) - CZ 527 — bolt action, excellent accuracy, popular for hunting - AR-15 uppers in 7.62×39 — unreliable, not recommended (steep taper fights straight mag well)

Pistols: - Draco / Micro Draco — Romanian AK pistols (short-barreled AK without stock)

Precision .308 Rifles

	RPR	Savage 110 Tac	Bergara B-14 HMR	Tikka T3x CTR	Henry Long Ranger
Price	~$1,300	~$750	~$950	~$950	~$1,100
Accuracy	0.5–0.75 MOA	0.75–1 MOA	0.5–0.75 MOA	0.5–0.75 MOA	1.5–2 MOA
Action	Bolt	Bolt	Bolt	Bolt	Lever
Purpose	Precision/competition	Precision	Precision	Precision	Hunting
AICS mags	Yes	Yes	Yes	Yes	No
Adjustability	Full chassis	Moderate	Moderate	Low	None
Trigger	Good	Excellent (AccuTrigger)	Good	Good	Standard
Weight	~10.7 lb	—	—	—	~7.5 lb

Ruger Precision Rifle (RPR): Gold standard sub-MOA precision platform, fully adjustable chassis
Henry Long Ranger: Lever action, faster follow-up shots, lighter — hunting rifle, not a precision platform
Savage 110 Tactical: Best value (~$750), nearly matches RPR accuracy, AICS compatible
Bergara B-14 HMR: Most recommended RPR alternative by precision shooters, matches RPR accuracy at $350 less
Tikka T3x CTR: Smoothest bolt in class, refined feel, less adjustable
Ruger American Predator (~$550): Budget entry, sub-MOA capable, AICS mags with aftermarket bottom metal

FAL-Pattern .308 Battle Rifles

The FAL (“right arm of the free world”) is a gas-operated semi-auto battle rifle chambered in .308/7.62×51 NATO.

	DSA SA58 OSW	DSA SA58 Standard	PTR 91	Century R1A1
Price	~$1,800–2,000	~$1,400–1,600	~$900–1,100	~$700–900 used
Pattern	FAL	FAL	G3 (roller-delayed)	FAL
Quality	Excellent	Excellent	Very good	Variable
Availability	Scarce	Limited	Good	Used market

DSA SA58 OSW: Short-barreled (11” or 13”) compact FAL, NFA paperwork may apply. DSA = only US manufacturer of new FAL-pattern rifles; long lead times
DSA SA58 Standard: Same quality, more available, more affordable
PTR 91: G3/HK91 clone (roller-delayed, not FAL-pattern) — same .308 role, ~$500 cheaper, better availability. Best practical budget alternative
Century R1A1: FAL-pattern, quality inconsistent — inspect carefully before buying
Imbel receivers: Brazilian military surplus, metric-pattern, generally good quality — popular for parts kit builds

Anti-Materiel / Extreme Long Range (.50 BMG)

.50 BMG optimized for: anti-materiel (vehicles, light armor), extreme range (1,500m+), barrier penetration. Ammo: ~$8–12/round.

	Barrett MRAD	Barrett M107A1	Serbu BFG-50A	Steyr HS .50	AI AX50
Price	~$6,000–7,000	~$10,000–12,000	~$5,000–6,000	~$3,500–4,500	~$8,000–10,000
Action	Bolt (multi-cal)	Semi-auto	Semi-auto	Single-shot bolt	Bolt
Notes	Modular, switches calibers	Iconic, Gulf War+	US-made, smaller co.	Best accuracy/dollar	British military

Best value .50 BMG: Steyr HS .50 (~$4,000)

Practical alternative: For pure long-range precision (not anti-materiel), .338 Lapua in RPR (~$1,400) outperforms .50 BMG in practical accuracy at ~$3/round vs $8–12/round.

Caliber	Platform	Price	Effective Range
.338 Lapua	Ruger Precision Rifle	~$1,400	1,500m
.338 Lapua	Savage 110 BA	~$1,800	1,500m
.300 Win Mag	Ruger Precision Rifle	~$1,400	1,200m
.50 BMG	Steyr HS .50	~$4,000	2,000m+

Reliable Platforms by Category (Summary)

Category	Top Pick	Budget Pick
Compact carry 9mm	Glock 19 / SIG P365XL	Taurus G3C (~$250)
Subcompact 9mm	Glock 26	Canik TP9 Elite SC (~$350)
Full-size 9mm	Glock 17 / SIG P320	PSA Dagger (~$325)
Mag-fed shotgun	Mossberg 590M	Rock Island VR80
Precision .308	Ruger Precision Rifle	Savage 110 Tactical
Battle rifle .308	DSA SA58 / PTR 91	PTR 91 (~$1,000)
AK-pattern 7.62×39	Zastava M70	WASR-10
.50 BMG	Barrett M107A1	Steyr HS .50