Which one of these weapons is better? Are they really useful as survival weapons or the people that use them supposedly for that are just fond of them?

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I don't think that assault rifles are valid survival weapons except, of course, in combat. You don't need such a weapon to survive in places like Nome, Iquitos, Namsos or Waimea. Certainly, having a gun of any kind could be a plus for hunting and signalling, but dese rifles and the corresponding ammunition (7,62 x 59 mm. NATO) have been designed specifically for war purposes. If you are planning to purchase a survival gun, you should consider other options first because there are less-expensive and more suitable designs.

As for which one is better, it depends on how you look at them. The G3 locking design is - in my opinon - better because it does a better job at avoiding jamming, but the FAL is slightly cheaper - the rolling block mechanism of the G3 is particularly expensive -, there are more versions available, including the FAL Para, designed for paratroopers (shorter, lighter and with a quality, stable folding buttstock) and is a little bit better at throwing muzzle-launched grenades. As you see, these considerations pertain to the military usage of both assault weapons.

Curiously enough, both weapons were designed around the same principles and for the same ammunition, which was a different one than the standard 7,62 NATO: the basic concepts behind the FAL, the G3 and the AK families were born in WWII, in German labs. All these weapons, at the prototype stage, used the then common 7,96 Kurz German cartridge. This was an excellent ammo design, and was considered very fitting for any further work in the realm of military weapons.

During the fifties, and due to pressure and lobbying from the United States, the much heavier and powerful - needlessly, for many - 7,62 x 54 was adopted, and both the Gewehr 3 and the Fusil Automatique Leger became heavier and bulkier in order to accept the new standard; there was also a pretty good 7mm design made by the British for a very advanced assault weapon that ultimately evolved into the one they have now. The Soviets, however, adopted the German concept of a shortened cartridge using their then-standard 7,96 bullets, and did the same with the ammo they used in their Moissin Nagant rifles, which were also 7,62 mm bore, and shortened their cartridge cases to 39 mm.

The Germans knew that the 7,92 rounds that they were using in their bolt action Mausers were far too powerful to be practical in mobile, urban combat. They had their 9mm. Parabellum rounds for their pistols and submachine guns, and while they loved the concept, they also thought that something a little bit more powerful, with a slightly longer range - albeit shorter than the standard 7,92 mm. shots -, combined with a weapon that could fire automatically, in bursts, as well as in semiautomatic mode would be a winner. They and in the end, won the bet.

German engineers and military officers just sawed off their standard cartridges and produced the new model, without letting Adolf Hitler know about the idea because he vehemently opposed it. However, when he saw the first results of the use of the 7,92 Kurz and the Stg 43 and Stg44 assault rifles, finally accepted the design without executing its engineers and logisitcs officers.

People might like such weapons - semiauto versions, in most cases - for hunting or just shooting, so I guess that they are fond of their rifles and like to use them in their hunting or outdoor expeditions. For me, other weapons such as short shotguns are better for survival purposes.

What is the effective range of both guns? Is there any variation of that range depending on the version or model?

In the standard versions of both, effective range of a 7,62 mm NATO bullet is around 600 metres. The G3 is a little bit more precise thanks to its internal characteristics and yes, there are variations in both precision and range, depending on each version.

For example, a FAL Para with a folding stock and shortened barrel is a little bit less precise than the standard FAL or the FAL Lourd - heavy FAL, also known as FAP - and its range is slightly inferior. These consequences evolve from the fact that folding stocks imply less precision due to the latching mechanism of the buttsock, and short barrels also develop shorter ranges.

In the case of the G3, the same applies and by the way, the folding stock of the FAL para seems to be a little bit better at keeping precision, but if precision is what you are looking for, combinet with selective fire capability, you should look upon a G3 or FAL with a standard buttstock and long barrel; that you will always get more precise shots with those.

Is the soviet 7,62 bullet compatible with NATO 7,62 projectiles?

In principle, they are not despite the same diameter; a Soviet or Russian 7,62 bullet would probably fit in a NATO cartridge, but whether it will be fired correctly by a 7,62 x 54 weapon is quite another matter: the rifling of the barrel would probably have to be changed.

Indeed, one could re-chamber these weapons to shoot the ammunition made either by the Russians or Westerners, and I believe that such modifications have been made in order to sell Dragunov sniper rifles - these still use the old Russian, long 7,62 - and AKs, but these mods implied always modifying a lot more than just the rifling. The Israeli Galil 7,62 and 5,54 NATO are examples of assault weapons based on the Kalashnikov but adapted to western standards.

The question is why would you like to fit a Russian bullet in a NATO cartridge or vice versa. It doesn't seem very practical given the current availability of ammunition of both types, unless what you want is to produce what hunters and hunting rifle enthusiasts somethimes refer as to a wildcat (don't confuse these wildcats with the ); that is, an experimental sort of projectile. Some of these are really bizarre designs, but as far as safety is concerned, I have my doubts.

Thorough you will find a few more articles about or related to the FAL.

What about customizing these rifles - fal or g3 - with other calibers like big-bore bullets? Is that possible? I suppose that since they shoot the 7.62 nato round they could be adapted to other big ones.

Of course you can, and it has been done in the past at an industrial scale, mainly to use the standard 5,54 NATO round. Consider this:

- In the case of the G3, Heckler und Koch has produced the HK93A2 and the HK93A3. These are G3 variants that shoot the 5,54 NATO bullet. The German company also produced the HK33 and HK33K for the Soviet M1943 round, also known as the 7,62x39 mm Russian.

- Fabrique Nationale, the main manufacturer of the FAL has made some 5,54 FALs in the late sixties, as well as the Argentine FM and the Brazilians under license. However, all these are relatively rare weapons. In the case of the FAL, a derivative model was designed. It was known as the CAL or Carbine Automatique Leger; it took a lot of the original components of the FAL and looks like on but was a different weapon. The CAL was too complex and expensive to manufacture and around 1976 the FNC, the FAL's substitute - using the 5,54 cartridge - was introduced and adopted by many different countries. It is not a 5,54 FAL, and it borrows a lot from the Kalashnikov concept, but you can consider it as its rightful successor.

- I suspect that licenced producers of non-metric FALs, like the UK (SLR model), India and Australia also have produced some 5,54 mm. variants on their own, but none was adopted in large numbers to my knowledge.