Join Date: January 2, 2011
Okay, this is from some research that I've done on the topic. I'm by no means an expert and this glosses over just some of the highlights.
FN FAL: Reliable with possibly the longest track record for both reliability and service history among all three of the ones you're looking at. That said, they're ridiculously rugged and reliable. They also come in all sorts of variations, from Side folder Paratrooper carbines to full 21" rifles.
They're exotic and rarely seen, you are more likely to see a HK/PTR-91 at the range than an FAL nowadays, that said though, parts are not necessarily scarce. DSA makes replacement parts, even complete rifles using modern metal technology (You can probably find one used if you hunt hard enough). If you go through DSA you can easily find a railed dust cover to mount optics later. (Mind you, kit guns have no easy provisions for optics from what I can tell without shopping for railed forends or going custom)
Accuracy, you mentioned is a big stickler with you. Understand that the FN FAL was designed for WAR and reliabilty first, it just so happens to be pretty accurate, for a battle rifle. It's not a tack driver, the best you'll get out of it is maybe, just maybe 2-3 MOA, that is with quality ammo (usually custom loaded) and a good unmolested israeli barrel (which may be bought on the surplus market), realistically, 3-6 MOA at 100m. If you choose to go the custom route, I know a number of smiths and so on that can help you find what you need to get your hands on a parts kit, all the way up to what type of receiver you'd need.
They're tough as nails but can be on the heavy side, you can choose from a variety of fixed stocks (depending on the variant) to suite your LOP if you so desired.
Magazines are relatively cheap if you search the surplus market (Which I recommend since they tend to be more reliable than the new ones from DSA)
Trigger pull is okay, but not great but the ergonomics are pretty sound, if you have small hands like me though, it can be a bit of a stretch to try and manhandle the safety.
HK/PTR-91: I've only fired the PTR91 before and from my experience, they're good rifles. They'll shoot just about anything from my experience (can't claim that for the HK91 as I've not shot one) and are somewhat of a rare sight on the range and are IMO the AK of .308 rifles in terms of reliability. Like the FAL they were designed for war first, accuracy second . That said, there are variants that have been accurized to fulfill the DMR/Sharpshooting role (The PSG1 comes to mind as does the G3SG/1) and if I recall PTR does indeed offer clones of those rifles. As for the accuracy of the latter more specialized rifles I cannot comment since I have no experience with them. The PTR91 however, I do have some experience with it. It's not a tack driver, again, it's a battle rifle, as such, you can expect similar results as with the FAL, 2-4 MOA with quality ammunition, 4-6 MOA realistically.
One of the biggest cons that I saw with the rifle is that if you like to reload, it's ridiculously hard on brass, the flutes in the chamber and the violent ejection of the spent casings usually end up badly dinging brass, limiting or in some cases rendering them completely un-reloadable. This can be remedied to some extent by purchasing deflectors or reducing the amount of gas the rifle gets, but it does not completely eliminate the problem.
Magazines are cheap, you can find a good number of them on the surplus market, some in bulk packs from Germany. The PTR91 that I fired had a custom trigger in it if memory serves, so I cannot comment on how it feels stock.
There is relatively large and active surplus market that you can purchase from RTG parts and HK-parts.com are the primary sources for all your HK clone parts needs (That includes the grandfather rifle of the G3 the CETME too)
Mounting an optic to one of these rifles is difficult and will require you to either purchase a rifle that has the welded rail (PTR offers this) to the receiver, or purchasing a claw mount (Which has weaver mounts if memory serves) that sits really high on the rifle and may be difficult to use or awkward for some.
M1A: I sadly do not have any experience with this rifle so I will limit my comments on it. From my understanding, among the three it is easily the most accurate...and one of the most expensive, they come in a decent variety of lengths, but are not friendly to mounting optics in their stock form. It is also the most friendly for those that reloads and are really reliable rifles to shoot.
End comments: Really, I'd say if you want accuracy (1 Minute of Arc or better), you're not going to find it in the HK/PTR91 or the FN FAL, only the M1A can offer that from what I've experienced and read, however, if you want Minute of MAN all three can easily fulfill that job. If you get the opportunity to shoot any of them, do so. I personally liked the feel of the FAL more the PTR91, but if given the option, I'd honestly would have all three, seeing as I love battle rifles period and am a collector at heart.
Good luck, I hope this helped.
Also, anyone who is more knowledgable than me (and there are many) please correct me if I am wrong on ANY of this.