Extrema Ratio AMF Survival Knife Field Review

Extrema Ratio AMF Survival knife. Advanced Multi Function Knife. AMF Survival knife (AMF Desert) tested out in the field. The Extrema Ratio AMF is a big 8.25″ Bowie style clip point knife with a design reminiscent of the Gerber BMF of the 80’s (minus the spine wire cutter notches) but with modern stainless tool steel Bohler N690, Forprene grip and stainless fittings. The Extrema Ratio AMF comes in either the Desert AMF or a Black Mil Spec coated AMF and corresponding black Cordura sheath. The sheaves are fully Molle compatible and come with 3, 2M brand malice straps. There is an optional “survival kit”.

Initially I was concerned with the rear guard of this big knife interfering with me using it but it proved not to be an issue at all. My hand size is about 8.5-9 so I guess about medium sized hand. The rear guard of the AMF Survival knife serves as good protection in the event of using the butt end of this knife to strike something which might cause injury to the fingers. I had the knife submerged over several days on and off and only stripped it once to dry it out and apply a small amount of good quality light machine oil. There was negligible corrosion present (slight staining-which was/is nothing). The water was full of tannins and as it was shallow (under 2 metres) probably high in oxygen content due to it’s fast movement.

The Forprene handle of the Extrema Ratio AMF totally encircles the tang, which the latter is very thick (6.3mm). The full blade thickness runs almost the length of the blade. The guards and pommel are of low magnetic stainless alloy and showed zero corrosion from submersion and use in a wet environment. There are 4 holes to which cordage can be secured in order not to loose the knife.
The Extrema Ratio AMF knife was very easy to keep sharp. I used a honing nail file about twice over a two week period. I never used the knife with gloves.
I carved sand impregnated rainforest hardwoods to test edge retention (which was excellent), cut up all sorts of tropical fruits (not shown) and bored with the tip to make a fire bow drill base board (not shown here).

As the Extrema Ratio Advanced Multi Function knife (AMF) knife is marketed as a “survival knife” it should be tough (in the true metallurgical sense and construction-physical sense), easy to maintain; offer good corrosion resistance in wet environments and where maintenance is not going to happen often; it should be of a design which lends itself to many tasks but an also take some abuse or perform functions generally relegated to other tools such as a machete or parang, such as chopping or prying (with care of course). I found that the Extrema Ratio AMF knife satisfied these parameters. it’s really no surprise as the blade design is not new and has been around for many many years.

Regardless of what one wants to call their knives, I found the Extrema Ratio AMF was/is well suited to some hard work and there is a good vibration absorbing grippy handle, especially when wet.

I think if you like the retro/traditional design look of this knife (ok you’ll only think of this knife as a retro look if you happen to be at least 50 years old LOL) and big tough but functional knives appeal to you, you might be interested in the Extrema Ratio AMF as your next big knife, only you can be the judge.


Lifetime warranty on the knife and 6 years on the scabbard.

To learn more about the Extrema Ratio AMF, please click on the blogger icon in the header and read about stripping the knife for cleaning and what my initial thoughts were plus a whole lot more information not presented here in this extensive video.
You can also see it here: