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  • Writer's picturePaul

Mauser Osmosis 5 Weight Fly Rod Review

Updated: Nov 4, 2021


It's no secret that I absolutely love a 5 weight with a fighting butt. In fact, out of all the fly rods out there, I'd have to say this is my favorite size and configuration. For small streamer duty and even very light saltwater action there is simply no other rod that is more enjoyable to use for these tasks. Outside of the custom world, however, there aren't a whole lot of readily-available production rods like this to be had.

I was intrigued when John Mauser, Owner of Mauser Fly Fishing contacted me a few months back about their upcoming Osmosis rod series. I was even more intrigued when I learned that one of the models included a 5 weight equipped with a fighting butt! Slotting into the lineup below the existing Arete and Waterman series, these are currently the most affordable rods Mauser offers and are touted as an "all water" series meaning they are suitable for both fresh and salt.

Length: 9 feet

Action: Fast

Line Weight: 5

Pieces: 4

Material: Graphite

Measured Weight: approx 3.76 ounces

Stripping Guides: (2) Titanium frame/Nano-Lite inserts

Snake Guides: Titanium Recoil snakes

Reel Seat: Aluminum

Rod Tube/Sock: Yes/Yes

Price: $495.00

The handle of the Osmosis is a full wells design that's sized right, comfy, and feels almost velvety to the touch. Mauser boasts that they use 1/4" flor-grade rings vs. the typical 1/2" rings for a better looking and feeling grip, so I'm sure that's at least partially why this grip feels so dang good.

Mauser outfitted the rod with a black anodized 6061-T6 reel seat adorned with the Mauser logo etched on the top. I really like the up-locking rings here because they are wide and have plenty of texturing that provides ample grip without being harsh to the touch. Below the seat is a pretty standard fighting butt with composite cork lower portion.

All Osmosis rod blanks are rolled in the USA and use a blend of 40 and 50-Ton graphite. While many manufacturers prefer to sand their blanks smooth and paint them a glossy color, these are left alone which results in a surface that's slightly textured and matte in tone. I personally love a blank painted a beautiful color, but actually slightly prefer a more "raw" blank like this for weight savings, the lack of fish-spooking flash, and just that no-nonsense appearance.

The Osmosis is adorned with an excellent guide set. The two stripping guides are titanium-framed with nano-lite inserts, while the remainder are Recoil snakes. Most of the guides are about the size you'd expect to find on most 5-weights out there, but the tip top is on the larger side to allow for easy knot passage. All guides are secured using charcoal wraps with jade green trim around the logo and both stripping guides.

I could find no faults in the way this rod was assembled. The Mauser crew pays a lot of attention to build quality and it shows with precise wraps and a very clean overall product.


With the Osmosis being marketed as an "all water" rod, I wanted to test it out with a fly line that wasn't particularly aggressive and was weighted to proper WF5F specs. I decided to go with one of my favorite fly lines—an Orvis PRO Trout textured line which carries a true-to-weight rating of 140 grains in the first 30 feet.

Simply put, the Osmosis 5 weight is awesome for typical day-to-day fishing.

The tip of this rod has noticeable softness which gives it excellent performance at short and medium ranges. It loads easily with plenty of feel, tracks well, and feels precise. I found accuracy to be top notch and the blank flexes with a buttery smooth feel to it. While this is a fast action rod, it definitely has some added soul to it and blows past other rods when fishing at close to modest distances. It really excels in this range and is incredibly pleasurable to cast over and over again.

Mauser touts the rod as having the power to "launch an entire fly line" and it does, but I noticed the blank loses steam when trying to reach out to those heroic distances. It will surely get the job done in the hands of a capable caster, but I like a more powerful-feeling rod if long-distance casting is going to be a major focus. For me, it is usually not.

The light feel of the Osmosis 5 weight was really the icing on the performance cake. While the measured weight of about 3.76 ounces sitting on my scale actually wasn't super impressive, the swing weight indeed felt light while casting. The saltwater-style grip/seat likely adds a bit of weight compared to a more standard package, but since this weight would be focused under and behind the hand and not way out in front of it, the rod is still able to feel lightweight and lively without a tip-heavy sensation.


The Osmosis is simply an awesome rod that excels at short to medium presentations thanks to a nice soft tip and light swing weight. Mauser is one of those under-the-radar companies that should really be getting more fanfare with the products they have out there. What's really refreshing is that the folks at Mauser have a distinct focus not just on overall quality, but also on their customers as well. Go look at some of their social media posts and you'll see what I mean.

Coincidentally, this review came at a time when I actually need a new fighting-butt-equipped 5 weight for my personal use. Well, after taking this thing for a spin, I'm sold. I've already spoken to John about ordering one when they become available and I'm really looking forward to getting a fresh one on my rack. Speaking of which, availability and a presence on the Mauser website should start around late January 2021.

The Osmosis lineup will start off small with 5,6,8, and 10 weights all offered in 9'0" four-piece configurations. Each rod will run $495.00 and includes an aluminum tube and sock along with a manufacturer's warranty against defects and lifetime repair coverage.

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