Stihl MS 271 Farm Boss vs MS 291: Paying for Pure Displacement
Same weight, same features, same family but the price gap between these two farm-and-ranch saws buys exactly one thing: five more cubic centimeters. Here’s when that’s the smartest money on the wall, and when it isn’t.
After seven comparisons full of feature splits, gauge traps, and convenience packages, this one is almost refreshing: the MS 271 Farm Boss and the MS 291 are the same saw except for the engine. Both weigh 12.4 pounds without fuel. Both carry the same farm-and-ranch equipment list. The difference is 50.2 cc and 3.5 bhp against 55.5 cc and 3.8 bhp and roughly seventy dollars. No tricks, no packages, no letters to decode. Just how much engine does your woodpile need?
Shared DNA Two Sizes of the Same Idea
Everything I wrote about living with the 271 applies straight across to the 291: translucent fuel tank, toolless fuel and oil caps, side-access chain tensioning behind a sprocket cover with two conventional bar nuts, the three-screw top engine cover, pre-separation air filtration ahead of a fleece filter that takes the HD2 upgrade, a sprocket-nose bar out front, and no primer bulb with standard recoil, old-school. Same NGK BPMR7A spark plug in both. These are siblings from the same farm-and-ranch drawer, built for the rancher and the firewood cutter who run a saw hard on weekends and expect it to shrug that off for a decade. Nothing about the ownership experience changes when you step up. Only the cut does.
The Engine Gap 5.3 cc, Free of Charge on the Scale
Both saws weigh 12.4 lb without fuel, so the 291’s extra 5.3 cc and 0.3 bhp ride along free. That takes the power-to-weight from 0.28 to 0.31 bhp per pound. That’s not a pro-saw leap, but you feel it exactly where farm saws live: a 20″ bar buried in oak rounds, dry locust fence posts, the storm-downed trunk that’s bigger than what you usually cut. The 271 handles all of that; the 291 handles it with more authority and less waiting on the chain. If most of your cutting is 12–16″ wood, the difference is a shrug. If your rounds regularly push past 16″, the 291 is the difference between one steady pass and riding the throttle.
From the parts side, these two are a stocking dream: same HD2 filter upgrade (1141 140 4400), same BPMR7A plug, same fuel filter, same bar mount, same 3/16″ file for the .325″ chain. If you run both saws on one property which plenty of ranches do, nearly everything in the maintenance drawer serves both. The only thing you have to keep straight is the chain, and that’s the next section.
One Saw, Two Gauges Read the Bar, Every Time
Here’s where this series’ running warning reaches its final form. The MS 291 sells with an 18″ or 20″ bar, and per Stihl’s own comparison data the groove comes in .063″ or .050″ depending on production run. The current US factory combos both run .050″ — 23 RM3 74 on the 18″ bar (74 drive links) and 23 RM3 81 on the 20″ (the exact same chain as the 271’s 20″ combo) — while earlier units shipped .063″ grooves. The same model number can legitimately take two different chains. So the rule isn’t “chain for an MS 291”, it’s the three stamps on your bar heel: pitch, gauge, drive links. Order those.
Your neighbor’s MS 291 and yours can take different chains and both be bone stock. Before you order (or borrow) read the numbers stamped on the bar. A .050″ chain in a .063″ groove will slop and derail; force the opposite and it won’t seat. Sixty seconds at the bar heel beats a return label every time.
Side-by-Side Spec Table
| Spec | MS 271 Farm Boss | MS 291 |
|---|---|---|
| Class | Farm & Ranch — same family | |
| Displacement | 50.2 cc | 55.5 cc |
| Engine Power | 3.5 bhp (2.6 kW) | 3.8 bhp (2.8 kW) |
| Weight (w/o fuel) | 12.4 lb — identical | |
| Power-to-Weight | 0.28 bhp/lb | 0.31 bhp/lb |
| Factory Bar | 20″ sprocket-nose light bar | 18″ or 20″ sprocket nose |
| Chain (factory combo) | 23 RM3 81 — .325″ · .050″ · 81 DL | 23 RM3 — .325″ · .050″ — 74 DL (18″) / 81 DL (20″); older units .063″ |
| Spark Plug | NGK BPMR7A — both | |
| Air Filter | Fleece standard; HD2 (1141 140 4400) drops in — both | |
| Bar Nuts | Two, conventional — both | |
| Top Cover | 3-screw removal — both | |
| Primer Bulb | No — standard recoil, both | |
| Tank / Caps | Translucent fuel tank, toolless caps — both | |
| Best For | 20″ firewood duty at the best price in the class | Bigger rounds, harder wood — most engine in the farm line |
Specs per Stihl USA published data; weights are Stihl’s “device weight without refuelling.” Gauge varies by bar and production run. Always confirm against the stamps on your own bar before ordering chain.
The Verdict From Behind the Counter
This is the easiest recommendation in the series because there’s nothing to decode. It’s a straight value question. Buy the MS 271 Farm Boss if your wood runs 16″ and under and the budget is doing the talking: it’s the best price on a 20″-capable farm saw, and you give up nothing in features. Buy the MS 291 if your rounds regularly run bigger, your wood runs harder, or you’d simply rather have the headroom — roughly seventy dollars for ten percent more engine at zero weight penalty is some of the cheapest performance money buys on this wall. One counter-honest caveat before you swipe the card: if you find yourself wanting the 291 because you cut a lot (near-daily hours and production quantities) pause and read the 261 comparison first. At that point you’re a power-to-weight buyer, and that’s a different saw’s job. For everyone else: count your rounds, pick your engine, and either one will still be starting on the third pull ten years from now.
Frequently Asked Questions
What’s the actual difference between the MS 271 and MS 291?
Is the MS 291 worth the extra money over the 271?
Do the MS 271 and MS 291 use the same chain?
Does either saw have Easy2Start or a primer bulb?
Should I buy the MS 291 or step up to the MS 261?
The Whole Wall, One Series
From the $199 MS 162 to the pro-grade MS 261, every current Stihl comparison lives here. Start anywhere and the related links will walk you up or down the ladder.