Just Bought a New Stihl MS-391. Help me ID the chain model# please (and other questions)

[120inna55]

(I hope this will let me post some pics. I'm a new poster, so maybe not.)

I used this model (MS-391) for years when I worked in maintenance at a local college. I grew to love it. I just bought a new one for myself. I had to travel out of town to get this model because my local dealer had it on backorder for longer than I'm willing to wait. But I'll keep my service with my local shop.

The bar is a 20" Rollomatic Super E (aka ES) #3003 000 9421. Stihl's chain guide doesn't have this bar on it. Can someone give me the model number of this chain? I just bucked some green red oak and sweet gum, and this is the chain I want to stick with. It's aggression I remember.

Also (and this one's a stupid question, so feel free to mock me): I use ethanol-free gas and I mix my chainsaw fuel in a 1 gallon container. I accidentally purchased the mix for 2 gallon (5.2 oz). Is there anything wrong with just pouring half (~2.6 oz.) the container in the 1 gallon tank? I measured in a measuring cup, so it's not precise, but it's very close.

I appreciate your patience with a new member.

 

[RED-85-Z51]

2.6 to 1 gal is fine.

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[Ryan'smilling]

That chain in stihl lingo is 35RM. In this case 35 denotes the gauge and pitch. RM tells you it's semi chisel chain. You want 72 driver links of it, so the dealer should be able to figure out 35RM72. Kinda uncommon to see .063 gauge on that size bar, but that's what it says. You could also try 35RS, which is full chisel. Will cut a little faster and not stay sharp as well.

 

[toadman]

That chain in stihl lingo is 35RM. In this case 35 denotes the gauge and pitch. RM tells you it's semi chisel chain. You want 72 driver links of it, so the dealer should be able to figure out 35RM72. Kinda uncommon to see .063 gauge on that size bar, but that's what it says. You could also try 35RS, which is full chisel. Will cut a little faster and not stay sharp as well.

36RM72, not 35

 

[Ryan'smilling]

36RM72, not 35

Goddamnit!! I knew it didn't quite feel right when I typed it. Thanks for catching that!!

 

[120inna55]

You're saying "RM" which, if I understand correctly:

R = Stihl Rapid
M = Micro (Semi-chisel)

How do you know that my chain is "semi-chisel" and not "full-chisel" which would be the "S" notation.

This is a yellow marked chain (and bar). I want the exact same chain that's in the pic.

 

[toadman]

cutter shape!
RM in your pic is slightly rounded on the working corner, which stays sharp longer, but cuts slightly slower.
the RS is full chisel & and the corners are sharp square edges with little to no roundness to them.

 

[120inna55]

RM in your pic is slightly rounded on the working corner

Thank you. I was hoping someone could tell by my pic as to whether I have full or semi-chisel. Honestly, despite my experience in using these chainsaws, I paid very little attention to what the shapes looked like. I do know they had yellow markings. It would stand to reason we didn't have full-chisel. Our work was rather dirty and general.

 

[120inna55]

Since there was some discrepancy at to whether this is full vs. semi chisel, I realize my pics were inadequate. Here are better pics:

So, it looks like the consensus is that I have 36RM72

 

[deye223]

Yep

 

[irhunter]

Just take the whole saw with you when you go to the dealer. Buy the correct chain; get the dealer to show you a full chisel chain...you will never again not know the difference.

 

[120inna55]

Well, I'm an idiot. I recognize, now, that I've been looking at the wrong thing. Here's the correct angle. Based on what I've seen, there's no doubt this is semi-chisel.

 

[RED-85-Z51]

If its been ground or filed...a full chisel becomes a semi if you use a round file or stone..

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[Ryan'smilling]

If its been ground or filed...a full chisel becomes a semi if you use a round file or stone..

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No. This is not correct. A square ground chain (only available in full chisel) becomes a round ground chain (still full chisel) if you use a round file or regular grinder. There is no way to convert a full chisel chain to a semi chisel. At least not if you want to keep the chrome on the top of the cutter.

 

[RED-85-Z51]

Yes, that, i get round ground chisel and square ground confused alot

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[HarleyT]

Chain on backwards?

 

[HarleyT]

Well?

Anyone else thinking this?

 

[Ryan'smilling]

Well?

Anyone else thinking this?

iPhone picture? Sometimes they show up mirrored.

 

[cuinrearview]

But then the writing would be backards

 

[CentaurG2]

Well?

Anyone else thinking this?

Every time I think, I weaken the nation. So, I was told not to do it no more.