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Gunsmithing my opinion on fluted bolts for field rifles...

300sniper

Gunny Sergeant
Full Member
Minuteman
Jan 17, 2005
3,438
23
Greenwood, Ca
it seems the topic of the benefits of fluted bolts come up about weekly here. there is always at least one poster that tries to justify the cool looks by saying the flutes give debris a place to go instead of locking up the action. in my opinion, this is false.

my opinion has been that when debris is flying around, it is more likely to just fall off of a smooth bolt body than a fluted bolt body. if the debris sits on the flutes, when you work the action, it is far more likely that that debris will get cammed into the receiver bore potentially causing a lock-up. any debris that did happen to come to rest on a smooth bolt body will fall off as soon as you work the bolt.

to prove this idea (and out of beer induced boredom), we headed to the kitchen to do a little experiment.

here we have a fluted and a non-fluted bolt.

flutedboltmyth1.jpg


today, sugar is going to substitute for field debris. from approximately four inches above, 1 tbs of sugar was poured above each bolt.

flutedboltmyth2.jpg


hmmm. that is very interesting. the fluted bolt appears to have more debris (sugar) sitting on it than the non-fluted.

let's see what happens when we lift the bolts approximately 90 degrees.

flutedboltmyth3.jpg


flutedboltmyth4.jpg


hmmm. again, very interesting. the fluted bolt seems to have retained much more debris (sugar) than the non-fluted.


to be as scientific as we possibly can, let's try it again.

clean bolts.

flutedboltmyth5.jpg


the debris (sugar).

flutedboltmyth6.jpg


let's get a good, close look at this.

flutedboltmyth7.jpg


flutedboltmyth8.jpg


the bolts were very carefully lifted up as to not disturb the debris resting on them. the debris in the catch pan was removed. now we shake off the loose debris (sugar).

flutedboltmyth10.jpg


here you can see how much debris (sugar) each bolt held.

flutedboltmyth11.jpg



in closing, each of you must decide what to do. if your ao is the kitchen while your girlfriend/wife/domestic partner is making brownies, do you want a fluted bolt or not?
 
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Re: my opinion on fluted bolts for field rifles...

I'd say it really depends, like most scientific experiments dealing with particle/debris flow the only way to really be sure how it would affect the action is to simulate what you are dealing with. You'd have to wind blow sugar into each action while trying to run the bolts to see how it worked. It may very well be that while the fluted bolts allow more crap into the action they also process it through the action much better. It could also be the flutes tend to present a higher angle surface to the debris keeping it from going around the bolt into the action, where the smooth both essentially funnels it right into the action around the bolt. Spend a few days in the desert and sand/dirt will get in anywhere, the fluted bolt probably allows for more of it to get into the action, but it also allows it to cycle with a LOT more debris in it. It would also be interesting to see how it handled a wet debris say like mud/slurry.

I agree though I think it's mostly cosmetic, the one exception to this is say the AI design that uses a smooth outer bolt surface when closed but has grooves where the bolt is enclosed by the action, perhaps the best of both ideas, more bolt smooth area to reduce the amount of crap getting in, but if it does get in the grooves on the inside allow it to run better.

Also, and perhaps not by design, the flutes in the bolt pictures are wound in such a way that lifting the bolt would encourage debris to move away from the chamber end.

An even more interesting experiment might be do they matter at all, or is the debris getting to the locking lugs the real problem that would lock the bolt up and not just into the rest of the action.
 
Re: my opinion on fluted bolts for field rifles...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ToddM</div><div class="ubbcode-body">

An even more interesting experiment might be do they matter at all, or is the debris getting to the locking lugs the real problem that would lock the bolt up and not just into the rest of the action. </div></div>

the only time i have had a rifle problem related to debris is exactly that. a small piece of range gravel got into the bolt nose counter bore and wouldn't allow the bolt to fully close.
 
Re: my opinion on fluted bolts for field rifles...

300, I agree with you but that test doesnt show much.
Run the bolts in rifles and do the test. Having the bolt lay there does show much.
Freeze the action together and try to open both bolts.

More tests
 
Re: my opinion on fluted bolts for field rifles...

Flutes on the bolt around the ejection port region don't do anything. If you want to see where flutes make a difference take a look at an AI bolt. The flutes are where the bearing surfaces of the bolt and receiver support the bolt.

300's right, this is a cosmetic fix only, flutes in this arrangement do nothing for "wiping dirt".

Fluting on the bearing surfaces has it's own set of hurdles with how the bolt moves under fire control part motion, I'm not an advocate of making flutes on the bearing surface in a manner that allows more bolt body to receiver race slop for accuracy reasons.
 
Re: my opinion on fluted bolts for field rifles...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: AZPrecision</div><div class="ubbcode-body">300, I agree with you but that test doesnt show much.
Run the bolts in rifles and do the test. Having the bolt lay there does show much.
Freeze the action together and try to open both bolts.

More tests </div></div>

you are welcome to run sugar through your actions to insure a more scientific test.

when frozen, most likely the point of lockup is going to be in front of and behind the ejection port. the same spots that aren't touched with most of the flutes i have seen on remington style actions.
 
Re: my opinion on fluted bolts for field rifles...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: wnroscoe</div><div class="ubbcode-body">I think where flutes help are when the bolt is worked to the rear and then to the front again. Not when the handle is raised or lowered. It's the angle of the flutes that act as a cutting or evacuation force for debris.

Having said that, I've never had a rifle fail due to having flutes or not..............chics dig em and they're cool looking, thats why I use them on my signature receiver. </div></div>

but if you have an bolt body to receiver fit of say .005", how is a piece of .005"+ grit going to get into it with a non-fluted bolt? if you have .093" deep flutes cut with a 3/16" cutter, i can certainly see a piece of grit .098"+(especially at our local range in the rain) getting into a flute and being cammed into the receiver when the bolt handle is lifted.
 
Re: my opinion on fluted bolts for field rifles...

Fluting minimizes bolt contact with the action. Capillary action that may wick moisture between the receiver and the bolt is restricted to a smaller surface area with a fluted bolt. This smaller area allows the shooter to break the bolt free easier.

In my opinion, the "sugar test" the OP performed actually demonstrates the advantage of fluting. The sugar settling into the flutes is exactly what is intended. The unfluted bolt shedding the sugar is an unrealistic demonstration because the bolt, under normal operation, is surrounded by a receiver- not out in the air. Particles that accumulate in the flutes are less problematic than those pinched between the bolt and the receiver.
 
Re: my opinion on fluted bolts for field rifles...

Just dont eat french toast while you are shooting and you will be ok, thats the moral of this right?

It seems you could have the same exact problems with both bolts as long as something happened just the right way.
 
Re: my opinion on fluted bolts for field rifles...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: J.Nixon</div><div class="ubbcode-body">Fluting minimizes bolt contact with the action. Capillary action that may wick moisture between the receiver and the bolt is restricted to a smaller surface area with a fluted bolt. This smaller area allows the shooter to break the bolt free easier.

In my opinion, the "sugar test" the OP performed actually demonstrates the advantage of fluting. The sugar settling into the flutes is exactly what is intended. The unfluted bolt shedding the sugar is an unrealistic demonstration because the bolt, under normal operation, is surrounded by a receiver- not out in the air. Particles that accumulate in the flutes are less problematic than those pinched between the bolt and the receiver. </div></div>

these cosmetic flutes we put on our remington style actions are only in the ejection port area. flutes in this area are doing nothing to stop or slow capillary action nor free ice that has formed because of it. if the flutes were in front of or behind the ejection port, them <span style="font-style: italic">maybe</span> i'd agree with you.

the bolt under normal operation is not surrounded by a receiver in the fluted area. the fluted area is in the ejection port. in that open ejection port, particles that accumulate in a flute have much more potential for creating a problem than particles that bounce off a smooth bolt and land on the ground.
 
Re: my opinion on fluted bolts for field rifles...

Anybody that has worked in the desert and in the oilfield industry or any outside job KNOWS that any slit,groove,corner,crack,flute will collect more ,dust,oil,scum,shit than a smooth surface .

Problem solved , screw flutes for a service weapon bolt .
 
Re: my opinion on fluted bolts for field rifles...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Cigarcop</div><div class="ubbcode-body">So is the sugar coated fluty bolt for sale now?? </div></div>

no. i baked it for 20-30 minutes until a tooth-pick came out clean and then i ate it with a scoop of vanilla ice cream.
grin.gif
 
Re: my opinion on fluted bolts for field rifles...

Awesome test 300! I have an old Remington with a riveted extracted that I am buying a new bolt with a Sako extractor. I was debating on what style to get, fluted or not? But now I'm just going to roll with a standard smooth bolt.
 
Re: my opinion on fluted bolts for field rifles...

I look at a bolt that is fluted as described as a really nice camouflage paint job on a rifle that will never get off the range. They look great and chicks dig them. What more do you need? I love all the talk of rifles failing that will never see combat. The argument “I don’t baby my rifle”, is silly. I don’t know of anyone carrying a sniper rifle in the real world that doesn’t. Why would you choose to abuse it on a one way range? It’s a bolt action rifle if you get into crud where the flutes in your bolt made or broke your ability to actually cycle it, there are probably going to be other issues with your rifle.

Neither the M24 nor M40 in any of their versions have a fluted bolt. If fluting the bolt in the ejection port offered any real advantage, I would like to think they would be. I will admit, that is a weak argument against flutes. The fact that they look cool and chicks dig them is definitely the best argument for them.

If a rifle is painted in some camouflage scheme, most owners will not tell you that they did it for a tactical advantage for when the country goes to shit and we are all shooting at each other. They paint it because it looks cool and chicks dig it. Why should you need any more reason to flute your bolt? If you like it, go for it.

I don’t think it will make or break your “mission” to the range either way. It looks cool and chicks dig it. You also have a good way to carry sugar to your coffee cup, should you forget your spoon….I like two bolts full for mine. I like my coffee sweet like my girl; oh she digs the fluted bolt and thinks they are cool.
 
Re: my opinion on fluted bolts for field rifles...

Robert if you have this much free time then I have something for you to start rebarreling!
grin.gif
 
Re: my opinion on fluted bolts for field rifles...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Driftwood</div><div class="ubbcode-body">I look at a bolt that is fluted as described as a really nice camouflage paint job on a rifle that will never get off the range. They look great and chicks dig them. What more do you need? I love all the talk of rifles failing that will never see combat. The argument “I don’t baby my rifle”, is silly. I don’t know of anyone carrying a sniper rifle in the real world that doesn’t. Why would you choose to abuse it on a one way range? It’s a bolt action rifle if you get into crud where the flutes in your bolt made or broke your ability to actually cycle it, there are probably going to be other issues with your rifle.



Neither the M24 nor M40 in any of their versions have a fluted bolt. If fluting the bolt in the ejection port offered any real advantage, I would like to think they would be. I will admit, that is a weak argument against flutes. The fact that they look cool and chicks dig them is definitely the best argument for them.

If a rifle is painted in some camouflage scheme, most owners will not tell you that they did it for a tactical advantage for when the country goes to shit and we are all shooting at each other. They paint it because it looks cool and chicks dig it. Why should you need any more reason to flute your bolt? If you like it, go for it.

I don’t think it will make or break your “mission” to the range either way. It looks cool and chicks dig it. You also have a good way to carry sugar to your coffee cup, should you forget your spoon….I like two bolts full for mine. I like my coffee sweet like my girl; oh she digs the fluted bolt and thinks they are cool. </div></div>


Actually the new bolts PTG is making for the m24s are fluted.

http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=1954971
 
Re: my opinion on fluted bolts for field rifles...

Yes they look nice but another downside I have seen with flutes is that they "ratchet" on the brass when the bolt is raised and lowered. I suppose some of this depends on how smooth the top edge of the flutting is but I have seen bolts that had a lot of brass on them from this.
 
Re: my opinion on fluted bolts for field rifles...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: dmg308</div><div class="ubbcode-body">
Actually the new bolts PTG is making for the m24s are fluted.

http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=1954971
</div></div>

I guess the Army just figured out chicks dig them too. I find it hard to believe it's taken them so long, over 100 years using a bolt action rifle in some really nasty places and they just now figured out that fluted bolts look cool and chicks dig them. I am sure their decision to put them on the new rifle was completely function based. No one could sell the goverment something that looked cool but had no real function.

The flutes as on the bolt are cosmetic at best and crud catchers at worst. If they were that concerned about dirt and crud getting in the action, they would put a dust cover over the ejection port.
 
Re: my opinion on fluted bolts for field rifles...

Damn, i need to flute my bolts so chicks dig me.
 
Re: my opinion on fluted bolts for field rifles...

Who are you? Me..I'm just a guy who likes saving money on car insurance..... and Pie! I'll take my pie with sugar on top and apples in the middle:)


I have nothing useful to add to this post, sorry guys.
 
Re: my opinion on fluted bolts for field rifles...

To be sure, you should do the Police Rifle test. Use a simulated glaze sugar. Like what they put on Donuts.
 
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Re: my opinion on fluted bolts for field rifles...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 300sniper</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: AZPrecision</div><div class="ubbcode-body">300, I agree with you but that test doesnt show much.
Run the bolts in rifles and do the test. Having the bolt lay there does show much.
</div></div>

you are welcome to run sugar through your actions to insure a more scientific test.
</div></div>

Sugar wont hurt my rifles
smile.gif


But I don't have any fluted bolts on hand. Like I said, I agree with you for the most part on fluting being for looks. Donate a fluted bolt and I'll run some "tests" on one of my actions/rifles.




Barrel fluting would be a good subject. Actually matters.
 
Re: my opinion on fluted bolts for field rifles...

Hooper that was awesome!!! I was just thinking jelly and powder sugar for the police rifle test. My brother and I can go for hours joking about cops and donuts!! Sorry, no offense intended fellas.
 
Am I the only one thinking you need to scrub your fucking sink? Oh, and put a drain it too while you're at it.
 
Last edited:
Max, I'm fairly certain that's an old cake pan.

The rest of you...Can we all just accept that some people like fluted bolts, and some don't for their own reasons?
 
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it seems the topic of the benefits of fluted bolts come up about weekly here. there is always at least one poster that tries to justify the cool looks by saying the flutes give debris a place to go instead of locking up the action. in my opinion, this is false.

my opinion has been that when debris is flying around, it is more likely to just fall off of a smooth bolt body than a fluted bolt body. if the debris sits on the flutes, when you work the action, it is far more likely that that debris will get cammed into the receiver bore potentially causing a lock-up. any debris that did happen to come to rest on a smooth bolt body will fall off as soon as you work the bolt.

to prove this idea (and out of beer induced boredom), we headed to the kitchen to do a little experiment.

here we have a fluted and a non-fluted bolt.

flutedboltmyth1.jpg


today, sugar is going to substitute for field debris. from approximately four inches above, 1 tbs of sugar was poured above each bolt.

flutedboltmyth2.jpg


hmmm. that is very interesting. the fluted bolt appears to have more debris (sugar) sitting on it than the non-fluted.

let's see what happens when we lift the bolts approximately 90 degrees.

flutedboltmyth3.jpg


flutedboltmyth4.jpg


hmmm. again, very interesting. the fluted bolt seems to have retained much more debris (sugar) than the non-fluted.


to be as scientific as we possibly can, let's try it again.

clean bolts.

flutedboltmyth5.jpg


the debris (sugar).

flutedboltmyth6.jpg


let's get a good, close look at this.

flutedboltmyth7.jpg


flutedboltmyth8.jpg


the bolts were very carefully lifted up as to not disturb the debris resting on them. the debris in the catch pan was removed. now we shake off the loose debris (sugar).

flutedboltmyth10.jpg


here you can see how much debris (sugar) each bolt held.

flutedboltmyth11.jpg



in closing, each of you must decide what to do. if your ao is the kitchen while your girlfriend/wife/domestic partner is making brownies, do you want a fluted bolt or not?
Sweet test
 
The difference in sugar consumption on those bolts was their size. The first is from a LA, the second from a SA. Geez, guys. Come on... not even comparing apples with donuts here!