Flutes on my cases?

[Steve morgan]

View attachment 1205143 View attachment 1205144 View attachment 1205145 View attachment 1205146 View attachment 1205147 You can see the lines going the length of these cases. A person mite think they were fired in an HK fluted chamber, though HK fired brass i have seen is not like this, but no they were fired in a chamber i cut a while back. there are lines the length of the chamber like this to. Ive posted about this before - my question now is how can the lenthwise groves be cut in the chamber when the reamer only goes radially. or mabie they are somehow cut when i remove the reamer to clean chips and push it back in getting ready for the next pass. for what it is the rifle seems to shoot good. Thanks

Reamer chatter is the only way this can happen.

 

[hoz53]

Reamer chatter is the only way this can happen.

Thank you - I will be working on it and will report here about what i find

 

[gunsandgunsmithing]

A reamer is usually ground with the flutes staggered slightly with all cutting edges ahead of center. So, flute no.1 might be .002 AOC with the other flutes at .004, .006, .004, .002 .004. with the flutes spaced at 60 degree intervals. An alternative might place all flutes at .002 ahead of center but spacing them at 0, 60-30minutes, 120-15, 180-45, 240. 300-30 and so on. The idea is the no two cutting edges are directly opposite another.
Beyond this, the clearance on each cutting edge can be too great and lead to chatter. There others much more knowledgeable than I and they will be able to correct any misstatement I may have made. WH

I dont know the specific numbers but your general point is what I was referring to as flute stagger in my post above.

 

[riflewoman]

Rather than wax paper, I cut an “X” in a cleaning patch (size depending on reamer/chamber diameter), slipped it over the pilot to the shoulder and made a cut. Very often two patches were required but it would get the chatter out. I tended to but all but the final pass or two with the patch on. I also found that this has a tendency to follow a lathe. Maybe something to do with the gearing or the speeds available. Flooding with cutting oil also helped.

 

[hoz53]

The 5r, a loose fitting pilot and reamer geometry can all play a part in chatter. Wax paper, IME, works if you catch it in time but if you keep going in, hoping the chatter stops...You're not likely to be happy.

IME, you will have to re chamber to get rid of your chatter. The good thing is, you have options since it's a small bolt face cartridge that has the problem. The bad part is that you already have a chamber and no bushing support. Still, I'd bet on it cleaning up without a problem with a different reamer in a larger cartridge.

Flute spacing, shoulder angle and pilot fit..are just some of the potential causes of chatter.

I've seen 5 groove bbls cut very well while others have what appears to be peaks and valleys in the throat area. That looks ugly but they still shoot like that. Mostly, it just doesn't look like we accept as what it SHOULD look like. Well, who determines that, if they both shoot?

I'd rather chamber a 4 groove and not have to worry about it. What has been said previously is true..that the bushing pushes off to one side as the reamer cuts a land when there is not a land directly opposing it.

well i knew about the 5r barrels but after this thread i know why. I will stick with 4 grooves for anything i pay much for. Ive also learned alot of other good info on this thread. I somewhat can understand the reamer geometry idea. Ill keep working on that. I just looked at the chamber of this barrel with the borescope and there are definately some grooves in there. The good news is this was a used remington varmint barrel the tenon had been cut off of. I machined it into an AR 15 barrel for general use, and its surprising accurate for what it is. Anyway Im not out 3 or 400 and i dont plan on messing with it anymore after i take it off this gun. I just have to figure out how to evaluate the reamer now. It cuts good so I think I will do another chamber with it and see how it goes. I did check the bore id with a pin gauge a little bit ago. a .219 would fit and I had used a .217 bushing on the reamer so that could have been part of the problem. I will use one within .0005 of the bore next time. Thanks Much

 

[hoz53]

A reamer is usually ground with the flutes staggered slightly with all cutting edges ahead of center. So, flute no.1 might be .002 AOC with the other flutes at .004, .006, .004, .002 .004. with the flutes spaced at 60 degree intervals. An alternative might place all flutes at .002 ahead of center but spacing them at 0, 60-30minutes, 120-15, 180-45, 240. 300-30 and so on. The idea is the no two cutting edges are directly opposite another.
Beyond this, the clearance on each cutting edge can be too great and lead to chatter. There others much more knowledgeable than I and they will be able to correct any misstatement I may have made. WH

Ok I think i understand that -- I guess i would probably have to set the reamer on V blocks and use indicator to be able to see some of that.

Rather than wax paper, I cut an “X” in a cleaning patch (size depending on reamer/chamber diameter), slipped it over the pilot to the shoulder and made a cut. Very often two patches were required but it would get the chatter out. I tended to but all but the final pass or two with the patch on. I also found that this has a tendency to follow a lathe. Maybe something to do with the gearing or the speeds available. Flooding with cutting oil also helped.

Thanks for all that info. I will try the cleaning patch method if i need it

 

[Davester]

Always been wary of floating reamer set-ups if that's the way this was done, as it seems more prone to chatter issues to me. Especially if the float doesn't allow any radial movement which is often the case. I use a rigid set-up and don't use a pilot but I do make sure everything is lined up properly. I use a True bore alignment system on a cnc lathe and spiral fluted carbide reamers so all high speed, high pressure and programmed chambering. I also pre-bore which probably helps too with eliminating chatter. If I didn't have this equipment I would wrap thick copper wire around the jaws and align the chamber axially using a spider and radially using a 4 jaw chuck. I don't subscribe to the idea of aligning the muzzle AND the chamber end. I would also mount the reamer in a toolholder and ensure it was aligned with the bore using a co-axial indicator before setting up the barrel. - Just my view, never tried a floating holder as so far this has worked for me

 

[hoz53]

Always been wary of floating reamer set-ups if that's the way this was done, as it seems more prone to chatter issues to me. Especially if the float doesn't allow any radial movement which is often the case. I use a rigid set-up and don't use a pilot but I do make sure everything is lined up properly. I use a True bore alignment system on a cnc lathe and spiral fluted carbide reamers so all high speed, high pressure and programmed chambering. I also pre-bore which probably helps too with eliminating chatter. If I didn't have this equipment I would wrap thick copper wire around the jaws and align the chamber axially using a spider and radially using a 4 jaw chuck. I don't subscribe to the idea of aligning the muzzle AND the chamber end. I would also mount the reamer in a toolholder and ensure it was aligned with the bore using a co-axial indicator before setting up the barrel. - Just my view, never tried a floating holder as so far this has worked for me

thats some interesting info --- I did use a floating reamer holder and i can see how this could contribute to chatter. I use a manual lathe and a 4 jaw chuck with alum shims between jaws and barrel with outboard spider. I try to align chamber/ throat area i use combinatiin of 4 jaw and outboard spider to do this. I havent bored yet but will try that soon. So you dont use traditional type reamers, you program the chamber in the cnc? also you mean you would mount the reamer in the toolpost toolholder instead of the tailstock? I do like the idea of mounting the reamer in a ridgid way if i can get it aligned. Ive learned some things from your thread and youve given me some things to think about. Thanks

 

[akajun]

Ok you say this was a used barrel, did it have a high round count? Fire cracking, carbon buildup, throat erosion? This would cause poor bushing fit especially if you didn’t clean it very well and were hitting carbon deposits or fire cracking
I’ve rechambered well used barrels for blasters Or other low dollar stuff before. To do it you have to clean the crap out of the barrel
I will use wipe out , fill it with soapy wAter, and even jb paste the throat to get any high spots down and get the largest bushing I can in it. You also may need to cut off more barrel than you like to get to a good section of chamber.
And while I pretty much do this on all chambers, I pre drill the chamber then taper bore the chamber. This all minimizes chances of chatter by making the pilot less important since reamer wants to follow a hole
I use a homemade pusher as well and the few times I’ve had chatter I’ve fixed it with the wax paper / tapping wax trick or stopping reaming and lightly taper boring to clean it up then resuming reaming.

 

[swd]

Did you pre bore the chamber? I haven’t had any chatter since I started pre boring chambers many years ago. And I’ve done plenty of 5R’s too. Knock on wood..

 

[DR_2297]

Had that happen with a new reamer in a broughton recently. Stuck a patch over the reamer, cleaned up in another .070. Everything measured coaxial to the bore and round so I set the shoulder and breech back to headspace and the rifle is shooting better than the owner could ever image. Sent the reamer back to the mfg and they reground it. Not sure what they did specifically but it is back in my hands. I need to take a stub and see if it will cut cleanly one of these days.

 

[Coyotefurharvester]

Last project the custom reamer cut an undersized(body diameter)and fluted chamber, fired brass(3 test rounds) would only chamber if indexed. Contacted the reamer manufacturer, they made a new reamer and my smith set the first barrel back slightly, perfect, then cut a second matching barrel. Both produce as near matching brass as I can measure. And are extremely accurate hunting rifles. The gunsmith said he had never seen test brass like that from hundreds of custom barrels.

 

[Davester]

thats some interesting info --- I did use a floating reamer holder and i can see how this could contribute to chatter. I use a manual lathe and a 4 jaw chuck with alum shims between jaws and barrel with outboard spider. I try to align chamber/ throat area i use combinatiin of 4 jaw and outboard spider to do this. I havent bored yet but will try that soon. So you dont use traditional type reamers, you program the chamber in the cnc? also you mean you would mount the reamer in the toolpost toolholder instead of the tailstock? I do like the idea of mounting the reamer in a ridgid way if i can get it aligned. Ive learned some things from your thread and youve given me some things to think about. Thanks

Yes I program it - I pre-drill to remove the bulk of material and then with a small boring bar bore the sides of the chamber at the same angle as the case. I don't program the neck or freebore, no need. I program these moves and then use a peck-drilling cycle for the reamer - Combine it all together, press cycle start and job done. I leave it a little short and finesse a little for final fit. Yes, I would mount the reamer in a toolholder in the post but only because it would be easier to align that way. Not so easy adjusting the Y axis if the tool is held in the tail-stock and even the X axis would be a pain. If the shims work for you then great. You will need a co-axial indicator to align the reamer in the X and Y axes. I use a precision ground bar in the chuck to dial it in then put the co-axial indicator in the chuck and put the bar in the ER32 tool holder on the turret and dial that in too. The co-axial indicator will clearly tell you if you are aligned or not. If you are using a manual lathe things will be a bit different for you but conceptually the same - like I said, I've not tried this on a manual lathe so YMMV. My concern would be rigidity, especially on older/cheaper manual machines - I would double check everything is tightened down before attempting.

 

[hoz53]

Ok you say this was a used barrel, did it have a high round count? Fire cracking, carbon buildup, throat erosion? This would cause poor bushing fit especially if you didn’t clean it very well and were hitting carbon deposits or fire cracking
I’ve rechambered well used barrels for blasters Or other low dollar stuff before. To do it you have to clean the crap out of the barrel
I will use wipe out , fill it with soapy wAter, and even jb paste the throat to get any high spots down and get the largest bushing I can in it. You also may need to cut off more barrel than you like to get to a good section of chamber.
And while I pretty much do this on all chambers, I pre drill the chamber then taper bore the chamber. This all minimizes chances of chatter by making the pilot less important since reamer wants to follow a hole
I use a homemade pusher as well and the few times I’ve had chatter I’ve fixed it with the wax paper / tapping wax trick or stopping reaming and lightly taper boring to clean it up then resuming reaming.

The barrel didnt have many rounds on it at all. I didnt clean it that well though. The bushing was a little small-- .0015 to .002---- Alot of good info here for me. Thank You

 

[hoz53]

Did you pre bore the chamber? I haven’t had any chatter since I started pre boring chambers many years ago. And I’ve done plenty of 5R’s too. Knock on wood..

nope I didnt prebore this one. Thanks for that info.

 

[hoz53]

Last project the custom reamer cut an undersized(body diameter)and fluted chamber, fired brass(3 test rounds) would only chamber if indexed. Contacted the reamer manufacturer, they made a new reamer and my smith set the first barrel back slightly, perfect, then cut a second matching barrel. Both produce as near matching brass as I can measure. And are extremely accurate hunting rifles. The gunsmith said he had never seen test brass like that from hundreds of custom barrels.

Interesting testimonial about all reamers not turning out perfect. I know there are alot of them out there that that arent. This one is an off the shelf but it may have issues. Thanks

 

[hoz53]

Had that happen with a new reamer in a broughton recently. Stuck a patch over the reamer, cleaned up in another .070. Everything measured coaxial to the bore and round so I set the shoulder and breech back to headspace and the rifle is shooting better than the owner could ever image. Sent the reamer back to the mfg and they reground it. Not sure what they did specifically but it is back in my hands. I need to take a stub and see if it will cut cleanly one of these days.

thats an interesting story. I may have to call the reamer manufacturer.
Thanks

 

[hoz53]

Yes I program it - I pre-drill to remove the bulk of material and then with a small boring bar bore the sides of the chamber at the same angle as the case. I don't program the neck or freebore, no need. I program these moves and then use a peck-drilling cycle for the reamer - Combine it all together, press cycle start and job done. I leave it a little short and finesse a little for final fit. Yes, I would mount the reamer in a toolholder in the post but only because it would be easier to align that way. Not so easy adjusting the Y axis if the tool is held in the tail-stock and even the X axis would be a pain. If the shims work for you then great. You will need a co-axial indicator to align the reamer in the X and Y axes. I use a precision ground bar in the chuck to dial it in then put the co-axial indicator in the chuck and put the bar in the ER32 tool holder on the turret and dial that in too. The co-axial indicator will clearly tell you if you are aligned or not. If you are using a manual lathe things will be a bit different for you but conceptually the same - like I said, I've not tried this on a manual lathe so YMMV. My concern would be rigidity, especially on older/cheaper manual machines - I would double check everything is tightened down before attempting.

Thanks for that info. Sure gives me some things to think about.

 

[Roeder]

Did you pre bore the chamber? I haven’t had any chatter since I started pre boring chambers many years ago. And I’ve done plenty of 5R’s too. Knock on wood..

I have only had this experience twice out of a couple hundred chambers and I did pre-bore those. I think this is one of those things that catches up to everyone if you chamber enough barrels. There does not seem to be one single cause, 5R barrels, reamer geometry, barrel steel, etc. I used the wax paper and packing the flutes with wax methods and was able to save those chambers but is was a pain for sure. The only sign that something was amiss was a little squealing noise. No noticeable vibration.

 

[Will Henry]

You will see chatter in various frequencies, as it were. A squealing sound will indicate a high frequency chatter with the result being, lots of flutes but fairly shallow. The lowest frequency will produce six, very significant, flutes. You should feel this one. By the way, the flutes result from chatter will always appear in multiples of six. If the flutes are the result of reamer deflection in a five groove barrel, there should be five of them but sometimes, the deflection will set up the chatter which will result in the multiple of six. Sometimes, if the reamer starts to squeal, you can beat it by just increasing the feed rate but, if it doesn't quit right away, you had better stop and wrap or pack the reamer to settle it down. WH