Gunsmithing Chamber Reaming Question

[Chris K]

I had a rifle built in 300WM on an existing M70 action this past year, I'll say right off the bat that it shoots well, I'm not complaining about a "custom" rifle built by a "smith" that just doesnt shoot...

Specs:
26" Shilen #8 contour bbl
M70 Classic action
HS stock
EGW 20MOA base
Vtac 35mm rings
IOR 3-18x42 SH edition

I had the smith true the action, lugs and bbl and lap the bbl

That being said, when I use virgin brass and eject it from the rifle after its been fired, it comes out polygonal from the beginning of the body below the shoulder about 1/3 down the case. its very hard to see, but if I twist the cases in my fingers it can be felt.
I went to go see the gunsmith today and he said that the reamer he used is for tactical rifles, and what I am feeling is similar to what HK does to some of their guns, it reduces surface area against the chamber wall and eases ejection of spent cases. I have to reiterate that this rifle does shoot well, but my concern is the longevity of my brass and if the chambering is needed in a bolt gun.
I wish I could explain the cases and what i am feeling more accurately, but I am not a smith and don't know much about reaming chambers.
Yesterday, I shot a few hand loads and when I found an accuracy node it was shooting 3/4MOA at 200, so, like I said I'm not feeling accuracy issues or quality issues I'm soliciting information and advice on chambering rifles and hand loaders concerning the life of my brass and the necessity of cutting a chamber like this.

Thank you

C_K

 

[Chris K]

Re: Chamber Reaming Question

Because gun porn is important...

 

[LRI]

Re: Chamber Reaming Question

<span style="font-style: italic"><span style="font-weight: bold">it comes out polygonal from the beginning of the body below the shoulder about 1/3 down the case. its very hard to see, but if I twist the cases in my fingers it can be felt.</span></span>

It's been my experience what you have is reamer chatter that someone attempted to buff out.

You have a case developing over 50,000 pounds of pressure. Its going to inflate to whatever shape the chamber is cut regardless of shape.

Another indicator of this would be chambers big on the web, resulting in fired cartridges with "muffin top disorder" right at the belt line. The workpiece/tool weren't aligned properly and the tool cut big on one flute as a result.

If he's insisting on it being some specialized chamber cut intentionally this way I'd demand to see the tool that cut it. A reamer is going to cut a round hole right up to the point that it starts rattling around like a marble in a can. (that'd be chatter)

The only way what you are describing can be machined on a repeatable basis is with a sinker EDM or some elaborate surface modeled helical boring operation on a multi-axis CNC milling center. If I were a betting man I'd say it wasn't done that way.

If you were to pull the barrel and look through the bore towards a frosted pane of glass I'd bet you'd see the facets in the chamber as you rotated it. Essentially what you have is kind of like a very expensive kaleidoscope that goes bang.

Only way your fixing that is setting the barrel back A BUNCH and even then its going to take one hell of a rigid setup for the tool to power through it and cut a concentric round hole again. But it can be done. Either that or pull it apart, get out the bong, and be mesmerized by the shiny spots.

Bummer.

 

[Chris K]

Re: Chamber Reaming Question

Dixon,

Thanks for the input, I'm going to go back tomorrow and mention chatter. He did say that he can change it, and I did talk to Ken at GAP tonight and he mentioned chatter as well. Now I'm stuck with; go back to this guy whose stuff I've shot and seen before and its nice work and trust that he can fix it, or send it down to GAP and have it done for sure...

This makes me sick to my stomach.

is there any safety risk involved? Either way, I know that the smith will warranty his work, but at what point do you want it "fixed"?

Dang.

C_K

 

[border_reiver]

Re: Chamber Reaming Question

yeah, you can't ream polygonal form into a barrel on purpose unless you forgot to turn the spindle on..That's chatter..As goes the adage, can't polish a turd. Hard to fix without going in deeoer with the reamer at least until the depth of the real reamer taper diameter matches the major diameter of the chatter. You might be starting over. Which means shoulders are pushed forward, or action face skimmed back. Or the combination.

JR

 

[Mark Housel]

Re: Chamber Reaming Question

Do most folks supply a couple fired cases when the return the rifle to the customer so that they can see that the chamber is OK?

Mr. Dixon, WRT to the cases being expanded just in front of the web.

I've checked chambers that I have reamed and they match the reamer, but the fired cases have this to some degree.

If the chamber is not over sized, (reamer doesn't rattle around in there), measures the same as the reamer....

Then doesn't this mean the factory unfired cases were undersized compared to the chamber, but not necessarily undersized per AAAMI specs?

Thanks,
Mark

 

[border_reiver]

Re: Chamber Reaming Question

Mark,

Not in my experience as general practice even with custom smiths..some might, but most would probably supply a shot target and perhaps some load data.

Depending on the cartridge, your mileage may vary as the web strength is directly proportional to the thickness and hardness of said case. Lapua brass acts differently than Winchester as does Remmy..SAAMI is an elusive tolerance at times.

JR

 

[LRI]

Re: Chamber Reaming Question

As a std practice I've always retained the first case ever shot out of a barrel that I've chambered. It's labeled, goes into a crack baggy and gets tossed in a bin. If the rifle is ever involved in any sort of incident, I have some form of record showing the condition of the chamber when it left my facility.

Maybe a little overkill but a story told to me about Fred Sinclair compels me to do it. He'd built a bench gun for a guy once and it was a neck turn PPC or something. The owner attempted to chamber a live cartridge with too little neck clearance. The rifle fired in his basement, shot a case of primers sitting next to a large quantity of powder and you can envision the rest.

He barely made it out of his house alive as the story was told to me. It cost Fred a great deal of time and effort to satisfy the court that he'd done nothing wrong. I was told he never built another customer rifle ever again.

 

[scotharr]

Re: Chamber Reaming Question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Chris_K</div><div class="ubbcode-body">...
I went to go see the gunsmith today and he said that the reamer he used is for tactical rifles, and what I am feeling is similar to what HK does to some of their guns, it reduces surface area against the chamber wall and eases ejection of spent cases. ...</div></div>

wow, now I've heard it all. So, he decided to "customize" a standard cartridge chamber? Did he ask for your permission? Is he going to provide you custom dies and go/no-go gauges? So,it comes out of your gun oblong, but then you size it with standard dies right? Sounds like a recipe for non-concentric ammo. You need to get a real gunsmith.

 

[Mark Housel]

Re: Chamber Reaming Question

Thanks Chad.<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">
Maybe a little overkill...</div></div>

This is the sort of process all of my instructors have said they follow, so while it may be 'overkill' it seems to also be 'standard of practice'.

I think I've heard similar stories from them also.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">
Depending on the cartridge, your mileage may vary as the web strength is directly proportional to the thickness and hardness of said case. Lapua brass acts differently than Winchester as does Remmy..S<span style="font-weight: bold">AAMI is an elusive tolerance at times</span></div></div>.

Makes perfect sense to me. Thanks

 

[Clark]

Re: Chamber Reaming Question

I am just an amateur gunsmith working on my own guns, and have only been involved with ~38 chamber jobs.
I have never seen chatter.
But I read lots of gunsmithing forums, and one line I remember is ~ anyone who cuts chambers with reamers will at some time get chatter~

I have been warned about chatter and how to prevent it by Randy Ketchum [a real gunsmith]:
A) As a precaution against low frequency vibration, I take the torque reaction out of the reamer with a low compliance coupling to the lathe bed [A piece of shotgun barrel slid over one handle of a tap wrench holding the reamer. The shotgun barrel rests on the ways]. The shotgun barrel is occasionally lifted for a second with the finger, to check that the torque is not too high. If it is too high, advance the tailstock slower.
B) As a precaution against getting a chip between the reamer and the chamber, when I pull out the reamer covered in chips, I clean it with a vacuum and then in a gasoline - motor oil mixture. I then paint Sulfured cutting oil on the reamer. I clean out the chamber with a vacuum cleaner, a nylon brush on a short cleaning rod, and Q tips. I paint the chamber with cutting oil. Then I put the reamer back in. When my brother is running the lathe, he uses compressed air instead of a vacuum. But the idea is no chips on the reamer and no chips in the chamber when the reamer gets put back in.
C) If the reamer is dull, stop reaming.

 

[LSandBinc]

Re: Chamber Reaming Question

Don't you just love when someone can't admit to a f**k up.

 

[Chris K]

Re: Chamber Reaming Question

I'm headed back in about 15 minutes, I'll tell you how it goes.

Thanks guys.

Dang.

C_K

 

[gunnergirl81]

Re: Chamber Reaming Question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Chris_K</div><div class="ubbcode-body">I went to go see the gunsmith today and he said that the reamer he used is for tactical rifles, and what I am feeling is similar to what HK does to some of their guns, it reduces surface area against the chamber wall and eases ejection of spent cases.</div></div>

That is friggin classic! I gotta write that one down!!! We need to know who this alleged smith is. You would be doing a public service by warning others who to avoid.

If he'd been honest it would have been different. Lets hope he owns up and corrects it.

 

[LRI]

Re: Chamber Reaming Question

Chatter is a function of one or several issues. Basic fundemental machining of anything calls for rigid work holding, apropriate speeds/feeds, and sharp tools.

Ignore any of these and your going to lose at some point

A tap wrench is not rigid work holding and it irritates me to know this is still taught in skoolz.

I've gone to the extreme, but it works. A 6500lb machine, up to 1000lbs of hydraulic pressure in my chuck. A non floating tool holder that weighs around 9lbs. Its socketed to a turret that weighs about 600 lbs.

I ream at 400-475 rpm with a feed of .002/rev.

The only time I've ever had a reamer "buzz" with this setup was an AI cartridge right at the breech during the initial cut. I slow it down, get some tool engagement, and then go back to 100% speed/feeds.

What I'm saying is if it doesn't work, change what your doing. Insanity is performing an identical process with the same outcome while expecting a different one.

 

[Chris K]

Re: Chamber Reaming Question

I'm not big on bad mouthing people, or businesses so I'll leave a lot of the slander aside. No one likes to have their work questioned and no one likes to be put on the spot for something they may have done wrong, but when I went back to the gunsmith today and said that I did my research and spoke to some people, I think what I am seeing is reamer chatter. He replied with "yeah? that's what it's supposed to look like...you go and talk to people on the internet and most of them don't know what they are talking about".

That set me back a bit, I don't play the "sniper card" for good reason, most of the time people just don't believe you and its not like graduating comes with a "cool guy card" but I have shot my share of really nice rifles, US, UK military sniper rifles, customs from around the states, and and have a fair bit of time behind the trigger. Snipers aren't gun smiths but we know what a good rifle is. that being said I was a little upset myself when my knowledge got called in to question...I am an army sniper, I have seen plenty of nice rifles and been fortunate to shoot some amazing sticks and to have someone basically say, you don't know shit, this rifle is done right, kind of upset me. I've never seen a precision rifle eject brass that has a slight polygonal shape to it, and I know that aint right...but out of respect I thought I'd go and check.

Needless to say the gunsmith didn't want to talk any further and said he's busy, it'll be at least a half hour until he has time to talk about this rifle. I grabbed my gun, cased it and walked away. not so much pissed off, but offended and disappointed. I have known this guy for a long time, and I have shot some of his other rifles that are superb, highly accurate, guns. But apparently he doesn't play well with people that have concerns about the work he does...and thats just poor service. what really got me is that he didn't want to talk to a customer that was in the shop at the sake of a rifle he was working on, no normal business ignores a body in the room for work on the shelf...its bad form and money walks away.

Could you imagine going to get your car worked on only to have the mechanic say I'll be an hour I don't have time for you, can you wait? I'd go to another shop...wtf?

I called GAP again today and Ken was understanding to my situation, tomorrow the rifle goes down to them and gets done right. I deploy before I will get it back, which sucks, but at least I'll have it to shoot when I get home.

Thanks for the advice guys, like I said, I'm no gun smith, but I did know what wrong looked like. You helped quite a bit...I just wish it hadn't happened this way.

C_K

 

[Clark]

Re: Chamber Reaming Question

There are many models for trust, but my favorite is that it starts near zero and ramps up slowly with every assumed promise kept, but falls quickly with an intentional breech.

Had I just gone through that chamber disappointment conversation with that smith, my trust in him would be at the bottom.
And he might not get any more chances to work his way back up.

 

[Chris K]

Re: Chamber Reaming Question

I agree whole heartedly. I explained this to my wife (a medical professional) that it is similar to seeing a new doctor, right off the bat there is a relationship building period where you feel them out and begin to trust them after advice and services are performed. once you find someone that you trust stick with them, but if it slips...its almost an immediate deal breaker.

I had a BIG deal breaker this week.

I'm a damn E5...you think I have tons of cash to toss on sticks like this! *Painful internal laugh at myself* But like anything else, drive on and get it right. dont make the same mistake twice.

C_K

KENDA!?!?! is that your ass??? WOW!
I stared at it...i guess I'm a perv.

 

[colchester]

Re: Chamber Reaming Question

Let me start by saying you have more restraint than I would being in your situation, I would be inclined to out the rat. Upon reading your initial post I drew similar conclusions to those posted by others and would have to call bs on a reamed "polygonal" chamber. In addition I believe the HK chambers are fluted and leave longitudinal marks on fired brass, perhaps there are some other models Im not aware of. I sure your on the road to getting this all worked out best TR

 

[Chris K]

Re: Chamber Reaming Question

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 73 fastback</div><div class="ubbcode-body">Let me start by saying you have more restraint than I would being in your situation, I would be inclined to out the rat. Upon reading your initial post I drew similar conclusions to those posted by others and would have to call bs on a reamed "polygonal" chamber. In addition I believe the HK chambers are fluted and leave longitudinal marks on fired brass, perhaps there are some other models Im not aware of. I sure your on the road to getting this all worked out best TR </div></div>

The HK's do (as far as I've read) but on a gas gun or MG I can see why you would want easy extraction...not needed on a tactical bolt gun. I implied BS, but I just don't like getting into pissing matches with someone that has turned out to me untrustworthy (IMHO).

All in all, if I got feisty he has the ball in his court because he chambered a gun that shoots 3/4 MOA, and its done 1/2 for me also, but 3/4/ consistently. So he can rest on the "1MOA guarantee" which is the standard for most shooters. I'm not a gunsmith, so I don't have the professional credentials to back up my argument, all I have is time behind a gun and training...

I like restraint, I take pride in restraint, because if you push a man self restrained far enough...we get nasty.

and I think people don't practice restraint enough these days, but thats another discussion.

C_K

 

[Chris K]

Re: Chamber Reaming Question

Had a nice talk with Ken at GAP today. Its shipping Monday. I lose some barrel length but should still end up at 24-24.5" plenty for 300WM.

man, the shit life throws at you some weeks...

C_K

 

[gamma]

Re: Chamber Reaming Question

Chad is bang on in his take. Anyone that cares for there work and has any respect for there client would never have let something like this out of there shop. Im sure anyone here will agree we've all had hairy moments and I certainly have had mine but never upon ever would a customer be subjected to this type of situation. I would always satisfy myself by testing the rifle first and if for any reason I wasnt happy with the spent shell then its back to the shop, rifle taken apart and put right without the customer ever knowing there was any kind of problem in the first place. Anyone that say's they never had problems is full of shit. Id say your smith is well capable of producing good stuff but for some reason he seemed a bit too lazy to bother checking this one out and correcting it before you saw it. BIG mistake, it will alway bite you in the ass if your stupid enough to chance letting it out unchecked thats a BIG NO NO in this game. I dont tend to check for accuracy, the chrono does that but I always fire at least 3 shots then check the brass, if the brass dont look right then something is wrong.

 

[FLIGHT762]

Re: Chamber Reaming Question

Chris, I know what you're going through. I'm dealing with a local builder who re-built my rifle with a Hart barrel. When I shot the rifle with Federal 168 GMM, I was getting 1 MOA or a hair over. I swapped out scopes and still got the 1 MOA.
I got the run around and was told the rifle just needs to find the right handload.

I ended up calling Hart. They were very nice and told me not to deal with the local guy. I sent the rifle to them to get the rifle to shoot. I don't care what it costs me, I just want the rifle to shoot.

Good luck with GAP. If I had to do this all over, I'd have sent the rifle to George in the first place.

 

[scotharr]

Re: Chamber Reaming Question

Hi Chris,

Sounds like you are on the right track sending your stuff to GAP. When your prior gunsmith spouted that BS about "polygonal" that was an instant indication he was not honest with himself or customers. We should all show zero tolerance for such losers. Case closed: move on.

Regards,
Scooter

 

[Chris K]

Re: Chamber Reaming Question

Done.

Moved on, and GAP was reasonable with the price too, so Im extra happy.

C_K