Bolt clicking on BR cases ??

[Hal]

I talked with a reamer maker today. He said he had had a couple of complaints from guys about their bolt clicking when they extracted cases.
He was wondering if I wanted to have the back of my 6MM Dasher reamer ground a little larger.

His reamers measure .4708 measured .200 up from the back of the case.
He suggested to increase the back of the reamer to .4718 ,.200 up from the back of the case.

Is this a common problem with BR based cases.

What diameter is everyone having the reamers ground to at the point .200 up from the back of the case?

Hal

 

[tclaunch]

I`m sure I know who you were talking to as he was very much the guy who suggested .470" for years and nobody was the wiser. The custom die makers loved this. Yes go larger, the Sammi dimension is .4714" @ .200"

 

[jlc204]

Ok guys, I'm a little concerned now as I'm having my first 6br chambered as we speak with a reamer that has the .470 at 0.20 dimension. Can someone provide me with a little more info as to what I should expect, and what course I need to take. From what you're saying, it doesn't sound good? Are certain sizing dies a better match for this dimension than others?
Thanks
Jason

 

[tclaunch]

If and only if your smith uderstands what you are conveying, then he can polish out the chamber (open it up) about .001 to .002" I have done this now that I am a lathe owner with 7/16" dowel rod and some 320 grit sandpaper super glued to the dowel rod. It took 4 to 5 times wearing the paper out to get my dimensions upened up. The result was great the click was gone, and the dies now actually can do their work as the base is big enough to actually be sized. The click is caused by the die being to close to the size of the fired brass in size so no sizing accomplished at all. basicly like neck sizing and that gets ugly over time. The reamer specs should not be made so close to the die dimensions.

 

[Hal]

T

That was what I was trying to get away from, a polish to fit chamber. I was wanting a correct diameter reamer to start with.

Since the reamers was made first, the die makes should make their dies smaller.


Hal

 

[gunsandgunsmithing]

There's absolutely nothing wrong with polishing the chamber in a lathe. It is a very precise way to finish a hole. Think about it like this...How hard would it be to take a cut as light as a hone does? Also, it leaves a better finish than machining or grinding..i.e., reamers are ground in most cases. Many precision machining operations entail polishing or honing to final dimension.--Mike

 

[Hal]

Mike

I understand polishing out a chamber to make it work and that polishing has its place..

Which would you rather buy a reamer that cut a chamber that needs polishing every time or a reamer that cut the correct chamber size to start with ?

You can spend your money on sandpaper , I'll spend mine on the correct reamer.

Hal

 

[tclaunch]

Since the reamers was made first, the die makes should make their dies smaller.
Hal

I bet all dimensions are based on the case dimensions not reamer or die. The chamber/reamer must be enough larger than the factory case for expansion. The reamer being speced to small at the base is the culprit.

 

[tclaunch]

Hal if the reamer is to small @.200" then the die maker you will have to hire will make a die off your fired cases. I`d go the larger diameter at the base and use factory Redding dies.

Many many shooters have had to do this from the very poor advise given from a toolmaker that isn`t a shooter, just a salesman.

 

[gunsandgunsmithing]

Mike

I understand polishing out a chamber to make it work and that polishing has its place..

Which would you rather buy a reamer that cut a chamber that needs polishing every time or a reamer that cut the correct chamber size to start with ?

You can spend your money on sandpaper , I'll spend mine on the correct reamer.

Hal

Hal, everything has tolerances...Reamers,Chambers, and dies all do.

 

[tclaunch]

Mike

I understand polishing out a chamber to make it work and that polishing has its place..

Which would you rather buy a reamer that cut a chamber that needs polishing every time or a reamer that cut the correct chamber size to start with ?

You can spend your money on sandpaper , I'll spend mine on the correct reamer.

Hal

You are dealing with the guy that must own stock in sandpaper companies. I assure there have been way more than a couple complaints, I am half that many. My complaints fell on deaf ears. Yours will too. You have other options.

Next time you speak with him, imagine you have dialed the wrong number and a used car salesman picked up the phone. You will start to understand.

 

[gunsandgunsmithing]

Hal and Tim...I went back and re-read the posts here and see that I was somewhat missing the point you guys are making. I agree, and a chamber that's too tight will cause more headaches than one that's a tad big. I've spec'd reamers to work with specific dies for a while, but like I said, all the components have tolerances and can benefit from polishing a small amount to final dimension. You're both right. The closer the chamber is to "right" before polishing, the better.--Mike

 

[Hal]

I have two reamer prints, one is from JGS and the second one is from PTG.
The JGS reamer measures .4707 @ .200.
The PTG reamer measures .4708 @ .200.
Both these reamers are list as 6MM Dasher/Robert Whitley.

Tom likes the .473 @ .200 reamer with a .461 sizing die.

Tim noted that ..4714 @ .200 is SAMMI.

I was just looking for a reamer that will work with factory dies like Forster.

Hal

 

[tclaunch]

I use Redding, but a very good buddy has a Forster and says they size smaller than Redding. My last reamers I have done I used .471" @ .200". The next ones will be .4714". I will use JGS and Henriksen for all my future needs. You might consider same.

 

[holstil]

This is why my br reamers were sent back to Kiff for a regrind to .002 bigger. I got tired of custom fitting the chamber to a die. Polish can mean different things to different people. Different degrees of polish. I'm not looking to increase bolt thrust, that could lead to a different kind of stick.

I think we either got carried away on the match thing or bit by a tolerance in manufacturing. I saw this topic over on brcentral awhile back. I believe I saw some running as large as .006 bigger.

I really hate bolt click. The learning curve can be steep at times, Jim

 

[jlc204]

Jim,
Please excuse my ignorance, but how is a reamer re-ground bigger?

 

[BoydAllen]

If your bolt is tight as you start to open it, your load is too hot.

The click that you asked about is the sound that is made as the root your bolt handle hits the primary extraction cam at the back of your rear receiver bridge, when your case is stuck in the chamber do to a slight interference fit just in front of the extractor groove. This usually happens when hot loads are fired repeatedly in a case, and the solid part of the head swells slightly. The other complicating factor is the difference in how far back on the case the chamber comes vs. how far down from the the cases shoulder the die reaches. IF the chamber comes farther back along the case than the die can reach to die, there is a very narrow band that can become a problem, if conditions are right (tight chamber, hot loads)

If you can bump your shoulders back with an unmodified stock shell holder then your chamber being set at absolute minimum shouldn't be a problem, unless and until repeated firings work harden that batch of brass, significantly changing its spring back. At this point you may not be able to adjust your die low enough in the press to bump your shoulders back, but fear not , all you have to do is to turn a few thousandths off of the top of your shell holder, and you will be back in business. Don't modify the die the die; make the change to the shell holder. If you do, and can get your bump back, having a minimum headspace chamber can actually be an advantage because you die will be reaching farther down the case.

First things first, if your bolt is tight as you start to raise it, you need to back off of that load. Just for grins, measure one of those tight cases at the shoulder, and about .3 above the head, and do the same after FL sizing. Do you have one of the Hornady (Formerly sold by Stoney Point) attachments for calipers that are designed for measuring headspace? If not, I suggest that you pick one up.

 

[Hal]

Thanks Tom I understand now.

Hal

 

[holstil]

Jim,
Please excuse my ignorance, but how is a reamer reground bigger?

The reamers are tapered and how much depends on reamer design. There is some restriction on how much bigger you can go. All they do is move the dimensions down the fatter part of the reamer. I had them regrind the neck to the blue box Lapua while they had em. I can get a picture if you like. They look a little different in that the nose is now longer.

Personally, I think there is an optimal amount of size changing that should happen between fired and sized cases, about .0015 to .002 in the base area. My Cooper had .013 oversized chamber. I won a factory class match with it once with an 8.250 group at 1k. I sent it back to get rechamberd because I could only get about 4 reloads from the brass. FWIW It did not shoot as well with a new barrel and tighter chamber.

Also, what you order may not be exactly what you get. There are tolerances and mistakes can be made. I've seen more than one reamer from more than one manufacturer not match the print.
I am just a hobbyist, it is not my intention to sound like an expert, just my observations/opinions.

Jim