Chamber issue causing clickers?

[Field_2_Fork]

The rifle in question is a Cooper M52 in 6.5-284. I bought it with a 26" Bob Jury barrel (well known barrel maker here in Alberta), that only had around 30 shots through it.
I bought new Lapua brass and loaded up some 140 VLD-H with H4831SC.

Started noticing clickers right away, at low powder charges. This was the first time I had felt this which led me to do as much reading as I could find, here and elsewhere online. I've measured the once fired cases and nothing seems to be out of line when compared to the virgin brass.

One thread was about how someone cured his clicker issue by turning the necks. Thinking this might be my issue I've spent some time buying turning equipment. Last night I was doing more measuring and recording the results, when I noticed what looks like machining marks on the brass where the body meets the shoulder.

I am able to reproduce these marks by simply chambering new brass, the marks are there when it is extracted.

Looking with my Teslong I see a raised burr of some type at the body/shoulder junction in the chamber. Is this small burr possibly causing this marking of the brass and creating friction, causing the tight extraction and clicking?

I'm hesitant to try turning the necks if that's not the issue.

Secondly, could this burr be cleaned up by a gunsmith?

Here you can see the small grooves/imprint going up the shoulder:

Just above 9:00 in the pic below you can see the raised burr, looking towards the barrel.

Here's the reflected image, looking at the burr from directly above, you can also see a 'snail trail', I suspect from the metal was gouged and created the burr.

The once fired brass shows little to no soot on the outside of the necks...

Does any of this make sense? I'd really like to start shooting this rifle.

 

[JMayo]

I found that my cases were too long and mouth was bottoming out. I thought it was the datum .200 line until i put a case in and scoped it from muzzle end. I cut a thou off and problem solved.

 

[INTJ]

Clickers are commonly caused when the base of the case near the .200 line expands and doesn't spring back enough. It is caused by a die/chamber mismatch. Solutions:

1. Polish the chamber and make the base a little larger

2. Get a custom die made and make sure it sizes the base enough

3. Get a small base die

4. Get a ring die

 

[338 Mollett]

Gain more information by making a cast of the chamber .

 

[JFrank]

The rifle in question is a Cooper M52 in 6.5-284. I bought it with a 26" Bob Jury barrel (well known barrel maker here in Alberta), that only had around 30 shots through it.
I bought new Lapua brass and loaded up some 140 VLD-H with H4831SC.

Started noticing clickers right away, at low powder charges. This was the first time I had felt this which led me to do as much reading as I could find, here and elsewhere online. I've measured the once fired cases and nothing seems to be out of line when compared to the virgin brass.

One thread was about how someone cured his clicker issue by turning the necks. Thinking this might be my issue I've spent some time buying turning equipment. Last night I was doing more measuring and recording the results, when I noticed what looks like machining marks on the brass where the body meets the shoulder.

I am able to reproduce these marks by simply chambering new brass, the marks are there when it is extracted.

Looking with my Teslong I see a raised burr of some type at the body/shoulder junction in the chamber. Is this small burr possibly causing this marking of the brass and creating friction, causing the tight extraction and clicking?

I'm hesitant to try turning the necks if that's not the issue.

Secondly, could this burr be cleaned up by a gunsmith?

Here you can see the small grooves/imprint going up the shoulder:

Just above 9:00 in the pic below you can see the raised burr, looking towards the barrel.

Here's the reflected image, looking at the burr from directly above, you can also see a 'snail trail', I suspect from the metal was gouged and created the burr.

The once fired brass shows little to no soot on the outside of the necks...

Does any of this make sense? I'd really like to start shooting this rifle.

Looks like your shoulder is rubbing the chamber, I would set the die a couple thousandths lower and report back.

 

[FeMan]

I would say you may have a tight chamber. Measure your brass at the 0.200 line. It wasn't until I was able to get my sized brass 2 thousandths smaller than the fired that the clickers finally disappeared. A small base body die helped a little but I finally had to order a reamer that was 0.502 at the 0.200 line to get rid of them altogether.

 

[Field_2_Fork]

I found that my cases were too long and mouth was bottoming out. I thought it was the datum .200 line until i put a case in and scoped it from muzzle end. I cut a thou off and problem solved.

Good idea, I hadn't thought to check that. Had a look tonight and both virgin and 1F brass look to have lots of room.

New


1F

 

[moondog]

As posted above, send fired brass in and get a die the sizes the .200 mark 1 1/2 to 2 thousands smaller.

 

[Field_2_Fork]

Clickers are commonly caused when the base of the case near the .200 line expands and doesn't spring back enough. It is caused by a die/chamber mismatch. Solutions:

1. Polish the chamber and make the base a little larger

2. Get a custom die made and make sure it sizes the base enough

3. Get a small base die

4. Get a ring die

The unfired and the once fired brass both measure .499 at the .200 line, so I don't think that's the problem.
Another landmark on a reamer print I found online is the 1.00 line, new brass measures .486 and the fired is actually smaller at .482.

 

[Field_2_Fork]

I would say you may have a tight chamber. Measure your brass at the 0.200 line. It wasn't until I was able to get my sized brass 2 thousandths smaller than the fired that the clickers finally disappeared. A small base body die helped a little but I finally had to order a reamer that was 0.502 at the 0.200 line to get rid of them altogether.

Boy, I hope that's not the case.
As mentioned above, my brass - both new and once fired appear to measure .499 at the .200 line.

Were you able to run the new reamer into the existing chamber and size it up, or start over with a new barrel?

 

[Field_2_Fork]

Looks like your shoulder is rubbing the chamber, I would set the die a couple thousandths lower and report back.

I'm seeing a shiny ring there, assuming that's what caught your eye?
Measuring at the shoulder I see .473 on new brass, and .4755 on once fired, some definite expansion there...hmmm.

I'm yet to size any brass for a second round of firing, will give that a try and hope for the best I suppose. May as well size some new brass while I'm at it and see if that makes a difference.

Any insite as to what is making those machine marks on the shoulder?

 

[INTJ]

The unfired and the once fired brass both measure .499 at the .200 line, so I don't think that's the problem.
Another landmark on a reamer print I found online is the 1.00 line, new brass measures .486 and the fired is actually smaller at .482.

That is tight. Typically, the fired brass is .002-.003" larger than unfired brass at the .200 line. Ideally your sizing die sized it down .002"-.003" under the size of fires brass as well.

This can probably be fixed by polishing the chamber.....

 

[FeMan]

Boy, I hope that's not the case.
As mentioned above, my brass - both new and once fired appear to measure .499 at the .200 line.

Were you able to run the new reamer into the existing chamber and size it up, or start over with a new barrel?

No, I just lived with it. You could do that but running a new reamer in a carboned chamber will dull the reamer and I didn't want to chance it.

 

[Dusty Stevens]

The base area in the chamber is too big, probably from already polishing too much, so that coupled with the gouge up at the shoulder is causing your 2 issues

 

[INTJ]

The base area in the chamber is too big, probably from already polishing too much, so that coupled with the gouge up at the shoulder is causing your 2 issues

If his new brass and his fired brass both have the same .200 line measurement like he said, how is that too large of a chamber?

 

[AckleymanII]

Winchester brass will more than likely solve the clicking issues. Lapua is larger in the web than Winchester,

Lapua = CIP spec

Winchester = SAAMI SPEC

 

[Will Henry]

If it was mine, I would set it back one thread and clean the chamber up. It appears to be slightly flawed at the shoulder. In addition, the surface finish on the shoulder angle is a bit more "textured" than I would like to see. Not having the rifle or the brass in hand, I am guessing a bit. It wouldn't hurt to try polishing first though. WH

 

[Tim Singleton]

the reamer did pickup a chip causing a burr up at the shoulder that is causing the marks on the case
that wouldn't cause the clickers tho

a reamer with that .502 dimension at the 200line someone mentioned earlier is the ticket

 

[Dusty Stevens]

If his new brass and his fired brass both have the same .200 line measurement like he said, how is that too large of a chamber?

It may not be at the .200 line but i can assure you if its a clicker the base is too large. Running it thru a small base die is a simple test. A new chamber is the best solution, especially with that shoulder

 

[Tim Singleton]

I think you could spin that barrel off send it to someone with a 502 reamer and have not much more in it than buying more dies.
once and done