Ejector swipe a false pressure sign?

[wildfowler]

How much case head expansion is too much?

Good question, I would like to know the answer to that also?

 

[centerlineseal]

I'll quote from Ken Water's "Pet Load" book (see contemporaneous thread) first chapter.

In cartridges that the factories load to maximum pressure levels, such as the .220 Swift and .243 Winchester, it is best to discontinue increases in powder charges once the case expansion equals that of factory ammo. If a handload in those cartridges shows an increase of 0.0005 inch over the factory-load expansion, it becomes evident that the top safe pressure level has been reached. Here I call a halt and back off - by three to five percent of the powder charge.

With a cartridge like the .30-06 where factory pressures run several thousand pounds lower in deference to autoloaders and older rifles, ... I can safely permit the pressure ring indications of handloads to increase by as much as 0.0010 inch over those of factory loads.

I try to hold to the 0.0005 benchmark.

 

[expiper]

Good question, I would like to know the answer to that also?

I try and use them until they will not hold a primer securely or are so fat tht they bind in the bolt face and wont eject smoothly ,,,,if your chamber is cut properly they will hold the pressure and not burst,,,Roger

 

[fguffey]

Good question, I would like to know the answer to that also?

Back in the day the case head expansion for factory loads was considered to be .00025". If the case head expanded .001" for the first firing the case head expansions was 4 times the daily recommended allowance. And then came the argument about how difficult it was to measure case head expansion, and then there was the Vernier micrometer.

Again, I had a Pratt and Whitney electronic gage, it made measurements as small as .000005", to me that was annoying so I remove the electronics and installed a dial indicator. Then as it is now, if the reloader was not in the habit of measuring before and again after they were wasting their time.

F. Guffey

 

[Geno C]

I've always believed that also. I went out again and shot the 31.9 and the expansion at the .020 line was little under .0005"

 

[PAshooter20BR]

Had the same problem with a custom gun of mine on a 700 action. Firing pin was bushed and had ejector swiped on brass. Thought it was pressure. Worked down from my load in half grain increments down 2.5 grains. Problem still occurred. Took bolt back to smith and the edge was very sharp on ejector hole in bolt face. He cleaned it up and problem solved. Hope This helps.

 

[MarkS]

I've finally gotten around to working up a load for my brx with formed brass. While forming I was shooting 29.4gr of Varget under a 105vld .010" jammed. It shot many sub 1/4 moa groups and didn't show any pressure signs up to 30.0 but shot great at 29.4 and 2770fps.

I figured with the former brass I'd start at 31.0gr and work up .3 at a time. The first cases showed ejector swipes. Primers looked good, not even a hint of stuff bolt. I thought that was odd so I backed off to .005" off the lands and shot 31.3; still got swipes. I strapped the magnetospeed on finally at 31.9 and got 2970 with an extreme spread of 17fps.

I guess I didn't expect to have the ejector swipe on my staring load and I'm wondering if anyone else is seeing the same at such a low charge?

Geno,
Are you cases tight to chamber? Are they tight on bolt lift. I know it is the first formed firing. But long cases can show ejector swipe. They will get tight close at the end of bolt closing. I'm not talking a lot, but just some tightness. Bolt lift will be tight in the butt. I F/L size every firing to make everything the same every time.
You must have a fast barrel, if you are getting 2970 f/s with 31.9 gr of Varget. 2970 to 2980 is the best speed to run a 6BRX. I have had 5 BRX barrels, all ran best at 2975 f/s. My last barrel is a 8.5 twist, the most accurate load was 33.0 gr Varget at 2975 f/s on the money.

Mark Schronce

 

[BoydAllen]

http://www.hodgdonreloading.com/rel...-trick-monitoring-pressure-your-rifle-reloads

Beyond what the article says, I tend to keep an eye on primer pockets, as the number of reloads on cases mount up. There may be loads that are not dangerous, but which loosen primer pockets over time. When I determine that that has happened, I re-tune to lower pressure. My experience with testing one belted magnum was that the belt moved on the first firing of a new case, using a load that was not hot, but as I continued my pressure test sequence with increased loads, using the same case, the belt did not increase until well past the point where ejector hole marks appeared.

 

[expiper]

Back in the day the case head expansion for factory loads was considered to be .00025". If the case head expanded .001" for the first firing the case head expansions was 4 times the daily recommended allowance. And then came the argument about how difficult it was to measure case head expansion, and then there was the Vernier micrometer.

Again, I had a Pratt and Whitney electronic gage, it made measurements as small as .000005", to me that was annoying so I remove the electronics and installed a dial indicator. Then as it is now, if the reloader was not in the habit of measuring before and again after they were wasting their time.

F. Guffey

finally ,,,someone who can accurately measure case head growth,,,,you would have to measure between heart beats,,,!!!...Roger

 

[savagedasher]

I would polish the bolt face first . The problem could go away. Larry

 

[fguffey]

It is just an observation but it seems reloaders have invented new terms without a good understanding of what is going on. Two new terms that seem similar and takes pages and pages of responses to explain are; bolt click and Ejector swipe. To me it seems like the two topics mentioned would best be ignored, something like 'donuts'. Again, I have donuts that are going to form and there is nothing I can do about it and then there are donuts that form from bad habits.

Bolt click; I would say the sound is caused by a 'snap', something like bolt snap and I wonder if bolt swipe and bolt snap are related. We may never know because it happens when the bolt is closed, that makes it a dark place.

F. Guffey

 

[HomeSlice]

In the middle of a f-class match last year the ejector plunger on my bolt failed to operate. I shout the rest of the match and removed each case manually.

Each of those cases fired while the ejector was stuck had pretty bad bolt swipes, some so bad I could t get the fired case into a shell holder on my press.

It was the exact same load that had no marks when the ejector was functioning properly.

Checking out your ejector might be an easy step to perform before you give up on load development though, OP.

 

[BoydAllen]

F.Guffey,
Do you write this stuff sober?

 

[pdhntr]

Back in the day the case head expansion for factory loads was considered to be .00025".

F. Guffey

That brings back memories of a very protracted and painful discussion on another site, many years ago.

I had hoped that......never mind.

Jim

 

[fguffey]

That brings back memories of a very protracted and painful discussion on another site, many years ago.

Jim, I believe this thread is a protraction of the first discussion. They did not know where to take measurements from, they did not know the diameters and they did not know it was necessary to measure before and after and then there were new cases and fired cases. A reloader that starts with fired cases is doing nothing more than staying busy.

I have unfired cases from the '60s,'70s, '80s and '90s, today reloaders claim cases are being manufactured with soft brass; when measuring case head expansion we all know soft case heads will not work.

F. Guffey