Case Head Seperation

[Rustystud]

I was at a match last week and a very experienced shooter a few squads down the line had a case head seperation. He was wearing safety glasses and took a hit to the surrounding face.,edited by author)

He was loading/shooting a 6mmBRX, light loads, good brass, and a proven rifle of several years.

He asked me to look at the blown case and give him my opinion. I too shoot the 6mm BRX so I have a good idea of the loading procedures.

I did not have headspace gauges at the range to check his gun. I did not have a case gauge to check some loaded ammo. I did not have a paper clip to check the inside of some of the fired cases web area. I did not have calipers or micrometers to measure the cases.

The brass had been loaded about 4-8 times which is noting for the BRX.

My opinion was the components were good, the load was not the problem. No mixed up powder. My thoughts were he was bumping the shoulders back too much and therefore caused a headspacing problem.

It is important to use steel headspacing gauges to chamber your rifle. It is just as important to set your dies correctly. It will prevent working your brass, and give you more consistant loads. If you are shooting a 6mmBRX and use your dies to also load 6mmBR then you need to make a .098 spacer and not continually be adjusting your dies. Get your dies adjusted correctly and leave them alone.

Good shooters and reloaders understand what SAAMI specs mean. The loaded cartridge properly fits the given firearm and is loaded within the pressure range of the given firearm. SAAMI specs allows a range of .0035" headspace length. Remember this is the max allowable. I prefer .001 to .0015" headspacing in a target rifle expecially a high pressure load like a 6mmBRX. I can get 15-20 loads out of my brass with no trimming. Loads this tight will have a slight preasure on bolt closing. We should prevent problems instead create them.

Safe loads don't just protect you the shooter they protect the guy beside you on the line.

Keep the smoke coming out of the muzzle and the bullets in the ten ring.
Rustystud

 

[rayjay]

I ordered my first Harrell's sizing die last year and had NO IDEA what the little brass bushing was for. Once it's use was explained to me it was like an awakening. In retrospect it seems stupid that the reloading industry does not teach how to measure the shoulder length instead of 'adjust the sizing die so that it touches the shell holder'.

I have a picture showing a Stoney Point OAL measuring tool and the Harrell's shoulder measuring bushing. I post this picture often when people ask questions about OAL issues or sizing die adjusting issues. I have never had someone say anything about the shoulder measuring bushing. I think most people don't have any idea of the possible consequences of an improperly adjusted sizing die.

I also think that people that advise others to adjust their sizing die based on the feel of the bolt closing are foolish. You can't teach feel over the internet. You can teach shoulder measuring.

 

[davek]

I was the shooter, I always wear safety glasses, for the past 36 years because I know this blow up can happen, anytime and any place, I also have the leather shooting coat and a full glove on, no I did not have to go to the hospital because I used protection. My load had 32.1 g of varget, the base of the case failed in a big way, take a hacksaw and cut a few lupa cases up and look how little brass there is in the base, then cut a .308 case and even a remington 6mmbr case . Now remember that you work that base over with a .308 sizing because of the bump you get when you shoot 32 plus g of powder in something that was designed for 30, good luck.

 

[rayjay]

A 'razor saw' as used by RC modelers works great for sectioning cases. I have found myself doing this more often lately.

 

[Rustystud]

Dave:

I stand corrected, I thought you had told Kent and I that you had to have trash removed from your eye. You did look like you had been shot with ratshot.,I have edited the first post)

You have brought up an interesting fact that you found the Lapua brass you where using was lighter in the backend/head/web than a 6mmBR Remington brass. If my memory serves me correctly your case gave way in the web not in the case head. It was short of the .200 mark. I have not made a water comparison of the to 6mmBR brass makes. I expected the .308 case to have a heavier case head and web. I know my test showed the 6mmBR Remington brass lost its primers after a couple loads and the Lapua brass lasted at least 3 times as long. Is there any chance you just got a lot of thin brass? I have not heard of other shooters having a common occurance of case head seperations in the 6mmBRX, or 6mmDasher. I know a number of shooters who routinely shoot 33 to 34 grains of powder. I have chambered a number of 6mmBRXs, 22BRXs, and Dashers and not had any known case head seperations. I know John Skowron has fired nearly 7000 rounds of 6mmBRX without a case head seperation. The 22BRX run even higher presures in the same case.

Are you going to send any of your remaining brass back to Lapua for laboratory examination?

Rustystud

 

[Preacher]

I also think that people that advise others to adjust their sizing die based on the feel of the bolt closing are foolish. You can't teach feel over the internet. You can teach shoulder measuring.

[/QUOTE]

No offence meant but,
Pretty easy to teach someone to just let the empty bolt drop of it's own weight as far as it will go, and then teach them to size a case till the bolt only falls 1/2 to 3/4 of the way on it's own weight and need a slight bit of pressure to close it the rest of the way.... it don't seem to be a big learning curve........

 

[RJinTexas]

Ray,
would you please re-post the pictures describing your method of using the Stoney Point OAL gauge in conjunction with Harrell's shoulder measuring bushing. As I for one have only used my Stoney Point gauge to determine the OAL and the empty bolt procedure described by Preacher to adjust my die.

Thanks
RJ

 

[rayjay]

Here is a pic of the bushing in use and a pic of the bushing.

 

[RJinTexas]

Ray thanks for reposting the pictures they should help keep someone less knowledgeable out of trouble. I'd like to hear anyone's comments on Hornady's head space gauge set, used with their comparator body.
Thanks
RJ

 

[rayjay]

I bought a lathe last year and one of the things I make for myself are the little bushings for measuring the shoulder. The Hornady set up seems way overpriced but it's a lot cheaper than my solution [ ie, buying a lathe ]