How to blowup your rifle

[bigngreen]

I think we can take the brass of the suspect list, measuring a sister case to the high pressure case and a new case I had they are in spec.
This weekend I'll run a test to measure accurately the amount of barrel constriction due to temp that is actually realized, I can measure the bore to .0002 and the OD to .00005, should yield some interesting data.
The high pressure case has some normal sooting around the neck which is a normal indicator the load was not super high pressure in the initial start of the bullet.
Looking at the load data for Retumbo on the Hodgdon web site and using a 220 Partition which should have more bearing surface than a VLD they are showing an 89 gr max load being 61,900 psi, there was a 5300 psi gain in 5 grains of powder. This really seems to make it hard to get this significant of pressure from a powder charge or mistakingly loading the lighter bullets charge.
One powder on the bench rules out a faster powder.

 

[Barrelnut]

This weekend I'll run a test to measure accurately the amount of barrel constriction due to temp that is actually realized, I can measure the bore to .0002 and the OD to .00005, should yield some interesting data.

I kinda dismissed an issue with brittle steel of shrinkage because the OP shot 20 rounds of the other load in about 1 hour before he shot the problem load. My thinking was that the barrel was probably somewhat still warm from the previous 20 rounds.

What we don't know is how long the OP waited after shooting the first load until he shot the problem load...

 

[bigngreen]

Agreed but I'm trying to cover anything with some merit, also it could be a couple of issues compounded so looking for any evidence of that.

 

[Barrelnut]

Didn't mean to discredit your test before you do it.
It will be interesting to see what you measure, for sure.

 

[charlie 7]

phorwath
Lubricating the chamber or exterior of a casing will increase the setback force applied to the bolt head.
But I can assure you that the engineers that designed the action determining the structural design for their action did not include the cartridge casing as any offsetting factor in the design strength of their action.
Otherwise the action manufacturer would include a warning that the chamber and cartridge casing must be cleaned and free of any and all lubrication. And how much sense does that make, when we all use lubricants on our firearms for wear and corrosion reduction/protection?

It's a non-issue, of no consequence, in comparison to the end result when this cartridge was fired.

Absolutely correct.

Designing the strength of bolt lugs and their abutments the friction between the chamber wall and the case is of no consideration.

 

[Pdvdh]

phorwath
Lubricating the chamber or exterior of a casing will increase the setback force applied to the bolt head.
But I can assure you that the engineers that designed the action determining the structural design for their action did not include the cartridge casing as any offsetting factor in the design strength of their action.
Otherwise the action manufacturer would include a warning that the chamber and cartridge casing must be cleaned and free of any and all lubrication. And how much sense does that make, when we all use lubricants on our firearms for wear and corrosion reduction/protection?

It's a non-issue, of no consequence, in comparison to the end result when this cartridge was fired.

Absolutely correct.

Designing the strength of bolt lugs and their abutments the friction between the chamber wall and the case is of no consideration.

Anyone depending on their "non-lubricated" brass casing to contain their maximum pressure reloads is more than likely red-lining the tachometer. Only fooling themselves. Acting the Fool. Etc, etc...

 

[desertcj]

Anyone depending on their "non-lubricated" brass casing to contain their maximum pressure reloads is more than likely red-lining the tachometer. Only fooling themselves. Acting the Fool. Etc, etc...

I agree. However an oily chamber CAN cause problems with otherwise normal/safe loads.

 

[Pdvdh]

I agree. However an oily chamber CAN cause problems with otherwise normal/safe loads.

We will disagree, as politely as I know how to disagree.

Because "normal/safe" loads according to SAAMI are determined by maximum pressure. Not the lubricity of the cartridge or the chamber.

If an action fails due to a lubricated chamber with factory ammo, or any other source of home-brew ammunition, loaded within SAAMI maximum cartridge pressure, then someone or something failed to measure up. Someone is at risk of legally liability, if the evidence is clear and presented clearly.

If the reloader exceeded SAAMI pressures by relying on a lube free cartridge and chamber and the action fails, no one is liable other than the reloader and his/her poor practice/judgement.

You exceed the speed limit at your own risk, and in this example, jeopardy/peril. No one to blame other than the guy in the mirror.

 

[desertcj]

We will disagree, as politely as I know how to disagree.

Because "normal/safe" loads according to SAMMI are determined by maximum pressure. Not the lubricity of the cartridge or the chamber.

If an action fails due to a lubricated chamber with factory ammo, or any other source of home-brew ammunition, loaded within SAMMI maximum cartridge pressure, then someone or something failed to measure up. Someone is at risk of legally liability, if the evidence is clear and presented clearly.

If the reloader exceeded SAMMI pressures by relying on a lube free cartridge and chamber and the action fails, no one is liable other than the reloader and his/her poor practice/judgement.

You exceed the speed limit at your own risk, and in this example, jeopardy/peril. No one to blame other than the guy in the mirror.

An action doesn't need to fail in order to experience problems of some type. I've experienced this myself with an oily chamber.

 

[RockyMtnMT]

A lubed case can show false signs of pressure from thrust back against the bolt. It won't cause primer failure, enlarged case head, or barrel swelling.

Steve

 

[Predator 22]

A lubed case can show false signs of pressure from thrust back against the bolt. It won't cause primer failure, enlarged case head, or barrel swelling.

Steve

And it Wouldn't give the extra fps.

 

[Bowfishn]

And it Wouldn't give the extra fps.

Yes that is one of the Key points, extreme Velocity and not as some have suggested that he was loading 230 Berger to 3129 fps. out of his 300 RUM. The 3129 fps was the result of what ever caused the pressure to rise to way above what is norm for 86.8 gr. of Retumbo behind 230gr Berger bullet at a COL of 3.600" using Federal 215 primers with Hornady Brass. That of coarse is relying on the Chono giving an accurate velocity reading and based on some of the pressure signs so far it was probably correct. Discount anything that would not have or could not have caused the velocity reading.

'Eliminate all other factors, and the one which remains must be the truth.'

Sherlock Holmes Quote

 

[my muzzle flash]

i was going to try retumbo in my 338 lapua buuut not now we shoot in the cold here in Canada so that wont work h1000 or re22 will do nicely thanks for the heads up and sorry for your loss.

 

[Pdvdh]

An action doesn't need to fail in order to experience problems of some type. I've experienced this myself with an oily chamber.

You've changed the discussion slightly but significantly. It's now solely "problems of some type".
Whereas your initial post included "problems with otherwise normal/safe loads."

I suppose it depends on your definition of problems.

I contend that normal/safe loads shouldn't generate malfunctions of the cartridge case or firearm when fired in a chamber containing some corrosion protecting lubricant. My definition of "normal/safe" is a load not exceeding SAAMI pressure limits for the cartridge.