Over-pressure Event --> At what point should you be worried about the gun?

What was the cartridge you fired to begin with? Can't make out headstamp. The pressure levels among the different cartridges certainly make a difference as does what firearm this cartridge was fired in as does the powder in the cartridge if you reload. A bit more information might help.

Here is an old THR thread including pix on overpressure indicators. Ceterus paribus, your load may have been 70000 psi or higher which is in proof territory or higher for a modern cartridge. If the primer blew out, then maybe even 80k psi.

Fired in a new modern bolt action rifle, your round probably resembles the proof loads for them so it might have minimal effects because the steel alloys and design of bolts/lug recesses are better than older ones. Check your bolt lugs and recesses along with the chamber. Fired in a lever action vintage Savage 99, it could have left some after effects on the action and parts that could require some disassembly to check. Fired in a low number Springfield 1903? the receiver might hand grenade the next time and so it should thoroughly be checked for cracks via magna fluxing if necessary along with the bolt lugs. Fired in a early pre WWI Mauser 98 receiver, check for lug setback and/or cracks. A later one might still suffer lug setback and more difficult operation of the bolt. Pressure can also vary because of the rifle's free bore, chamber, etc. and the brass strength of the cartridge can vary a bit. Bunch of variables to determine safety.

boom boom said:

What was the cartridge you fired to begin with? Can't make out headstamp.

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Looks like "300 REM ULTRA MAG".

You should had stopped at pressure sign #2 and back down. Continuing on is just foolish and dangerous.

Step one can be a major factor depending on which brand of primers being used.

If Wrong Handed is correct, the SAAMI pressure limit is 65000 psi to begin with. You do not have a lot of margin to play with at that level if redlining loads.

At what point should you be worried about the gun?

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This>

Field Gauge: Field Gauges correspond to the maximum safe headspace dimension. If a rifle will chamber a field gauge, it should be inspected and repaired by a competent gunsmith prior to use.

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If it fails the field gauge after a high pressure event maybe Magnaflux it? - https://www.magnaflux.com/Magnaflux to look for cracks?

If pressure was high enough to do damage, the bolt could not be beat open with a block of wood. IMO.

It all depends on your gun, cartridge, and how much you enjoy solid foods. More than one person has eaten a bolt.
One guy I knew of had his jaw wired shut, with a set of wire cutters next to the hospital bed. If he started vomiting he had to cut the wires so he wouldn't drown.
I like my face too much to piss around with super hot loads.

I regularly flatten primers (Winchesters seem to be bad for it) and don't think twice about it, because I know the cups are soft and the load is well under max for the gun.

Flowing into the FP hole suggests that you need to bush your FP hole.
Pierced primers are usually either too-small FP or too soft primer cup.

Similarly I will ignore ejector "smileys" on certain brass, because I know the load is good and the brass is soft.

Case head seperation, could be hot load, could be old brass. Neck splits? same.

Do I advise that everyone ignore "the signs"? NO absolutely not.
Simply that knowledge tempered by experience will lead you, hopefully, to making sensible decisions about your own safety.

Heavy bolt lift is reason for me to back off. It may not ever be catastrophic, you could put 100 round through and hammer each one in and out and probably still have a servicable (modern) gun.
But it's annoying.

I'm not sure what you mean by "some bridged"? A 300fps spike. I'd check your seating depth, you could well get that going from jump to jam.

Over the years I've picked up some 30-30 and .308 brass from the area where the locals would sight in their rifles. Some of these had cracks running the length of the case so someone was loading some super-hot loads. I kept a few as examples of what not to do.

Saw a Ruger 77 in 25-06 that a guy (accidently ) fired a .308 round through! After the extractor was replaced, the gun was good to go! Overpressure? Y'think?

critter said:

Saw a Ruger 77 in 25-06 that a guy (accidently ) fired a .308 round through! After the extractor was replaced, the gun was good to go! Overpressure? Y'think?

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Would depend on the bullet. There's only 1000 CUP between the pressures (.308 being lower, assuming they're standard loads) There's also 3/4" of chamber, then whatever leade, to dissipate the pressure. Conceivably gas would have got ahead of the projectile, further reducing pressure.
Difference in bullet diameter is .058" which could plausibly be jacket thickness, stripping the jacket at the end of the chamber and letting the core carry on.
Would have been very interesting to recover the slug.

Lucky man, at any rate.

atblis said:

If headspace has opened up, that's indicative of something. What about perhaps cracks in the bolt lugs, that eventually lead to failure? Does that happen?

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Absolutely, and you may not see any visible warnings of impending failure.

I wouldn't worry too much about somewhat flattened primers with the RUM. Loads that are within SAAMI max will cause some flattening, especially if they're softer ones like Winchester & Federal. It's a large primer, and they have big flash holes to ignite the 90-100 gr charges. You see it with others, too, like .454 Casull.

tight bolt and sticky extraction means you probably need to back off.

If primer pockets are getting loose, you have a problem.

Your load was way overpressure to form that ridge where the chamber is counterbored for the bolt head on a 700. That's a thick case head, takes a lot to make that happen. The case head has been expanded by the compressive force, taking up all the available room on the bolt face. While it's hard to know the compressive yield strength of the brass in a given cartridge case unless you have access to the manufacturer's TDP, I would wager that case suffered pressure well in excess of 80KSI to do that. It's also obvious from the rim damage imparted by the extractor that the case was locked in the chamber so hard that it wouldn't rotate with the bolt. I'd have the rifle's headspace checked for sure, along with at least magnafluxing the bolt head.

The RUMs, SAUMS and WSMs are already very high pressure cartridges with a tremendous amount of bolt thrust (almost 15,000 lbs) due to the large rim diameter. There have also been published loads that were later found to be over pressure. Be careful.

MihiT said:

Would depend on the bullet. There's only 1000 CUP between the pressures (.308 being lower, assuming they're standard loads) There's also 3/4" of chamber, then whatever leade, to dissipate the pressure. Conceivably gas would have got ahead of the projectile, further reducing pressure.
Difference in bullet diameter is .058" which could plausibly be jacket thickness, stripping the jacket at the end of the chamber and letting the core carry on.
Would have been very interesting to recover the slug.

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The additional chamber (closer to 3/8" than 3/4") is not the least bit meaningful in terms of Boyles law and reducing chamber pressure. Chamber pressure is measured with a bullet that fits the bore going down it, not a fully charged case in a sealed chamber.

I would not consider a rifle that had that done to be safe ever again without SEM analysis. Every time you fire a rifle that's had a chamber pressure way beyond any proof load could be the one that shears lugs and sends a bolt into your cranium or blows up the receiver and takes your face or arm off.

MachIVshooter said:

The additional chamber (closer to 3/8" than 3/4") is not the least bit meaningful in terms of Boyles law and reducing chamber pressure. Chamber pressure is measured with a bullet that fits the bore going down it, not a fully charged case in a sealed chamber.

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I'm not sure what pictures you are looking at? The SAAMI OAL on .308 is ~2.5", base to tip, the .25-06 is 3.25.
The .308 round will not be sealing the bore at all.

atblis said:

Hmm, wonder if Remington would be my best bet to get it checked out.

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I would not expect any free help from Remington. A Remington authorized repair centers may check rifle for a fee?

There warrent info.. ,https://www.remington.com/support/firearm-warranty-information

Proof loads are 93,000 PSI. Normal working pressure is 66,600PSI.

Get someone to run Quickload using your velocity of 3350 fps and other data. OAL is needed.
Quickload would possibly give an idea of the pressure reached from your overload?


Olin info-

modulus of elasticity- Cartridge Brass- Material is 70 copper/30 zinc with trace amounts of lead & iron , called C26000. Material starts to yield at 15,000 PSI when soft (annealed), and 63,000 PSI when hard. Material yields, but continues to get stronger up to 47,000 PSI when soft, and 76,000 PSI when work hardened. Modulus of Elasticity is 16,000,000 PSI. This means to pull a 1.000 inch long strip to 1.001 inch long induces a 16,000 PSI stress. So if you pull a 1.000 inch strip to 1.005 inch long, you get about 76,000 PSI, which is the max obtainable.

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atblis said:

Does one need to remove the barrel to inspect the receiver bolt recesses properly?

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One is a cheap bore camera via amazon that hooks up to your computer or cellphone is one option (or better yet someone with a Hawkeye such as most gunsmiths). Second, use marking fluid on the bolt and work it to determine degree of bolt lug and recess contact. If the bolt feels like it is binding then the lug recesses could have been affected. Angled dental mirrors with sufficient light can work on some receivers depending on space, and last but not least, fingers are very sensitive and feeling ridges, or other such irregularities with them inserted into the receiver can give you some feedback. I've mainly worked on Mauser or Mauser derivatives and have never messed around with Remington 700 series receivers so these are general instructions that might or might not give you some idea of any possible damage. I would also demount the receiver from the stock and give it a thorough investigation as well including the recoil lug area.

atblis said:

Does one need to remove the barrel to inspect the receiver bolt recesses properly?

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Yes, but the bolt lugs are where it would fail. There's a lot more meat in the receiver. Start with the bolt. If it shows distortion or cracking with magnaflux, then look at the receiver.

atblis said:

Hmm. This has just jumped to the front of my list. The gun is chambered much tighter than I would have thought for a factory gun.

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Weatherby rifles have generous free bore like a military bore.... so I'm guessing most if not all magnum rifles are the same? Do you have a OAL guage?