Can I rechamber a barrel after overpressure round?

[Jakeonthekob]

So... I made a huge booboo. Was shooting my 7-300 win mag and get a hugely overpressure round which results in not being able to extract the brass. Completely my fault, most likely issue with too much powder and bullet seating depth trying to chase the lands. But the main issue is my barrel chamber. I got the brass out then borescoped and it looks like brass residue in the chamber. To my untrained eyes the throat and rifling seem ok with usual copper fouling.

My question is, am I able to have the barrel set back and rechambered or would there be potential issues with the structural integrity of the barrel and better to just rebarrel?

Yeah I made a pretty stupid mistake but live and learn right?

 

[Kadams1563]

If you got the brass out and didn’t destroy the action I’d bet the barrel is just fine. Just get it all cleaned up. I doubt you could actually damage a chamber with an over pressure round unless it was catastrophic failure.

 

[Elite_KG]

If you have fire-formed brass before the overpressure round, you can load a minimum powder charge round (or even less than minimum) using full-length sized brass and fire-form in the chamber post incident. Comparing the brass before and after the overpressure can give you indication if any chamber distortion exists. Just measure all the case dimensions and compare a chamber fired brass from before the overpresssure and the min or less than min powder, chambered fired case.

Metal does expand and swell under pressure. Under extreme pressure it may not return to the original size. If the chamber is distorted then I would consider a new barrel as the integrity of the grain structure will be compromised.

I imagine you will not find any distortion as there is a fine line between distortion and catastrophic failure especially at the pressure of a magnum cartridge overpressure. It is possible…

Good luck and glad your made it out safely. Thats like my worst fear in reloading. Any idea how you ended up with an overpressure charge of powder? In many cases the cartridge will not hold a double charge.

 

[Schw15]

So... I made a huge booboo. Was shooting my 7-300 win mag and get a hugely overpressure round which results in not being able to extract the brass. Completely my fault, most likely issue with too much powder and bullet seating depth trying to chase the lands. But the main issue is my barrel chamber. I got the brass out then borescoped and it looks like brass residue in the chamber. To my untrained eyes the throat and rifling seem ok with usual copper fouling.

My question is, am I able to have the barrel set back and rechambered or would there be potential issues with the structural integrity of the barrel and better to just rebarrel?

Yeah I made a pretty stupid mistake but live and learn right?

I shoot 7mm-300 win mag as well what was the load you had when you had the issue? Were you able to get the bolt open and then knock the case out? Was the brass broke? I wouldn't think it damaged the chamber without any other major issues with bolt action ect.

 

[Jakeonthekob]

Thanks all. I used 73gr retumbo, or apparently it was. Maybe I made a mistake and accidently loaded 75gr. I could barely get the bolt to open, but no split case. After I got the case out, dry running the gun, everything seems to be ok. I am working with Erick from straight jacket who's been very helpful. May just rechamber in 7 rem mag. Problem is finding brass, like with most things these days.

 

[Schw15]

Thanks all. I used 73gr retumbo, or apparently it was. I could barely get the bolt to open, but no split case. After I got the case out, dry running the gun, everything seems to be ok. I am working with Erick from straight jacket who's been very helpful. May just rechamber in 7 rem mag. Problem is finding brass, like with most things these days.

What grain of bullet?

 

[Jakeonthekob]

What grain of bullet?

195 berger.

 

[Schw15]

195 berger.

What brass are you using? I would say just back it down to 67 and work back up. I'm sure you will be at the 68 to 71 grain range for a good load. What are your speeds? If you were able to open the bolt but hard I don't think anything is damaged and your good to go just don't test your luck anymore

 

[Jakeonthekob]

I used poor quality jag brass while waiting for something better quality to come up. Yup, I should have double checked. Now I'm triple checking my loads.

Also not sure about speed. Probably about 3050+ fps.

 

[Schw15]

Lapua makes it and you can find it but make sure the neck is big enough in chamber. Adg is good brass but I actually run norma brass for mine. I'm currently running 71 to 73 grain imr 8133 with 183 smk. The imr 8133 is very close to retumbo and I've seen a touch of speed loss with imr 8133 than what people get with h1000 in the 7mm-300 win mag. I mainly went with it because of brass its everwhere

 

[Schw15]

This might help load data from a 7mm-300 practical. Which is a improved version so it hold a little more powder.

 

[Jakeonthekob]

Thank you for all the advice. Still debating if I will stay with 7-300 or just change to 7 rem mag. I'll prob need to get a neck turner too.

 

[Schw15]

My reamer has a .317 neck and no need to neck turn on adg or norma brass necking them down. My bushing is .310 and loaded round is .312

I had a 7 mag and went to 7mm-300 win mag. Both good options. Is this a target rifle or hunting?

 

[Jakeonthekob]

Target rifle. Got it in a cadex chassis with kelbly atlas action with APA fat bastard brake. Pretty sweet to shoot when I do my part.

 

[Schw15]

Target rifle. Got it in a cadex chassis with kelbly atlas action with APA fat bastard brake. Pretty sweet to shoot when I do my part.

Yeah they are awesome to shoot. The 7mm-300 win mag is a very easy caliber to tune up. Mine pretty much shoots good with anything and my other barrels have been the same.

 

[Jakeonthekob]

So I got my borescope and saw this in the chamber not to mention a lot of longitudinal scratches. This definitely needs a rechambering job. So lesson to the wiser... Double check your loads haha.

 

[pyrotechnic]

Did your smith chamber your barrel with a dremel? What does the fired brass look like? From your post you make it sound like it's in one piece. Did it rupture? Looks to me like a shitpot chambering job. The steel barrel is going to be just fine long after your brass is extruded into your ejector recess and your firing pin is wearing your primer like a tophat.

ETA: The above was unhelpful. A rechamber job might be in order for you. Not because you had an overpressure round (especially if it the brass came out in one piece). But because it looks like you have rough chamber walls that will cause cases to stick as soon as your reach the elastic limit of brass. The brass will deform into the rough chamber walls creating a mechanical lock.

 

[Phil McGrath]

It maybe a little ruff polish the leade and clean the chamber with a green scotch-brite pad. You have nothing too loose.