30-30 Possible Over Pressure What to Inspect

[Chestnut]

I was shooting subsonic loads from my Marlin 336 in 30-30 today. On the 2nd to last shot i hear a much louder noise and the bullet must have gone through the target sideways. Instant red flag. When trying to eject the brass the lever was stuck and wouldn't eject. I didn't use too much force and just packed up.

Getting home I scoped the rifle confirmed nothing was split in the chamber or anything super drastic had happened. I grabbed a bit of 1/4" brass rod and knocked the cartridge free as i figured it was better to do that then gorilla the lever of the rifle. Couple light taps and the brass ejected. I measured the shot brass and it missed a trim and was right at 2.039". I normally trim to 2.027" so carbon must have built up and pinched the bullet.

My main question is did I damage anything? What should I carefully inspect to ensure the rifle is still in functional order? I'm not very knowledgeable with Marlin 336s so I don't know what to check for.

Again it was a subsonic load. Specifically 6.74gr of titegroup behind a 190gr projectile with CCI200 primer The chronograph didn't measure the velocity so my guess is it was over 1600 fps. Pictures to show the brass in the chamber before knocking out and after removal.

With carbon buildup in the neck what's the best size brush for .30 cal to remove carbo?

 

[Oso]

A couple of quick questions.
How old is your Marlin 336?
Were you using a suppressor while shooting the subsonic loads?
What type of bullet… cast lead?
How much of a crimp do you use?

Hodgdon reloading data says 7.4gr Titegroup pushes a 175gr bullet at 1,071fps.
> You’re loading was with a heavier bullet (190gr) with less powder (6.7gr). It sounds like the cartridge in question might have been traveling 2x the speed…

What’s the chance of a double charge?

 

[Chestnut]

A couple of quick questions.
How old is your Marlin 336?
Were you using a suppressor while shooting the subsonic loads?
What type of bullet… cast lead?

Manufactured 2019 336BL with 18.5" barrel to be specific
Yes Dead Air Nomad XCTI
Hornady sub-x 190gr bullets so copper jacketed

 

[Oso]

I just edited my above post. Barrel is new steel so able to handle pressure.
Any sign of a baffle strike?

 

[Chestnut]

What’s the chance of a double charge?

Slim i cap each brass with a bullet after dumping the charge because of the double charge fear. Running GRT I'd be able to double charge and not over pressure. Though who knows if that's accurate.

No baffle strike, that was my first thought so i inspected the suppressor extensively, removed front cap etc.

 

[Coyotefurharvester]

Bolt would be a much weaker part than the barrel, inspect it carefully. Clean the chamber/bore to bare metal, keep it clean.

 

[Chestnut]

Bolt would be a much weaker part than the barrel, inspect it carefully. Clean the chamber/bore to bare metal, keep it clean.

What size brush is best for the neck / chamber of a 30-30? I have a .45auto brush but that seems too large.

 

[dellet]

Was the primer flat?
Was it sticking out of the case head?

 

[Coyotefurharvester]

Maybe a .410 shotgun brush for the chamber,338 for the neck? I think pro shot makes a flexible chamber rod for lever actions?

 

[dellet]

And what’s the twist rate of the barrel.
You probably have two different probmems