7mm is very close to .30, so I would think it would be just fine. It's not as precise a job as you may imagine. You're just running a cord with bristles on it through a hole. If it was me, I'd do it.
I wouldn't, they make 7mm (.270) bore snakes that would be better suited. The .30 caliber brush is going to be really tight in that bore and may run a risk of eroding the crown with excessive use. Besides, patches will clean the bore properly themselves.
If the bore snake erodes the crown, then the chamber leade will also wear. I'll say to get the proper size snake or correct cleaning rod tip for patches.
I went looked up the diameter of 7mm Mauser, it's .285. Hoppes shows them being different models in regards to 7mm/.270 vs. the .30 calibers. Due to that, I wouldn't suggest doing it on a regular basis. However.....I'd do it if I didn't have the correct one. Then I'd get the right one as soon as possible.
Sorry to go a bit off-track here, but are you recommending not using brushes in general? I use brass brushes for cleaning all my rifled gun barrels...just wondering if I shouldn't be. Thanks!
I had used brushes, and bore snakes in the past, but honestly I find it to be overkill. I've seen rifles that were extremely dirty, with deposits all over the crown, that shot sub-MOA shot after shot. I would cater the cleaning to the particular aspect of the gun. If it's an AR / AK platform that's just used for run and gun, then I'd use a brush, solvent, etc. and really clean it out. If it's a bolt rifle used for accurate work, then I'd stick to patches. Faster rounds will require a good copper solvent, stuff like .204 Ruger, .223 Remington, etc. Whereas the larger slow-boat rounds tend to have less build-up and require less aggressive cleaning. .22s are another beast. You deal with alot of lead build-up so you need a proper lead solvent and a brush. Running copper washed bullets will help cut down on the cleaning cycle. Like caliber, everyone is going to suggest something different, and a number of methods seem to work just fine. I personally believe in the minimal end of the spectrum in regards to cleaning.
