I accidentally fired a .270 bullet through a Rem 7mm Mag Rifle. Should I be concerned about the next round?

Question

The rifle appears to be undamaged. I had shot about two dozen rounds sighting in the rifle, when I accidentally grabbed a .270 round, which must be similar in length to a 7mm Mag round. The gun fired, and hot gas shot out the back (into my cheek) and smoke was around the chamber. I was able to pop the cartridge out with a cleaning rod without too much difficulty, and the bullet had been expelled. The casing was torn from the gas expanding, but the bolt on the rifle seems to be fine, and the rifle appears to be no worse for wear.

Should I have the rifle professionally examined before I re-fire? I was going to fire off a round from a distance with a string and see how that goes. I feel lucky that the barrel did not explode in my face! Like I said, the rifle seems to be ok, no cracks in the bolt or the barrel. Thanks.

P.S. I don't need any patronizing comments (Roger), I'm a lifelong hunter too. I had finished the new box of 7mm shells, and didn't realize there was ONE 270 bullet mixed in with the rest of the 7mm mag bullets I pulled out of a hunting vest, as I was loading them one at a time. Constructive comments only please.

That said, how does a professional gunsmith check for micro-fractures? Doesn't the barrel undergo as much or more stress from firing 7mm rounds than the undersized .270 round? My late season hunt starts Saturday and I am not near any gunsmiths here in the mountains. Borrowing someone elses rifle is not too appealing either, but better to be safe than sorry.

Answer 1

As a qualified Gunsmith, personsally I would take it to a local Gunsmith and have it checked out before you take it hunting or shoot it again. If in fact there are "stress fractures" referred to as "striation cracks", the will be difficult to see with the naked eye. A magnifying Fiber Optic device is used with an artificial built in light source, with magnification adjustment to examine/scope and check the Bolt, chamber, throat & leade (The area just in front of the chamber where the rifling begins) for any surface damage and/or fine hairline cracks....Not every Gunsmith has this equipment, so it might take you a while to locate a Gunsmith equipped to do this.Chamber castings are useless to diagnose any of these problems, and Magna Fluxing hasn't been used for the last 15 years or so (Suggested by another answerer)

You aren't going to like this part either, but I would stay on the side of caution and not use the rifle...even if it means using another. It isn't safe to fire so there is no way to insure that there isn't damage enough to effect the accuracy anyway...You don't want to go on your hunt only to take a chance that your rifle won't hit anything accurately or God forbid you get hurt or someone else does.....Sorry, but thats the straight scoop.

P.S. You might be perfectly OK, but if it is in fact damaged, a few rounds down the road and that thing could just come apart in your hands and face..You lucked out this time, don't tempt fate again....

Answer 2

To repeat what others have said, you were way lucky! I bet you keep closer track of your rounds now :) I could be wrong, but from what I know about metallurgy, there is really no way for a gunsmith or anyone else to really be able to tell by a visible inspection if there are no visible cracks or distortions, you will need to have it examined under a device, which for the life of me I can remember the name, it's a x-ray type of device that checks for metal stress and fractures. You could also take a micrometer and run it down the barrel and see if there is any change from a new barrel.

With no facts to back this up, and just as a guess, I think the gun would be fine. Barrels are made of some incredibly hard steel and as long as there was no obstruction causing gases to distort it, you should be fine. The .270 is close enough to a 7mm in diameter, so you the other problem, the bullet bouncing around the barrel damaging the lands, shouldn't be a problem either. If it was me, I would put the gun in a vice and use the string on the trigger method and fire a couple of boxes through it, and call it good. Good luck and definitely say your prayers tonight, someone had their little finger on you with that accident!

Answer 3

This Site Might Help You.

RE:
I accidentally fired a .270 bullet through a Rem 7mm Mag Rifle. Should I be concerned about the next round?
The rifle appears to be undamaged. I had shot about two dozen rounds sighting in the rifle, when I accidentally grabbed a .270 round, which must be similar in length to a 7mm Mag round. The gun fired, and hot gas shot out the back (into my cheek) and smoke was around the chamber. I was able to...

Answer 4

Don't feel too bad, before the 280 remington was what it is, it was the 7mm express, which unfortunately found its way into many a 7mm mag without too many incidents. The issue with this subload is not pressure, the 270 and the 7mm mag operate at the same pressure loads. The real issue is a case rupture which can be catastrophic. The 270 bullet being a smaller diameter will pass through the bore (.280 diameter for the 7 mag) without causing any problems.

To answer your secondary question, the best way to check for cracks is magna flux for the bolt body and chamber. Some smiths will make a cast of the chamber, but finding hairline cracks will be tough, but it will let you know if the chamber is out of spec. That being said, it would be a wise idea to have it checked out.

John

Answer 5

As with any firearm, pressure difference is the enemy. I believe the 270 has higher pressure than the 7mm when fired, but since the chamber was bigger than the 270 brass could expand the brass was compromised, higher pressure was negated into the reciever and it couldnt build normal pressure. Basicly, it acted as a "squib" load or subsonic round.
Think of it this way. A .22 can achieve good velocity if fired from a rifle. The same round if thrown into a campfire would at the most just "poof" because there is no barrell to hold the pressure up and speed the bullet out. Kind of like popping a balloon. Once popped, the air pressure goes every direction. If it is contained in an opened end container like a milk carton it will direct all of the pressurized air in one direction concentrating it for a good blast of air.
All in all, having someone check it is not a bad idea, but if it is a decent rifle you shouldnt have anything to worry about.

Answer 6

Your rifle is probably OK, but have it looked at before you fire it again. Luckily a .270 bullet (.277") is smaller than a 7mm bullet (.284")so I'm sure it went down the barrel with no problem. The problem was that since a .270 case is smaller in diameter than a 7 mag, when you fired, the case expanded to fit the larger chamber, and as you discovered, it ruptured. Most modern bolt action rifles are designed with mishaps like this in mind, and are designed to direct as much escaping gas away from the shooter's face. Lucky for you you weren't injured. Good idea to wear shooting glasses for just this reason.

Answer 7

I'll leave out the lecture, and consider that the .270 has a a smaller diameter bullet and roughly the same working pressure I'd say your fine. The bullet never seated in the lands so it could not build up enough pressure to even seal up the chamber {why smoke came out the rear}. And while this is an extreme example of "case forming", that is how cases are formed for wildcat rounds. Lucky you though, the hot gasses can blind you. Clean the rifle and go shooting.

Answer 8

The rifle has probably survived. I doubt there is anything wrong with it but for liabilty's sake, I would recommend having it looked at by a competent gunsmith.

The things you will want to do is make absolutely sure that all of the bullet left the barrel, make sure the jacket didn't seperate and stay behind. Second, use a few patches and clean your chamber in the barrel as that you will have some fouling in it.

If you absolutely don't want to spend the money to get it looked at, the next best thing is to tie it down and fire several rounds with the string as you desribed. That is how I test my legally manufactured homebuilds.

Answer 9

quik66gt;
Well said, there is no way that this can damage a rifle.
I have examined 308's that have fired 243's and just about every other combination that you can imagine, and never, in 40 years of being a gunsmith, have I witnessed any damage to the gun by firing a bullet smaller than the bore. If the bullet that is accidentally fired is smaller than the bore, as in this situation, just clean the chamber and bore and carry on.

Answer 10

You aren't the first to do this little switch and likely won't be the last, either. There really shouldn't be any damage to the rifle if you've got all the brass and fouling out. It isn't as if you'd shot a proof round. You just had a brass failure for obvious reasons. A good stripping and cleaning and you should be able to finish your hunt, and then get it double-checked if you're worried when you get back to where it's convenient. I'd sure double-check to make sure there's a belt on the rest of the cartridges you feed it, though!

Answer 11

The gun should be fine. Basically all you did was "fire form" the brass. The .270 is .277 and the 7mm is .284 so the bullet exited the barrel and rifles have built in safety features in case of something like this. That's why you felt the hot gas escaping. I'm not going to give you the "be more careful" lecture since you've already had it first hand. And although JD said magna-fluxing hasn't been used in years, we still use it every day to check for microscopic cracks in metal.