Throat Erosion and Accuracy

[RonDeer10mm]

I once shot my first rifle a .270 without giving it time to cool down I shot 40 rounds in about an hour or less you guys think that that could have eroded it a bit?:banghead: the barrel was hot

 

[redneck2]

Depends on the time between shots. I know it was an hour, but if you shot 39 in a couple of minutes (just an example), it might have gotten too hot.

Easy way to tell is to shoot a group. If it's good, you're OK. Don't drive yourself crazy.

 

[RonDeer10mm]

Thats the thing I dont remeber but that was three years ago and ive moved on to a new .30-06 but it was a $900 rifle ive learned alot since then :banghead:

 

[LoonWulf]

i doubt you hurt your gun much if you only did it once. but again as redneck said, if you machine gunned it "ya might have a problem". Again tho i doubt it would be a major impact. Ive seen rifles get hot enough to give minor contact burns and be none the worse for ware.

 

[Slamfire]

Don't worry about it. I regularly shoot 40+ rounds in an hours when sighting in my centerfire rifles.

Now if you were shooting those rounds rapid fire, that is five rounds in 30 seconds, you would have increased throat erosion over five rounds in five minutes.

 

[dakotasin]

^ agree.

don't worry about it. very few people will legitimately shoot a barrel out of your average deer rifle anyway.

 

[RonDeer10mm]

Is there a way to measure throat erosion? I want to find out.

 

[briansmithwins]

Is there a way to measure throat erosion? I want to find out.

Yes, you need a throat erosion gauge. It's going to cost a significant fraction of what your rifle did and it's only going to be good for that caliber.

Pratically, shoot your rifle. If it groups the same as it did before you went all crazy, you don't have any real damage to the throat. BSW

 

[Al Thompson]

I actually shot a used M70 somewhat out. Had to really extend cartridge OAL to the point my old reloads wouldn't chamber in a replacement M70. My round count was probably close to 3k rounds, some fired quite quickly. Forty rounds is pretty mild compared to some of the stupid things I did.

 

[RonDeer10mm]

Thanks for the helpful feedback guys

 

[NCsmitty]

They have bore scopes that range from simple 4x magnified tubes to fiber optic state of the art versions with which you can do endoscopy's on the side.

The 270 is a pretty intense high pressure cartridge, but it is also a large enough bore to avoid the problems of the smaller bores that blow torch the metal like the 6mm-284 or the 22-243.
I'm sure that the 40 rounds in an hour will not do much but leave a bit of copper wash buildup in the throat. Solvent and a brush will take care of that.



NCsmitty

 

[MMCSRET]

I put almost 8000 rounds thru a Winchester Model 70 in 270 Winchester over a period of 20 years using Winchester 760 powder and 130 grain bullets. It was my only CF rifle for most of that time and got used for everything from ground squirrels to elk. The accuracy started to fade at about 5500, I rebarreled at just short of the 8000 mark, we cut the old barrel to look at the throat and bore, the throat was pretty well eroded, but the bore and rifling was still strong for the last 15" or so.
I rebarreled it to 338-06, as I had already bought another M70 in 270.
I bought the rifle in 1973 and rebarreled it in 1993.

 

[stubbicatt]

I realize that the topic of longevity is an important one, but I sort of feel like I've accomplished something whenever I have to replace a barrel because it is shot out.

 

[Howard Roark]

Throat erosion can be measured by measuring the distance to the lands with an OAL guage (Hornady, formally Stoney Point) or simply by progressively seating a bullet out longer and longer to find when it meets the lands. A base measurement has to be made before the first round is shot. The measurement is taken every few hundred rounds to see how the throat length grows longer. The same bullet type must be used so that ogive bearing is always the same.

My .260 has eroded .012 in 1000 rounds. This number will grow longer quicker as the throat erodes in the future.

 

[Geno]

When we shoot the machineguns, we have to limit our bouts to 150 rounds. It doesn't take any time to launch 150 rounds through an M16 or MP5...as in seconds. No damage done there.

Geno

 

[USSR]

No problem. In F Class Matches, we shoot about 25 rounds in 30 minutes. Yes, the barrels do get warm.

Don

 

[lencac]

I regularly shoot 40+ rounds in an hours when sighting in my centerfire rifles.

What possibly could be wrong with this picture

 

[Uncle Mike]

It's not so much a 'measurement' or 'distance' that is the determining factor with throat erosion, but it is 'how' the throat erodes....the throat does not erode symmetrically, or even, so while a standard OAL gauge will get you throat erosion information, only a bore scope will tell the real story....and you'll have to know what your looking at in that scope.

 

[twofifty]

When accuracy dropped off on my target rifle, I used the Stoney Point OAL gauge to see if this might be due to throat erosion.
Sure enough, the gauge told me that I could seat the bullets a bit further out. So I reloaded longer OAL ammo and accuracy returned.