questions on throat errosion, again... lol

std7mag · November 26, 2013, 07:52 PM

Ok, so lets say someone has a rifle chambered in 6mm Remington BR.
After "x" amount of rounds, said person notices that it is not as accurate as it once was, and discovers throat erosion.

My question is, to what length does the throat typically erode?
aka could this person rechamber the barrel to say a .243 Win AI?

And once that erodes, could you go to say a 6mm-284?

Each rechambering being slightly longer than the previous.

Or am I waaay over simplifying this???

Rimfire5 · November 27, 2013, 09:53 AM

I have a Savage 10 FCP-K that I measured the chamber for when it was unfired and after 800 rounds.
The chamber to ogive measurements for Sierra 168 SMKs increased by 0.013 inches.
A buddy with a slightly older (1500 rounds) 10 FCP-K had a chamber increase of 0.030.

I put over 6000 rounds through my original Savage 10 FP before it started to lose accuracy and I sent it back to the factory for a new barrel. The chamber length increased over 0.1 inches by the time I decided it was ready for a new barrel.

I just got it back from Savage with a new upgraded threaded and fluted target barrel with the action bright and shiny and the stock looking brand new. They did a great job in cleaning it up.
The total bill was $429 including shipping back to me. If I didn't upgrade the barrel and have it fluted, the total price would have been about $333. It took about a month from the time I sent it to the time it returned.

It goes to the range for its first range session on Friday morning.

FrankenMauser · November 27, 2013, 03:00 PM

Unless you want to make all of your existing dies and brass obsolete, there's no reason to rechamber the barrel to another cartridge.

There are two cheaper options for fixing a eroded throat:
1. "Throat" it. - Cut the throat deeper, to clean it up. Of course, some people will feel the need to load bullets to OALs that put them right on the lands; while others are fine with a little more bullet jump. It's your call.
2. Set the barrel back. - Pull it, take a small slice off the chamber end, recut the chamber, and reinstall it.

Every throat erodes differently. The most extreme case I've seen was a .223 WSSM that had over 0.300" 'sand blasted' into oblivion by a shooter that would fire continuously, until the rifle was too hot to handle. He bought it new and only took the rifle to the range 3 times, before he had completely cooked it.

tobnpr · November 27, 2013, 06:12 PM

Sounds to me like you're way overcomplicating it, not oversimplifying.

Like FM said. Why change chamberings? Keep what ya got.

November 26, 2013, 07:52 PM	#1
std7mag Senior Member Join Date: June 23, 2013 Location: Central Taxylvania.. Posts: 3,609	questions on throat errosion, again... lol Ok, so lets say someone has a rifle chambered in 6mm Remington BR. After "x" amount of rounds, said person notices that it is not as accurate as it once was, and discovers throat erosion. My question is, to what length does the throat typically erode? aka could this person rechamber the barrel to say a .243 Win AI? And once that erodes, could you go to say a 6mm-284? Each rechambering being slightly longer than the previous. Or am I waaay over simplifying this???

November 27, 2013, 03:00 PM	#3
FrankenMauser Senior Member Join Date: August 25, 2008 Location: In the valley above the plain Posts: 13,424	Unless you want to make all of your existing dies and brass obsolete, there's no reason to rechamber the barrel to another cartridge. There are two cheaper options for fixing a eroded throat: 1. "Throat" it. - Cut the throat deeper, to clean it up. Of course, some people will feel the need to load bullets to OALs that put them right on the lands; while others are fine with a little more bullet jump. It's your call. 2. Set the barrel back. - Pull it, take a small slice off the chamber end, recut the chamber, and reinstall it. Every throat erodes differently. The most extreme case I've seen was a .223 WSSM that had over 0.300" 'sand blasted' into oblivion by a shooter that would fire continuously, until the rifle was too hot to handle. He bought it new and only took the rifle to the range 3 times, before he had completely cooked it. __________________ Don't even try it. It's even worse than the internet would lead you to believe.

November 27, 2013, 06:12 PM	#4
tobnpr Senior Member Join Date: August 1, 2010 Location: Tampa Bay Posts: 4,556	Sounds to me like you're way overcomplicating it, not oversimplifying. Like FM said. Why change chamberings? Keep what ya got. __________________ Remington 700/Savage Rebarreling /Action Blueprinting 07 FFL /Mosin-Nagant Custom Shop/Bent Bolts Genuine Cerakote Applicator www.biggorillagunworks.com

November 27, 2013, 09:53 AM	#2
Rimfire5 Senior Member Join Date: January 2, 2009 Location: Northern Virginia Posts: 923	I have a Savage 10 FCP-K that I measured the chamber for when it was unfired and after 800 rounds. The chamber to ogive measurements for Sierra 168 SMKs increased by 0.013 inches. A buddy with a slightly older (1500 rounds) 10 FCP-K had a chamber increase of 0.030. I put over 6000 rounds through my original Savage 10 FP before it started to lose accuracy and I sent it back to the factory for a new barrel. The chamber length increased over 0.1 inches by the time I decided it was ready for a new barrel. I just got it back from Savage with a new upgraded threaded and fluted target barrel with the action bright and shiny and the stock looking brand new. They did a great job in cleaning it up. The total bill was $429 including shipping back to me. If I didn't upgrade the barrel and have it fluted, the total price would have been about $333. It took about a month from the time I sent it to the time it returned. It goes to the range for its first range session on Friday morning.