Throat erosion in 308 Win

[BCoates]

I just rechecked my dead length seating measurements for the bullets I shoot last night. My rifle has about 500 rounds down the tube and I'm seeing about 0.020" longer distance to the lands measurements than when the rifle was new.

My question is has the throat of my rifle really eroded 0.020" in 500 rds or did I not measure correctly the first time? The first time I measured I was using the Hornady tool and a different lot # of bullets. This time I just removed the ejector and firing pin and used a case that I cut slits in the neck to allow the bullet to slide.

 

[jonbearman]

Do you know anyone with a bore scope?

 

[savageshooter86]

My 308 match rifle has only changed 0.002" in little over 1200 rounds. This is distance to "touch"

 

[kevinbritvec]

In order to get accurate measurements you have to use the same individual bullet every time. Bullet base to ogive measurements vary within a given box and between different lot numbers. Unless you saved and reused the original bullet from the first measurement your current measurement is probably flawed.

.020" isn't a lot. A would expect that the throat's wear will slow down from this point forward.

4000 accurate rounds is a general guestimate for .308. Some get less, some get more, but it's a very good caliber as far as barrel life is concerned.

 

[Down South]

I just rechecked my dead length seating measurements for the bullets I shoot last night. My rifle has about 500 rounds down the tube and I'm seeing about 0.020" longer distance to the lands measurements than when the rifle was new.

My question is has the throat of my rifle really eroded 0.020" in 500 rds or did I not measure correctly the first time? The first time I measured I was using the Hornady tool and a different lot # of bullets. This time I just removed the ejector and firing pin and used a case that I cut slits in the neck to allow the bullet to slide.

I use the same bullet i started checking with since the barrel was new. I use the Hornady tool as well and after 550 rounds on my current barrel i'm only seeing about .003 erosion as far as i can tell.

 

[BCoates]

Thank you for all of the replies. My guess is I didn't measure correctly the first time. My initial measurements were before I shot any rounds down the barrel, so there could have been a little bit of roughness from chambering that wouldn't allow the bullets to reach all of the way to the lands.

I don't know anyone with a borescope, but I did give the barrel a good cleaning with JB bore paste after I shot it last so I'm sure that it is very clean. Now to recheck my loads for the proper seating depth. Hopefully I can get a little bit more accuracy out of it.

 

[Camaro80z]

There is a possibility that a high energy double base powder like the vv500 series could cause premature throat erosion what powder are you using?

 

[Dos XX]

There can be a lot of variation within a lot of bullets as well as between different lots of bullets. You need to use the exact same bullet to measure throat erosion.

My last .308 barrel had .030 erosion after 3500 rounds.

 

[artbosco]

I just rechecked my dead length seating measurements for the bullets I shoot last night. My rifle has about 500 rounds down the tube and I'm seeing about 0.020" longer distance to the lands measurements than when the rifle was new.

My question is has the throat of my rifle really eroded 0.020" in 500 rds or did I not measure correctly the first time? The first time I measured I was using the Hornady tool and a different lot # of bullets. This time I just removed the ejector and firing pin and used a case that I cut slits in the neck to allow the bullet to slide.

Whose barrel are you talking about and which grade? ???

 

[BCoates]

I've been shooting with a load of 44.5 gr IMR4064 with the 168 SMK. This load is not particularly hot, and I'm not using high energy powders. The barrel is a Bartlein SS 1:11 twist with a Palma Bisley chamber with 0.090" freebore.

The bullets I used to check the distance to the lands with are the 168 SMK and 168 Berger Hybrid.

 

[dragman]

First: I am not a .308 guy, but it sounds to me like the problem is the different lot of bullets! I have seen different lots very quite a bit so that would IMHO probably account for 80% of what your seeing as wear.