Throat Erosion Question.

[T.Rhodes]

@46and2 No. I'm going from my load sheets that I did in 2015. Same Lapua bullet but 5 years difference. Hopefully not a lot has changed.

 

[searcher]

Every couple of thousand rounds on my varmint rifles, the accuracy starts to fade a bit. Despite a bit more throat erosion, there are other factors at work such as bore smoothness that effects when bullet leaves muzzle in relation to the vibration in the barrel. If ANYTHING affects your velocity, your accuracy window on your load might be compromised. Check your load on your chronograph. If using your same batch of powder - it is possible some moisture got in your powder VIA humidity. Put the powder in a sealed container with Silica Gel packs to draw out as much as you can get out of it, then re-tune your load - or just try a new batch of powder and then re-tune your load. I load 1,500 rounds at a time for each varmint rifle after a THOROUGH cleaning which includes JB bore paste. Once the bore looks like a mirror, no sign of carbon ring, etc. - then I re-tune rifle and once I'm happy with what I have - I load 1,500 rounds for that rifle. I have used that regimen for many years. I cite this only to highlight the fact that I have never had a load go so bad before the 1,500 rounds were fired so as to cause the group to open up to more than 1/4" more than the tuned load started at - which is usually .2" to .375" or so. I think in your situation, the 1" flyers are indicative of something other than throat erosion. Maybe even your scope mounting screws, action guard screws/bedding, having problems resulting from a carbon ring in the chamber or perhaps you changed something relative to your reloading procedure. I'd soak your chamber overnight using Shooter's Choice or other "mild" solvent you can leave in overnight. Apply heavily to a .410 gauge bore mop or similar and insert in the throat over night. Then scrub with bronze brush - then about 50 strokes with JB bore paste applied to patch wrapped around a nylon bore brush. Then use a chamber brush twisted in circles to remove any sign of the carbon ring. Then get some perfectly dry powder and re-tune your load. Your barrel likely has a lot of life on it, though that is a very subjective topic, depending on what you expect from it. Good Luck

 

[Pawnee Bill]

Post a picture when you get your borescope.

 

[davidjoe]

The suggestion of purchasing one of the Teslong borescopes for about $50 is a good one, particularly in this circumstance. Carbon buildup, or some other issue that you can't visualize without a borescope might be affecting the measurement. Just be aware that purchasing a new borescope can sometimes result in what I like to call "Borescope Anxiety Disorder", or BAD. Those that haven't looked at their barrels routinely sometimes become distressed over every little fire-crack, pit, or other anomaly they might see when they start using their new borescope. If you decide to buy one, I would suggest starting with the "big" picture first. Is there a lot of fouling in the throat?

That’s no joke. Once you have partaken of the forbidden apple meant only for barrel makers and wholesale appraisers, you cannot unsee what the Teslong magic wand revealed. There is no blue pill to erase the encounter.

These are 7 lessons my Teslong Borescope taught me:

1) “slow fire” rifle matches are the Barrel-equivalent of dragging your scoped rifle home behind the car, rather than inside of it, rapid fire matches are using your rifles to scuff the yellow paint below a Caterpillar’s tracks.

2) Stainless steel my butt, you need to oil barrels periodically; just sitting still being cherished, somehow the inside of some barrels can spontaneously break out in surface rust spots as if the makers activated Manchurian chips telegraphing to you it’s time to buy more;

3) you only “thought” that guns were a semi-decent investment;

4) you want the used gun that shows the careless handling marks of someone who was gifted it, but never interested in it;

5) the unspoken criteria for steel selection is a) it cannot melt in direct sunlight, b) now in reference to “a” - what then is easiest on cutting tools to machine;

6) so, ... what would these look like if they weren’t hand lapped?

7) with respect to rust and a judicious bit of copper fouling left to remain, I have never seen a rusty penny, nor have I seen the metal inside a penny’s copper cladding bubble up with corrosion.

All in good fun WI guys.

 

[Jet]

You have a lot of great advice but don't overthink this. It's time to adjust your tune. Get the bullet closer to the lands and increase your powder charge 1/10th-2/10ths of a grain and you might see your old barrel come back to life.

Do a new ladder and seating depth test.

Good Shooting.

Rich

 

[T.Rhodes]

@Pawnee Bill Got the scope yesterday - fast delivery. I really didn't see anything that looked bad to me.

The one on the right shows where the groove begins.

I'm impressed with the unit. Easy to assemble and use and good quality photos.

Based what I see with the scope, I think the barrel is in good shape. So, I'll be putting it all back together and re-starting my load work and shooting.

 

[tominboise]

Your barrel looks great compared to a few I have been working on. I think you have no problems there. I am still coal mining a couple of mine...

 

[JEFFPPC]

I seldom have chased the lands. If I think the barrel is going away I go to the tuner. Recently a 6BRX barrel with 1700+ rounds seemed to loose it's edge. I shoot 107s with a pretty stiff load of Varget. So as an experiment after looking at some erosion figures on the PRS site, I seated plus .003, plus .006, and plus .009. I first shot a five shot group with my established depth. The .003 shot tighter, like it originally shot. The .006 shot like my original load shot now, the .009 was a pattern. In 2 matches since it has gotten a second and a third. One bad wind call at each match, one at 400yd and one at 500 yd cost me a match win. The .003 improvement made was much less than I would think needed from the information in the PRS article but is was still a good move. Something worth considering. Once the season starts I base everything on , Am I
competitive. I evaluate based on the results on target by other shooters compared to what I am doing. Those pretty little groups on your home range don't count in head to head matches.

 

[DGP4]

Looking at those borescope pics, I'd say you are in very good shape. If the erosion bothers you, a good gunsmith will remove the barrel cut off the chamber and re-chamber it for you at not much cost. You may find however that a good jump with the right powder and bullet will often give you better accuracy. Varget and SMKs are the gold standard in all my .308s.

 

[T.Rhodes]

Thanks, @DGP4 . Now that I've scoped it and it does look in good shape, I've re-assembled and done a little shooting with Lapua 167's and some H-380 45.5gr. Shows some decent groups. I'll keep as is and get more rounds down range and see what I see.

 

[DGP4]

Wow! Those targets look mighty good to me! I'd say you have nothing to worry about.

 

[Steve Ladino]

Lots of good advice here. @coldboreshot was probably spot on with slow down, take a breath, ...not my usual mode of doing things. I have been doing some serious cleaning with brushes, jags, Hoppe's 9, Sweets 7.62, and J B Bore paste. I got a little blue from the Sweets.

I've had it in two different stocks , H-S Precision and Magpul Hunter. Not a significant improvement in either.

I'll put all back together and start from scratch to see where I am now with.

I had carbon and copper build up on top of my lands almost from the start and I thought that the lands were eroded away ( first few inches that is ) turns out as I said it was carbon on top of the lands that showed little tiny flecks of shiny copper imbedded in the carbon. I cleaned and cleaned but the carbon didn't diminish, even with Iosso and JB .
One day I relayed my predicament to a friend ....his advice was to use carburetor cleaner.... I did......it took the carbon right off and revealed an under layer of copper which I quickly removed with Sweets. My gun shoots great again, like new. Possibly you may have something similar and the bore scope will really reveal what's what after you figure out what you are looking at.

 

[JEFFPPC]

Steve, what brand of carb cleaner and what method did you use with it.

 

[hambone1971]

I have a Savage 12FV 6.5 CM with 5000 rounds through it now. Still 1/2 MOA gun but I've never run hot loads, just an accurate lower node that does the job. If you look at the barrel with a bore scope you would swear the first couple inches after the chamber is toast and the gun could never shoot, But it does. I've never chased the lands ever. I did lower my load slightly from 41.9 to 41.8 of RL-16 shooting Hornady 147s and Hornady brass. Still wondering when it's going to give up but for now it's a great shooter. I think your gun barrel is just fine..HB

 

[Steve Ladino]

Steve, what brand of carb cleaner and what method did you use with it.

Walmart brand ( super tech I believe ) sprayed on a patch.

 

[JEFFPPC]

Walmart brand ( super tech I believe ) sprayed on a patch.

Steve, thanks.

 

[Steve Ladino]

Steve, thanks.

Yes Sir.

 

[hambone1971]

I have a 700 that I have shot since 2013 and has 2-3,000 rounds through it (about- I haven't been diligent about round counts). I haven't been able to get it to shoot well this year and was wondering if the barrel is done for. I'll get one or two sub 1/2moa shots, then a flier 1+moa.

Checking old load sheets and how I'm loading the same bullet today ( Lapua 167gr Scenar) there is a difference of .077" in bolt face to ogive. The ogive is, naturally, further out now.

My question is; is the .077" enough to say it's time to re-barrel, or is this normal? I have heard 308's have a long barrel life, but I could use some input from others.

Thanks in advance.

One of my books suggest that 308 barrel life can be upwards of 6000 rounds before accuracy falls off. See "Fundamentals of Long Range Shooting" by Ralph T. Hicks, page 88 he's talking about barrels. He shoots 3000 rounds a year normally. Just food for thought....HB