Is my barrel worn out?

[Bluefinger]

Hey all, I've got a question for those of you that have worn out a barrel on a rifle. I'm sure that there's plenty of you on here. First, let me tell you what I have going on.
I have a Remington 5R Milspec in .308 with the 24" barrel. I've been using it shooting F T/R and have just under 2400 rounds on it. I bought the rifle new and worked up a load using 175gr SMK's, Varget, Lapua brass and Fed 210M primers. I found a very accurate load at a high node of 45.9 gr of powder. This gives me 2730 fps with no heavy bolt lift or signs of real excessive pressure; the primers are pretty flat though... it's hot. Anyway, this combination was a consistent .5 moa load. The cartridges were loaded just short enough to go in the magazine, I never measured to see my rifles OAL to the lands, I was lucky that they shot so good right where I started so I never checked it.
Last week while shooting at the range, my accuracy seemed to just "go away" after about 25 rounds. I always start each session with a 3 shot group at 100 yrds just to confirm my zero before moving out to the steel. After several misses, I went back to the 100 yrd target and fired about a 2.5" 3 shot group. Tried three more, same thing. Packed up went home.
That night, I gave it a good cleaning. I use a mixture of Kroil and Shooters choice. After that I filled the barrel with Wipe Out foaming cleaner and let it set for 4 hours before patching it clean. I normally use the Wipe Out every 150 rounds or so, the Kroil, SC mixture in between. After that, I checked the rings, base, and action screws/ bolts for proper torque. Everything was in spec.
I went back to the range today. The best that it would do was a 2" group at 100 yrds with no rhyme or reason where they landed. Scattergun.
Finally, my question. Is this how a "shot out" barrel behaves? This one was shooting really good, then pretty much took a sudden dive. I did measure the OAL length just before writing this; It's 2.37 to the ojive of the bullet.

 

[diego-ted]

That's how my 6.5x47 went. :-[
Diego

 

[GNERGY]

Are you sure you got all the carbon out of the neck throat area. ( there is nothing that dissolves carbon ) When my 308 starts shooting larger groups then normal I take a brass brush and scrub the throat and then take some patches with your cleaning solution and you will see the black come out of there. You might have to do it twice, when you don't see any more black coming out the carbon is gone and then go shoot it some more, my groups come back to normal.
That is what works for me
Tarey

 

[Alex Wheeler]

Do you have any one who can borescope it? Get some iosso and a iosso nylon brush and give the throat a good scrubbing. You probably have a carbon issue if you only use a solvent. Also take a look at the crown for damage.

 

[Bluefinger]

I've been working it over with Holland's Witches Brew. I think it's a mixture of iosso or something similar and kroil. We'll see what happens. I looked at the crown with a magnifying glass, it looks perfect.
How many rounds would you expect a barrel to last with my "hot" load. I run it pretty hard... Shooting while it's hot, etc. This is the rifle that I bought to get into F class shooting. My plan was to wear it out learning to read wind, and it has served that purpose very well, I just thought I'd get 3000-4000 rounds out of it at least.

 

[savagedasher]

My Dasher did the same thing. We were a 1/2''x ring at 100yds.I had 18 x all on the inside of the line. The 19 just touched the line . My last 5 open up to 1 1/2''. I gave it a good cleaning and tried 5 more . All 5 were around 1''. Larry

 

[djporter]

Ditto what Diego said

 

[bobinpa]

I'm definetly no expert, but I would think that you could/should get more than 2400 rounds out of a 308. I would try a different scope just as a precaution before you assume it's shot out. Maybe something went south inside the scope. And, as others have said, get it bore scoped.
Just my .02 Good luck

 

[bobinpa]

By the way Bluefinger, it's nice to see that you are a site contibutor with only 7 posts.

 

[Bluefinger]

Bobinpa, speaking of contributing to the forum, I need to do it again. This place is a wealth of information and I'm grateful for it. I don't post much, but I read things on here every day.

I'm going to keep cleaning until I don't get a trace of anything on the patch. I have access to a bore scope. I'll check it out.

 

[Bluefinger]

The scope is a Nightforce NXS 5.5-22x50. It's always been dead nuts on, but it is possible that it could be the problem. I'll try a different scope if the super cleaning doesn't work.

 

[lrgoodger]

Do you clean regularly with Holland's Witches Brew? It really cuts the carbon out, so if you use it regularly, I would not expect carbon buildup. It cuts so well it is possible to over-clean with it. I would definitely recommend a bore-scope to anyone using that product so you don't keep scrubbing with it once everything is out. It will keep coming out black even after the barrel is clean.

I've never seen a barrel go south all at once like that. Mine have gone gradually. I'm not saying it can't happen, but I would check everything else closely, and definitely eliminate the scope variable by trying a known good scope.

If you are loading your cartridges to the same length since the beginning, your bullet jump is increasing bit by bit as the throat wears. I would not expect a sudden, massive change like you describe, but it could change things over time as the throat moves out from wear.

 

[DennisH]

I'm definetly no expert, but I would think that you could/should get more than 2400 rounds out of a 308.

Some will go quick, some will last 4,000 rounds. Depends on your load. The load you stated is pretty stout for a 308. I shoot a similar load and my barrels go around the 2,500 count.

All of a sudden my 1/2 MOA barrel is shooting 2 1/2 MOA's. Change the barrel and I have my 1/2 MOA group back. It almost seemed it happened overnight.

 

[DennisH]

there is nothing that dissolves carbon

There is a few automotive grade chemicals that will make it like tar. It cleans out very easy. The good chemicals are available at dealers only.

 

[CJ6]

All of a sudden my 1/2 MOA barrel is shooting 2 1/2 MOA's. Change the barrel and I have my 1/2 MOA group back. It almost seemed it happened overnight.

Borescope the barrel, if it looks good change scopes

 

[Lapua40X]

Do you have any one who can borescope it? Get some iosso and a iosso nylon brush and give the throat a good scrubbing. You probably have a carbon issue if you only use a solvent. Also take a look at the crown for damage.

You can chase possibilities for ever and waste a lot of time and ammo with nothing to show for it but a weak s.w.a.g. Scope it and you'll know for sure.
If you don't have a scope post a notice on the bulletin board at your local range. I've never known a group of shooters within which there wasn't at least one bore scope and a guy who would gladly scope it for you.

 

[Alex Wheeler]

there is nothing that dissolves carbon

There is a few automotive grade chemicals that will make it like tar. It cleans out very easy. The good chemicals are available at dealers only.

The old formula GM injector cleaner is the best carbon remover I have ever used. Leave it on a piston overnight and you can wipe all the carbon off the top with a rag. It didn't touch the carbon in my barrel. Don't know what happens in a barrel to make that stuff but its on there good.

 

[Syncrowave]

I would try some Sweet's 7.62 and JB to get out most of the carbon and copper, and use some JB or Iosso and go over the throat real good to make sure you don't have a carbon ring and then see how it shoots.

 

[lpreddick]

the element carbon when placed under extreme pressure and temperature becomes diamonds. i'm surprised our barrels aren't coated with them as the temp(3000+ f) and pressures(?) occur with each firing. bore carbon deposits are literally ironed and baked into the bore and is very resistant to removal. i'll try any solvent that will remove it, but thus far the only way i can get the "baked on" carbon out is with a bronze brush or abrasives. i'v tried a ceramic bore coating suspension with mixed results. the meanest carbon deposit i believe is the "carbon ring" that occurs in the CHAMBER just in front of the case mouth. a bronze brush passing over this ring takes some time to get to a clean patch. rotating a bronze or nylon with jb will get it out, but if established and overlooked, it can be a nightmare.! this ring can be so hard that it can crimp the mouth of a case and pressures go up and groups go weird. no question, a borescope will tell it all.

 

[Rustystud]

If you don't have a bore scope, put a piece of white paper in the back of the bolt opening. Provide plenty of white light. Look down the muzzle from about 8-10" from the muzzle. If the last 8" of rifling looks flat and dished out your rifling is shot. The first 8"inches and the last 8" are what is critical. You could slug your clean barrel and if the first 8" feels rough but has less drag than the middle of the barrel then the last 8" pushes easy that would be a sign your barrel is shot out. On good barrels there should be .0002"- .0003" of choke in the last 8" of the barrel the slug should not have tight and loose spots between the chamber and muzzle. It should get progressively tighter within the last 8". I have seen factory barrels that would not shoot from the start. I have seen many go south after 500 rounds and most factory barrels are spent after 1600-2000 rounds. I have seen some custom shop 308 barrels go over 4000 rounds depending on how brutal the shoot is on the barrel with heat and pressure. The military expectations from a barrel and a target shooter often are quite different.
Nat Lambeth