Huuuge groups today, what's going on?

[HelloLarry]

Rate of fire and what you quantify as acceptable accuracy leaves a lot of room for variation.
And are you talking Cr lined?

No.
although as someone else pointed out, a Cr lined barrel can go from stellar to crap at the loss of a chip too. But usually they last longer than unlined.

[georgeib]

If this is a SS barrel, those have a tendency to quit shooting all at once. FWIU, they can lose chips from the rifling in the lead. Once you lose a chip off one of the lands, forget about it - it's trash. I've seen it happen with mine. I had a SS button barrel that went from MOA to about 8 MOA from one round to the next at about 4,500 total.

Now, that IS interesting! Thanks for posting that, good to know.

[georgeib]

From this picture it looks like your gas tube isn't centered. Kind of a long shot, but that could be at least part of the problem.

Also, try taking the pictures from behind the receiver instead of from under. Might be able to see the throat.

[Pappabear]

This thread has me thinking I have a 16 SS NOVESKE that fell off a bit. I cleaned it but not full copper clean. I’m going to do that and see if it’s back to tack driver status.

PB

[Coal Dragger]

Couldn’t get a great angle with the phone camera so I’m not sure this shows anything except that I didn’t wipe off any of the lube first.





I did reach out to Noveske and they are going to take a look at it. Like I said, I wasn’t sure that they would since I’ve changed so much but they didn’t seem to care which is cool.


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The first thing that is really evident in those photos is the cracked chrome lining in the chamber. Look closely at the dark high contrast somewhat jagged lines. That is not carbon. That is not oil. Those appear to be cracks.

I’m going to go out on a limb and say this may be a chrome lining job that is defective. If the lining is cracked in the chamber, can you imagine what has blown out of the throat and the barrel?

Also might explain why it looks rough after thorough cleaning.

[Wake27]

The first thing that is really evident in those photos is the cracked chrome lining in the chamber. Look closely at the dark high contrast somewhat jagged lines. That is not carbon. That is not oil. Those appear to be cracks.

I’m going to go out on a limb and say this may be a chrome lining job that is defective. If the lining is cracked in the chamber, can you imagine what has blown out of the throat and the barrel?

Also might explain why it looks rough after thorough cleaning.

I was wondering about that, but really have no experience here so I assumed that it was some type of residue.

Interestingly enough, I went through a deep clean of my BCM today since I plan on grouping it on Saturday and have never really paid attention to that barrel either. It’s just over 1,964 rounds on it, so a little less than 2/3 of what is on my Noveske. I’ve owned it longer than the Noveske and ROF and ammo has been similar, though it did not go to the RB1 course which put about 1k on the Noveske in five days. I also don’t think it’s seen nearly as much Freedom reman.

Anyways, I got it cleaned in about an hour or so and it went how I would expect it to so I’m curious to see how it shoots the BH. Since I had everything out, I grabbed the Noveske. I wish I had taken pictures of the last few patches before I called it quits the last time I cleaned it because it has seen less than 200 rounds through it since and here’s what I got:



The top row was first, then I ran a nylon brush with copper eliminator through it 50 times, then started running the bottom patches through. Instructions on the bottle said to do all that and then let it sit for 15 minutes, then start with dry patches until it comes out clean. I already went through so many patches in this barrel that this seems ridiculous.

A problem with the chrome lining wouldn't do this, would it?

ETA - here are the patches that were sent through dry. They’re on the rag backwards, so the top right one was first, which is probably obvious. The ones on the second rag came last and are similar to what I remember seeing before I decided it was good enough last time. I'm also wondering what the chances are that the Bore Tech is giving me a false positive.



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[Coal Dragger]

If you have failing chrome lining, stands to reason the barrel will be rough and pick up a lot of copper.

Be curious to see what that chamber looks like when clean from similar angles as those photos.

[Wake27]

Some more photos after a little more cleaning, haven’t been able to get the angles of the earlier photos though.

I can’t get a picture of it, but the barrel still looks like absolute shit.










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[twm134]

That amount of copper may or may not be more than I would expect for 200 rounds, but I have had barrels that took far longer and were more fouled than that and would still easily shoot M193 as well as you can expect.


Last year I tore apart the first BCM upper I ever purchased and threw out the barrel because it was finally past the point that I would waste ammo on it: about 6 inch groups at 100 yards with M193 from IMI or Federal. Match ammo was still barely about 3 inches, maybe a bit more. All ten shot groups.

This was a button rifled, chrome lined 14.5 middy with over 13,400 rounds. At least ninety percent of that ammo was steel jacketed. Every summer where I live we have months of high humidity and I shot it many times in the rain. The throat of that barrel did have pitting from corrosion because of this, however after a little copper fouling filled the pits it shot well enough with standard quality 55 grain ammo, without cleaning, for any purpose that doesn't require magnification. It easily shot match ammo into about 2 MOA up until the last case or two of ammo. I know this for a fact because once the round count started to get up there about every 1000 rounds I would shoot several groups from a bench with quality ammo and whatever M193 I had laying around and usually with a scope just to see how it was doing. At times the rate of fire was fairly high and on numerous occasions it was simply too hot to comfortably shoot even with gloves. I'm not in the habit of mag dumps but this barrel didn't have an easy life.

The same can be said for a 4140 chrome lined RRA barrel I purchased before I knew better. It lasted 9,000 rounds.

I replaced the barrel on a factory stainless Remington 700 in .223 at just shy of 4,000 rounds that would still shoot about 2 inches.

Anyway, I just can't imagine a chrome lined Noveske shooting this poorly at 4,000 rounds. Sorry our advice to clean didn't work for you. I hope Noveske has some answers because I don't.

[Coal Dragger]

I can still faintly see the same imperfections in the chamber, they must have trapped carbon fouling. I still suspect a bad chrome lining is flaking out of the bore, and has manifested a bit in the chamber. However I’m no metallurgist so I’m making a guess.

For comparison here is the chamber on a brand new KAC SR-15 chrome lined barrel.