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Been looking at the Criterion 22" medium weights in chrome vs. non-chrome. As I understand, both are solid barrels. Modern chrome barrels seem to be more accurate and better machined than USGI barrels.

Much has been said about chrome vs. nonchrome, but I'm curious about how accuracy wears out over time in both.

As I understand, chrome moly is more linear degredation (sub-MOA for first 4K, 1MOA until 5K, 2 MOA until 10K etc). For chrome lining, however, is that wear still linear? Or does it maintain the same accuracy from 0 to 14999 rounds, the chrome flakes on the 15000th round, and then it goes totally downhill?
 

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Be it chrome lined or not, the rounds shown for accuracy after X amount of rounds I would question. It would be great if that is a fact, but to begin with it is a rare M1A/M14 that repeatedly gives sub moa accuracy from the very beginning. It is the throat of the barrel that receives the most wear and after 4000rnds. there will definitely be quite a bit of erosion for that area of the bore is exposed to initial heat/pressure. Simple solution for bolt gun, remove barrel, recut chamber, and rule of thumb is you will restore barrel for some 1500 more rounds, can't do that on the M1A/M14, only replace barrel. The treatments mentioned may well prolong the wear factor and maintain acceptable accuracy. Flaking of chrome lining does occur from time to time, but have been told reason the chrome lined barrel is not as accurate as non lined is that the lining is not the same thickness from breech to muzzle, is that true,can't say?? From my experience after some 6000rnds. the barrel is toast, accuracy much degraded and needs replaced. The very platform as the M14 is not an inherent accurate rifle and if you make a list of all the things that owners go through to improve the accuracy it is a long list. Upon firing the rifle there is a huge amount of activity with bolt, op rod, gas system, etc., etc. and requires modifications to give better accuracy over and above the barrel quality. With 10,000rnds down the barrel have no doubt that the bullet will fly out of the barrel upon being shot, but certainly not acceptable accuracy for target shooting. Not for chrome lined or treated bores, but if you take a look down the bore after some 1000rnds. of normal chrome moly you will see metal fracturing, crystalizing of the surface at this early stage in it's life. Fiber optics bore scope will reveal lots of things that scare you. Rapid firing with associated heat will accelerate this wear and show up quickly.
 

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It is not that the new chrome lined barrels are better machined, it is that the chrome plating is more uniform in thickness than the old USGI barrels.

In any barrel, the throat will wear before the bore does. As stated above, 4-5k rounds usually show a degradation in accuracy. Don't just blame the barrel, though. Your bedding may be worn as well.

You should never use a bore scope to check a barrel. If you do, you won't sleep at night and will most likely sell every barrel you have. RNGR2

The only way to tell if a barrel is accurate is by shooting it. Pitting, peeling, flaking, etc, are unsettling to the eye, but not necessarily to the bullet.
 
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