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Barrel Wear and Bimetal Bullets?


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I did see that the article was about a SLR-106. I should have done some followup on that before posting the link. I just did some followp. The SLR-106 is an Arsenal rifle with a US barrel. That might explain the problem. A low quality US barrel.

Edited by tbryanh
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K-Var sells the SLR-106 and lists it as having a US Barrel:

https://www.k-var.com/shop/SLR-106-Series-5.56x45-Caliber-Bulgarian-Stamped-Receiver-Rifles

 

Waffen Works rifles come with US barrels:

http://www.classicfirearms.com/ak74riflewuspartsw1magonlycodeb

 

AK-Builder kits com with US barrels:

http://ak-builder.com/index.php?dispatch=products.view&product_id=30034

 

It seems that any rifle that is not imported to the US as a new sporter rifle is imported as a used rifle that has been demilled into a parts kit. The original barrel never appears to be included in these parts kits. These parts kits are from used rifles that probably had shot out barrels. It is probably more profitable for the foreign countries to sell the used rifles as parts kits to the US rather than installing new barrels in them for use in their countries.

 

All the manufactuers in the US that sell Bulgarian, etc. rifles are made from parts kits from used rifles with US barrels.

 

It seems countries like Bulgaria do not want to make new sporter versions of their rifles to import to the US like Russia does.

Edited by tbryanh
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It may not be fair to say US barrels are low quality. They are probably made for US ammo and last a long time if you use US ammo.

 

I don't think they are made for Russian ammo. That is the problem.

 

Hopeflly Russia did not make lower quality barrels for their .223 rifles with the idea that these rifles would only be shooting American ammo or that they only needed to meet the spec that is common in the US for this particular caliber. This is a question that somehow needs to be answered.

Edited by tbryanh
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Does Bulgaria and Romania use bimetal 5.56 or copper jacketed 5.56? Does NATO spec specify copper jacketed? What is NATO spec in this regard?

Here you go, probably everything you wanted to know about  5.56x45 Nato. Here’s a good thread on AK Files on the subject, maybe not what you asked but a good read nevertheless. I found this reply about the bootleg Nato interesting.

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Here is a good video that explains the use of a throat errosion guage. Among other things, the video explains that there is no absolute measurement that can be made to determine if the throat is erroded too much. It is a relative measurement that is compared to the measurement taken when the barrel was new. You learn over time what the readings mean by taking readings on many barrels with various round counts and grouping accuracies for each particular barrel manufactuer. A bore scope is probably a better tool for determining throat errosion than a throat errosion guage.

 

Edited by tbryanh
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It may be possible that the reputation for the long barrel life of the AK came from the AK-47 rifle and that it is a mistake to believe that AK-74 barrels last as long as AK-47 barrels do.

It appears possible that velocity, not bullet composition, has the biggest effect on barrel life. The AK-47 uses a low velocity round, 2350 ft/sec, while the AK-74 uses a high velocity round, 3,000 ft/sec. The difference in velocity is significant.

Problem is, the soldiers that use AK-74s in combat do not return home to this country after seeing action, so we here in the US do not get first hand accounts about the barrel life of the AK-74.

It appears that AR barrels last about 10,000 rounds with copper jacketed bullets, and about 7,000 rounds with bimetal jacketed bullets. What reason does anybody have to beleive that somehow AK barrels are made so well that no other type of barrel can come close to how long they last?

Edited by tbryanh
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It appears that AR barrels last about 10,000 rounds with copper jacketed bullets, and about 7,000 rounds with bimetal jacketed bullets.

 

This conclusion is not warranted by the LuckyGunner experiment. They abused the barrels with an extreme rate of fire.

 

There are people on theakforum.net who have shot well over 10,000 rounds of 7N6 with no noticeable loss of accuracy.

Edited by Jim Digriz
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K-Var sells the SLR-106 and lists it as having a US Barrel:

https://www.k-var.com/shop/SLR-106-Series-5.56x45-Caliber-Bulgarian-Stamped-Receiver-Rifles

 

Waffen Works rifles come with US barrels:

http://www.classicfirearms.com/ak74riflewuspartsw1magonlycodeb

 

AK-Builder kits com with US barrels:

http://ak-builder.com/index.php?dispatch=products.view&product_id=30034

 

It seems that any rifle that is not imported to the US as a new sporter rifle is imported as a used rifle that has been demilled into a parts kit. The original barrel never appears to be included in these parts kits. These parts kits are from used rifles that probably had shot out barrels. It is probably more profitable for the foreign countries to sell the used rifles as parts kits to the US rather than installing new barrels in them for use in their countries.

 

All the manufactuers in the US that sell Bulgarian, etc. rifles are made from parts kits from used rifles with US barrels.

 

It seems countries like Bulgaria do not want to make new sporter versions of their rifles to import to the US like Russia does.

there's a barrel ban on imported parts kits that's why all ak kits went sky high and why theres even American companys making ak barrels. Before the ban there's want any us made barrels.
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The photo shows the chamber cast I made from sulfur of my Saiga .223.

It appears that my rifle is 5.56 x 45, not .223.

As a side note, chamber casts apparently can be used to check throat errosion. I picked up my rifle from someone who bought it new and traded it to me 6 months later. He said he only shot about 200 rounds through it. I have probably put about 200 rounds through it too. The leade/throat in the picture appears to have no errosion, and the cast feels smooth to the touch in the leade/throat area. The leade/throat is apparently in like-new condition.

 

post-44407-0-89486900-1401598944_thumb.jpg

Edited by tbryanh
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7n6 has a copper jacket (well, "gilding metal" actually, but that's mostly copper and is definitely not a bi-metal jacket).

 

 

 

A copper plated steel jacket bullet is bi-metal.

 

M

Edited by m1key
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  • 1 month later...

Freakout exaggerated. Took it to my cousin's place and was shooting nearly as tight groups as his newer AR.

 

Well even with a chipped-up throat, the rifle still shoots like this scoped. Threw on my 3-12x yesterday and made some shots off the back of my Jeep before it got too hot outside to hold the rifle steady. I cannot shoot well once the temp gets up past 90.

 

Group on the left 69gr HP BT Prvi match, 75yds. Took three shots and adjusted scope, took remaining four shots. Group on right is Tulammo 55gr. Probably could've shot better groups off of a better rest than my spare tire.

 

p23vLJe.jpg

 

I am probably going to pick up an extra barrel from AKBuilder so that some day I can rebarrel the Saiga once the barrel is shot out. Maybe when I get older and give it to my son. For now it seems to shoot more or less like you would expect it to, despite the throat damage.

Edited by mancat
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  • 2 months later...

I am thinking that it might be best to avoid shooting .223 in the Saiga. As we know, the Saiga is chambered for 5.56.

 

Now I know it is safe to shoot .223, but I am thinking it might damage the throat of the barrel.

 

I am thinking that .223 travels a longer distance in the throat than 5.56 does. This causes more combustion to take place in the throat with .223 than with 5.56. More combustion means more heat, more heat means more stress/wear.

 

Also, 5.56 probably travels better through the throat than .223 does. In other words, it probably does not bounce off the walls of the throat as much as .223 does. The throat is designed for 5.56, so 5.56 probably "fits better" in the throat than .223 does.

 

Just my thoughts. Not sure if they are correct or not, but I figure why take a chance. Just shoot what the rifle was designed to shoot.

Edited by tbryanh
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