Gunsmithing Interesting read on BrassVs.Steel

[Sam Dunham]

https://www.google.com/url?sa=i&source=images&cd=&ved=2ahUKEwjtqfSHpLDgAhUnhlQKHf-uDzMQjRx6BAgBEAU&url=https://www.luckygunner.com/labs/brass-vs-steel-cased-ammo/&psig=AOvVaw3xM8cjJUzEs2Jg6ILpM_ac&ust=1549856314534587


"The upper receiver assemblies of the two problem carbines were completely disassembled in order to determine the cause of this issue. It was immediately apparent that the problem related to improper barrel nut torque values – the barrel nuts, which slide over a collar on the barrel and thread onto the front of the upper receiver, required less than 5 ft-lbs to break loose.
Proper torque values for this part are 30-80 ft-lbs. Once the components were properly reassembled, ten shot group sizes shrank to approximately 3.5 MOA, which is a realistic result to expect from standard carbines firing bulk ammunition."

 

[GH41]

I cannot open the link. Let me guess.... Extension and barrel assembled before meloniting.

 

[Sam Dunham]

Which Ammo Was Most Reliable?
The data which will probably be most interesting to everyone who reads this article is how often each rifle malfunctioned. To satisfy that particular thirst, here are the basic results:

• Federal: 10,000 rounds, 0 malfunctions.
• Brown Bear: 10,000 rounds, 9 malfunctions (5 stuck cases, 1 magazine-related failure to feed, 3 failures to fully cycle)
• Wolf: 10,000 rounds, 15 malfunctions (stuck cases)
• Tula: DNF (6,000 rounds in alternate carbine, 3 malfunctions)

 

[Sam Dunham]

Couple this with the .058″ gas port used on the Bushmaster rifles – about the same as a Colt 6920 with a 16″ barrel, and just about the smallest gas port you’ll see on any 16″ carbine AR-15, and you’re bound to encounter problems. The Spike’s Tactical midlength did not have a small gas port relative to its longer gas system, and so it functioned without any short stroking issues.

 

[Timberwolf911]

It's a very good read. Most enlightening.

I've never shot steel cased ammo out of mine.

The most interesting part, to me, was the wear on the extractors.