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Discussion Starter · #1 ·
Something interesting on a gun forum:


Plenty "noisy-know-nothing-naysayers" opine at length: 'you can't even do this!' ... but .... cast steel compressed around a mandrel has been a process since 1850s ... Which arguably produced the best accuracy in sniper rifles during American Civil war.

Quote from Forum posted above: "Joseph Whitworth was making barrels from what was called "Fluid Compressed Steel" in the 1850's.
My understanding is that molten steel,not iron was poured around a mandrel and then before it
solidified, it was compressed to close any flaws or fissures that could have occurred during the casting
process. Whitworth's long range shooting experiments of the time mandated a strong barrel and he
was being paid by the British Government to find why the Enfield rifles were so inaccurate from one
gun to the next. Lack of uniform dimensions was the problem and he proved it with methods of precise
measurement that were unknown at the time. A bullet of over 500 grains was required but Whitworth,
instead of staying with the 577 went to a 451 with a hexagonal rifling pattern and the improvement in
accuracy was startling. The 451 could hit a dinner plate at 500 yards and the 577 couldn't come close.

Bob Roller"

I am well aware that the front trunnions in AK rifles is widely touted necessarily forged & cannot be cast... Seems common knowledge has more consensus that rear trunnion doesn't take the same beating as the front trunnion & isn't that important to be forged, but could be cast.

It is humorous to me that people who have no experience doing something also have an opinion which they want to have respected as "correct" irregardless of lack of knowledge. Reminds me of the saying: "You are the perfect parent. Plenty of ideas and no experience" lol 馃構

One hysterical historical example comes to mind: "How many angels can dance on the head of a pin?" Yep, people really got hot and bothered and argued about that one! lol 馃槃

This has really made me scratch my head wondering how much of an AK could you cast rather than needing to machine from forgings?

Home casting is a thing, witness many YouTube tutorials. This technology is more affordable and accessible to more people than forging and machining.

Folk almost won't do AK builds anymore, due to skyrocketing cost of parts kits & missing pieces in parts kits, excepting those of us who enjoy building, constructing, experimenting and appreciate the process and learning involved.

So how much of an AK could you actually cast?
 

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One of the design goals of the AK and later AKM was low cost and ease of manufacture. The original AKs were stamped receivers, but Russian stamping tech hadn't quite progressed far enough so they switched to milled for several years. Once the tech was available, they switched to stamped and called it the AKM. For decades the front sight base and gas block were pinned in place, requiring holes be drilled and pins driven in. Current production uses "stakes", essentially the pieces are pressed onto the bbl, put in a fixture, and punches slam in, dimpling the pieces where pins used to go, securing them to the bbl. Relatively low stress application, note the bbl is still pinned into the trunnion where it has to resist the forces of firing trying to shove the bbl out of the trunnion. If the Russians thought the trunnion would be "good enough" made from a casting, likely that would be how they are doing it. But they aren't, maybe in the future the metallurgy and casting tech will progress far enough to make it work.

A few US makers have tried cast parts, including the trunnion. US made AKs are considered bottom of the bbl quality wise, compared to Combloc produced ones. The cast parts failing is just one of the reasons.

The Soviets went to cast components over the service life of the AK, parts which have transitioned to cast include the front sight base, gas block, rear sight base, handguard retainer, recoil spring/cover latch piece, selector axle, and the rear trunnion.
 

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Discussion Starter · #3 ·
One of the design goals of the AK and later AKM was low cost and ease of manufacture. The original AKs were stamped receivers, but Russian stamping tech hadn't quite progressed far enough so they switched to milled for several years. Once the tech was available, they switched to stamped and called it the AKM. For decades the front sight base and gas block were pinned in place, requiring holes be drilled and pins driven in. Current production uses "stakes", essentially the pieces are pressed onto the bbl, put in a fixture, and punches slam in, dimpling the pieces where pins used to go, securing them to the bbl. Relatively low stress application, note the bbl is still pinned into the trunnion where it has to resist the forces of firing trying to shove the bbl out of the trunnion. If the Russians thought the trunnion would be "good enough" made from a casting, likely that would be how they are doing it. But they aren't, maybe in the future the metallurgy and casting tech will progress far enough to make it work.

A few US makers have tried cast parts, including the trunnion. US made AKs are considered bottom of the bbl quality wise, compared to Combloc produced ones. The cast parts failing is just one of the reasons.

The Soviets went to cast components over the service life of the AK, parts which have transitioned to cast include the front sight base, gas block, rear sight base, handguard retainer, recoil spring/cover latch piece, selector axle, and the rear trunnion.
Good to know which parts are cast in current AK production.

Ian McCollum on "Forgotten Weapons" did video mentioning why American built AKs are considered inferior quality.

Best I recall, Ian's main take away had to do with competitive market economics & maintaining profit margin.

Somewhat to the effect: Americans can build quality AKs, just not build cheap enough to compete with foreign imports/surplus who's manufacturing cost have previously been paid for, where the market is people paying for the use of what has already been produced, versus producing new AKs in our American economy, when building from scratch.
 

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Discussion Starter · #4 ·
It would be most intriguing indeed to see some destructive testing of American made front trunnions, comparing cast and forged trunnions.

Using aforementioned 1850s method utilizing cast compressed steel, would be quite interesting to compare results.

One thought that comes to mind as a workaround to metal fatigue would be using a layered approach.

I'm picturing weldments being cast into molded aluminum.

Perceive strength of steel backed up by flexibility of "cast into the steel weldment" aluminum's absorbing impact. Is there a metallurgist in the house? LOL Might need to layer something else between steel and aluminum, I don't think they play well together.

I'm supposing that would be an "ask an engineer" question, rather than someone like myself, a home gun-crafting enthusiast/hobbyist? idk 馃馃え馃槓馃檪馃榿馃槒
 

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The cast US made parts are one of the cost-cutting measures to keep their product competitive. As Ian said, the Combloc producers are using the Soviet tech package and equipment made in a socialist economy where the state owned everything from the iron ore mine to the spraygun that applied the coat of paint as it exited the assembly line. Producing "national security" items had top priority and quality was kept up with essentially slave labor by everyone knowing too much scrap could get you pegged as a "wrecker" and sent off to the Gulag.

So essentially the Combloc producers of semi auto AKs started out with a "free" factory filled with equipment, a huge pile of already produced parts, and a workforce experienced in making them who work for a fraction of what a US maker would have to pay even an unskilled employee. That is why we used to see $300 AKs that had already passed through 2-3 middlemen who each took a cut. Current pricing is insane, and is mainly due to the internet. The guys who sold their AKs to the middlemen for $125 each saw they were selling them here for $300 and started demanding $275 per rifle as they were having to produce more and more new parts as stocks ran out. Now they were $500 and then the factory owner wanted $450, etc. Plus the demand went up and so did prices to match.

Compared to the US maker who basically has to reverse engineer an AKM, setup machines and tooling to produce them, and pay employees a prevailing wage for that type of work. Corners have to be cut or they are selling $3,000 AKs that re competing with the genuine article that costs a third or less of that. You see it in magazines too, surplus AK mags go for less than $20 and some around $11. US made ones we get thinner steel, less reinforcing, and plastic lugs. They could make an identical copy of a surplus mag, but it would cost $60.
 

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Discussion Starter · #6 ·

The cast US made parts are one of the cost-cutting measures to keep their product competitive. As Ian said, the Combloc producers are using the Soviet tech package and equipment made in a socialist economy where the state owned everything from the iron ore mine to the spraygun that applied the coat of paint as it exited the assembly line. Producing "national security" items had top priority and quality was kept up with essentially slave labor by everyone knowing too much scrap could get you pegged as a "wrecker" and sent off to the Gulag.

So essentially the Combloc producers of semi auto AKs started out with a "free" factory filled with equipment, a huge pile of already produced parts, and a workforce experienced in making them who work for a fraction of what a US maker would have to pay even an unskilled employee. That is why we used to see $300 AKs that had already passed through 2-3 middlemen who each took a cut. Current pricing is insane, and is mainly due to the internet. The guys who sold their AKs to the middlemen for $125 each saw they were selling them here for $300 and started demanding $275 per rifle as they were having to produce more and more new parts as stocks ran out. Now they were $500 and then the factory owner wanted $450, etc. Plus the demand went up and so did prices to match.

Compared to the US maker who basically has to reverse engineer an AKM, setup machines and tooling to produce them, and pay employees a prevailing wage for that type of work. Corners have to be cut or they are selling $3,000 AKs that re competing with the genuine article that costs a third or less of that. You see it in magazines too, surplus AK mags go for less than $20 and some around $11. US made ones we get thinner steel, less reinforcing, and plastic lugs. They could make an identical copy of a surplus mag, but it would cost $60.
My recently purchased M70 AB2 parts kit came from the usual auction site missing rear trunnion and pistol grip nut, so it sold for less than some more complete ludicrously high priced parts kits.

Paycheck to paycheck I've been gathering up American-made parts to meet 922r compliance so I can complete an M70 AB2 automatic build.

One part that I've not been able to find in stock is the rear trunnion for M70 AB2 underfolder, so I'll get to report how hard it is to make a DIY rear trunnion from weldments, with filing & Dremel work to get everything to fit.

To let you know how ridiculous some of these prices for parts have become, I've seen some rear trunnions (which were out of stock) being priced from $50 to over $100! OUCH! There goes over budget for this poor man's build LOL馃
 

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Discussion Starter · #7 ·



My recently purchased M70 AB2 parts kit came from the usual auction site missing rear trunnion and pistol grip nut, so it sold for less than some more complete ludicrously high priced parts kits.

Paycheck to paycheck I've been gathering up American-made parts to meet 922r compliance so I can complete an M70 AB2 automatic build.

One part that I've not been able to find in stock is the rear trunnion for M70 AB2 underfolder, so I'll get to report how hard it is to make a DIY rear trunnion from weldments, with filing & Dremel work to get everything to fit.

To let you know how ridiculous some of these prices for parts have become, I've seen some rear trunnions (which were out of stock) being priced from $50 to over $100! OUCH! There goes over budget for this poor man's build LOL馃
You really have to watch those text-to-speech engines... I read back over my post and I see that it said "automatic," when what it should have said was "semi automatic" build.
 
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