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Old June 11, 2019, 09:52 PM   #1
Cheapshooter
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450 Bushy buffer and spring

Will the milspec buffer and spring from PSA handle the 450 Bushmaster OK. Or do you recommend something like a Wolff extra power spring, and H3 heavy buffer.
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Old June 12, 2019, 06:40 AM   #2
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"Will the milspec buffer and spring from PSA handle the 450 Bushmaster"

Again, the size of the cartridge doesn't determine the specs for the buffer & spring. In fact the bigger bore of the 450 may require a lighter buffer than a .223.
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Old June 12, 2019, 08:08 AM   #3
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Of course it depends on how much gas the system is getting. Have not seen any .450BMs that run properly with a standard AR15 spring and buffer. Heavy buffers and springs are the norm. Especially if you have a DPMS .450 upper with the short carbine length gas.

The heavy slugs will need more spring and buffer than the lighter slugs, in the same gun all else equal.
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Old June 12, 2019, 11:00 AM   #4
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It's the AR Stoner from Midway that I mentioned on a previous post. Carbine length gas system. Just read elsewhere that the Bushy with a standard strength and weight buffer system tend to beat themselves up pretty bad, and fling brass into the next county.
I ordered the Stoner H3 buffer, and Wolff spring anyway. Probably start with it, and work backwards from there if it doesn't function right.
Got the complete upper, the Magpull ACS-L with ept lower kit ordered from PSA. Just need to pick up a stripped lower.
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Old June 12, 2019, 11:44 AM   #5
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Quote:
Again, the size of the cartridge doesn't determine the specs for the buffer & spring. In fact the bigger bore of the 450 may require a lighter buffer than a .223.
Off the top of my head these big bore cartridges run at around 30 to 35 k peak psi if I recall correctly.
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Old June 12, 2019, 07:56 PM   #6
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Stag, I don't think most people understand gas expansion vs bore volume vs bullet speed.
It's so common for them to relate bullet diameter to higher pressure when the reverse is often true.
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Old June 12, 2019, 08:01 PM   #7
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Old June 12, 2019, 09:11 PM   #8
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But you failed to include bullet mass. The "object" that Newton dude said exerts an equal and opposite reaction. So doesn't the total recoil impulse include the bold mass, speed, and the equal and opposite force from the bullet three times heavier than a 5.56 being pushed out. Then slowing the bolt would help reduce that total recoil impulse.
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Old June 12, 2019, 09:49 PM   #9
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I have had no issues with my 450 using milspec buffer and spring. Running on a carbine upper 16" barrel.
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Old June 13, 2019, 12:20 AM   #10
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Quote:
But you failed to include bullet mass. The "object" that Newton dude said exerts an equal and opposite reaction. So doesn't the total recoil impulse include the bold mass, speed, and the equal and opposite force from the bullet three times heavier than a 5.56 being pushed out. Then slowing the bolt would help reduce that total recoil impulse.
True that--both my 458 socom and 45 70 run at similar pressures with similar bullets, and both deliver very "respectable" felt recoil. The difference is the AR uses the gas to operate, so 30 to 35 K isn't much to begin with and you might risk cycling issues when upping your weight and stiffness since there's not a lot of "pressure reserve" to begin with to fully cycle the carrier. I'm not certain of this--but my guess is that the vast majority of all 458 socom and 450 bushmaster barrels are carbine type set-ups
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