D Anderson
Member
- Joined
- Aug 15, 2012
- Messages
- 16
I think that a simple blowback .223 is more feasible than most of the posters here believe. The bolt would not need to be all that heavy. Bear in mind that one of the biggest strengths of the .223 is low recoil. Using a recoil calculator, I found that to achieve the same bolt velocity as a blowback 9mm carbine, a .223 carbine would need a bolt only around 50% heavier. Blowback 9mm carbines typically have bolts around 1.2 to 1.5 lbs. So a .223 would only need a bolt around 1.8 to 2.25 lbs. This is only about one pound heavier than the BCG in an AR. This would make the weapon about a pound heavier than the AR, which would be a disadvantage, but not so much as to be impractical. If you were willing to accept a bolt velocity of 25 fps (as in the G3), this could be done with a bolt weighing only 1.7 lbs.
The recoil spring weight would depend on the free recoil energy. The fre of the .223 is about twice that of the 9mm. However, due to the length of the cartridge, the spring on the .223 will get compressed about twice as far. So the spring tension on the .223 should actually be about the same as the 9mm.
Fluting the chamber would eliminate the need to oil the cartridge. It would work the same as in the G3. Note that in the G3 the bolt and cartridge do start moving back while the bullet is in the barrel. The rollers may not unlock, but the bolt must move backward to make the rollers unlock. So the bolt and cartridge must move back before the rollers unlock.
I don't mean to insult anybody here. I've been thinking about this idea for years, so I had already researched it before reading this post. If you disagree with me, I would be glad to hear your reasons.
The recoil spring weight would depend on the free recoil energy. The fre of the .223 is about twice that of the 9mm. However, due to the length of the cartridge, the spring on the .223 will get compressed about twice as far. So the spring tension on the .223 should actually be about the same as the 9mm.
Fluting the chamber would eliminate the need to oil the cartridge. It would work the same as in the G3. Note that in the G3 the bolt and cartridge do start moving back while the bullet is in the barrel. The rollers may not unlock, but the bolt must move backward to make the rollers unlock. So the bolt and cartridge must move back before the rollers unlock.
I don't mean to insult anybody here. I've been thinking about this idea for years, so I had already researched it before reading this post. If you disagree with me, I would be glad to hear your reasons.