What would cause factory 220gr subsonics to keyhole at 25yds out of a 7.5" 1:7 twist barrel? Would a suppressor make the velocity increase to supersonic, causing destabilization? It's sounding louder than my 10" 223 and 7.5" 7.62x39.
I plan to reload. Will I be able to handload 220gr subs that stabilize or should I start with getting a new barrel?
300 Blk subsonics destabilizing
Re: 300 Blk subsonics destabilizing
Does it keyhole without the suppressor at any yardage 25, 50, 75, 100?
http://www.youtube.com/watch?v=BDtd2jNIwAU MUSAFAR!
http://www.youtube.com/watch?v=8CrOL-ydFMI This is Water DavidW
Complete Form 1s http://www.silencertalk.com/forum/viewtopic.php?f=10&t=79895
http://www.youtube.com/watch?v=8CrOL-ydFMI This is Water DavidW
Complete Form 1s http://www.silencertalk.com/forum/viewtopic.php?f=10&t=79895
Re: 300 Blk subsonics destabilizing
Did you do an alignment check?
300 blackout form 1: http://www.silencertalk.com/forum/viewtopic.php?f=10&t=137293
5.56 form 1:
http://www.silencertalk.com/forum/viewtopic.php?f=10&t=141800&p=955647#p955647
5.56 form 1:
http://www.silencertalk.com/forum/viewtopic.php?f=10&t=141800&p=955647#p955647
Re: 300 Blk subsonics destabilizing
Yes, I checked for alignment. I didn't try supersonics because I don't really plan to shoot anything but subs through the suppressor. I set up my reloading station last night and started prepping cases. I have some Nosler 220 subsonic green tips to try out.
Re: 300 Blk subsonics destabilizing
you are shooting a really long bullet is a short barrel. 223 in a 10" barrel or 7.62x39(what weight bullet?) in 7.5" barrel are scale wise a lot higher barrel length/bullet length ratio. I shoot 240/250grain 308 in 308x1.5" BARNES(1 in 8") and also do 240grain 308 in handy rifle with 1 in 10" with suppressor but each of these are normal length barrels. I think your 7.5" barrel isn't imparting enough spin on that longer 220 grain bullet even though it is of the correct rated twist, to give it stability.
Re: 300 Blk subsonics destabilizing
What the hell does barrel length to bullet length ratio have to do with anything? A 7.5" barrel Is plenty long enough to get a 300 blackout bullet up to velocity. Velocity * twist rate = rpm. Twist rate is constant and velocity should be fine. A 2" barrel will stabilize a bullet as long as it can get it up to speed.r wrote:you are shooting a really long bullet is a short barrel. 223 in a 10" barrel or 7.62x39(what weight bullet?) in 7.5" barrel are scale wise a lot higher barrel length/bullet length ratio. I shoot 240/250grain 308 in 308x1.5" BARNES(1 in 8") and also do 240grain 308 in handy rifle with 1 in 10" with suppressor but each of these are normal length barrels. I think your 7.5" barrel isn't imparting enough spin on that longer 220 grain bullet even though it is of the correct rated twist, to give it stability.
300 blackout form 1: http://www.silencertalk.com/forum/viewtopic.php?f=10&t=137293
5.56 form 1:
http://www.silencertalk.com/forum/viewtopic.php?f=10&t=141800&p=955647#p955647
5.56 form 1:
http://www.silencertalk.com/forum/viewtopic.php?f=10&t=141800&p=955647#p955647
Re: 300 Blk subsonics destabilizing
Maybe it's a Franklin barrel.fishman wrote:...
What the hell does barrel length to bullet length ratio have to do with anything? A 7.5" barrel Is plenty long enough to get a 300 blackout bullet up to velocity. Velocity * twist rate = rpm. Twist rate is constant and velocity should be fine. A 2" barrel will stabilize a bullet as long as it can get it up to speed.
http://www.youtube.com/watch?v=BDtd2jNIwAU MUSAFAR!
http://www.youtube.com/watch?v=8CrOL-ydFMI This is Water DavidW
Complete Form 1s http://www.silencertalk.com/forum/viewtopic.php?f=10&t=79895
http://www.youtube.com/watch?v=8CrOL-ydFMI This is Water DavidW
Complete Form 1s http://www.silencertalk.com/forum/viewtopic.php?f=10&t=79895
Re: 300 Blk subsonics destabilizing
Progressive twist barrel, cut too short??
Did you actually measure twist rate? I was defrauded once by a gunsmith who was supposed to install a new barrel on one of my rifles, he was supposed to deliver a brand new 1:12 twist in .224 cal, but instead reworked an old 1:14 twist factory barrel that he had removed from another customers rifle.. The idiot did not think I would measure the twist .. Then the idiot tried to run away from it, by referring to the bill, which did not state the delivered twist rate, saying that I "Never specified the twist rate"
Fortunately I had a photo of the original order slip ... on the guys own headed paper ..
Did you TESTFIRE the setup (Gun+Barrel+ammo) without the suppressor installed .. I have never had better grouping or improvement in "wobbly" bullets from adding a suppressor .. Don't think that can ever happen.. but I may be wrong ..
Did you actually measure twist rate? I was defrauded once by a gunsmith who was supposed to install a new barrel on one of my rifles, he was supposed to deliver a brand new 1:12 twist in .224 cal, but instead reworked an old 1:14 twist factory barrel that he had removed from another customers rifle.. The idiot did not think I would measure the twist .. Then the idiot tried to run away from it, by referring to the bill, which did not state the delivered twist rate, saying that I "Never specified the twist rate"
Fortunately I had a photo of the original order slip ... on the guys own headed paper ..
Did you TESTFIRE the setup (Gun+Barrel+ammo) without the suppressor installed .. I have never had better grouping or improvement in "wobbly" bullets from adding a suppressor .. Don't think that can ever happen.. but I may be wrong ..
DKDravis
"Sapere Aude": Dare to KNOW!
"Do not adjust your mind, there's a fault in reality!"
"When Wrong becomes Right, Resistance becomes our duty!"
Postal code 8541
"Sapere Aude": Dare to KNOW!
"Do not adjust your mind, there's a fault in reality!"
"When Wrong becomes Right, Resistance becomes our duty!"
Postal code 8541