Hi all. I've been fooling around with Trail Boss and 208gr A-Maxes(successfully). 7gr TB, 208gr A-Max, 2.800 OAL. Blew up my knee last week so haven't chronied yet. My question is, what's the logic behind using round nose vs spire point bullets?
Subsonic 308 Bullet Selection
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Re: Subsonic 308 Bullet Selection
the logic.... would you rather get poked in the chest w/ a finger or punched w/ a fist...
subs don't tend to expend well, so a RN transfers more of it's energy into the target
the logic.... would you rather get poked in the chest w/ a finger or punched w/ a fist...
subs don't tend to expend well, so a RN transfers more of it's energy into the target
Re: Subsonic 308 Bullet Selection
The round nose bullets are much more stable at subsonic velocities than a spire point which tends to have most of its weight centred toward the rear.
If you spin the spire point fast enough you're ok, but if not it will spiral towards the target and tumble. I've actually seen this happen though the scope, its interesting to watch (just don't shoot em with a can on!)
The round nose bullets are much more stable at subsonic velocities than a spire point which tends to have most of its weight centred toward the rear.
If you spin the spire point fast enough you're ok, but if not it will spiral towards the target and tumble. I've actually seen this happen though the scope, its interesting to watch (just don't shoot em with a can on!)
Re: Subsonic 308 Bullet Selection
Subsonic flight favors a different shape than supersonic flight if I am not mistaken. Even more importantly, the stubbier flat or round nosed bullets are easier to stabilize.
Oh yes the 30 30 stuff works.
I really like the 150 and 170 flat nose 30 30 bullets. They shoot great out of my 11 twist with trailboss. FWIW the 180 round noses shoot well too, but in my rifle the flat noses do better.
Buy a box of each and try it out. I bet you will be surprised.
Subsonic flight favors a different shape than supersonic flight if I am not mistaken. Even more importantly, the stubbier flat or round nosed bullets are easier to stabilize.
Oh yes the 30 30 stuff works.
I really like the 150 and 170 flat nose 30 30 bullets. They shoot great out of my 11 twist with trailboss. FWIW the 180 round noses shoot well too, but in my rifle the flat noses do better.
Buy a box of each and try it out. I bet you will be surprised.
Re: Subsonic 308 Bullet Selection
I've read in several different forums that the pointy bullets do much better loaded backwards. I've never tried it personally, but it seems to make sense that with the heavier end leading the way there would be less tendency for the bullet to de=stabilize. With my 1-in-10 twist I haven't needed to try this but I might do so anyway just for shits and grins. I've only just started to experiment with subs, so I have much to learn and little to pass on.
The only loads I have now are 11.5 gr Trailboss behind a 180gr Rem Corlokt bullet for my 308 AR.
As others have stated-do all your testing WITHOUT the suppressor until you know they're stable when they leave the muzzle.
My 223 load is 4.4 gr Trailboss with 55gr FMJs.
I've read in several different forums that the pointy bullets do much better loaded backwards. I've never tried it personally, but it seems to make sense that with the heavier end leading the way there would be less tendency for the bullet to de=stabilize. With my 1-in-10 twist I haven't needed to try this but I might do so anyway just for shits and grins. I've only just started to experiment with subs, so I have much to learn and little to pass on.
The only loads I have now are 11.5 gr Trailboss behind a 180gr Rem Corlokt bullet for my 308 AR.
As others have stated-do all your testing WITHOUT the suppressor until you know they're stable when they leave the muzzle.
My 223 load is 4.4 gr Trailboss with 55gr FMJs.
Re: Subsonic 308 Bullet Selection
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Force_Multiplier</div><div class="ubbcode-body">the logic.... would you rather get poked in the chest w/ a finger or punched w/ a fist...
subs don't tend to expend well, so a RN transfers more of it's energy into the target</div></div>
If you were poking with a copper jacketed finger with the velocity of a punch, then I would imagine the poke would be a lot worse
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Force_Multiplier</div><div class="ubbcode-body">the logic.... would you rather get poked in the chest w/ a finger or punched w/ a fist...
subs don't tend to expend well, so a RN transfers more of it's energy into the target</div></div>
If you were poking with a copper jacketed finger with the velocity of a punch, then I would imagine the poke would be a lot worse
Re: Subsonic 308 Bullet Selection
I suggest the Sierra 220gr .308 RN Pro-Hunter Soft Point.
I think a slower round needs as much mass as possible to achieve best energy delivery/transfer at subsonic velocities.
The Pro-Hunters are listed as being designed to expand better at lower velocities, and the RN Soft Point should maximize that without paying any aerodynamic penalties at subsonic speeds.
I like a flat base bullet design for shorter distances, where boat tails appear to have less advantage. I think the flat base stabilizes/'goes to sleep' quicker than the Boat Tail.
Greg
I suggest the Sierra 220gr .308 RN Pro-Hunter Soft Point.
I think a slower round needs as much mass as possible to achieve best energy delivery/transfer at subsonic velocities.
The Pro-Hunters are listed as being designed to expand better at lower velocities, and the RN Soft Point should maximize that without paying any aerodynamic penalties at subsonic speeds.
I like a flat base bullet design for shorter distances, where boat tails appear to have less advantage. I think the flat base stabilizes/'goes to sleep' quicker than the Boat Tail.
Greg
Re: Subsonic 308 Bullet Selection
In the wind, for the same bullet mass, the HPBT will drift about 30-40% less than the RNSP when both are launched at 1000fps. Drops are about 10% less with the HPBT as well. (Compared a 220gn SMK w/G7 to 220 RNSP w/G1). Also wanted to add that the boat tail has the most effect below 2000 fps or so, since above that the air doesn't cut behind the bullet when going faster. Above 2500 fps or so, the boat tail has little effect, behaving like a flat-based bullet.
I believe the logic with the flat-base soft point is you can get more mass/energy for a specific twist rate, since the bullets are shorter per unit mass. It also allows for the neck to grip fully on the bearing surface on high mass bullets without having huge OAL.
The Terminal performance is another thing though. I think a HPBT that expanded well at low velocity could be made (but it likely would not work so well at HV and hence would be limited).
In the wind, for the same bullet mass, the HPBT will drift about 30-40% less than the RNSP when both are launched at 1000fps. Drops are about 10% less with the HPBT as well. (Compared a 220gn SMK w/G7 to 220 RNSP w/G1). Also wanted to add that the boat tail has the most effect below 2000 fps or so, since above that the air doesn't cut behind the bullet when going faster. Above 2500 fps or so, the boat tail has little effect, behaving like a flat-based bullet.
I believe the logic with the flat-base soft point is you can get more mass/energy for a specific twist rate, since the bullets are shorter per unit mass. It also allows for the neck to grip fully on the bearing surface on high mass bullets without having huge OAL.
The Terminal performance is another thing though. I think a HPBT that expanded well at low velocity could be made (but it likely would not work so well at HV and hence would be limited).
Re: Subsonic 308 Bullet Selection
Actually, there is some literature that suggests the HPBT may actually fly better with a subsonic if loaded into the case base to front.
An exposed lead lockbase bullet might convert into a trashcan hollowpoint that way. Don't laugh, this is a real possibility.
Greg
Actually, there is some literature that suggests the HPBT may actually fly better with a subsonic if loaded into the case base to front.
An exposed lead lockbase bullet might convert into a trashcan hollowpoint that way. Don't laugh, this is a real possibility.
Greg
Re: Subsonic 308 Bullet Selection
A lot of what I read about loading bullets backwards was on some website called box o' truth or something like that. May do a search when I get more time and study up on it some more.
A lot of what I read about loading bullets backwards was on some website called box o' truth or something like that. May do a search when I get more time and study up on it some more.
Re: Subsonic 308 Bullet Selection
I've tried loading some 168's backwards (cheap Privi not SMK's) and they went all over the place - I'm talking a 2 yard group at 100 yards! I suspect I was not driving them fast enough. I could see them hooping through the air quite clearly on the way down.
The 180 Sierra RN produced sub 1" groups at 100 yards driven just below the sound barrier with Trail Boss.
I've tried loading some 168's backwards (cheap Privi not SMK's) and they went all over the place - I'm talking a 2 yard group at 100 yards! I suspect I was not driving them fast enough. I could see them hooping through the air quite clearly on the way down.
The 180 Sierra RN produced sub 1" groups at 100 yards driven just below the sound barrier with Trail Boss.
Re: Subsonic 308 Bullet Selection
the reason is guys you have to keep the center of mass forward of the center of gravity on the bullet. the twist of the barrel to stabilize can't overcome the laws of physics and the bullet will gyroscope off into who knows where. RN bullets tend to keep the mass toward the front.
the reason is guys you have to keep the center of mass forward of the center of gravity on the bullet. the twist of the barrel to stabilize can't overcome the laws of physics and the bullet will gyroscope off into who knows where. RN bullets tend to keep the mass toward the front.
Re: Subsonic 308 Bullet Selection
12.2gn of TB with the 220gnRN and 10.5gn with the 170FN are both submoa at 100yds. The 220 is 17moa low from my standard full-house load.
12.2gn of TB with the 220gnRN and 10.5gn with the 170FN are both submoa at 100yds. The 220 is 17moa low from my standard full-house load.
Re: Subsonic 308 Bullet Selection
you gotta wear special gloves and hold on real tight while a buddy pulls on the other end...
you gotta wear special gloves and hold on real tight while a buddy pulls on the other end...
Re: Subsonic 308 Bullet Selection
Lapua make a bullet head specifically for subsonics, I got some off Midway. Seems like the real deal, something about a forward centre of mass
Lapua make a bullet head specifically for subsonics, I got some off Midway. Seems like the real deal, something about a forward centre of mass
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