Contemplating an AR

[Dolomite_supafly]

9 twist will shoot anything I might load or find. And it is still slow enough to tumble which starts the fragmenting process. And even if the bullet doesn't fragment the act of tumbing creates a larger wound channel.
 
8 twist will not do anything for me that a 9 twist doesn't already do. It would serve exactly the same purpose as a 9 twist except it would not tumble as quickly as a 9 twist.
 
12 twist results in near instantaneous tumbling when shooting 55-62 grain bullet. And the tumbling is was causes the bullet to fragment.
 
7 twist generally does not tumble inside of a smaller target with a 55 or 62 grain bullet. So the bullet just passes through and acts like a 22lr. And if the velocity is below 2,600 fps it can't even fragment even if it does tumble. There are tons of stories of soldiers shooting bad guys dozens of times and the bad guys continue to fight. This is because the 14.5" barrel reduces the velocity enough the beyond 200 yards the bullet will not fragment even if it did tumble which most times it doesn't because the twist is too fast.

Here is a pretty good read on the subject.
http://stevespages.com/pdf/5_56mm_military_info.pdf
 

Tumbling can reduce the velocity needed for fragmentation but if the twist is too fast the bullet will never tumble and in turn never fragment. This is why we are hearing of the problems overseas. We have reduced the barrel length which causes a reduced velocity, on top of that they have increased the twist. The combination of a slower bullet that is spinning faster results in a bullet that is too slow to fragment and spinning too fast to tumble. Which results in a 22 lr type wound.
 

What happens when a bullet is overstabilized is it will not tumble. And the tumbling is what leads to the bullet fragmenting. And it is this fragmenting that does the damage. When the bullet can't tumble it can't fragment and will only pass through. Now this can be mitigated using different bullet designs but for most tumbling is what you are wanting the 223 to do for best results. Velocity can also cause the bullets to fragment but the velocity has to be high enough to force the bullet to loose its structure integrity. This is the reason why we are hearing all the poor reports from soldiers overseas. The bullets are being overstabilized which kills the hopes of tumbling and the velocities have been reduced by the heavy bullets which kills the hopes of the bullet coming apart from velocity.We never heard of complaints from the military until they shortened the barrel to 14.5" and went to a 7 twist barrel. There is a reason for this.

Also, a 7 twist will not shoot the lightweight varmint type rounds. I know because I have watched them turn into gray mist 25-35 yards out of the muzzle of a 7 twist gun I owned.

A 9 twist barrel will shoot 40 grain bullets and all the way up to a 77 grain bullet. A 7 twist barrel will not shoot anything under 50 grains without the risk of the bullet coming apart under its own centrifugal force. And the 8 twist barrel is the best of ALL worlds. It will shoot any weight of bullet that can be fed from the AR magazine.
 

There is nothing to gain with a 7 twist unless you are shooting tracers exclusively. A bullet that is spun faster than it needs to be will be less accurate than the bullet that is spun to the correct RPM. If you look at all the sucessful long range benchrest shooters they are using barrels taht have a very slow twist. There is a reason for this.

 

Dolomite

Edited November 18, 2013 by Dolomite_supafly

[Oh Shoot]

9 twist will shoot anything I might load or find. And it is still slow enough to tumble which starts the fragmenting process. And even if the bullet doesn't fragment the act of tumbing creates a larger wound channel.....

 

My understanding is that fragmentation is primary dependent on minimum velocity while tumbling is primary dependent on least possible stabilization for a given velocity, at least with FMJ. No?

 

If so, would seem that achieving both would take a quite narrow set of parameters, and then only within a fairly narrow range also?

 

- OS

Edited November 18, 2013 by Oh Shoot

[Dolomite_supafly]

Not necessarily.

 

Anything 2,600 fps is the accepted fragmentation velocity with FMJ. So as long as the bullet is going at least that fast when it tumbles it will fragment. And as long as you have a twist slow enough to tumble then you will fragment.

 

Now if you have a twist rate too fast it will not tumble and more than likely will not fragment unless the velocity is fast enough to cause the bullet to fragment without tumbling. And that velocity is much higher than 2,600 fps.

[Oh Shoot]

Not necessarily.

 

Anything 2,600 fps is the accepted fragmentation velocity with FMJ. So as long as the bullet is going at least that fast when it tumbles it will fragment. And as long as you have a twist slow enough to tumble then you will fragment.

 

Now if you have a twist rate too fast it will not tumble and more than likely will not fragment unless the velocity is fast enough to cause the bullet to fragment without tumbling. And that velocity is much higher than 2,600 fps.

 

Gotcha.

 

Well, I think we tend to forget that 55gr and more traveling at 2400-3200 fps also have quite the temporary wound channel not to mention hydrostatic shock to tissue/organs quite a distance from the channel, so even just a "punched 22 caliber hole" at those speeds is pretty significant too.

 

- OS

[jcluff]

Awesome response there Dolomite! Thank you!


Sent from my iPad using Tapatalk HD

[mikegideon]

Gotcha.

 

Well, I think we tend to forget that 55gr and more traveling at 2400-3200 fps also have quite the temporary wound channel not to mention hydrostatic shock to tissue/organs quite a distance from the channel, so even just a "punched 22 caliber hole" at those speeds is pretty significant too.

 

- OS

 

Y'all should just move to .458 SOCOM and ditch those poodle shooters. A TTSX reaches full expansion (better than 3/4") at 1000 fps or greater. Don't have to worry about hydrostatic shock when you can see daylight thru the hole :)

[Oh Shoot]

Y'all should just move to .458 SOCOM and ditch those poodle shooters. A TTSX reaches full expansion (better than 3/4") at 1000 fps or greater. Don't have to worry about hydrostatic shock when you can see daylight thru the hole :)

 

I can't risk the hernia carrying the damn ammo!

 

- OS

[mikegideon]

I can't risk the hernia carrying the damn ammo!

 

- OS

 

It's heavy. But, unlike the 45 ACP, you really do only have to shoot 'em once.

[Jonnin]

I never thought I would say this...  I am thinking about getting an AR.  For all my love of leverguns and revolvers I am finding the lack of a defensive rifle concerning.  I was hoping y'all might have some advice.  My experience with the AR is totally restricted to the military, so I don't know much about one other than how to shoot it and clean it.

 

MONEY IS AN OBJECT.  This must be as low cost as possible.  I am not saying that I don't want to spend a good amount of cash, just saying that I cannot afford to.  $700 is it.

 

Aside from money, it is also important to me that the lower is Alum and not poly.  I also want a flat top.

 

I have been looking at two options.

 

#1. DPMS Oracle. 

 http://www.budsgunshop.com/catalog/product_info.php/products_id/70770/DPMS+Oracle+Semi-Automatic+223+Remington5.56+NATO+30%2B1+Cap

 

#2.  Del-Ton M4 rifle kit.

https://www.del-ton.com/ProductDetails.asp?ProductCode=RKT100-C

 

I would then have to get a lower, of course.

 

Opinions?  Other options?

 

Also, what difference does a 1:7 or a 1:9 barrel make?

 

The barrel twist does not matter for a defensive rifle.  If you want to shoot long range, or specialty ammo (extra light or extra heavy) in a competition gun at a "long" (for an AR) range, then it matters.  For a 25 -100 yard defense situation (and 100 is really, really pushing any normal use of the word "defense") using standard ammo, ANY twist rate that you can buy will deliver the round accurately enough to stop an attacker.  

 

That said I am another big fan of the S&W.  I have 3 of them now,  2 in 223 and one in 308.   One of them is the sport and the other is the next grade up that has a dust cover and FA.   I don't even know the twist rates of any of them off the top of my head!  

 

So my advice is to look for the other features you wanted, and ignore the twist rate. 

Edited November 18, 2013 by Jonnin

[Will H]

It's a moot point now...  I was out and about today, and saw this Ruger American in .308.  It looked lonely sitting in there with no owner, and well, she followed me home along with a 6-14x scope.  I tried to shake her, told myself that I needed to keep saving for an AR, but I could not help it.  I was powerless to resist.

 

 

Now she is propped against my newest $0.00 wood recycling project for my Lee Classic Turret

[Guest Bonedaddy]

For somebody that hunts deer in their house shoes, you probably want a Blackout anyway :)

Yea, I do but I was gonna take the upper from the Sport and put it on that poly lower I have and use the Sport lower for the BLK. No reason why I couldn't, is there? Anything 5.56/.223 will just be a yote or SHTF gun, anyhoo.

[Guest Bonedaddy]

Y'all should just move to .458 SOCOM and ditch those poodle shooters. A TTSX reaches full expansion (better than 3/4") at 1000 fps or greater. Don't have to worry about hydrostatic shock when you can see daylight thru the hole :)

And it's a hoot ta shoot, too! I'd love to tap a yote @ 25 just to see what happens. Frontal head shot, of course.

Edited November 19, 2013 by Bonedaddy

[mikegideon]

And it's a hoot ta shoot, too! I'd love to tap a yote @ 25 just to see what happens. Frontal head shot, of course.

 

Yote turns into abstract art :)

[mikegideon]

Yea, I do but I was gonna take the upper from the Sport and put it on that poly lower I have and use the Sport lower for the BLK. No reason why I couldn't, is there? Anything 5.56/.223 will just be a yote or SHTF gun, anyhoo.

 

Seems a shame to yank that sport apart permanently. That's a good little rifle, based on what I saw with OhShoot's. I would almost just swap lowers when needed. 

[mikegideon]

It's a moot point now...  I was out and about today, and saw this Ruger American in .308.  It looked lonely sitting in there with no owner, and well, she followed me home along with a 6-14x scope.  I tried to shake her, told myself that I needed to keep saving for an AR, but I could not help it.  I was powerless to resist.

 

 

Now she is propped against my newest $0.00 wood recycling project for my Lee Classic Turret

 

I love that press. I load all my blaster stuff on one.

[Will H]

So much for contemplation...  I just finished this beauty and she fired like a dream.

 

 

Special thanks to LCPfraTN for the trade.

[whitewolf001]

So much for contemplation...  I just finished this beauty and she fired like a dream.

 

 

Special thanks to LCPfraTN for the trade.

 

DETAILS MAN, DETAILS!!!!!!

[Will H]

Nothing special

NATMTL multical lower

PSA upper

PSA lower parts kit

A3 carry handle

[Guest Darthlaidher]

Nice mine started out in that configuration and ended up like this, if you are anything like me, once I got my AR I tinkered with it until I was happy or until I got tired of what it looked like. 

Cut off the front sight post and went free float. 

Edited January 3, 2014 by Darthlaidher

[Guest carter]

if someone could PM me if they know... i just ordered 2 stripped lowers from PSA and i put the FFL info in the correct spot...do i need to do anything else? never ordered anything from them before... do they call and get them to fax a copy of the FFL? or do i need to do that... i ordered them on the 10th and its still processing 

[Garufa]

if someone could PM me if they know... i just ordered 2 stripped lowers from PSA and i put the FFL info in the correct spot...do i need to do anything else? never ordered anything from them before... do they call and get them to fax a copy of the FFL? or do i need to do that... i ordered them on the 10th and its still processing 

 

I would go ahead and call your FFL with the PSA order # and have them fax a copy of the license.

[Oh Shoot]

I would go ahead and call your FFL with the PSA order # and have them fax a copy of the license.

 

Yeah, that's wise. Also, IF you can get through to the PSA FFL dept (803-724-6932, ffl@palmettostatearmory.com) you can see if your FFL is already on file with them.

 

PSA has actually called and emailed me in the past when there was a prob with my FFL, but no guarantees on that I guess.

 

- OS

Edited January 15, 2014 by Oh Shoot

[Guest carter]

Yeah, that's wise. Also, IF you can get through to the PSA FFL dept (803-724-6932, ffl@palmettostatearmory.com) you can see if your FFL is already on file with them.

 

PSA has actually called and emailed me in the past when there was a prob with my FFL, but no guarantees on that I guess.

 

- OS

guess i'll try calling on monday and see what or if they need anything