1:7 vs. 1:9 Twist, bullet grain & prices

[Wolvee]

zzzzzzzz

[mechredd]

62gr and up for 1:7, and 55gr is ok. 50-62 for 1:9, but 55 is ideal. 45 and under for 1:12.
1:9 is a bit more universal than other twist rates. It can accurately fire the widest range of bullet weights, but has problems with the extreme ends of the scale.

For range play, I'd go with 1:9 ans 55gr FMJ are cheap and widely available. My AR is a 1:7. At first I didn't like it because the ammo was harder to find and more expensive. I like it a bit more now because I can fire some very heavy 75gr defensive loads with better long range accuracy over a 1:9, provided I do my part.

[RECON762WT]

A good do all is a 1 in 9" twist rate. Good for 55 grain (cheap) ammo.

1 in 7" is more geared towards 69+ grain bullets.

[mechredd]

Recon's post reminded me that twist rate is as much about the length of the bullet as the weight of it. The 62gr ss109 (M855 surplus) has a steel core which is lighter than lead, and therefor longer than a lead core of the same weight. A 69gr lead core should be about the same length as the 62gr ss109 steel core. Pure copper rounds will also be longer than standard lead bullets of the same weight.

[Joeywhat]

It's actually all about bullet length...1:7 is what the military uses because of tracers...they're very long despite not weighing a lot (for the size, at least).

You'll find that each barrel is a little different. Some 1:7 bbls don't like 55 gr...some do. 1:9 is generally a good compromise, some run heavy loads fine some don't.

It's all about what you want to run through it. You can buy cheap ammo in a number of bullet weights.

[silverbullet2005]

All I know is that with the 1:7 barrel you can run a higher grain ammo like 62, with the 1:9 barrel you want to stay around 55 grains.

[Joeywhat]

All I know is that with the 1:7 barrel you can run a higher grain ammo like 62, with the 1:9 barrel you want to stay around 55 grains.

A 1:9 should have zero issues with 62 and even 69 gr ammo. 1:7 shines with 70+ gr.

1:12 is the twist rate that can't go much over 55 gr.

[CoponPatrol]

I hope this is not hijacking wolvee's thread, but what about using a .22 conversion in a 1/7? I use one in my 1/9 right now without any problems, and I just purchased a 1/7 upper. No?, Yes?

[mechredd]

I hope this is not hijacking wolvee's thread, but what about using a .22 conversion in a 1/7? I use one in my 1/9 right now without any problems, and I just purchased a 1/7 upper. No?, Yes?

Aguila makes some really heavy subsonics that they recommend using a 1:9 with. Most 22 conversion kits seem to accurate with most any barrel, but I've never seen anyone try to shoot them past 25 yards.

[Buffman]

I've shot the 75gr Hornady 5.56 out of my Stag with a 1:9 and had no keyholing at 30yds. Can't speak of accuracy because of open sites and just was blasting at the paper.

[Ol` Joe]

There`s chart in the lower page of this link that gives the recommended twists for various calibers and the bullet wgts they recommended you use in them.
The needed twist is determined by bullet LENGTH NOT WEIGHT but it works out quite close unless VDL type bullets are being used. BTW the 5.56 uses .224" bullets
http://www.riflebarrels.com/products/caliber_twist_rates.htm
I have personally shot 69gr bullets from a 223 with a 1/9" twist and had perfect results, even with medium velocity loads. Keep in mind to you can under spin a bullet easier then over spin one. Too fast of twist will still stabilize the lighter bullets but, they tend to fly a bit weird once they get way out to extreme ranges where they tend to ride slightly point up instead of level. This is likely not going to show @ 500yds with a 223/5.56 so you are best off with a twist that will handle the longest bullet you plan to shoot rather then go for one that is acceptable for the one you plan to use most. Even if you do over twist a bullet, the accuracy you get at very long ranges will likely be as good as the average shooter is capable. The 1000yd bench boys or other extreme accuracy nuts are a different story

[PaulB84]

I love these threads......

Like Buffman, my 1:9 MP-15 shoots TAP 75 grain with aplomb (.223 not 5.56, haven't been able to lay hands on that yet!) I've heard rumors that Stag may make S&W lowers, but thats neither here nor there...

It is the most accurate load I've shot out of that gun and what I have currently loaded for HD. Shoots sub MOA at 100 yards with magnification, and with an Aimpoint I can empty a mag inside 3-4" Great stuff.

[Wolvee]

zzzzzz

[RECON762WT]

All things being equal, meaning you are purchasing a rifle with the same accessories. I would go with the M&P hands down. Roll the savings into an optic or different upgrades.

[no im not squinting]

Which is a better rifle, a Colt w/ a 1:7 twist for $1200 or an M&P w/ 1:9 for $900. Is there so much of a difference in them that someone should be compelled to buy the Colt?

If you can wait a few weeks how about a Spikes w/ a 1:7 for $785 shipped. Use the ARFCOM code to knock 5% off. If you let the spec sheets influence you then the Spikes is more attractive than the M&P and almost as nice as the Colt. My brother has an M&P and its an excellent rifle-and I can find no faults with it. I dont knw exactly what you are loooking for but CDNN has had some absolutely crazy deals on M&P 15's.

[919cw313]

...I dont knw exactly what you are loooking for but CDNN has had some absolutely crazy deals on M&P 15's.


Like this? I'm not very interested in AR's, but am tempted to buy at this price.

Smith & Wesson M&P15 .223 16" M4 Profile Barrel Detachable Carry Handle
6-Position Collapsible Stock Bird Cage 1-30rd Mag New
#SMI811000 $799.99

[PDinDetroit]

All things being equal, meaning you are purchasing a rifle with the same accessories. I would go with the M&P hands down. Roll the savings into an optic or different upgrades.

I have an M&P 15 MOE in Flat Dark Earth. Very accurate, very nice AR-15.

[moreguns]

I use 1x7 twist 12.5" barrel and a 1x8 24" barrel for my AR's. They like 70,75,77 gr bullets.