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Centerfire Rifles - Semiautomatic or Gas Operated Centerfire rifles, carbines and other gas operated rifles.

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  #1  
Old 04-23-2013, 3:43 PM
cc426 cc426 is offline
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Default How much does this stuff actually matter (twist rate/free floating rail)

So I'm about to purchase my first AR and i'm confused by all the different options. I realize a lot of it can be done after the fact, but I don't want to pay twice for something if it makes that big a difference.

I don't think i'll be shooting over 200 yards or so with this rifle and it's mainly for range use. However I do get quite a bit of satisfaction putting bullets through the same hole in my targets.

I've read the free floating rail help accuracy, and 1:7 is better for heavy bullets and 1:9 is better for light bullets while 1:8 is a good compromise for both.

All that being said, how much do these variables actually make a difference when it comes to accuracy vs how much of it is just a very opinionated bragging rights?
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Old 04-23-2013, 3:50 PM
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I'm also going to throw in 14.5-20" barrels and carbine vs midlength

I've done research and understand the general agreements on these topics, but how much does it make a real life difference?

Is this like buying a Porsche vs a Ferrari? In this analogy, both excellent cars, the Ferrari is marginally better (sorry Porsche fans) but i am not a good enough driver to ever notice the difference...
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Old 04-23-2013, 4:01 PM
barrage barrage is offline
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Trade it in for an M1A and then you won't have to worry about that kind of stuff ever again, let alone the endless 5.56 vs. 7.62xLittleGirl (39) debates you're going to inevitably find yourself engaged in every minute of the day.

But that's just my opinion, which happens to be that an M1A is the answer to most of life's problems.
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Old 04-23-2013, 4:08 PM
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Default My heavy barrel varmint AR

is now tapered to 0.750. I deleted the float tube and switched to a Magpul handguard. It is now at least as accurate as it was.

Consistently prints groups at 0.4" - 0.5" at 100 yards.

It has a stock trigger and a 5 power Nikon scope.

The chamber and reloads are more important than probably any other feature if you want accuracy...
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Old 04-23-2013, 4:08 PM
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You are on the right track

With a 20" barrel you are getting 2+ turns on the bullet from a 1:9" twist
Almost 3 turns with the 1:7" twist.

The longer barrels are less sensitive to the 1:7 or 1:9 twist rate issue.
If you shoot mil spec surplus ammo 45-62 grain, 1:9 is fine

For a short barrel such as the 14 1/2" with a welded flash hider to bring it to 16", then many favor the 1:7.

Most of the heavier bullets are longer and require a longer throat than mil spec.

-

Free floating does help accuracy as the barrel is isolated against pressure on the stock.

What you want depends on what and how you will use the rifle.

Most folks cannot shoot anywhere near the accuracy of the rifle from standing or sitting. That is if the rifle can shoot a 2" group, they cannot shot 2" at 100 yards.

So free floating to increase the accuracy of the rifle from a 2" group to 1 1/2" will not make any functional difference. The 1/2" improvement is just an example. Typically when you tighten a sling you add pressure onto the barrel. This can shift the group based upon the pressure on the barrel. Some are able to be very consistent with the sling and the shift is consistent. Others are not consistent so both the pressure and direction of the pressure changes.
The freefloat eliminates the pressure to the barrel so you keep the same zero.

I hope this help some

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Old 04-23-2013, 4:13 PM
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Unless you plan on handloading 69+ gr bullets, 1:9 should be fine. And unless you plan on shooting <45gr bullets 1:7 will also be fine.
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Old 04-23-2013, 5:54 PM
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Proper use of a free float system will reduce group size about 30% co pared to a non-floating barrel.
The quality of the bullets, barrel and then trigger will likely be the biggest mechanical factors in group size.
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Old 04-23-2013, 5:58 PM
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I'd go with less expensive and what looksbest. Those things will hardly matter at the range
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Old 04-23-2013, 6:37 PM
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Quote:
Originally Posted by oc2a View Post
I'd go with less expensive and what looksbest. Those things will hardly matter at the range
When you are trying to do this...

Quote:
Originally Posted by cc426 View Post
However I do get quite a bit of satisfaction putting bullets through the same hole in my targets.
It all matters, even if its just a little bit.
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Old 04-23-2013, 7:00 PM
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Don't forget that regardless of what twist rate you get, you will need to find the ammo that works best in your rifle, making all the worrying about which twist rate you get less important. Than is unless you get a less common twist rate.

I also believe that at 100 to 200 yards, a free floating barrel will help, but if you are strapped for cash, a better trigger would be a better value.
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Old 04-23-2013, 7:32 PM
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If you want to prove that a free floating hand guard helps a lot, try an experiment. Rest your barrel, not the hand guard, on a barricade and shoot at 100 yards. It can shift your POI several inches versus resting the tube on the barricade.

Spend some time finding the load your barrel likes. Mine likes 69gr SMKs over 23.8 gr of TAC (it's a 1/9)
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Old 04-23-2013, 7:34 PM
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OP what is your budget? This will help out deciding which way to go.
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Old 04-23-2013, 8:38 PM
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Quote:
Originally Posted by nothing4u View Post
OP what is your budget? This will help out deciding which way to go.
Its less abut budget and more about what's available right now...I mean I don't want to pay panic price, but I'm OK with paying more for something if I'm getting something for it

What sparked the question is that I found a stag 3g for just over $1600 (which is around msrp) and a s&w m&p15x for just under $1000 (which I think is a deal even during non panic time?). Wondering if its worth the more than $600 difference
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Old 04-23-2013, 8:40 PM
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Every little thing you do can help shrink your groups . Free float , match grade heavy or bull barrel , lite 2 stage trigger with very crisp break , non chrome lined barrel , fixed stock , match grade ammo and so forth and so on . To shoot accurately you do not need any of those things but each and every one of those things can incrementally help your accuracy . I would say the two things I would start with if I was looking to have a accurate AR would be a quality barrel and a nice trigger group . I would build around those two things .

Quote:
I've read the free floating rail help accuracy, and 1:7 is better for heavy bullets and 1:9 is better for light bullets while 1:8 is a good compromise for both.
1:7 is great for heavier bullets and heavier bullets will help you shoot longer distances . Most 1:7 are chrome lined and this extends the life of the barrel but can reduce accuracy. 1:9 is a good all around twist and will shoot up to 69gr bullets no problem . You can find 1:9 non chrome lined all day long . IMHO the 1:8 is no compromise , It's the perfect twist for the AR and what common bullets are available . I find that a lot of the 1:8 barrels are of high quality and chambered in the 223 Wylde , the 223 Wylde is another great choise .

Quote:
I'm also going to throw in 14.5-20" barrels and carbine vs midlength
The accuracy should not really be effected by the barrel length it self . Longer barrels will give you more velocity wich will intern give you longer range and less bullet drop . Longer barrels will give you a longer sight radius when using iron sights and that will help with accuracy .

OK the gas systems get a little more interesting . Im sure you know how the gas system works but do you understand it ? When the gun is fired the bullet is basically pluging the barrel and the gasses behind it are forcing the bullet down the barrel .When the bullet passes the gas port there is still a tremendous amount of pressure behind the bullet and some of that pressure is diverted threw the gas port and back down the gas tube cycling your bolt . Here is where it get interesting . The length of your barrel will often dictate what gas system you have . Everything after the bullet passes the gas port is called dwell time . The longer the dwell time the more gasses and pressure gets diverted back down the gas tube. Carbine length is 7" Mid is 9" and rifle is 12" . The 20" barrel has a rifle length gas system . The 14.5" barrel has a 7" gas system . Are you starting to see a pattern here , Both have about 8" of dwell time . 16" barrels can have either 7" or 9" gas systems . In the 16" barrel the mid length system will run better cus it's closer to the better dwell time then the carbine . If you have 2 16" barrel ARs one with a carbine system and the other with a mid . Check out how much farther the carbine throws the brass compared to the mid length . That extra 2" of dwell time rocks that BCG back . That all being said there are a few things you can do to adjust how the gas system works like buffer and spring weight to name a few .

Any ways to make a long story longer. If you get a 16" barrel I'd get a mid length system . It will be easier on your action in the long run .

Quote:
I've done research and understand the general agreements on these topics, but how much does it make a real life difference?

Is this like buying a Porsche vs a Ferrari? In this analogy, both excellent cars, the Ferrari is marginally better (sorry Porsche fans) but i am not a good enough driver to ever notice the difference...
Yes if you can't shoot worth a darn . None of what has been said in this thread will matter . The fact that you said

Quote:
I do get quite a bit of satisfaction putting bullets through the same hole in my targets
Makes me think all this info will help .

Hope this helps .
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Old 04-23-2013, 8:52 PM
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Quote:
What sparked the question is that I found a stag 3g for just over $1600 (which is around msrp) and a s&w m&p15x for just under $1000 (which I think is a deal even during non panic time?). Wondering if its worth the more than $600 difference
Have you considered just building one . They are really not that hard to build . With what your budget appears to be you could build a pretty nice one . If you were to build one , You might want to start with the BCG ( Bolt Carrier Group ) They seem to be the hardest thing to find right now . Maybe not start but as soon as a quality one comes is in stock grab it .
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Old 04-23-2013, 9:08 PM
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Quote:
Originally Posted by oc2a View Post
I'd go with less expensive and what looksbest. Those things will hardly matter at the range
^^ This.
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Old 04-23-2013, 9:12 PM
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Its all voodoo, its all in the shooter.
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Old 04-23-2013, 11:01 PM
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Get what you can get at the best price & be happy for now! Normal range work, your twist won't matter. If you can get a "good" 1/7, 1/8, or 1/9 barrel at a good price right now jump on it!~
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Old 04-24-2013, 12:35 PM
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The standard saying is barrel, bullets, trigger. For me, a fairly decent match shooter, the barrel is everything. So to answer your question, yes, twist rate and free float are very important but you have to have the shooting/loading skills to match.
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