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Discussion Starter · #1 ·
So I've pretty much made up my mind that my next rifle is gonna be an RDB, had looked at the C "Hunter" model, but since I live in a free state I thought I'd grab the original by the pistol grip before some jerk decides I can't have that.

I know I'll get a little more velocity out of the 20 inch barrel versus the 17, but is there any kind of real accuracy difference between the two? Either way I'm sure it'll outshoot my Mini-14 all day long and with an overall profile 7-10 inches shorter!
 

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Yeah, Minis are hit or miss on accuracy. :ignore:

Surely a longer barrel will be more accurate at greater distances due to more stability, however I doubt 3” would make much of a difference in the 200 yd effective range of this ammunition. I have a 20”, but no bench rest to truly determine a proper group.
 

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With the same barrel diameter, I'd expect a 20" barrel to be slightly less accurate than a 17" barrel. The accuracy is related to barrel stiffness (resistance to barrel whip) and the stiffness of a column is inversely proportional to the square of the length, roughly analogous to Euler's beam or column equations.

https://en.wikipedia.org/wiki/Euler–Bernoulli_beam_theory

That Wikipedia page has a nice graphic showing I-beam deflection. Barrel whip is similar, but generally the muzzle is whipping around in a more complex pattern than simply up and down.

To make a rifle more inherently accurate, make the barrel shorter or larger in diameter. In practice, there are also tricks reloaders do to optimize loads to maximize accuracy by having the bullet exit the muzzle when the muzzle is moving the least, and that's when it's at the extreme end of the barrel whip excursion and is reversing directions (at the maximum point of barrel whip deflection).
 
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Discussion Starter · #4 ·
I was already leaning 17 based on the smaller profile, increased potential for barrel stiffness and the fact that is typically a little cheaper and more easily found versus it's 20 inch equivalent. Unless somebody can give me a solid reason to reconsider the 20, I think 17 it is...
 

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The things that have given better accuracy, assuming the shooter is doing his part, is using the heavier grain balls E.G. 70+, and removing any slop out of the hand guard.

I would get a pistol grip.
You can join the rest of us in wondering why it didn't get a push button mag release.
 

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If you have long arms, and prefer an extended gorilla grip clamp with your support hand, you may want a little more wiggle room offered with a longer barrel. I have short arms, but sometimes grab the very end of the hand guard. This leaves my fingers close to the muzzle ...
 

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I don't think there's much advantage for a 20" barrel over a 17" with .223/5.56.

As far as barrel whip is concerned it's not a metric that's easily measured without head to head comparison between the 2 from a benchrest as the barrel profile isn't just a consistent size and also the fact that everything on this rifle hangs from the barrel. Note that putting force on the front handguard of this platform is known to cause POI shift. The Lucky Irish Raptor rail seems to address this by locking down the handguard tightly and stiffening the assembly making it a little harder for you to induce POI shift from your hold. I can't really comment further on it as I haven't used his rail myself yet though.
 

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So I've pretty much made up my mind that my next rifle is gonna be an RDB, had looked at the C "Hunter" model, but since I live in a free state I thought I'd grab the original by the pistol grip before some jerk decides I can't have that.

I know I'll get a little more velocity out of the 20 inch barrel versus the 17, but is there any kind of real accuracy difference between the two? Either way I'm sure it'll outshoot my Mini-14 all day long and with an overall profile 7-10 inches shorter!

I have a RFB in 308 with an 18" barrel and that sucker is plenty accurate enough out to 200 M. Also have a DPMS AR with a 20" that has the same accuracy out to 200 M so, for about the first 10 shots or so both are accurate. After 10 that little RFB tends to beat your cheek up if you are scrunching down to get accuracy out of it. The RFB is definitely an urban battle rifle the DPMS with it's carry handle is more nostalgia for me.
 

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If you live in a free state, one consideration in favor of the conspicuous, evil pistol grip is heat. On the RDB-C (I live in a non free state) the top where you would wrap your thumb around gets quite hot to the point that I dont wrap my thumb around the top. This was not a high rate of fire either since I was just putting a round or two in all of my new mags to see if the rifle or me has a preference in mags

I know. This is not the end of the barrel you are talking about. But it's an RDB-C consideration in my book.
 

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With the same barrel diameter, I'd expect a 20" barrel to be slightly less accurate than a 17" barrel. The accuracy is related to barrel stiffness (resistance to barrel whip) and the stiffness of a column is inversely proportional to the square of the length, roughly analogous to Euler's beam or column equations.

https://en.wikipedia.org/wiki/Euler–Bernoulli_beam_theory

That Wikipedia page has a nice graphic showing I-beam deflection. Barrel whip is similar, but generally the muzzle is whipping around in a more complex pattern than simply up and down.

To make a rifle more inherently accurate, make the barrel shorter or larger in diameter. In practice, there are also tricks reloaders do to optimize loads to maximize accuracy by having the bullet exit the muzzle when the muzzle is moving the least, and that's when it's at the extreme end of the barrel whip excursion and is reversing directions (at the maximum point of barrel whip deflection).
I saw a review of both the 17 and the 20 in and the muzzle flash off of the 17 was a great deal more.
 
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