Armory Sponsor
Posted: 12/14/2009 11:34:41 PM EDT
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I'm playing with an idea of building something along the lines of a PDW type build. The shortest barrel looks to be 7.5" or there about. I'm doing this on the cheap so I'm not looking at anything too fancy. The barrel seems to be my biggest issue. I will most likely only shoot 55gr ammo(I have lots of cheap 55gr) as I do not see the reason for shooting better ammo for such a short barrel for just a "fun gun". BUT I want the best shooter I can get for the type of build I'm doing.
I have found cheap 1/9 twist barrels. I have also found 1/8 and 1/7 twist barrels for double the cost. Would I be better off with a tighter twist in a shorter barrel? Or at 50yrds does it really matter? I know twist rate is more a bullet weight/length thing but my thinking is that a tighter twist would spin 55gr a little faster but since its only 7.5" it would not have the chance to over spin the bullet. Or am I way off base. And please forgive some of my terms used. Thanks for any useful thoughts. |
| If you are just using 55grn ammo then i would go with a 1/9" twist. If you plan on using heavier ammo like 75grn, then go with a 1/7" twist. It doesn't matter the barrel length, it's all about bullet weight that decides what twist rate you should go with. And since it's just supposed to be cheap and for range use only, then go with the cheaper 1/9" twist barrel, it will still be plenty accurate. |
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Two thoughts:
––If you ever decide to add a suppressor, go with the faster twist. A 5.56 projectile needs about one full turn before it is stable enough to consistently clear tight suppressor baffles (and the most quiet cans are set up tight). Also remember that barrel length is measured from the boltface, not the front of the chamber, so a 7.5" barrel only has 5.5" of rifled length to start spinning the projectile. ––The shortest reliably functioning 5.56 barrel I've seen is 4", on the uppers made by the M2 Corp about a decade ago. Haven't seen any since then. |
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