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Posted: 12/17/2007 9:33:39 PM EDT
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I have a Colt carbine with a 6920 barrel, lo-pro gas block, covered by a midlength Troy Ind. free float railed handguard. I also have rail mounted Troy Ind. front and rear flip up sights. It has not been fired so I decided to test it out. I went to an indoor range where I was limited to frangible ammunition (backstop won't stop rifle rounds) and only had 1 box of International 42gr frangible ammunition. The set up on my upper appears straight as an arrow, i.e. looking down the bore at a vertical line the sights line up. However when I shot the 42gr frangible stuff, it shot way to the right at 25yd range. Cranking the sight way over brought some of the shot placement closer to center but still favoring the right. I am assuming this is the ammunition being so light out of a 1/7 barrel. I was able to adjust the vertical shot placement. I guess my question is could it be that the 1/7 twist spin on such a light bullet throw it toward the right like that? Of course this stuff won't be my ammo that I normally use. I mainly wanted to function check due to new gas block and to get the sights half ass'd adjusted for when I do go out and shoot "real" ammo. It's just too damn cold out this time of year to go out and shoot outdoors.... |
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I sell 42gr. frangible non-lead bullets and ammo. Your situation is that a 42gr. non-lead bullet is really a 55gr. jacketed bullet in LENGTH. The 9" twist is best for this bullet. If you have a 7-8" twist barrel, you will need our 55gr. frangible that is the length of a jacketed bullet weighing 72gr. in jacketed/lead length. The non-lead frangible concept works. Just ask Barnes. I sell their 223 Branes Grenage loaded to 4400 fps in 22-250. It's very accurate and makes "The Seekers of the Red Mist" very happy. It is pure copper and only weighs 36gr. Shoot it in your 9" twist barrel. Weight of the bullet is not related to twist, length of bearing surface is what is important. The best illustrations are the 6.5 Swede military round in the 7 3/8" twist using a 160gr Hornady RN. it shoots great. A round ball flintlock uses a 66" twist, it shoots great too. Don't try to reverse the concept. Remember the 223 Viet Nam barrel twist issue? Bullets that were barely stabilized had good knock down and only fair accuracy. Now military AR's are great in accuracy (Camp Perry/David Tubb) and some want to change them to 6.5/6.8 for better stopping power! Give me a shout, we can talk, [email protected] Captain |
I did not know that. Thanks for the clarification. A 1-7 twist rifle should be able to shoot a 55gr length bullet without being off that far. |
I will just have to wait and see when I can go and shoot some "normal" ammunition thru it. It will bug the hell out of me if it is really shooting that far to the right. I am just hoping it's an ammo- twist- barrel- whatever related thing that is causing it to shoot to the extreme right.... |
From the Barnes web site:
As far as shooting way to the right, could you have a canted FSB or poorly installed hand guard? That will make your rounds impact way off to the side, and make it hard to get back right by adjusting the sights. |
| From the looks of it, the Barnes bullet is more of a typical bullet in the way it is constructed. Frangible ammo is powdered metal sintered under extremely high pressure. I wouldn't call the Barnes ammo frangible as much as "super easy to fragment". True frangible ammo behaves more like a solid unless it hits steel or something very hard and wouldn't blow up varmints very well. |
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