March 4, 2018 at 6:41 pm #49437JHSFunParticipant
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Well with all the ban the ar stuff going on I talked to the wife for about 5 min and talked her in to buying a Ar upper/ lower. that I can build up for her
This will be a range only paper puncher at 100 yds
I have 12 twist and 9 twist in 223 and shoot cast and 50-55g jacketed in them
But I think my wife will like a shorter barrel — looked around all the shorter 14-16 barrels for sale are 7 twist
Will the 7 twist shoot the 50-55 g jacketed ok — or will it do shot gun groups ? 100 yds
the longest range i have at the club is 300 yds
Internet says yes and says no depending on where you look– Barrel twist caculator says I need a 12 twist
Lowest cost bullet is FMJ 55g boat tail 0.744 in length and I keep velocity down 2900- 3000
FYI I have 20in 12 twist barrel as a spare under the loading bench:)
I do not think she will like anything less than a 12- 14 because of loud muzzle blast
Thanks for your input
March 5, 2018 at 7:54 pm #49454GoodsteelKeymaster
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The 1-7 will do fine, especially if you use long bullets and load concentric ammunition, however, the AR platform cannot use the 1-7 twist very well because the magazine precludes the use of the really long bullets.
The thing with stability is you have to spin fast enough. Once you’re spinning fast enough to be stable, you’re stable. Spinning faster does not make you “more stable”, nor does it make you less stable. Stable is stable, and anything over the bare minimum RPM is on THAT side of the fence and you’re golden.
The problem is that nasty little thing called centrifugal force. As the RPM goes up, so does centrifugal force. The best way I can explain it is by comparison to a football being thrown. Too slow a spin, and the ball goes end over end. Too much spin and it starts to wobble and loses distance. The laces are the reason it wobbles. If the ball were perfectly balanced you could chuck that pigskin and spin the fool out of it. I’m sure you noticed the inherent sweetness of the Nerf footballs kids play with? Those puppies just seem to pencil through the air and are ever so easy to get thrown straight no matter how much spin you put on them. The reason is there is far less imbalance for the centrifugal force to get ahold of.
Our ammunition is no different. Using cheap bullets and firing them through a rough throat and barrel is akin to the NFL football. Those bullets come out of the barrel with inherent imbalance which the centrifugal force will act on, so it behooves you to use the slowest twist you can get away with if you are shooting that style of ammunition. However, say you load premium bullets to excellent concentricity, and you are shooting them through a premium lapped target barrel? Obviously, these bullets will emerge from the barrel with very little imbalance for the centrifugal force to get ahold of, thus, you can spin the living crap out of them and maintain precision. This is like throwing the perfectly balanced Nerf football.
Incidentally, no bullet is perfectly balanced, and our cast bullets are worse than most, which is why using the correct twist barrel for the length of the projectile was so very effective at getting excellent groups at high velocity. There are other benefits to using the slow twist barrels, but kicking CF right in the shorts from the get go absolutely cannot be understated as a positive effect.
Back to the jacketed bullets, there are always compromises and prices to pay for performance, and there’s a big difference between building a rifle for a specific style of ammunition, and building it to be effective with a range of ammunition styles. If your goal is to use premium ammunition loaded with the absolute longest bullets you can schtuff in the magazine and tossing them at long range, then 1-7 is the twist you want. However, if your objective is to have a close quarters battle rifle that will eat anything from a 77 grain SMK to a gas check seated upside down and get pretty reasonable precision from anything you can get your hands on, from rag head freedom pills, to premo hunting ammo, to handloads with bargain bin rejects, then the 1-8 twist scratches the itch. If you want to limit yourself to 62 grain and less bullets, then go 1-9. If you want to stay below 55 grains, then go 1-12.
In my opinion, 1-8 is by far the most versatile in an AR style rifle.
March 6, 2018 at 10:04 am #49493JHSFunParticipant
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Thanks for your reply
Will have to do some looking around .. maybe a used shorter barrel 9-12 twist
the cost of reloading stuff up here is higher by a fair bit
lowest cost 223 plinker bullets is 12 c each — 68g and heaver 27 plus cent each — Premium even higher
loaded 62g are .70c each , Primers are 52$ for 1k
if the wife was shooting at the longer ranges all the time I would go with the 7 twist and just pay the $$ but she will most just shoot at the 100 ( with a bit of a drive i could get to a 1000y range) Have to get her to the 300 club range but still should be able to do that with a 12 or 9 twist
i do have a savage in 9 twist to do varmit shooting if it comes up
all AR’s north of the border are limited to gun clubs only shooting paper. — the black scary gun that you can’t use for hunting.. because they are black and Scary and limited to 5 rounds
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