how light of a bullet will a 1 in 7 twist stablize

[winky]

and shoot accurately

[Alaskagrown]

I wouldn't go lighter than 55grn

[winky]

thanks.

[robocop10mm]

Theoretically you can always go lighter and keep the accuracy. The bullet would be "over stabilized" and not exhibit the classic yaw upon impact. Every gun will have a load it "likes" it is difficult to predict which bullet/powder/primer/case combination a particular gun will shoot well.

The real problem IMHO is the lighter bullets tend to have thinner jackets that do not withstand the extreme forces the fast twist barrel will put on them. I have had 52 gr. FBHP's literally come apart with in 15 feet of the muzzle from a 1/7 barrel. If I load them down to about 2800 fps, they hold up well and are accurate.

I don't see the point of going lighter than 55gr. The performance can get spotty and the bullets are more expensive.

[Geilt]

An AR with a 1in7 twist is intended for heavier bullets between 65-90gr but sings with bullets around 80gr. You can probably go as low as a 55gr but load it with a light powder charge.

Robocop is absolutely correct when he says the lighter bullets have thinner jackets and at higher speeds they will fly apart. Hence why you start slow and build up from there in .25-.50gr powder charges until you find a combination that works.

Of course if you want to go light and fast right out of the gate you could go with a solid copper bullet like what Barnes puts out. No worries about the jacket flying off. The biggest issue there is cost.

Out of curiosity, with a fast twist like that, why are you looking to go light?

[winky]

Im not really conserned about going that light. its just that i have a pile of 55grain soft nosed and fmj bullet that i need to burn up. I bought 8 boxes of various bullets today from 60 to 69 grain. I have some 80 grain seirras that the guy that had the rifle gave me but the problem with them is if you seat them deap enough to work in a mag. they tend to fall into the case. Probably work fine single loaded but thats not what i want.QUOTE=Geilt;23144]An AR with a 1in7 twist is intended for heavier bullets between 65-90gr but sings with bullets around 80gr. You can probably go as low as a 55gr but load it with a light powder charge.

Robocop is absolutely correct when he says the lighter bullets have thinner jackets and at higher speeds they will fly apart. Hence why you start slow and build up from there in .25-.50gr powder charges until you find a combination that works.

Of course if you want to go light and fast right out of the gate you could go with a solid copper bullet like what Barnes puts out. No worries about the jacket flying off. The biggest issue there is cost.

Out of curiosity, with a fast twist like that, why are you looking to go light?[/QUOTE]

[rep30cal]

You shouldn't have any problem with 55g bullets at all. I have 55g soft points
that are full nelly power loads and they shoot and group just fine from my
Colt 1/7 HBAR. Just as Robocop10mm said, I have had 50g Hornady SX bullets
fly apart in just a few feet from the muzzle. The 55g soft points that I have
loaded were Winchester, Speer and Hornady, I have some from MidSouth
Varmint Supply (I think is the name) that I haven't tried yet.

[Alaskagrown]

An AR with a 1in7 twist is intended for heavier bullets between 65-90gr but sings with bullets around 80gr. You can probably go as low as a 55gr but load it with a light powder charge.



No need to use a light powder charge military ammo doesnt have a light charge and it works great in M4's

[Geilt]

No need to use a light powder charge military ammo doesnt have a light charge and it works great in M4's

The light powder load isn't because I'm afraid of over pressure causing a problem in the rifle, it's because if you drive a small bullet in a 1in7 twist barrel like that it'll break up. A 1in7 barrel is really intended for a heavier bullet but will work on the lighter one fine if they aren't pushed too fast.

[bullseye]

"I have some from MidSouth Varmint Supply (I think is the name) that I haven't tried yet."
Now that's funny. :) I think you meant Midsouth Shooter's Supply http://www.midsouthshooterssupply.com/

[rep30cal]

Hey, That's the place, yeah, yeah, that's the place, that's the place.
Yeah Bullseye, I got them second hand so I wasn't sure of the name.

[winky]

ran over 300 rounds through it today. Not one malfuction so thats a pleasant change from the oly! Kind of odd results though. 80 grain sierras shot like crap. Figured though it was probably because there suppose to be seated out and shot single shot and i had them deap enough to feed through the mag. The 70 grain black hills stuff was poor too though and that was surprising. The best bullet of all of them was the 55 grain siera btsp. It went consistantly under an inch. The hornady 60 vmax and the sierra 60hp averaged about an inch. A couple surprises as coyotee remanufactured 55 grain soft points went an inch too not bad for 10 buck a box ammo and another surprise was the 50 grain vmax it went into 1 1/2 inch. Seems this one in seven likes the light bullets better then the heavys. Granted i havent tried any other 70 grain stuff and maybe something other then the load black hills shoots will do much better but overall im very impressed with the gun. When a carbine lenght light barreled ar shoots well into the one inch catagory thats good news. Especially considering my rest is an improvised handgun rest that isnt good for steadying a rifle and the gun has a terrible trigger and the cheap scope, which by the way is in the junk box made circles on targets at a 100 yards look like eggs. Id bet with the right loads and a good trigger the gun is capable of 1/2-3/4 minute accuracy.

[Alaskagrown]

The light powder load isn't because I'm afraid of over pressure causing a problem in the rifle, it's because if you drive a small bullet in a 1in7 twist barrel like that it'll break up. A 1in7 barrel is really intended for a heavier bullet but will work on the lighter one fine if they aren't pushed too fast.


M193 and Q3131A are both mil-spec and loaded hotter than most commercial ammo available for purchase both are 55grn and will not spin apart. there is nothing to worry about with 55grn ammo in a 1/7 twist barrel. of course don't take my word for it take the US military and pretty mch every other country shooting 223 in their rifles

[Geilt]

M193 and Q3131A are both mil-spec and loaded hotter than most commercial ammo available for purchase both are 55grn and will not spin apart. there is nothing to worry about with 55grn ammo in a 1/7 twist barrel. of course don't take my word for it take the US military and pretty mch every other country shooting 223 in their rifles


BAH!! What do they know...

(smirk)... point taken.

[Lon Moer]

- I use 55gr FMJ mil-surp in my 1/7's just fine

- much to read at the Ammo Oracle (ammo-oracle.com)

[richl]

this Will answer most if not all of your questions.

just good old reading material....



http://www.ammo-oracle.com/body.htm

[Player]

i've read that the lighter bullets will pull itself apart if shot through barrels that have too high of a twist

[zb-30]

Here is a related question, any problem shooting heavier grain bullets out of a 1/12 twist barrel?

[Alaskagrown]

Here is a related question, any problem shooting heavier grain bullets out of a 1/12 twist barrel?

well they won't stabalize properly so you will most likely keyhole have less than stellar accuracy and if shooting suppressed you will more than likely clip a baffle or just totally shred the inside of the can

[zb-30]

Thats good to know! So whats the deal with the 1/9 barrels, are they supposed to be able to shoot light and heavy ok?

[RMTactical]

55gr