question?

I was thinking about getting some varmint bullets and wondering how light I could go. Any one have experiences with this?
 
Construction is a big consideration.

Varmint bullets are lightly-constructed, and designed for slow-twist barrels. Shot from a fast-twist barrel, they may blow apart in midair from spinning too fast unless they're downloaded.

The Speer 55gr TNT, for example, is designed to run @ 3200fps from a slow twist barrel. From a 1:7 twist, it'll spin way faster than it was designed, and will come apart.

From the Speer manual:
Independent studies by several component bullet companies have shown that a 55-grain 22-caliber bullet must have a muzzle velocity no higher than 2800 ft/sec to hold together in a 1-in7 inch twist barrel. Even this assumes a barrel in top-notch condition; the critical speed drops for worn, rough, or pitted barrels.
Click to expand...

IOW, you'd need to download this bullet to run no higher than 2800fps in a 1:7 barrel. And I note Speer doesn't distinguish this generic 55-grainer from a varmint 55-grainer, which is particularly susceptible to shear. I'd be conservative by considering something more like 2600fps as my starting place, then working up if needed.
 
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I recently read a good article by a fellow that tested various weight 223 bullets in various twists. The light bullets (40grain) shot quite well. Do not assume, without testing with your rifle, that a light bullet won't give good accuracy.

Buy some 40 gr Nosler Ballistic Tips and if they don't shoot well in your rifle, I'll buy them from you. I use a lot of them, so a few more is good.
 
40 gr. Sierra Blitzkings should work through your 1-7 twist. I have a 22-250 with 9 twist and contacted Sierra. They replied that their Blitzking bullets would be good for my application. I emptied both my outbox and in box on email the other night, or I would look up their communication. The point is, some bullets can't hold together at ultra fast rpm's. So heavier bullets that shoot slower are better for fast twist.

Here is the formula for calculating rpm:

720 X velocity in fps divided by twist

For example--If you're shooting a bullet at 3500 fps then it would be

720 X 3500 = 2520000 divided by 7 = 360,000
 
what poweders work good with those nosler and sierra bullets? I am trying toget everything togather while I save my brass thx for the advice.
 
I have shot lots of 55 gr FMJ .556 ammo through my 1:7 AR over the years. Never had any issues. I've gone as light as 50 gr with no issues, just not shot nearly as many. Never tried anything lighter. I get somewhat better accuracy with 60gr and heavier projectiles, but the 55's function just fine and provide adequate accuracy.
 
I've heard that the light Hornet bullets would come apart in fast twist barrels but I've never seen it.

The Army makes a Mann Accuracy device which they issue to different ammo makers to test the ammo they make for the military.

This is a Remington Action with a heavy short barrel in 1:7 twist.

Mann%20in%20stock.JPG


To test the device (to see if they are being shot out) they use a variety of handloads, the most accurate I've seen in reports uses Remington Cases, and 52 gr. Hornady A-Max being pushed by 25 gr. of 3031.

I got the above Mann device from the CMP, it's quite the tool for checking my ammo for my 223s. Lots of fun experimenting with different components. Wish I'd gotten one in 308 when they had them.
 
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