.223/5.56 bullet weight, size brand questions.

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.223/5.56 bullet weight, size brand questions.

Postby Cloudwraith » Fri Mar 08, 2013 2:20 pm

So I picked up a set of .223 dies (Lee) and I plan on using Varget powder in my loads. My barrel is 1/7 twist government profile (Spike's Tactical) and i've read stories about the fast twist rate possibly disintegrating lower grain bullets or tumbling (54g and below).

Please help with the following:

What grain range will reliably be accurate with 1/7 twist.

What brand in that range will be affordable/obtainable in the current market

What diameter is recommended?

TIA
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Re: .223/5.56 bullet weight, size brand questions.

Postby shooterwolf » Fri Mar 08, 2013 4:03 pm

1) 55-90 grain bullets, With 55's being the cheapest and most common (usually).

2) What ever you can find, good luck.

3) .223/5.56 require a .224 diameter bullet for best accuracy.



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Re: .223/5.56 bullet weight, size brand questions.

Postby mreising » Fri Mar 08, 2013 5:17 pm

The rifling twist is actually based on the length of the bullet, not the weight. We just use weight because it is easier to determine (most of the catalogs don't list the length) and the assumption is that a heavier bullet is a longer bullet. Another factor is the muzzle velocity (MV) of the round, which affects the RPMs that the bullet spins based on a particular twist. In other words, a 2000 fps bullet will spin at lower RPM than a bullet fired at 3000 RPM. Each particular length bullet has an ideal RPM range. The formula for bullet RPM is: Bullet RPM = MV X 720/Twist Rate (in inches). The Greenhill Formula (do a search for it) gives an approximation of the ideal twist rate for a given bullet, although there are more complex formulas that take other factors into account besides caliber and length (Greenhill has no specific factor for velocity included although there is a constant that some people change depending on whether velocity is greater than or less than 2800 fps).

In repsonse to your original question, some lightly constructed bullets could shed their jacket at exceptionally high RPM and 55s may not be ideal in a 1/7 barrel but I would not sweat it unless you have stability issues or the bullets come apart. Do a few test runs to see. Also, you can load to a lower velocity for the 55s and save powder and barrel wear.
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Re: .223/5.56 bullet weight, size brand questions.

Postby Hedgelj » Fri Mar 08, 2013 6:47 pm

mreising wrote: Also, you can load to a lower velocity for the 55s and save powder and barrel wear.


How much barrel wear are you really going to save? My DD barrel is rated to maintain POA/POI for 15-20K rounds. Even at 30 cents a round that's $4500+ in ammo alone and then you spend $300 on a new barrel. What is there to save?
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Re: .223/5.56 bullet weight, size brand questions.

Postby mreising » Fri Mar 08, 2013 7:16 pm

Hedgelj wrote:
mreising wrote: Also, you can load to a lower velocity for the 55s and save powder and barrel wear.


How much barrel wear are you really going to save? My DD barrel is rated to maintain POA/POI for 15-20K rounds. Even at 30 cents a round that's $4500+ in ammo alone and then you spend $300 on a new barrel. What is there to save?

I guess I should have put a smiley after that as the amount of wear one saves is negligible and it was tongue in cheek.
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Re: .223/5.56 bullet weight, size brand questions.

Postby Hedgelj » Fri Mar 08, 2013 8:41 pm

mreising wrote:
Hedgelj wrote:
mreising wrote: Also, you can load to a lower velocity for the 55s and save powder and barrel wear.


How much barrel wear are you really going to save? My DD barrel is rated to maintain POA/POI for 15-20K rounds. Even at 30 cents a round that's $4500+ in ammo alone and then you spend $300 on a new barrel. What is there to save?

I guess I should have put a smiley after that as the amount of wear one saves is negligible and it was tongue in cheek.


Tongue and cheek and or sarcasm I can read when the smileys help me out with it, otherwise tone is hard to read in text.
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