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Muzzle velocity estimate without Chronograph

13219 Views 22 Replies 9 Participants Last post by  BKeith
I don't have access to a chronograph at this time and I don't want to spend the money. And I just need a rough rule of thumb or experience with this matter.

So what should I expect the muzzle velocity difference to be when using a
Rock River AR15 with a 16 inch barrel 1 in 9” rate twist instead of a
Remington 700 26”, 1 in 12” twist (Hornady Data used from their reloading book)?
My guess is a loss of 150 fps.

I reloaded the 223 Rem using Hornady Data:
55 gr #2266 SP w/c
B.C. 0.235 C.O.L.: 2.200”
Varget 25.5 gr
Velocity per book 3100 FPS
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Quickload suggests that load, with a 16" barrel, will come in right at 2900fps and with a 26" barrel, velocity would be around 3240fps. A gain of roughly 350fps, or 35fps per inch of increased barrel length. That's a lot, but then again, the .223 Rem really needs more than a 16" barrel to burn all of the powder it can hold.

Incidentally, QL shows that as being a 110% compressed charge. A slightly faster powder, like H322 or IMR4198, might be in order. Both show the same velocity and higher ballistic efficiency, without being compressed so much. Particularly if you do most of your shooting with the 16" barrel, the Varget load is not ideal.
I supect a tad more due to the ARs gas operation...

375ish
When it comes to ballistic guessing without a chronograph, any guess within reason is about as good and accurate as any other.

so true... I agree 100%

All reloaders should really get a chronograph
This has already been discussed, ad nauseum, but why would you think reloaders need a chronograph? If your loads function properly in your gun and they're very accurate, isn't that sufficient? Knowing your velocity is nice, but hardly necessary, simply because you loaded the components yourself. Consider that people have been loading and reloading for decades (centuries, if you count muzzle-loaders) without having any idea what velocity they were getting, and yet, their guns were safe and effective. Many hunters go afield each year with factory and handloaded ammo, completely oblivious to their exact velocity, and harvest game with surprising efficiency.

It's just a thought...
Well since you ask…

Once we know the real velocity our loads we produce, we can build real drop charts… Which is very useful in my book, and you can also see how stable your velocity is.

I just believe there is no downside to know how your loads are performing velocity wise.

<O:p</O:p
I do understand… Opinions vary
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