Hornady 450 Bushmaster ammo #82244

Talk about the AR15 style rifles chambered in 450 Bushmaster.

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Hornady 450 Bushmaster ammo #82244

Postby galeforcerm » Tue Feb 07, 2017 1:36 am

I chronographed this ammo from an AR15 with a Trident 17 3/4 ported barrel. It was 27 degrees out when I was shooting.

Is it normal to get this much deviation in speed? Or do I have a bad batch of ammo? Here are the numbers:

1943
1990
1943
2164
1907
2032
1943
2089
2008
2126
2023
2070
1996
2008
2123
2113
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Re: Hornady 450 Bushmaster ammo #82244

Postby Hoot » Tue Feb 07, 2017 6:06 am

That's a little wide. Its not uncommon to see 50-90fps variation, which is the result of varying degrees of crimp IMHO. However, if the velocity slowly ramps up, that's more due to starting off with a clean, lubed bore that slowly fouls. This cartridge is dependent to a certain degree upon bore friction to get the powder up to full pressure. Take that set of readings and separate it halfway down the list. Those two halves averages are more like what I experience when testing loads. I de-lube the barrel and dry patch before shooting several foulers and then start taking my readings.

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Re: Hornady 450 Bushmaster ammo #82244

Postby Pig_Popper » Tue Feb 07, 2017 9:53 am

I see up to 100 FPS difference in my handloads but accuracy is stellar - I'm baffled having the majority of experience with bottleneck crenterfire cartridges that don't behave this way.

I too believe the crimp is to blame for the wide spread.
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Re: Hornady 450 Bushmaster ammo #82244

Postby HoytFlinger » Thu Feb 09, 2017 4:04 pm

Is your chrony set up level with clean sky screens? Might want to get some Ely Tenex 22 ammo and fire through it. Tenex is very consistent.
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Re: Hornady 450 Bushmaster ammo #82244

Postby Hoot » Thu Feb 09, 2017 8:37 pm

I realize seeing this image gets old but in the interest of reducing worry about not getting small, bottle neck cartridge SD numbers;

This 100yd 5-shot group's SD was 89!

Image

PS: The bullet was the 225 FTX loaded to 2.12 COL and taper crimped down into the cannelure. Shot from a factory Bushmaster 20" upper, wearing a Ross brake, off of a bench.
You can get these bullets from numerous sources for around 26¢ each. Even less if you watch for sales and factory seconds on Midway. A little over a year ago, Midway had Factory seconds for something like $16/100 IIRC. Dawg, you bought some right? Needless to say, they sold out very quicky, so check the Facory Second page at Midway every few days. Ditto for other 45 cal bullets.

They may be a little overspeed at 38gr of Lil Gun but this test round held together in a water shot:

Image

still rockin' the oldies
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