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  #1  
Old 05-25-2017, 04:18 PM
moorepower moorepower is offline
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Default .221 Fireball barrel length

So my question, is how much velocity would one loose by going to a 18-20" barrel on a Fireball? I am looking at a compact, threaded for quiet PD shooting. I would like to compare to a 24" long barrel.
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  #2  
Old 05-25-2017, 04:36 PM
TinMan TinMan is offline
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For a 223/5.56, the answer was 29 fps per inch of barrel length. I did the Chrony experiment many years ago, but can't find the data anymore (computer died). Used the same 55gr FMJ ammo on different firearms of barrel lengths: 26 inch M70HV, 22inch M70, 20 inch AR, 16 inch AR, 14 inch T/C and even a 8 inch HK53. Hope this helps. Let us know what you decide. Barrels shorter than 16 inches had lot of muzzle blast/concussion, so hope your suppressor helps.
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Old 05-25-2017, 05:10 PM
moorepower moorepower is offline
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So I would guess that the .221 would loose less velocity due to smaller case. 18-20" is about as short as I would want to go, but I want a compact as possible rifle. If I gave up 100 fps I could live with 18" barrel.
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  #4  
Old 05-25-2017, 06:48 PM
squirrel_slayer squirrel_slayer is offline
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I would think (again this is a theory) that the smaller capacity case would likely lose less ft/sec per inch than a larger capacity case.

the powders used in the smaller cases burn faster which makes them more efficient in shorter barrels.

going up in bullet weight will be a lot more sensitive in the smaller case though. (think greater velocity loss per weight increase vs larger capacity case)

all that being said I'm currently testing the theory and it appears my hypothesis is seeming true.

I'm running a wildcat based off the .223 (or fireball if you want to view it that way) it's roughly the same jump down from the fireball as the fireball is the .223. it's a 1.125" long case with 16.3gr capacity, my current barrel is 18.5" and soon i'll be testing a 6" barrel in a AR that will likely get chopped to around 5".

using lil gun powder I'm getting 3260 ft/sec avg from the 18.5" barrel with a 40 gr v-max and I still plan on working the load up higher until I run into pressure. (more so to find the pressure celing for a data point)

I did try a 55gr hornady sp but the velocity was all over the place as were the groups so I abandoned them. I did get into the low 2700's velocity wise for inquiring minds again with no pressure signs.(likely room to go higher)

The next bullet I plan to try is one of the new 53 gr bullets, either the hornady (boat tail for ease of loading) or the nosler (insane bc for the weight! but a flat base which may be best for accuracy but a pita to load)
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  #5  
Old 05-25-2017, 10:04 PM
moorepower moorepower is offline
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I plan on using a 40 grain Vmax or 50sx. I have plenty of other guns for longer ranges , I am looking for a quiet shooter that doesn't heat up too fast
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  #6  
Old 05-25-2017, 11:50 PM
squirrel_slayer squirrel_slayer is offline
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Quickload shows over 3300 ft/sec with lil gun and a 18" barrel and mid 3200's with 1680 and the 40 vmax
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  #7  
Old 05-26-2017, 04:54 AM
17tbs 17tbs is offline
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Default quiet loads

use bluedot or trailboss
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  #8  
Old 05-26-2017, 01:06 PM
TAJ45 TAJ45 is offline
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Default Insane BC??

I just checked the Noslers site, RDF et al, but only found a 70 gr 224 - nothing lighter.
What bullet were you referencing please?
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  #9  
Old 05-26-2017, 01:11 PM
Alex Alex is offline
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Default Velocity when comparing barrel lengths depends...

... as much on chamber, free bore, barrel condition, etc., as it does on the length. The only way you can do it properly is to actually chop the barrel and measure the velocity for each length.

I've tried several times to make the comparison in different rifles with different barrel lengths. Only once was there any correlation between the length and velocity, and I later found marked differences in the chamber.

In one case, two Coopers with 24" and 20" barrels were the same, but faster than two rifles with 22" barrels.

In some cases, such as the 17HMR, there is an optimum barrel length somewhat between 16" and 26". Measurements were made while cutting the barrel down in 1" increments.

Age is robbing me of memory, and i cannot remember the commercial outfit that posted the HMR velocity measurements, but my data appeared in Small Caliber News in articles on the 17AH and 17M4..

Alex
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  #10  
Old 05-26-2017, 03:11 PM
moorepower moorepower is offline
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Quote:
Originally Posted by TAJ45 View Post
I just checked the Noslers site, RDF et al, but only found a 70 gr 224 - nothing lighter.
What bullet were you referencing please?
I think he is talking about the 53 Vmax.
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