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Old March 25, 2013, 02:04 PM   #1
nanewt02
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mossberg 695 safari rifle barrel length

im working on a wildcat cartridge and am using the mossberg 695 action, after all my barrel blank questions, ive finally come up with a caliber. the barrel will be 1.35 straight cylinder outer diameter, but what length should i use. i want to keep the wieght down and have decent balance, a 16 inch barrel would we very wieldy and im not concerned with the velocity loss too much, but it seems all safari rifles all have a barrel length of the mid 20 inches,
so, im stuck on the length
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Old March 25, 2013, 04:53 PM   #2
PetahW
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I would think barrel length would depend somewhat upon your wildcat's interior ballistics.

It'd be a shame to make it the "proper" length, only to have whatever projectile bounce off some target because the load didn't have enough space to develop the correct working pressure.


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Old March 25, 2013, 05:07 PM   #3
Archie
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Yes, like Petah W said...

One of the critical factors to know in regard to barrel length is the Expansion Ratio (ExRat).

ExRat is the ratio of the internal volume of the loaded cartridge prior to firing in relation to the internal volume of the fired cartridge AND the internal volume of the bore to the muzzle.

One finds that an ExRat of less than 7 gives relatively low velocity for each unit (weight) of powder. (In other words, longer barrels [with greater ExRat] give more velocity.)

So, what is the caliber in question, and roughly how much space is in the powder area of the cartridge (allowing for a seated bullet)?

And to anticipate your next set of questions, velocity is a function of the ExRat AND the ratio of propellent weight to bullet weight.

So what weight bullets do you intend to use and how fast do you want them to go?
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Old March 26, 2013, 11:39 AM   #4
nanewt02
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I will unveil the cartridge when i get back my letter from the ATF .Plugged in some numbers in recoil calculator, a sixteen inch bull barrel will potentially, with a expansion ratio of 8 to 9 produce recoil at a velocity of 45 fps and 300 ft pounds of recoil, so, problem is solved! Go with longest heaviest barrel possible
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Old March 26, 2013, 01:04 PM   #5
TX Hunter
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I hope your not trying to neck down .50 BMG to .17 and shoot it out of Your Shotgun !!
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Old March 26, 2013, 01:16 PM   #6
nanewt02
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i think someone already did that, i think it was called the loudenboomer. no way am i doing that
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Old March 26, 2013, 02:08 PM   #7
TX Hunter
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LOL. Good luck with Your project. Safety First
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Old March 26, 2013, 09:49 PM   #8
Jimro
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Quote:
I will unveil the cartridge when i get back my letter from the ATF .Plugged in some numbers in recoil calculator, a sixteen inch bull barrel will potentially, with a expansion ratio of 8 to 9 produce recoil at a velocity of 45 fps and 300 ft pounds of recoil, so, problem is solved! Go with longest heaviest barrel possible
With numbers like that you are either using an ultralight design, or a round that I wouldn't want to use in a Mossberg 695 action. Not a lot of metal on metal interference keeping that bolt in place, kinda like a really big 22 rifle where the bolt handle is the locking lug.

Of course I don't know what you are trying to do, so this is all just guesses on my part.

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Old March 26, 2013, 10:34 PM   #9
nanewt02
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good guesses, fortunately the mossberg has dual rear locking lugs. the large surface area of the case should help minimize bolt thrust. loads will be worked up VERY carefully, these numbers are ideal, not set in stone, it is an ultralight, unfortunately if i make it heavy it will defeat the purpose of a safari rifle and im not sure the max wieght the aveage person cares to carry, allthough a 4 ft long heavier gun would look awsome,
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Old March 26, 2013, 10:35 PM   #10
nanewt02
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may add additional lugs if the need arises
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