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RJ-35-40
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Optimum 32 Caliber barrel length..?
Yesterday at 11:46am
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Optimum 32 Caliber barrel length..?

This is a long shot ball park inquiry,  so please ignore if there is too much involved. 

So I have a 34.75" X 1" 32 cal gain twist barrel blank. (Round)
I am planning on having chambered & fitted on a Hi Wall.

If someone out there has "Quick Load" or similar loading software, would you please give me a "rough" idea of how many inches of barrel travel would a 200 grain projectile have to traverse in order to complete the combustion process with any one of the listed powders that I have in stock. I'm hoping to ultimately find a combination utilizing either a 32 Miller / short or similar cartridge akin to 32-40 short / 32-357 case.

Looking to keep it about 1350-1400 fps. 

In stock powders:
Enforcer
WC820
300MP
H322
1680

Any thoughts in general are appreciated.
If I had a lathe (and a gunsmith who was so skilled) I could just pick a cartridge and experiment by testing by cutting off an inch at a time.

THX

Bob
  
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calledflyer
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Re: Optimum 32 Caliber barrel length..?
Reply #1 - yesterday at 12:00pm
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Well, if it were a project I was having done, the gunpowder would be among the last parts of the questions to answer. Intended use would be most of the parts to worry about- weight, offhand or bench, intended bullet(s) to determine twist (seems already done here) and sighting radius if no scope is planned. My guess is that in many loadings the mentioned powders would all be able to be consumed unless you end up building a snub-nose .32. Just my take on your question.
  
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Schuetzendave
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Re: Optimum 32 Caliber barrel length..?
Reply #2 - yesterday at 1:02pm
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Basically a 30 inch barrel is required to burn black powder before it exits the barrel. 

For the longer cases with more black powder compressed inside; and the bullet exposed to increase the case capacity, a bit longer barrel may be required to combust all of the black powder in a barrel.

Smokeless powder combusts more rapidly and is fully used to maximize barrel pressures in barrels 22 inches long.

After the powder is completely combusted within the barrel to maximize the optimum pressures any additional barrel length will not improve accuracy when using scopes.

However longer barrels minimizes sight angle for shooting iron sights so then a longer barrel does improve your ability to shoot more accurately.

The testing of barrels by cutting off an inch at a time has already been done and we already know that you need at least a 22 inch barrel length to shoot the smokeless powders you have listed.
  
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RJ-35-40
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Re: Optimum 32 Caliber barrel length..?
Reply #3 - yesterday at 1:22pm
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Called Flyer,

Thanks for the clarifying observations, the following is what I am contemplating 

1, A bench gun,
2, Weight of rifle, N/A see #1
3, 200 grain bullet range
4, Sight radius, probably scoped but if I were to use a tang mounted vernier sight I would expect that as close to 36" sight radius would be desirable

I do have a 32-40 with a 26" barrel which might get me some idea of powder ignition percentage, but due to the larger case capacity I think the ignition characteristics will change.
 
Given that the 32-40 is oversized (inefficient @ + - 2" long) for most smokeless powder charges (13-14 gr. I shoot in a 32-20) I really want to explore the shorter 32 cartridge case profiles to get in the 90% + case full range. 

Honestly I have not done much shooting in this realm to have baseline knowledge. 

 
calledflyer wrote yesterday at 12:00pm:
Well, if it were a project I was having done, the gunpowder would be among the last parts of the questions to answer. Intended use would be most of the parts to worry about- weight, offhand or bench, intended bullet(s) to determine twist (seems already done here) and sighting radius if no scope is planned. My guess is that in many loadings the mentioned powders would all be able to be consumed unless you end up building a snub-nose .32. Just my take on your question.

  
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RJ-35-40
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Re: Optimum 32 Caliber barrel length..?
Reply #4 - yesterday at 1:30pm
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DAVE,

Thanks for your insights.. I really appreciate the BP vs. smokeless observation. 

As I enjoy experimenting I was thinking of having two different barrels fitted for this action. 

At my age I better get busy so I can use up my stockpiles of components. 

RJ

Schuetzendave wrote yesterday at 1:02pm:
Basically a 30 inch barrel is required to burn black powder before it exits the barrel. 

For the longer cases with more black powder compressed inside; and the bullet exposed to increase the case capacity, a bit longer barrel may be required to combust all of the black powder in a barrel.

Smokeless powder combusts more rapidly and is fully used to maximize barrel pressures in barrels 22 inches long.

After the powder is completely combusted within the barrel to maximize the optimum pressures any additional barrel length will not improve accuracy when using scopes.

However longer barrels minimizes sight angle for shooting iron sights so then a longer barrel does improve your ability to shoot more accurately.

The testing of barrels by cutting off an inch at a time has already been done and we already know that you need at least a 22 inch barrel length to shoot the smokeless powders you have listed.

  
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Re: Optimum 32 Caliber barrel length..?
Reply #5 - yesterday at 3:14pm
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RJ,
Just throwing this out there, if you were cutting an inch at a time off the barrel with a gain twist, you'd want to do it from the chamber end.  That means re-chamber each time, cut the extractor each time, etc.   
For a bench rifle, personally I prefer the heft.  Length, I'd go 30" to 31".  Some say shortening below that is better, if you jerk rather than squeeze a 26" barrel gives you less time for the bullet to be disturbed on it's path, I'm not a believer in that - you practice bench methods to eliminate that part of the equation.    The sight radius that works about the best for irons if you do the math, is 34.378".  That calulates to .010 on your staff to one minute when making adjustments.  A 30" or 31" barrel with most actions allows you to get to that length.
My 2¢ 
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Re: Optimum 32 Caliber barrel length..?
Reply #6 - yesterday at 5:31pm
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All my rifles with barrels by old masters like Pope, Schoyen, etc. are all 32"-34" barrels, and shoot well with heavy .32-40 bullets. None are gain twist, but they are faster twists for the era they were built. Now days a lot of guys shoot even faster twist than what used to be considered fast.
  
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Re: Optimum 32 Caliber barrel length..?
Reply #7 - yesterday at 5:40pm
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My 32-40 14 twist Green Mountain barreled high wall has a 31" barrel and although it has shot very well (2 match 250s) with some loads the last inch seems to be fouled more.  My 32-40 12 twist Douglas barreled high wall shoots just as good with its 28" barrel.
  
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Re: Optimum 32 Caliber barrel length..?
Reply #8 - yesterday at 6:45pm
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bpjack wrote yesterday at 5:40pm:
My 32-40 14 twist Green Mountain barreled high wall has a 31" barrel and although it has shot very well (2 match 250s) with some loads the last inch seems to be fouled more.  My 32-40 12 twist Douglas barreled high wall shoots just as good with its 28" barrel.


Are you getting a good lube star on the muzzle Jack?
  
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