barrel length V fps

[bigted]

i know huh...who posts more questions then me?? hope im not irritating anybody yet!

set up the new rcbs chronny today and let fly with some loads i been waiting for weather with and wowww why didnt i get one of these a looooong time ago?

first thing i found was the seemingly best load performance wise for my winchester hiwall...68gr 2f goex behind a 1/8th felt and compressed enough to seat the 457125 520 gr lyman to cover the greese grooves with the brass. this averaged for ten at 1090 fps with 11.5 variation with the 10 shots and shot like a business like rifle should.

this same load would shoot at 1112 fps average thru my ped sharps with its 34 inch barrel but the variation is 38 fps with the same loads.

my ruger shot 1052 with these loads but with a spread of 31 fps.

now after looking at the book i keep my info in it occured to me that with the longest barrel...34 inches...and the shortest barrel...20 inches...that the difference was only 60 fps velocity loss. im amazed with this small variation between velocity with a 14 inch barrel difference. i thought it would be over twice as much...what gives here?

another question is why the winchester hiwall gave such tight averages with fps spread of the 11... and the ruger and sharps were 31 and 38 fps spread respectivly....with the same 68gr load and weighed as well as assembled the exact same including the thrust of compression given on all loads.

still dont know about 1 or 2 or 3 hundred yd accuracy yet as i wanted to examine the consistancy of my loads first before exhausting the range with smoke before i am ready to test some loads with promise.

if these are any indications about the differences in velocity with regard to barrel length then its gonna be a no brainer about which rifle go with me into the brush this year.

another thing i noticed with regard to these rifles was recoil...meaning this...the ped sharps [even at 12 lbs] bucked harder then the winchester...and then the winchester believe it or not recoiled more then the ruger! after cleaning these rifles i did a very exact experiment with them.......i layed the sharps down and layed the winchester on top to inspect roughly the length of pull and drop at the butplate...then i examined the ruger on top of the winchester in the same fasion and this is what i see with my scientific examination.......the sharps dropped 1/2 inch more then the hiwall....the hiwall dropped around 1/2 inch more then the ruger!.......WALLA! discovered why the recoil diferences between these rifles........thinkin about turnin the ruger into a 45/90 now.......so take that...

ok so there ya have it...another learning day for teddybear!

answers anybody??

thanks for the patience with me...ill continue to charge ahead tho till ya get tired of answering these silly questions for me.

[Don McDowell]

Ted looks like you answered your own recoil questions..

The tighter spread with the hiwall may come from two seperate things. The hiwall's chamber and barrel are likely tighter tolerances than the other 2, and that load is likely just better for the hiwall. Good possibility with some tweeking you could taylor it down for the other two rifles.

[doubs43]

WRT the seemingly small loss of velocity between your 20 inch barrel and one that is 14 inches longer, my GUESS is that it has to do with the rapid burn rate of your black powder. It may not completely burn in your short barrel while it would be fully consumed before the boolit was near the muzzle in the 34" barrel.

I've read that frontiersmen with Pennsylvania/Kentucky rifles would shoot over fresh snow while adding additional powder until the point that unburned grains appeared on the snow. They then knew the maximum powder load their rifle would burn completely without waste. I suspect that your 20 inch barrel would leave a little unburned powder on the snow.

[powderburnerr]

I have an old loading manual from shiloh from the early 80s , there are some loads that shoot faster in a shorter barrel , I would say it has to do with the pressure curve of the load and when it , being the pressure, runs out, and you start pushing the bullet with out expanding gasses.your load perhaps was optimal in the fastest gun and lacking in the others, as doubs43 states.

[Lead pot]

It
s sort of like a .22 rim fire. You get just about the maximum velocity with a 18" barrel and the velocity drops as the barrel gets longer.
I was working with the .50-90 recording velocity's with different powder granulations with the same volume loads and when I used the load with .4FG it was slower then the 3FG.
Could have been because of the faster burn of the powder.

[bigted]

thanks...this is kinda making sence to me. i guess i always considered that the barrellength was the cinch for more velocity in a particular load...[it being a top shelf load that is]. is this a thing that does not affect the other smokless stuff then? i have read numerous tests with this very thing and as memory serves...the loss of velocity was around 100 fps per inch of barrel loss.

this theory makes sence to me when explained thusly however i am curiouse about the tests ive read in the past now...[unless the smokeless is different in the case of expanding gass...which i now know it is].

just puzzeled me as i really considered that the sharps would develope more velocity becouse of the extra 14 inchs of barrel length.

so while im asking here....has anybody had a ruger 45-70 reamed to the extra length for the 45-90 chamber? if so...how did it work for a hunting gun when shooting blackpowder? seems like a good fit to me but my ruger shoots so good now i would hate to ruin it with a modification that is useless and just wont work. [consider that i would be shooting blackpowder fulltime with it].

thanks

[Lead pot]

I dont know what the maximum barrel length is when velocity is max in smokeless or black powder rifle
As far as the 45-70 It will put anything down here in the USA in good shape.

[Dragoon 45]

A few years back I got interested in the development of Artillery from about the Civil War to when the switch over to cordite and other smokeless powders started.

The US Army Ordinance Corps ran a series of tests trying to figure out the needed barrel length for artillery pieces that used BP. They tested cannons from 8pdrs all the way up to the really massive Parrot guns some of which had 16" bores. The long and short of it was that for powder burn a cannon did not need more than about 8' of barrel to get max velocity; but for maximum accuracy the length of the barrel needed to be about half again that length. Of course this changed when smokeless powders were introduced where chemists could vary the burn rate of the propellent.

While I may be full of it, it has always been my belief that BPCR rifles only needed around 20" of barrel to burn the powder efficiently. But when you are concerned with accuracy half again that barrel length 30" seems to give the best accuracy while adding a longer sight radius which also improves the accuracy. The extra barrel length added weight also which if the stock was designed correctly helped to cut down on recoil.

A more interesting experiment would be to take four as nearly identical BPC Rifles as possible and have different barrel lengths of say 20", 24", 30", and 34". Weight would be different due to barrel lengths. Shoot identical ammo through each rifle. Then measure velocity, accuracy, and recoil forces. I would guess that the results obtained by the US Army back in the 1880's with cannon would probably be repeated with these rifles.

[bigted]

dragon 45

im bettin you would be rite and this explanation sounds sound to me as well. id love to do this experiment and would gladly provide the powder n lead if some body would pony up the four rifles...make em hiwalls for my tastes.

just to show my heart is in the rite place...ill provide a scope for the test as well....what do ya think???

[semtav]

dragon 45

im bettin you would be rite and this explanation sounds sound to me as well. id love to do this experiment and would gladly provide the powder n lead if some body would pony up the four rifles...make em hiwalls for my tastes.

just to show my heart is in the rite place...ill provide a scope for the test as well....what do ya think???

Well I've got a Winchester High wall 45-90 with a 34" barrel and one with a 30" barrel. If someone wanted to send me another of the 34" guns cut off to 32" I could do it.

[NickSS]

My guess would be that a rebore to 45-90 would net you around 100 fps velocity with the same bullet. I base this on my own experience with two rifles that I owned that were identicle except for caliber. I had two 1886 Winchesters with 24 inch barrels one in 45-70 and one in 45-90 both shot about the same and I chonographed many different loads in them. In general my 45-70 loads using the same type powder, primers and wads and compression levels for both rifles ended up in the 75 to 125 fps difference between the two cartridges with the 45-90 being the higher velocity.