1" in 48" twist rifles

[TCU SHOOTER]

I am under the impression that shooting heavy loads ie.100 grs or more of BP or what ever, degrades accuracy in a 1 in 48 twist rifle using RBs.. I have done quite well with 70 to 75 gr. loads. I have not tried any more than that. MY rifle is a CVA 50 cal. Deer Hunter. What is the consensus ?

[srussell]

ive shot 80 with patch r.b

[tacklebury]

Didn't have too great of luck on my 1:48 traditional with sabot's.  Wasn't horrible, just not as good as patched RB.  I currently shoot my hawken with 80 Pyrodex/65 Trip7.  It does shoot great plains 385 gr. conicals good, but I have to use a limbsaver slip-on because in the sub-7 lb rifle, it beats me up, especially if the points dig in.  8(

[quickdtoo]

If you want to discuss sabots and jacketed bullets, post in the modern ML forum, they can't be discussed here, please read the sticky on what can and can't be discussed in this forum.

Tim

http://www.gboreloaded.com/forums/index.php/topic,102791.msg1098280539.html#msg1098280539

[necchi]

Under heavier loads, consideration of the actual patch and lube as well as a possible "over powder cushion" needs to come into play.
 It's not so much the 1-48 twist thats the factor as the land/groove configuration. Heavy loads can cause the PRB to "skip" shallow grooves and not impart proper spin.
 Most shooters will find an opening of the group as loads increase. There is a following of "Magnumitis" out there, and some that believe they need heavy max loads,(usually new to the sport shooters and many times people that come from a cartridge loading back ground), and these folks go to great length to pad, cushion and patch roundball to maintain some form of accuracy,,

[Landngroove]

I find that 90 grains of FFG Goex is usually the maximum amount for greatest accuracy in most of my .50's, and .54's with a 1 in 48" twist with a PRB. I also feel that this is a very good load for a clean kill, deer hunting.   

[TCU SHOOTER]

Thanks guys you have confirmed my belief that more is not always the best. I think I will stick with my 70 to 75 gr. load for deer hunting. 90 gr. would probably be better for that extra 25 yards over a 100 yards. I do think that 100 + gr. loads behind RB's are over kill and a waste of powder. This is easley confirmed by putting a white sheet on the ground about 20 feet in front of the muzzle of the gun and see how much unburned powder is on the sheet especially with a short barrel like the Deer Hunter has.

[coyotejoe]

A chronograph will tell you a lot more than will a white sheet and the chrono will tell you heavier loads produce higher velocity regardless of barrel length or unburned powder grains. The Lyman BP handbook lists loads for a .50 caliber with 24" barrel. They went in 10 grain increments from 40 to 120 grains and the velocity and energy were still climbing at the last increment. With Goex 2f and a .490 ball the numbers were:
110 grain= 1707 fps and 1146 ft.lb energy
120 grain= 1792 fps and 1262 ft.lb energy
Now that represents a 9% increase in the powder charge for a 10% increase in energy, which ain't bad efficiency in my book, who cares if there are unburned grains on the snow. I'm not saying anyone "needs" to load 120 grains but that business of checking for unburned powder is pure bull, an old wives tale from the days before anyone had any way to measure velocity.
As for accuracy of the 48" twist, for the past 8 or 10 years I've had a T/C .50 caliber 48" twist shallow groove barrel. For hunting loads I stopped at 80 grains as being all I wanted to shoot and groups were about 2" at 50 yards, not great but OK. I mostly used 50 grain loads for rendezvous shoots and plinking and got 50 yard groups of about 2 1/2", which I thought was the best it would do. When preparing for this season's hunt I just for the heck of it doubled my rendezvous load to 100 grains and WOW, one ragged hole! I've never seen anything close to that with lighter loads. So you just never know until you've tried it.

[Swampman]

You don't need heavy loads.  60 grains of 3f is plenty for deer.

[coyotejoe]

Da.

[Brazos_Jack]

Forsyth (The Sporting Rifle and its Projectile – circa 1860) proved the same thing that Greenhill proved with his famous artillery formula a few years later. Rifling should be approximately :

Rate of twist = 150 x projectile diameter squared / projectile length

In the case of a round ball this simplifies to:

Rate of twist = 150 x ball diameter

1 in 48” is simply too fast for round ball is most common calibers and deeper rifling only causes more rapid fouling.

In 1977 I bought a T/C Hawken .45 cal barrel and had it re-bored to .50 cal with 1 in 75” twist and .005” deep rifling with wide grooves. I have shot it with up to 120gr of powder with no degradation of accuracy. (I was afraid to push it any further). The wide shallow grooves allow the patched ball to wipe the bore completely clean on loading, so I can shoot all day with black powder without cleaning.

If you can find a copy of Forsyth’s book, I believe he actually found the grooves as shallow as .002” worked just as well for round ball, providing the proper slow twist was used. His experiments were with .69 cal rifles so he usually used 1 in 8’-8” twist, but actually got good results with rifling as slow a 1 in 12’-0”. I chose to stick with the 1 in 150 ball diameters (1 in 8’-8” for a .69 cal) since it coincided with Greenhills later work.

The very deep rifling found in most early 19th century rifles was a vain attempt to keep the patched ball from stripping the grooves in the too fast rifling of the day. The stress of the high angular accelerations was more than the patch material and lead ball could stand.

Deep rifling and extremely tight patch/ball combinations may allow a few more grains of powder before stripping occurs. But properly thought out rifling will give great accuracy with any sane powder charge with a just snug, easy to load patch/ball combo. In addition it removes the need to clean the bore every few rounds. 1 in 48” .50 cal barrels generally must be cleaned every 8 or 10 rounds with real black powder and patched round balls.

[Swampman]

All twist must be swabbed between shots.

[coyotejoe]

No, not really. I use spit patches exclusively for my target and general plinking loads and have never found a rifle I couldn't shoot as much as I wanted without having to swab the bore. With a spit patch I am swabbing every time I ram a load. I think residue from the various commercial patch lubes cause more fouling than does the powder. I won't say you can shoot "all day" without swabbing because I've never actually tried to shoot "all day" but I can shoot as much as I have ever wanted to with Green Mountain, T/C, Lyman, Hoyt and Rice barrels. The Forsyth book is available as a free download if you like but one should keep in mind that few people, at the time or since, have ever agreed with Forsyth's theory. Roundball bench rest shooters all go with deep groove barrels and they are serious enough about accuracy to have barrels custom made to any specifications they favor, none favor Forsyth rifling. No doubt very large bores do better with very slow twists but for run of the mill hunting rifles of .50 and .54 caliber the 48" twist is not bad, though deeper grooves are better for patched balls than the .005"  groove depth that most 48" twist barrels are using as a combination ball and bullet bore.

[tacklebury]

Forsyth (The Sporting Rifle and its Projectile – circa 1860)

PM me if you want a copy of his book electronically.  

[surveyor47]

I shoot 1:48 twist in 58 caliber and get fantastic accuracy with minnie balls matched to the barrel.  For example, my Parker Hale Enfield takes a 0.577 bullet and my Fayetteville musket takes a 0.578 diameter bullet.  I cast my bullets to 0.580 and size them to the necessary diameter.  The Parker hale will shoot a 1 hole group at 100 yards and the Fayetteville a small cluster.

I wonder if bullet diameter is not equally critical in T/C 50 and 54 caliber guns.  Most bullets are of the rifle engraving upon loading type, where the bullet is essentially jammed down the barrel.  I get good 50 yard accuracy, but 100 yard- forget it! I am now using Lyman Great Plains bullet molds and am thinking about sizing bullets down to match the barrel. Does anyone know the groove diameter of T/C 50 caliber barrels?  Has anyone else tried this?

[coyotejoe]

Several T/C's I've checked out all were .500" bore, .510" groove.

[surveyor47]

Have you tried sizing bullets to match groove diameter?
Thanks.

[coyotejoe]

I only shoot patched balls and I believe that is what we were discussing here.

[tacklebury]

One other thing I meant to mention is that Forsythe rifled barrels can also be used with shot as the twist is slow enough not to mess with the pattern.    For a .62 cal or 14 bore rifled barrel, recommended twist is like 1 in 108". 

[tscott]

70 gr. 777 .490 hornady rb .010 pt pre lubed = 2" circle at 50 yards all day long! (CVA kit Hawken)...

[woodswatcher]

i have shot many types of powders and loads in my 1 in 48 Renegade factory barrel.  T7 being my latest experient this weekend. BP and Pyrodex shooting 60gr volume loads - 2 spouts of a 30gr nozzle on the powder brass, gives me 1 hole groups at 40-50 yards. If i move up in volumes, the groups migrate and open up. same with T7 my same patched RB with 2 spouts of the 30gr nozzle was all over the place. i am thinking about trying a 50gr volume charge in T7.

i do know that 60gr of GOEX FF is a beautiful load in my rifle. it seems to be the perfect match for that rifle. the drawback is the nastiness of BP.

[coyotejoe]

The "nastiness of BP" is easily avoided, just get a 30/30, most folks did that more than 100 years ago.

[yellowtail3]

70 gr. 777 .490 hornady rb .010 pt pre lubed = 2" circle at 50 yards all day long! (CVA kit Hawken)...

Nice!!

[keith44]

I have two rifles with 1:48 twist, One is a Traditions Hawken in .54 the other is my .32 flinter.  Both will touch holes with their favored loads.  The .54 shoots 85 grains of 2F under a patched .535 roundball like a target rifle, out to 70 yards the group size is less than 2", often two or three out of five will be clustered tight enough to be touching.  With the smallbore 15gr of 3F will keep all shots touching out to 50 yards, if I do my part.

[Winter Hawk]

tscott,

Is that CVA a Hawken or the Mountain Rifle (looks like the later).  The Mountain Rifle had a 1:66 twist, not 1:48.  They shoot round ball very well.

-Kees-

[tscott]

The rifle is a CVA Hawken kit. My wife saw it for sale at Bass Pro years ago for $139... It shoots RB well, and 295 Powerbelt really well... I use only RB on deer, and keep my shots under 80 yards or so! I'm thinking of going peep, as there is way too much latitude in the factory rear sight. Accuracy is consistent. Therefore, a peep will certainly tighten groups!

[Co. Batguano]

I shoot 26 gr FFFg in my 42" Douglas barreled 40 cal flinter.  With .390 PRB's the holes touch but it shoots about 6" low.  I stepped it up to 50 gr. and it's right on, but the holes no longer touch. 

[keith44]

My .32 flinter shot about 6" low till I trimmed the front sight