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What 40 cal TWIST are you shooting

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gard72977

40 Cal.
Joined
Jan 14, 2013
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I worded the question to those of you who are shooting a 40 cal. Its time to order my barrel and after much consideration this will be a 40 cal. Its a custom Soddy TN flinter. It will be a custom barrel so I have my choice of twist. Im thinking 1/56 or 1/60. This gun will be mostly a target gun.
 
Most .40's are 1 in 48 twist. The smaller ball needs a little bit faster twist for accuracy.
 
My .40 has a Douglas barrel with a 1:66 twist rate, 8 lands and grooves, groove depth .012". I've been shooting it for 40 years for small and large game, loads from 25 gr. 3F to 70 gr. 3F, and it shoots good groups with whatever I put in it. If I ever bought another .40 it would be one just like it.

Spence
 
Shoot three forties, all percussion.
GM 48" twist x 1"ATF x 28" long. Nice shooting gun.
GM 48" twist x 1"ATF x 38" long. It's uh, rather steady.
Rayl 16" twist x 15/16"ATF x 32" long. Shoots minute of squirrel with round ball and splits differences with cast bullets.

I'd really like to have a 32" twist but just can't talk myself into it.
 
Colerain - 36" 13/16" ATF 1:48 round bottom rifled stocked as a half-stock Ohio.

Shoot .390 RB .018 pillow tic (pre-lubed Ox-Yoke) over 50 grains FFF.

Max range for hunting 50 yards (self imposed). Longest kill shot taken, 31 yards.

My "main" deer rifle for the past 9 seasons (4 deer taken - other seasons my tag got filled in the early bow season).

If you buy into science/math (Greenhill formula) you would use .4 (cal in inches) X 120 (constant)

.4 x 120 = 48 - so 1:48

Modified Greenhill = cal x 1.25

40 x 1.25 = 50 (so either custom 1:50 or 1:48 which is the closest "standard" twist)
 
Gard,
While most small cals are a fast twist....the .40 is kind of a crossover caliber. A slow twist is more forgiving with varied loads. A fast twist is more narrow in its best load. Most custom makers use a 1:56 to 1:72 for that reason. I've got a 1:66 that will shoot accurately from 40g to 75g of FFFg.
The .40 is a GREAT all around caliber.
 
My Colerain is 1 in 48" twist. But I don't think the twist rate is as important as the depth of rifling.
 
I have heard a lot about faster twist being more picky with loads. From what people are posting I doubt there will be any difference in accuracy. I would like the option of loading heavy for steel falling targets. I know this caliber is light for steel but I may want to shoot steel from time to time. You don't always have to win! You just need to look good doing it!
 
"Generally", a slower twist is more forgiving of a heavier charge (and vice versa).

Have to remember this is "just a 40" and diminishing returns sets in with a lower powder charge change than in larger bores.

I can't find the data I had. Chrono'd my rifle a few years back. After 65 grains the "gains" started to drop off fairly significantly for every 5 grain powder increase.

Think we took her all the way up to 90 grains (which is way over the top with a 40), but I do remember that it barely squeeked out 20 or 30 fps over 80 grains - probably just blew the extra 10 grains right out of the barrel.

If you are looking at shooting "heavy" powder charges you would be better served to look at a 46" barrel that at least has some hope of consuming the powder.
 
My Late Lancaster has a GM 38" x 1:48" x .012" square groove barrel...have range tested & hunted 30-70grns Goex so far with single PRB, 2XPRBs, and a 200grn REAL...all extremely accurate.
 
I want to do a thorough work up of loading with double ball loads in the .40.
The 48" twist barrels are gosh awful heavy with 1" across the flats and that extreme strength oughta be put to some out front use.
 
gard72977 said:
I worded the question to those of you who are shooting a 40 cal. Its time to order my barrel and after much consideration this will be a 40 cal. Its a custom Soddy TN flinter. It will be a custom barrel so I have my choice of twist. Im thinking 1/56 or 1/60. This gun will be mostly a target gun.

A .40 is a good choice for target shooting out to 100 yards. I like to call it the .270 of MLs due to it being a fairly "flat shooter". But that light ball can be pushed around by the wind pretty easily. I have 2 GM .40 X 13/16 X 42 with 1/48 twist which as noted is pretty much standard. I shoot a .395 ball over an .018 tick patch and 60 grs of fffg GOEX. Anything less than 50 grs and the group opens up. I don't know if your target shooting is mostly offhand or bench, so I can't advise as to diameter, but a 13/16" is pretty good for both. If your game is bench shooting a diameter up to 1" would be great. You could still shoot offhand if you have the arms. It also depends on how slender you plan on building the rifle. Of course you also have the choice of a tapered or swamped barrel. I'm not real familiar with the Soddy-Daisy rifles so I'm not sure about the type of barrel you need. Seems like I read somewhere that they have a pretty heavy barrel, though I might be thinking of somethin else.
 
my nephew and his boy both shoot 40 caliber Douglas barrels 1 in 66 twist and shoot very very well. :idunno: :idunno:
 
Eterry said:
Roundball, I have been looking for a 40 REAL mold; where did you get yours?
Eterry
I don't think they're commercially available...Member 'oldnamvet' had Lee Precision make one for him and he was nice enough to make a few for me to run some tests together.
There are some good threads of info about it that the search feature should pop up...and/or send 'oldnamvet' a PM.
 
I want to do a thorough work up of loading with double ball loads in the .40

Really has nothing to do with the discussion.

This thread has come up with more myths and misstatements in a short time than we usually see. :youcrazy:
I feel sorry for the OP trying to sort out the nonsense from what will help him. :(
Good luck guy.
 
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