Catpop
Member
Is there an established minimum neck length for 30 caliber cartridges that are used in lever action rifles? Neck tension, bullet grip, bullet stabilization, etc.
Cartridge Neck Length
- Thread starter Catpop
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Sunray
Member
No. Lever actions come in every .30 cal imaginable and every one if 'em has a different neck length. .30-30's is .478". .30-06's is .385", .308's .305".
Isn't something to be concerned about anyway.
Isn't something to be concerned about anyway.
OP
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Catpop
Member
Sunray,
well it is kinda important to me to spec out my new 30/32-40 Ballard reamer. Yes, I to notice they are all over the board. I want to go minimum acceptable for this endeavor and am seeking some expert knowledge from the high road.
Do you think 1/4" would be acceptable. It looks good on my dummy cartridge.
well it is kinda important to me to spec out my new 30/32-40 Ballard reamer. Yes, I to notice they are all over the board. I want to go minimum acceptable for this endeavor and am seeking some expert knowledge from the high road.
Do you think 1/4" would be acceptable. It looks good on my dummy cartridge.
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spitballer
Member
This is a subject I wish our resident wildcatters would discuss a little more. Neck length is "all over the map" very well stated. A write-up at 6mm bench rest.com suggested that many target shooters like longer necks (6mm Rem, 6.5 Creedmoor) to protect the throat area from turbulence, and the shoulder angle certainly factors into this area of turbulence also. A lot of modern cartridges have steeper shoulder angles (see Ackley improved).
I can't imagine neck length would be designed specifically for use in lever action rifles but if I were designing a wildcat I'd want to know, for sure.
I can't imagine neck length would be designed specifically for use in lever action rifles but if I were designing a wildcat I'd want to know, for sure.
witchhunter
Member
A basic rule of thumb is one bullet diameter in the neck, so I would make it at least one bullet diameter long. Anything shorter than that could mean the bullet is taking up space in the case not the neck.
OP
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Catpop
Member
Witchhunter,
That sounds like a pretty good rule of thumb to me. So a 30 cal (.308) would need just shy of a 5/16 (.3125) neck. So my original 1/4" guess was a little short.
Thanks for help!
That sounds like a pretty good rule of thumb to me. So a 30 cal (.308) would need just shy of a 5/16 (.3125) neck. So my original 1/4" guess was a little short.
Thanks for help!
witchhunter
Member
Not trying to talk you out of it, but I don't think you will see much improvement over the ol' 30/30.....keep us posted.
OP
OP
Catpop
Member
Back to me being nuts----- uh huh, I do resemble that remark! Haha
I really don't want to improve the 30-30, I think Ackley already did that. I just want to see what a 30-40 straightwall will do.
BUT, I CAN'T AFFORD TO DO THIS TWICE! So I'm like a good carpenter, MEASURE TWICE, CUT ONCE. Haha
I really don't want to improve the 30-30, I think Ackley already did that. I just want to see what a 30-40 straightwall will do.
BUT, I CAN'T AFFORD TO DO THIS TWICE! So I'm like a good carpenter, MEASURE TWICE, CUT ONCE. Haha
stubbicatt
Member
I shoot a 32-40 which is an amazing cast bullet target chambering. Even with small charges of SR4759 or IMR4227, the old girl will shoot the lights out. My bore is a tapered throat designed for breach seating, so my fixed ammunition has been crafted to form a snug fit of a tapered bullet in the seat of the throat. I only have 1 ½ bullet bands in the case using a 200 grain Saeco plain base, non gas checked, tapered, bullet. I have to press the ammunition into the chamber for the last 2/10ths of an inch or so, and size the cases so that they have about a .002" neck tension.
Fixed ammo is not as accurate as the breach seated bullet in my rifle, but it has been a compromise made necessary by using this rifle in the lever action silhouette game. I also leave the neck flared to reduce the amount of gasses which blow by the case brought about by comparatively low chamber pressure.
I understand your need to arrive at a proper neck length, especially if you are using fixed ammo.
If it were me, I would choose a longer neck dimension, about the length of the 32-40 case, for the chamber dimensions. I would do this to assure that the base of the bullet is not suspended in the "boiler room." Especially if you shoot cast bullets. This will also allow you to shoot heavier slugs which, if the twist rate is adequate, may be something you would find desirable. If you are going to use the short neck as in the photos above, and shoot cast bullets, you may have to resort to a "nose riding" design, of which there are several good examples around, but it is somewhat harder to get to shoot accurately, and alloy has to be matched to velocity to avoid nose slumping, and to avoid stripping the relatively small driving band in the rifling.
As far as the taper or leade, I guess that will depend on whether you are shooting cast or jacketed bullets. It really does make a difference. If you are going to use a cast bullet, perhaps it would be best to design your chamber around the bullet you intend to use in it. This will make your fine tuning less extensive, and maybe less frustrating.
If you intend to shoot jacketed bullets, I think you will find the Ackley Improved will be a better choice than what your photo above shows as your choice for chambering.
Fixed ammo is not as accurate as the breach seated bullet in my rifle, but it has been a compromise made necessary by using this rifle in the lever action silhouette game. I also leave the neck flared to reduce the amount of gasses which blow by the case brought about by comparatively low chamber pressure.
I understand your need to arrive at a proper neck length, especially if you are using fixed ammo.
If it were me, I would choose a longer neck dimension, about the length of the 32-40 case, for the chamber dimensions. I would do this to assure that the base of the bullet is not suspended in the "boiler room." Especially if you shoot cast bullets. This will also allow you to shoot heavier slugs which, if the twist rate is adequate, may be something you would find desirable. If you are going to use the short neck as in the photos above, and shoot cast bullets, you may have to resort to a "nose riding" design, of which there are several good examples around, but it is somewhat harder to get to shoot accurately, and alloy has to be matched to velocity to avoid nose slumping, and to avoid stripping the relatively small driving band in the rifling.
As far as the taper or leade, I guess that will depend on whether you are shooting cast or jacketed bullets. It really does make a difference. If you are going to use a cast bullet, perhaps it would be best to design your chamber around the bullet you intend to use in it. This will make your fine tuning less extensive, and maybe less frustrating.
If you intend to shoot jacketed bullets, I think you will find the Ackley Improved will be a better choice than what your photo above shows as your choice for chambering.
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OP
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Catpop
Member
Stubbicat,
Geez, I got a lot more to learn about ths! So you think I should design the neck to fully encase the body of the soft lead boolit I intend to shoot first?
Geez, I got a lot more to learn about ths! So you think I should design the neck to fully encase the body of the soft lead boolit I intend to shoot first?
rcmodel
Member in memoriam
I would suggest you buy, borrow, or steal a copy of 'Cartridges of The World'.
There is a whole chapter in it covering each of the many black powder cartridges of the time.
Including the successful ones, and the failures.
http://www.amazon.com/dp/1440230595...vptwo=&hvqmt=b&hvdev=t&ref=pd_sl_2zwuru4he2_b
Were it me??
Intending to shoot cast lead, or gas check bullets?
I would make the case neck long enough, or the rifling leade long enough to seat long?
In order to keep the base of the bullet, base grease groove, & gas check out of the powder and retained inside the neck.
If you look at the old black powder target rifle, and military rifle cartridges??
They pretty much all had long necks to keep the bullet lube out of the powder charge.
If you are talking smokeless powder, and jacketed bullets, none of that applies.
For those, the rule of thumb is one bullet diameter seated inside the case neck, at a minimum.
rc
There is a whole chapter in it covering each of the many black powder cartridges of the time.
Including the successful ones, and the failures.
http://www.amazon.com/dp/1440230595...vptwo=&hvqmt=b&hvdev=t&ref=pd_sl_2zwuru4he2_b
Were it me??
Intending to shoot cast lead, or gas check bullets?
I would make the case neck long enough, or the rifling leade long enough to seat long?
In order to keep the base of the bullet, base grease groove, & gas check out of the powder and retained inside the neck.
If you look at the old black powder target rifle, and military rifle cartridges??
They pretty much all had long necks to keep the bullet lube out of the powder charge.
If you are talking smokeless powder, and jacketed bullets, none of that applies.
For those, the rule of thumb is one bullet diameter seated inside the case neck, at a minimum.
rc
OP
OP
Catpop
Member
Again thanks to all for input!
I have been studing my "THIRD" edition of Cartridges of the World very hard! (Yeap, I'm very frugal) I have learned, as rc and stubbicat stated, the older lead bootlit BP cartridges did have much longer necks than the newer bottle neck jacketed bullet cartridges. And this was to keep the soft and easily melded lead and lube out of the "boiler room".
Next step is to determine the lead bootlit I will use and factor that into my case design.
Any suggestions on this cast .308 150-180 gr bootlit?
Thanks
I have been studing my "THIRD" edition of Cartridges of the World very hard! (Yeap, I'm very frugal) I have learned, as rc and stubbicat stated, the older lead bootlit BP cartridges did have much longer necks than the newer bottle neck jacketed bullet cartridges. And this was to keep the soft and easily melded lead and lube out of the "boiler room".
Next step is to determine the lead bootlit I will use and factor that into my case design.
Any suggestions on this cast .308 150-180 gr bootlit?
Thanks
stubbicatt
Member
Catpop, bullet choice depends on your velocity goals for the cartridge. Once you have arrived at that determination, then you decide on nose profile. If anything above, say 1500 fps, you will probably want a gas check design. The longer, bore riding, nose designs typically require a harder alloy, Snover and Postell excluded, which aren't really nose riders. Then there is the issue of single shot versus magazine fed, where your OAL is determinative of its usefulness.
I may have missed whether yours is single shot or fed from tubular magazine.
In the 30-30 I like the RCBS 180 grain gas check bullet. Carries lots of lube, and has a short nose with flat meplat, and several driving bands to help prevent stripping in the rifling. The nose *just* fits the throat of the barrel, and like the Pope style bullet, doesn't slump that I can tell. It meets the needs of that cartridge pretty well. I can cast of a comparatively soft 20-1 alloy, and keep velocities around 1500 fps and get good accuracy. It might go faster, but for my uses this is plenty fast. I am considering a 170 grain custom mould from Accurate Molds, as the base band of this RCBS 180 is *just* into the boiler room of the standard 30-30 cartridge. However, this is a design detail you can determine once you have settled on the bullet.
Once you have determined which bullet you like, the remaining dimensions of the cartridge will sort of fall into place. The neck length will be easy to determine once you have chosen your bullet. Then the throat dimensions and the taper of the leade will present themselves. The neck diameter of the chamber can be specified to allow a .004 to .005" bullet release, which is really as tight as you will want to go with a cast slug. You may have to neck turn your brass, but this is typically a one time proposition for low intensity cartridges. Especially those with a tapered profile, or even the shallow shoulder of a 30-30.
Chamber length will also be a variable you will want to address. If you are using 32-40 brass, there are many who will want to assassinate you, as that stuff is near impossible to find, and the 32-40 shooters hoard it like the gold it is. If you are going to use Starline 38-55 brass, which is what I have resorted to here recently, then you might want a longer chamber, as that brass, once reformed to 32-40 dimension, is quite long. Probably even longer for you since you are making a 308/32-40. No big deal to trim it, but it is something you might wish to consider. Conversely, if you choose to form your cases from 30-30 brass, those tend to come in relatively short, at least when formed to 32-40 brass. I personally prefer to keep my brass about .01" short of the end of the chamber as I find that it seems to slow the buildup of residue in the leade area of the barrel. Your experience may differ. -Of course if you are using shorter brass, and a shorter chamber, this will impact the location of the junction of the neck/shoulder (taper?) of the case neck, and consequently the taper of the body of your cartridge case as measured from the case head.
One nice thing about the straight taper of the 32-40 is that full length resizing hasn't been required for me when I load fixed ammo, though I do index my cases for my single shot rifle.
I hope I have been helpful.
I may have missed whether yours is single shot or fed from tubular magazine.
In the 30-30 I like the RCBS 180 grain gas check bullet. Carries lots of lube, and has a short nose with flat meplat, and several driving bands to help prevent stripping in the rifling. The nose *just* fits the throat of the barrel, and like the Pope style bullet, doesn't slump that I can tell. It meets the needs of that cartridge pretty well. I can cast of a comparatively soft 20-1 alloy, and keep velocities around 1500 fps and get good accuracy. It might go faster, but for my uses this is plenty fast. I am considering a 170 grain custom mould from Accurate Molds, as the base band of this RCBS 180 is *just* into the boiler room of the standard 30-30 cartridge. However, this is a design detail you can determine once you have settled on the bullet.
Once you have determined which bullet you like, the remaining dimensions of the cartridge will sort of fall into place. The neck length will be easy to determine once you have chosen your bullet. Then the throat dimensions and the taper of the leade will present themselves. The neck diameter of the chamber can be specified to allow a .004 to .005" bullet release, which is really as tight as you will want to go with a cast slug. You may have to neck turn your brass, but this is typically a one time proposition for low intensity cartridges. Especially those with a tapered profile, or even the shallow shoulder of a 30-30.
Chamber length will also be a variable you will want to address. If you are using 32-40 brass, there are many who will want to assassinate you, as that stuff is near impossible to find, and the 32-40 shooters hoard it like the gold it is. If you are going to use Starline 38-55 brass, which is what I have resorted to here recently, then you might want a longer chamber, as that brass, once reformed to 32-40 dimension, is quite long. Probably even longer for you since you are making a 308/32-40. No big deal to trim it, but it is something you might wish to consider. Conversely, if you choose to form your cases from 30-30 brass, those tend to come in relatively short, at least when formed to 32-40 brass. I personally prefer to keep my brass about .01" short of the end of the chamber as I find that it seems to slow the buildup of residue in the leade area of the barrel. Your experience may differ. -Of course if you are using shorter brass, and a shorter chamber, this will impact the location of the junction of the neck/shoulder (taper?) of the case neck, and consequently the taper of the body of your cartridge case as measured from the case head.
One nice thing about the straight taper of the 32-40 is that full length resizing hasn't been required for me when I load fixed ammo, though I do index my cases for my single shot rifle.
I hope I have been helpful.
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thub
Member
For neck tension use other than Remington brass for there will not be enough neck tension, due to the thinner brass.
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Catpop
Member
Stubbicat, you have been beyond most helpful. Thank you! I take it the 32-40 is right down your alley. I'll keep yawl posted.
Thanks again to all.
Thanks again to all.
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