Author Topic: how many lube groves and what size (Read 1889 times)

white feather · « **on:** July 25, 2004, 10:13:37 AM »

Howdy gents
I need your input, im working on a design for a bullet, 40 cal.285-325gr.
What works best to slow or stop leading, lots of small groves or a couple of large groves.
Also does anyone know how to figure the twist rate ill need to use?
I have been working on this idea for a couple of months, think thinge are about to come together, one more thing, any good gunsmiths who work on lever guns who can re-bore a barrel for me, thought i would go this way to save money and just screw the barrel off re-chamber then re-install, as always thanks for all the help, ill keep you informed about this little exp.

haroldclark · « **Reply #1 on:** July 25, 2004, 06:24:32 PM »

White Feather,
If you have Microsoft Excel Spreadsheet software on your computer, I can send you via email attachment a spreadsheet that you can calculate your required twist.

You can also, calculate up to what bullet length you can shoot in a given twist rate. If you already have a rifle with a given twist, you can callculate what the maximum bullet length it will shoot.

The bullet length is a major figure in determining the required twist rate. If you are currently designing a bullet, you probably know the weight and length of the bullet. With that info and the velocity you plan on, you can tell all kinds of things about twist rate.

Send me a PM with an email address if you need the spreadsheet.

Harold Clark

white feather · « **Reply #2 on:** July 26, 2004, 12:09:42 PM »

Harald
Is it hard to run this spread sheet, im kinda dumb when it comes to puters

haroldclark · « **Reply #3 on:** July 26, 2004, 12:19:21 PM »

It is not hard at all, to me. I designed it to be easy. Do you hasve Excel?

Harold

white feather · « **Reply #4 on:** July 26, 2004, 05:44:19 PM »

Harold
Im running windows 98 and its crashed twice and had to have it re-installed, im not sure if i still have all the things it came with, just getting it back up and running, i have 2 cases in mind and i may go with a off the shelf mould till i get all this up and running, im looking for someone who can bore out the barrel from 30 cal. to 40 cal. and rifle it for lead bullets, im just not sure of the twist, if this all works out it should be a real honey, lots of power or downloaded for fun, maybe you wouldnt mind useing your software and see what it would take to make a 324 gr. bullet work in a 24 inch barrel, im thinking in the 1800 fps range, round nose flat point thanks for being so patient with a computer dummy :-)

calvon · « **Reply #5 on:** July 26, 2004, 06:52:37 PM »

Greenhill formula: (150*Bullet Diameter)/(Bullet Length/Bullet Diam)

Culp formula: ((.06*Muzzle Velocity)*(Bullet Diameter Squared))/Bullet Length

Greenhill formula has been around forever. Culp formula is detailed in a story in the November-December 1994 issue of Rifle Magazine. It considers muzzle velocity whereas Greenhill does not.

All measurements in inches.

haroldclark · « **Reply #6 on:** July 27, 2004, 06:16:02 AM »

Good Morning,

Since you are referring to "40 Caliber", I used .408" bore diameter and bullet diameter.

I utilized the formula to determine the maximum bullet length if you used a 1 turn in 14" of barrel.

I used 1800 fps with a bullet that weighs 324 grains with the 1 in 14" twist and the Maximum bullet length is 1.77 inches.

I have a shooting buddy and we shot his rifle 87 rounds yesterday for accuracy. He had the rifle barreled in 40-82 (408 Caliber and 82 Grains of Black Powder). The original barrel was a 40-65 and a slower twist.

The new barrel has a 1 in 14" twist and it stabilizes the bullets great so far.
He used a 425 grain bullet yesterday and it worked very well.

You will not have too tight a twist at 1 in 14". However, it will allow you a full range of bullets. I have been around the Black Powder/cast bullet shooters and spotted many 500 meter matches over the past few years. Barrel twist is always a serious conversation. The twist determines the stability of the bullet in flight. Most BPCR shooters keep the velocities to less than 1400 for 1000 yards and 1200 for 500 meters.

At 1800 fps, I would suggest a gas checked cast bullet to help prevent leading. Note: That bullet weight at that velocity is going to let your shoulder know the rifle went off.

It takes very little mechanical effort to twist a bullet in the bore and in the barrel as long as you don't over do the velocity with cast bullets. The soft cast bullets will strip by the rifling and no telling where the bullet will hit.

I don't know if you are going to use cast or jacketed bullets.

I have shot a 444 Marlin for 10 or more years. originally, the barrel came with a 1 in 38" twist. I could only shoot a 265 grain bullet with any degree of accuracy out to 220 yards. I could not get it to shoot the longer (.886" Long) 300 grain bevel based bullet.

In your case, if you used a 1 in 16" twist, you could run a 300 to 400 gr. bullet out the barrel up to 1800 fps and down to 1200 fps for light loads and the bullet will stabilize. However, the maximum length of the bullet can be between 1.5" to 1.6". The twist and bullet length are the two factors that you have to predetermine and velocity is the remaining issue. With the proper twist and bullet length, you can change the velocity from high to low and still retain your accuracy.

You can shoot a heavy bullet that is no longer than 1.6". If you make a long spire point bullet that weighs 400 grains and is 1.8" in length, it most likely will not stabilize and be accurate.

I hope this has been of some help to you.

Harold Clark

white feather · « **Reply #7 on:** July 27, 2004, 10:34:36 AM »

Harold & Calvon
I would like to thank you both for your time and effort, this is the info im looking for.
I was going to use a 30/30 case or maybe a 375 win. case and seat a 400 dia. bullet in it, i think ill go ahead with the 444 marlin case insted, i also have a good supply of them, what i was looking for was a caliber i could shoot the .400 dia. pistols bullets and also shoot a heavy lead bullet for larger game, but use the pistol bullets for plinking and small game, i know i should just get a marlin in 444 but i wanted something different, also thought after i got it up and running of pitching it to winchester and telling them to set it up in a model 94 and call it the 400 winchester, i like winchesters always have but it seems they need a kick in the seat of the pants to come out with some new calibers in the 94, i would love to see them come out with a 38/55 with a 26 in. barrel, and a model 92 in 32/20, i may be just spinning my wheels but i think a .400 winchester would be the kick in the pants they need, thanks again gentlemen, Happy Hunting.

fffffg · « **Reply #8 on:** July 28, 2004, 04:51:08 AM »

my opinion only. you talk of 38 55 and 444 marlin in the same post.. these guns are miles apart in tecknolagy.. that doesnt mean the 38 55 is a bad deer cartrige.. i heard last week that the only way you can kill a deer with a 38-55 with a hard cast bullet is with a brain shot.. i read in an old cartriges of the world last night that the 38-55 at 1700 fps was a better deer killer than a 30-06. what is being left out of all this is that the originall 38-55 did not have jacketed bullets .. and for some reason cast bullet shooters cant get thier lead hard enough., the case and point is unless yhour shooting a very large caliber gun .45 cal or larger your hard lead bullet will just go thru a deer. and whith out a kill shot your in for some tracking.. that is all fine if that is what you want like for hogs and bear... i shot a 8.7 x 72 r with a pure lead paper patch bullet into 7 one inch thick encylcopedias the other day. im getting 1500 fps second. it turned sidways half way thru the first volumn, and started to come apart at 35 yards.. three volumes further it started to look like a knife 1 1/2 inches long and thin as it quit a total of 3 1/2 inches deep into some tough old ecylopedias.. i showed them to all the good hunters i know.. some said you ahve to add some tin, some said it will go right thru a deer, the guy that had trouble with the 38-55 and hard cast is one of the most avid hunters i know and has been to africA three times said "go shoot a deer" .. one friend of mine said not to shoot a deer at too close with that gun.. just what i wanted to hear about the little 8.7x72 r (drilling), .. the 444 is a fine cartrige, but miles away from a 38-55, all these guns worked when they were using the type of loads they were disigned for. twist, bullet design, hardness, caliber, freebore, case volumn, barrel lenth , bullet wieght, bullet lenth are more things you have to consider when designing a target or hunting load/gun. when we as home builders start guessing it useually takes a long time to get it right.. before jacted bullets came out paper patch was just starting to take off, and it looks like it was a good idea for the time,considering the velocity, strength of the old guns.. they even used them will good success on bufalo with probably a little harder lead formula and larger caliber.. it is uncanny how pure lead tends to open up and be quite nasty imparting all the energy to the victim. make sure the action will be strong enough and will feed the new cartrige you rebarrel for, and the tube willhold it, and you can get flat nose bullets for the tube. .. good luck dave..

white feather · « **Reply #9 on:** July 28, 2004, 12:53:46 PM »

fffffg
Thanks for your coments, but i didnt just fall off the turnup truck, i would never think of loading up pointed bullets in a tube magazine, nor would i chamber a rifle for a caliber that it wont stand, i had a gunsmithing shop for a short time, also worked as a gunsmith in San Antoino Texas for awhile, did my app. with a good friend in Georgia who used to build bench rest rifles, so i kinda know what i doing, except when it comes to rifle twist, i have been reloading sence 1972, started when i got home from the navy, im almost the same age as you, we probably went to the same school, (school of hard knots), i have told lots of people you dont get a brain till your 40, you dont learn how to use it till your 50, so im not about to go out and blow up a good gun hurt or kill myself or someone else, as for the 38/55 coments i just wanted winchester to bring it out again in something besides a $8,000 custom gold inlay model 94 that nobody can afford, as for the 444 marlin, had one sold it thats why i have the brass, i dont know why your friends are haveing so much trouble killing game with a 38/55, i killed a spike and a feral hog the same day with one that belongs to a buddy, shooting straight wheel weights, felex lube sized .380, one shot on the spike went in behind the shoulder went out in front on the other shoulder, hog was shot right behind the ear, hog didnt go more than 20 yards, i have also shot 1 ferrel hog with my browning 40/65, useing swiss black powder, my buddy was laughing so hard after i shot, cant see if you hit him or not, dont know what your buddies are doing wrong but i have killed lots of game with a lead bullet, didnt have to track them more than 40 yds. dont add tin, dont heat treat, dont drop in water, just my 2 cents worth, no flames intended.