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  #1  
Old 09-06-2015, 11:25 PM
WayneShaw WayneShaw is offline
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Default 6MM weight/jacket length

What are the max bullet weights per jacket length, with .790, ,825 and .900 from an accuracy stand point?
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  #2  
Old 09-07-2015, 02:24 PM
redrock ranger redrock ranger is offline
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Depending on the bullet shape,a 10 ogive will make a 79 gr open tip flat base using a .825 J4 ,if i remember correctly.
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Old 09-07-2015, 03:44 PM
Randy Robinett Randy Robinett is offline
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Quote:
Originally Posted by WayneShaw View Post
What are the max bullet weights per jacket length, with .790, ,825 and .900 from an accuracy stand point?
Wayne, what nose radius is your point-up die? Here's one example: my [Niemi] 8.5 caliber nose x .0625" me'plat , using .825" long jackets, will make a decent 73 Gr. - not much more. A larger me'plat (knock-out pin) will make a heavier bullet, as it will have a longer shank, and vice-versa.

An aside: on a 6mm bullet, every 0.010" of me'plat diameter reduction is worth roughly 0.030 points of BC, or, equivalent to putting a BT on a FB. Of course, going the opposite way with the KO pin, decreases the BC by about the same amount! Good luck. RG
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Old 09-08-2015, 10:33 AM
WayneShaw WayneShaw is offline
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Flat base bullet with a 7 ogive. It seems the "rule of thumb" is a 65-66 grain for a .790, 66-68 for a .825, and perhaps an 80 for a .900 jacket. But just because that's the "norm" doesn't mean that Gospel.
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Old 09-10-2015, 10:01 PM
Randy Robinett Randy Robinett is offline
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Quote:
Originally Posted by WayneShaw View Post
Flat base bullet with a 7 ogive. It seems the "rule of thumb" is a 65-66 grain for a .790, 66-68 for a .825, and perhaps an 80 for a .900 jacket. But just because that's the "norm" doesn't mean that Gospel.
"Abbaluby"! As you point out, the jacket lengths & weights you list, represent the accepted norm. You may be surprised how light you can go - and how well lighter than normal will shoot! With a 7 ogive, you may be able to reach/exceed 75 Gr., and still close the point to K.O. pin diameter - especially if the K.O. pin diameter is 0.070" or larger. And, the bullets may still shoot - you just have to try it.

Your original question: "What are the max bullet weights per jacket length, with .790, ,825 and .900 from an accuracy stand point?" has no absolute answer! The variables include the nose radius, me'plat diameter/shank length, core alloy, etc. I simply provided one example.

A GREAT coyote trapper concluded a lesson by advising me, "keep an open mind - you may go down the road 50 miles and see a guy setting his traps upside-down in the barrow-pit, and pissing on them, who catches more coyotes then I do." Some of the best advice I ever received! If ya get an idea, just do it! RG
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  #6  
Old 09-26-2015, 02:43 AM
Bryan Bryan is offline
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Ahhhh, yes! The light side is another way to go. I won a fair amount of wood with my 58 gr bullet on a .790 jacket.
BTW Randy, I still want to test some of your .22/52's in the Hornet. Nearly out of my stash of Zia 52's.
Bryan
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  #7  
Old 09-27-2015, 04:17 PM
ackleyman ackleyman is offline
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Default .750 jackets

when making the conversion from BR Shooter Back to Varmint shooter, I had a set of 6mm bullet making dies. I wanted to dispatch ground squirrels, p. dogs, and jack rabbits with authority and still have groups in the sub 1/4" area. I did my bullet testing with BR Rigs with Hall M's and Stolle Panda's as the platform.

I played with heavier weights

68g on .750 jacket
70g on .825 jacket
75g on .900 jacket

I am sure that you can go heavier on the .900 jacket and you are getting into the relm of needing a 11.9 twist or better on these longer jackets

Then I went with lighter weights and came up with some surprising results.

Also, I started playing with the size of the HP. I found a size of the 65g Boat tail Hp on an .825 jacket that would simply make a ground squirrel just disappear, and p. dogs would detonate. The boat tail eliminated some bearing surface which meant that I would have less copper in the barrel. I had a flat base version of the same size meplat that would not shoot a hole though a coyote in a 243 while driven fast.

Then, I started thinking about light fast bullets. So, I started making 40 and 45g bullets on 6mm .750 jackets. I had to overcome the issue of the tapered jacket and size of the punches. The jacket gets thicker as the lead level drops, so the Bob Simenson helped me with a set of smaller punches.

In the 6ppc, I was shooting the 40g bullets at 4000-4050 with amazing accuracy, lots of groups in the very low 1's, same for the 45g bullets. These bullets were pointed up with a .070 meplat.

My life was changing around this time, and I moved out of state and the bullet making dies had to go before I ever got to shoot any ground squirrels with the 40 and 45g Bullets. I have often wondered why no one ever used these weights for the 100 yd short range benchrest as my tests were really impressive in accuracy with two different rifles. I shot a lot of groups in the zero's with these light bullets at 100 yards and high 1's were just ho hum. I do remember that jamming these bullets .030 into the lands was where the bullets grouped the very best.

There is a break even point between speed/BC/sectional density in trying to achieve the best ballistics for a given range. Since I was interested in dispatching small pest rodents, I have lost interest in registered benchrest a long time ago.

Last edited by ackleyman; 09-30-2015 at 10:04 PM.
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  #8  
Old 09-30-2015, 11:45 PM
Randy Robinett Randy Robinett is offline
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Quote:
Originally Posted by ackleyman View Post
when making the conversion from BR Shooter Back to Varmint shooter, I had a set of 6mm bullet making dies. I wanted to dispatch ground squirrels, p. dogs, and jack rabbits with authority and still have groups in the sub 1/4" area. I did my bullet testing with BR Rigs with Hall M's and Stolle Panda's as the platform.

I played with heavier weights

68g on .750 jacket
70g on .825 jacket
75g on .900 jacket

I am sure that you can go heavier on the .900 jacket and you are getting into the relm of needing a 11.9 twist or better on these longer jackets

Then I went with lighter weights and came up with some surprising results.

Also, I started playing with the size of the HP. I found a size of the 65g Boat tail Hp on an .825 jacket that would simply make a ground squirrel just disappear, and p. dogs would detonate. The boat tail eliminated some bearing surface which meant that I would have less copper in the barrel. I had a flat base version of the same size meplat that would not shoot a hole though a coyote in a 243 while driven fast.

Then, I started thinking about light fast bullets. So, I started making 40 and 45g bullets on 6mm .750 jackets. I had to overcome the issue of the tapered jacket and size of the punches. The jacket gets thicker as the lead level drops, so the Bob Simenson helped me with a set of smaller punches.

In the 6ppc, I was shooting the 40g bullets at 4000-4050 with amazing accuracy, lots of groups in the very low 1's, same for the 45g bullets. These bullets were pointed up with a .070 meplat.

My life was changing around this time, and I moved out of state and the bullet making dies had to go before I ever got to shoot any ground squirrels with the 40 and 45g Bullets. I have often wondered why no one ever used these weights for the 100 yd short range benchrest as my tests were really impressive in accuracy with two different rifles. I shot a lot of groups in the zero's with these light bullets at 100 yards and high 1's were just ho hum. I do remember that jamming these bullets .030 into the lands was where the bullets grouped the very best.

There is a break even point between speed/BC/sectional density in trying to achieve the best ballistics for a given range. Since I was interested in dispatching small pest rodents, I have lost interest in registered benchrest a long time ago.
Nice report, Ackleyman! My experience mirrors yours - the reason nobody shoots them - not enough BC to make most people happy! Many years ago, I made a very nice 58 gr. 6mm, using the .750" long jacket - took several years to sell a case (about 9,600) of them! They made GREAT competition AND varmint bullets. Never mind, that, at close range, BC isn't worth much . . . RG
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