The Solid Bullet Debate

[noel carlson]

Edge,

It will be done next week. You do not mind if I use copper, do you?

- Noel

 

[Michael Eichele]

IMO, the nose which is normally hollow and low in mass is expendable. The worst thing a bullet can do is to "pencil" through the game. So losing the nose ( shape ) asap and retaining the bulk of the bullet mass at the lowest velocity should be your goal for long range hunting bullets.

I envision a steel shank with a foam rubber ogive as the "magic bullet"!
High BC ogive that will instantly disintegrate when it encounters hide, and a shank that will hold up to the highest impact velocities

edge.

Launch those new prototypes from an all copper barrel and we are in buisness.

 

[edge]

Noel feel free to use copper, and Michael I can't wait to see the rail gun

edge.

 

[noel carlson]

Edge,

I was partially serious. A bullet that performs in the way which you describe will be ready for testing next week.


Michael,

This may surprise you, but one of my 50 cal projectiles is made from leaded steel. Copper in those weights gets pricey, and the engraving-band design permits the use of steel, provided the bore hardness exceedes 60 HRC.

Best,
Noel

 

[Michael Eichele]

I was just joking.....

Steel bearing surface, copper barrel.............


Bad joke.......

 

[Jon A]

the 180 HAT (BC of .7+)

I think taking this as a fact is helping to skew your hopes and dreams the wrong way.

I do agree with the Berger being conservative for how we think of BC's. If you measure at high velocity (close to the muzzle) you should get a higher G1 BC. In fact, you can see this by plugging in their G7 number of .323 and converting that to a G1 with an average velocity of 3000 fps (which would be typical if measured over 200 yds from a 300 RUM) and it comes out to a G1 of .656 (using the JBM converter). That's only a hair higher than I measured the 210 SMK by using that method but lower than the 208 A-Max.

 

[noel carlson]

Michael,

• I liked your joke.

 

[MontanaRifleman]

I think taking this as a fact is helping to skew your hopes and dreams the wrong way.

I do agree with the Berger being conservative for how we think of BC's. If you measure at high velocity (close to the muzzle) you should get a higher G1 BC. In fact, you can see this by plugging in their G7 number of .323 and converting that to a G1 with an average velocity of 3000 fps (which would be typical if measured over 200 yds from a 300 RUM) and it comes out to a G1 of .656 (using the JBM converter). That's only a hair higher than I measured the 210 SMK by using that method but lower than the 208 A-Max.

MR,

You are making an error which is understandable. Do not use manufacturer supplied BC specifications for your estimates. Two of the companies you mentioned are good on this kind of reporting, the other is not... you are relying too heavily on the one that is not.

Jon and Noel

I agree that some BC #'s are questionable. In fact, I look at ALL BC #'s with a grain of salt )sometimes a shaker of salt) after reading the many threads in this forum. Some are probably more accurate than others and I see all of them as starting point of reference.

A number of things can affect BC in a single type and weight of bullet, probably the most significant being velocity. Typically, higher MV's produce higher BC's in a bullet, and as the bullet flies down range, the BC usually deteriorates.

Michael reported testing the 208 Amax (listed BC of .648) with a BC of .671 and another member, MT300RUM reported a BC of .6443

http://www.longrangehunting.com/forums/f17/1200yd-culligan-water-jug-shot-43669/index2.html

I dont doubt any of the BC reports for the Amax bullet, and take each for face value with a grain of salt. There are a number of reasons that the BC's may differ, including possible errors in data. There may have been no errors in data and the differences may be purely enviromental and/or differing velocities, etc.

On the mentioned bullets I used for a relative refference, the 180 E-Tip probably has a fairly relaible BC and I read one post where a forum member tested them to be just about right on. At what velocity and range, I don't know. The overall lengths differ by .110, 1.47 vs 1.58, the noses differ by ~.12, ~.7 vs .82, and the tail of the E-Tip very roughly "appears" to be about half the length of the 177. The only BC edge for the E-Tip is a pointy poly tip vs the unknown HP meplat of the 177. I see those differences as fairly significant, maybe enought to account for about a .07-.08 difference in BC?

With the 210 Berger, the OAL is 1.484, .096 shorter than the 177, the tails "appear" to be the same and the noses are the same except the Berger has a smaller meplat. So with essentially the same tail/nose length and more mass and a smaller meplat the Berger certainly would have a better BC, but by how much and is it's BC actually conservative relative to other bullet BCs? I have read several posts from members saying the old BC's worked spot on for them.

The HATs are definitely more of an unknown commodity. They have been advertized to be greater than .7 and I have not seen anything posted to dispute that, nor confirm it. The HAT tail is slightly longer than the Berger, maybe .003? And the nose is .002 longer than the Berger and the overall length is .091 longer than the Berger, so shape wise it is more BC freindly, but the Berger has more mass. Hmmmm....

Based on all this, I still believe the 177 could possibly have a BC of .6, especially if fired at speeds in excess of 3500 fps, and the fact that it's design boosts its velocity over that of similar weight bullets actually also boosts its BC, a factor we haven't really considered.

Anyway, I am hoping to give them a try in my 300 RUM as soon as I can get some, which probly wont be until early fall. When I do, I will also shoot them against the 210 Bergers for grins. That should be interesting.

Noel,

Congrats on your ZA50/6.0-M tests. Hopefully these results will bode well for your other projectiles.

Also, If you can develop a 195 gr pill with a BC in the upper .6's I think you should a good advantage over the other current offerings. I think the upper velocity limit needs to be higher than the 338 though.

Best,

-MR

 

[noel carlson]

MR,

Thanks for the congratulations. We were very surprised by the fact that a .50 projectile this long, and heavy, could be made to stabilize in the standard 15" twist. This has huge implications for use by the military.

It also means that I have been too conservative on twist requirements for the 6.0 projectiles in other calibers, and very likely the 6.5, and 7.0 projectiles, as modified to the new tail configuration. My earlier reccommendations will be fine, but over-kill.

For example;

The lollowing is a list of 30 caliber-length twist rates...

.224 = 6.72"
7mm = 8.27"
.30 = 9.00"
.338 = 10.4"
.375 = 11.25"

... these fall within the ranges currently available in barrels on the mass market.

Common artillery rounds, which virtually always have projectiles less than 6.0 caliber projectiles (even the rifled 120mm), can have a twist as tight as 20 calibers. The finding that a full 6.0 caliber projectile can now be stabilized, with 1/3 less twist, really is a big deal.

Regarding upper limit velocity expansion, apparently I have been placing an artificially low one on the ZA based on petal shedding requirement assumptions. The shaft, and tail, will survive any impact possible with conventional case/propellant combinations.

Best,
Noel

 

[edge]

Just as a caveat, you might want to verify that the projectiles are stable over ALL conditions.

If you drop the temperature to below freezing and raise the elevation to 8,000 feet you might find that you are marginal or worse. Add a crosswind or imperfect crown and if you were marginal you might not stabilize.

I am not saying that you are, but you might want to verify before you publish.


edge.

 

[noel carlson]

Edge,


Latitude - 36 N

Longitude - 104 W

Altitude - 6,680 feet

Temperature - 85 Farenheit

Barometer - 30.22

Wind - 9-10 mph

 

[edge]

My most accurate combo is a 150 grain NAB 30 caliber @ around 3100 fps. 14 twist barrel.

If I use Don Millers Formula ( from Bryan ), using your temperature and pressure my load shows a stability factor of 1.17

If I drop the temperature to 32 degrees my stability drops to 1.06 and if the temperature drops to zero I am below 0.99 stability.

edge.

 

[MontanaRifleman]

MR,

Thanks for the congratulations. We were very surprised by the fact that a .50 projectile this long, and heavy, could be made to stabilize in the standard 15" twist. This has huge implications for use by the military.

It also means that I have been too conservative on twist requirements for the 6.0 projectiles in other calibers, and very likely the 6.5, and 7.0 projectiles, as modified to the new tail configuration. My earlier reccommendations will be fine, but over-kill.

For example;

The lollowing is a list of 30 caliber-length twist rates...

.224 = 6.72"
7mm = 8.27"
.30 = 9.00"
.338 = 10.4"
.375 = 11.25"

... these fall within the ranges currently available in barrels on the mass market.

Common artillery rounds, which virtually always have projectiles less than 6.0 caliber projectiles (even the rifled 120mm), can have a twist as tight as 20 calibers. The finding that a full 6.0 caliber projectile can now be stabilized, with 1/3 less twist, really is a big deal.

Regarding upper limit velocity expansion, apparently I have been placing an artificially low one on the ZA based on petal shedding requirement assumptions. The shaft, and tail, will survive any impact possible with conventional case/propellant combinations.

Best,
Noel

Noel,

What is a 30 cal-length? I assume that a 6.0 in .308 cal = 6 x .308 = 1.848"

On your projected twists, to the best of my knowledge, the standard mass produced twists in 7mm are about 9 1/4 - 9 1/2 and in 30 cal they are 10 - 11. Your twists sure dont look excessive, but I'm not sure you can get them in the mass commercial rifles? The 338 and 375 are in there though. It would be great if you could come up with a 30 cal 6.5 BC bullet that would stabilize in a 10" twist. Maybe this could be accomplished with MV's of 3400 fps and higher and 26" barrels?

And yeah, I kind of figured that a monometal body and tail should hold together which is why I asked the upperlimit question in the first place.

 

[noel carlson]

MR,

Twist-rates are also measured in calibers, ie., a 15" twist in a .500" diameter bore;

15/.50=30

Also, I am sure you are correct on the smaller caliber commercial twist rates, but there are few rifling machine that will be unable to handle these.

Best,
Noel