The Solid Bullet Debate

[MontanaRifleman]

Just for kicks, I decided to run some hypthetical numbers comparing the 177 GS HV and the 210 Berger VLD in 30 cal. I uesd MV's of 3150 for the 210 and 3500 for the 177. These are realistic MV's out of a 300 RUM with 26" bbl. I used a BC of .631 for the 210 and BC's of .55 and .6 for the 177. I used a base Montana elevation of 3000'. Here are the results at 1200 yds...

Bullet-BC/vel/KE/momentum/windage(10 mph)

210-.631/1670/1301/50.11/76.2
177-.600/1840/1330/46.52/69.8
177-.550/1720/1163/43.39/78.6

Overall the stats are fairly close and the 177 with a BC of .6 has a definite advantage in all areas except momentum. The 210 however shows a marginal velocity for expansion, as 1800 is the "safe" recommened expanding velocity. The 177 is still well above it's expanding velocity of 1600. With a .55 BC, the 177 looses some ground but still fairly close overall and still retains more than enough expanding velocity.

At 1200 yds, the 210's effectiveness is questionable depending on weather or not it expands. The 177 is definetly a deer killer and quite possibly an elk killer with a BC of either .6 or .55.

Also, for those who prefer a controlled expansion bullet, the 177 is a one bullet solution from the muzzle, on down range.

Of course, this is a keyboard comparison. It's field performance that counts.

-MR

 

[Jon A]

I agree if those assumptions are correct, it will be a fine performing bullet--good enough it seems the 210 won't have much of any advantage. There are a couple big "ifs" though. The first is even the .55 comparison assumes it has a better form factor than the 210 Berger. I think the chances of this are pretty low. Next it assumes you can get an extra 100 fps or so due to its lower friction. This could very well be the case, I don't know. I ran the 173's up to 3460 with a 26.7" barrel and considered it a max load; it's possible I could have pushed them faster but I didn't try. If you need to run the 177's at 3500 to compete, even with the low friction, it's possible your brass might not last very long (especially if it's Nosler!), but like I said I don't really know.

.30 = 9.00"

It just so happens my 300 RUM is a 1:9, so if you need me to put that to the test, let me know.

 

[noel carlson]

Jon,

I had not even planned on a 30 caliber when this thread began, but if your rifle is sub-minute, I may be interested in doing something within the next couple of weeks.

Do you have any objection to signing an NDA?

Best,
Noel

 

[Jon A]

Yup, it's easily sub-minute. I have no objections to signing an NDA.

 

[noel carlson]

Yesterday we learned that the ZA50/6.0-M stabilizes from a 30 caliber twist. Today we learned that it hits nothing but 10's, and X's at 1,000 yards (and this was during load refinement from a less than ideal bench set-up).

It will be competing in the 50 caliber, light rifle class, at Ratone NM on Friday, and Saturday. I hope the wind kicks up by then.

Jon, send me an e-mail at [email protected]

Best,
Noel

 

[MontanaRifleman]

I agree if those assumptions are correct, it will be a fine performing bullet--good enough it seems the 210 won't have much of any advantage. There are a couple big "ifs" though. The first is even the .55 comparison assumes it has a better form factor than the 210 Berger. I think the chances of this are pretty low. Next it assumes you can get an extra 100 fps or so due to its lower friction. This could very well be the case, I don't know. I ran the 173's up to 3460 with a 26.7" barrel and considered it a max load; it's possible I could have pushed them faster but I didn't try. If you need to run the 177's at 3500 to compete, even with the low friction, it's possible your brass might not last very long (especially if it's Nosler!), but like I said I don't really know.

I bekieve the form factors of the two bullets are probably very close with edge going to the Berger because of a smaller meplat. But I'm *guessing" that the meplat of the 177 isn't a whole lot bigger. Why would you say that the 177 couldn't have a BC of .55 unless it had a better form factor? Do you think 33 gr of mass will make that much difference... .081 in BC? I'm thinking if the E-Tip BC really is .523, the 177 should be at least .55 if not more. Aslo, the greater velocity of the 177 (~ 3500 fps) will/should boost it's BC performance. I suppose 3500 fps is an "if", but I think it's doable without over pressure. On your experience with the 173... did you see any pressure signs beyond 3460, or did you just stop, and what powders did you try with it?

Too bad that I'll probably have to wait fro 3 months to shoot these things

 

[MontanaRifleman]

Yesterday we learned that the ZA50/6.0-M stabilizes from a 30 caliber twist. Today we learned that it hits nothing but 10's, and X's at 1,000 yards (and this was during load refinement from a less than ideal bench set-up).

It will be competing in the 50 caliber, light rifle class, at Ratone NM on Friday, and Saturday. I hope the wind kicks up by then.

Jon, send me an e-mail at [email protected]

Best,
Noel

Noel,

Congrats again today.

Glad to see Jon stepping up to test some 30 cal bullets. If I had a 9 twist, I would step up also. Please keep us posted on progress

-MR

 

[Jon A]

Do you think 33 gr of mass will make that much difference... .081 in BC?

More, actually. If the form factor is held constant, the BC will be proportional to SD, which means for bullets of the same caliber it will be proportional to mass. That's just the way it works. If the form factor is exactly the same and one has 19% more mass, it'll have a BC 19% higher. It just will.

Now of course, even if the form factors are similar they won't be exactly the same, the drag curves won't exactly match so G1 BC's measured at different velocities wont all show an exact flat 19% increase, etc. But it's important not to confuse the minutia with magic that somehow gets around and makes us lose sight of the big picture. In order to not have a BC lower by the same percentage it is lighter, it needs a more efficient shape.

I didn't hit pressure signs with the 173 so I very may well have been able to run it faster, I just didn't try. I was using Retumbo.

 

[MontanaRifleman]

More, actually. If the form factor is held constant, the BC will be proportional to SD, which means for bullets of the same caliber it will be proportional to mass. That's just the way it works. If the form factor is exactly the same and one has 19% more mass, it'll have a BC 19% higher. It just will.

Now of course, even if the form factors are similar they won't be exactly the same, the drag curves won't exactly match so G1 BC's measured at different velocities wont all show an exact flat 19% increase, etc. But it's important not to confuse the minutia with magic that somehow gets around and makes us lose sight of the big picture. In order to not have a BC lower by the same percentage it is lighter, it needs a more efficient shape.

I didn't hit pressure signs with the 173 so I very may well have been able to run it faster, I just didn't try. I was using Retumbo.

Jon, you make some good points. Are you sure the mass % factor is directly proportional? That being the case, the 180 E-Tip should have a lot lower BC compared to the Berger based on both form and mass. The E-Tip's BC may also be just based on higher end velocities out to about 500 yds.

I think 3500 fps is a reasonable estimate for the 177 out of a 26" RUM. It's presently being shot at 3650 out of a 30-338 LM Imp, 28" bbl. Time will tell.

 

[noel carlson]

MR,

Jon is 100% correct.

Thanks again for the congratulations, I hope the current trend holds out through Saturday afternoon.

Best,
Noel

 

[noel carlson]

UPDATE;
Raton, New Mexico 7/3/09

The first day of the annual FCSA 1,000 yard 50 cal match got off to a slow start today because of technical problems.

Scott Nye, a five time winner of this event, started off with the ZA50/6.0-M (930 grains) in the light rifle class. He shot two five-shot groups before rain began at ~11:00 AM.

The first was 48/50 (two X's)
The second was 50/50 (two X's)

During the pause for rain, Scott loaded a somewhat slower series of rounds. When the shooting resumed, temperature had fallen, and light drizzle persisted until 1:00 PM.

His first three shots, in these new conditions, went through the 10 ring. The fourth hit the dirt at ~800 yards. The fifth, once more, went through the ten ring.

Conditions were as follows;

Elevation - 6,352' ASL
Temperature - 71oF
Humidity - 61%
Pressure - 30.01 inHg
Wind - 8 to 12 mph SW-SSW

We may be riding the edge of stability in the 1: 15" constant-twist barrel. In comparing this performance with his standard projectile ( 800 grain brass ), he noted that ZA wind-drift was minimal, in relative terms, even though the 800 grainer has an ~100 fps velocity advantage. Elevation settings for both were roughly equal at 1,000 yards.

Tomorrow, Scott will be competing in the heavy rifle class using the ZA. Weather is expected to be similar, but this time all of the loads will be hot.

Assuming the single projectile failure has no association to band failure in a constant-twist, lapped barrel (as opposed to a honed LGT), the occurence does have equivalent implications for the twist-rates of the ZA6.0's in other calibers. Still... not a bad showing for a one week turn-around time from drawing concept... to range. It gives new meaning to the phrase "rapid prototyping".

Happy Fourth of July,
Noel

 

[noel carlson]

Continued...

7/4/09

Saturday another two projectiles flew unstabily, for a 10% overall failure rate. I am virtually certain, at this point, that the ~2,600 fps MV is too low to provide reliable gyroscopic stability from a 1: 15" (30 caliber) twist barrel.

The positive results from this test are actually quite encouraging however. The ZA50/6.0-M impacts at 1,000 yards on the same elevation setting as a conventional match projectile with 86% the mass, 109% the MV, and 104% the propellant charge. We are looking at an exceptional BC.

As a result, I have decided to produce a high pressure component case, in a 50BMG exterior geometry, so that I will be able to run high-explosive propellant in standard 50BMG rifles. The >3,000 fps MV should address the stability issue even at low altitudes, and temperatures. This cartridge will also dispense the ceramic lubricant/throat-protectant to achieve barrel life, at least, equal to that produced by use of Vihtavouri 20N29.

Regarding 375, 338, and 30 caliber equivalents; the necessary stabilization velocities are obtainable with conventional propellants. It will be necessary, consequent to the 50 caliber test results, to prove these loadings in very high air-density conditions before application in hunting.

A high velocity 375 experiment will take place in the next few weeks.

Best,
Noel

 

[royinidaho]

Lookin' forward to this:

A high velocity 375 experiment will take place in the next few weeks.

 

[RockyMtnMT]

Hi all,

I am the guy that MR referred to as trying out the 177 HV's. All I have done to this point is the initial load development. Here is what I know...

I am shooting a 30-338 Lap imp, 30" Lilja 1-10 twist. The 1-10 twist is marginal according to GS Custom. So far so good though.

I am loading the 177 HV over 104g of H-1000 and a CCI 250 primer. This chrono'd at 3650fps, and held just under 1" at 200yrds.

I think I could get more vel out of the bullet if I tried some different powders, but I don't feel the need to try and tweak another 50fps or so out of it at the expense of using up the bullets that I waited so long for. When I get out and do some long range work I will post my findings. I am not sure when this will happen because there are a lot of lakes in the high country here that I have never seen, and I am trying to see a new one each weekend. That is the other half of the reason I never left MT and have made a meager living all my life.

For what it is worth, GS lists there bullets with 3 bc's like Sierra. For the 177 HV they list: @ 3300fps .638, @ 2450fps .603, and @ 1600fps .589.

Steve