375/408 Banded Solids Test

[kellyzier]

KZ, I have fired several of the bullets mentioned in this thread, I have done almost all of the testing on the various ZA 375, I have also shot the SMK and the Rocky MTN bullets. Here is what I have found:
An 8 twist will explode the Rocky Mtn hollow point and alum. tip
The SMK shot OK in the 8 twist, nothing spectacular
The 6 cal ZA works nice in the 8 twist
The 6.5 ZA is going to need at least a 6.5 twist
The 7 cal will most likely need a 5.5 twist to stabilize at 2900
The gain twist barrels should have entrance and exit twist with less deviation
than my 13-6.5
A 375 Chey w/o a break is not fun to shoot.

LOL!! I imagine the 375 cheytac would just about knock my shoulder off without a break...I'm going to have a real ear blaster of a break for my 375 and I'm working on a stock design that will take at least 30% of the recoil off this big gun in addition to the break. I hope to share the results on this forum in the future.

Back to the bullets.......I need to order a barrel shortly....Are you guys suggesting a twist starting at 12 and down to 7 ish?? I would like to know the most aggressive twist I can have and still stabilize the 350 smk's for the 375 cal......Sorry, Im just not well versed in the barrel dept.

KZ

 

[kellyzier]

LOL!! I imagine the 375 cheytac would just about knock my shoulder off without a break...I'm going to have a real ear blaster of a break for my 375 and I'm working on a stock design that will take at least 30% of the recoil off this big gun in addition to the break. I hope to share the results on this forum in the future.

Back to the bullets.......I need to order a barrel shortly....Are you guys suggesting a twist starting at 12 and down to 7 ish?? I would like to know the most aggressive twist I can have and still stabilize the 350 smk's for the 375 cal......Sorry, Im just not well versed in the barrel dept.

KZ

I just read one of Dave's old posts....16 to 7.75 twist up to 6.5 cal....7 cal would be for super super high bc's (lazers as Dave pointed out). I would like to come up with the best twist for real long bullets and still be able to stabilize bullets like the 350 smk.....So perhaps the 16 to 7.75 is the sweet spot...You guys agree?????????????

 

[Black Diamond 408]

Kelly,
I don't think you can get the best of both worlds with one twist rate. My barrel was designed so i could shoot the 350 smk and some customs longer like the 6 cal. ZA bullet, i have not shot any of these so i can't comment. Augustus stated that the 6.5 cal might need a 6.5" ending twist to stabilize it, and im pretty sure the jacketed bullet would come apart in that barrel. My barrel might work for that particular bullet, but i know it will not work for the 7 cal. lenght bullets.
If your going to build a rifle for the loooong bullets then that is all you will be able to shoot. It would be a dedicated rifle. OR you can get an extra barrel and have a Switch gun set up to shoot a wider range of bullets.
I mainly shoot the SMK's, RockyMtns, Predators and HATS when they come out. Any bullet that has a BC over .900 will be a monster down range.

So you have to decide on what bullet your going to shoot and build the rifle around that.

Dave

 

[kellyzier]

Kelly,
I don't think you can get the best of both worlds with one twist rate. My barrel was designed so i could shoot the 350 smk and some customs longer like the 6 cal. ZA bullet, i have not shot any of these so i can't comment. Augustus stated that the 6.5 cal might need a 6.5" ending twist to stabilize it, and im pretty sure the jacketed bullet would come apart in that barrel. My barrel might work for that particular bullet, but i know it will not work for the 7 cal. lenght bullets.
If your going to build a rifle for the loooong bullets then that is all you will be able to shoot. It would be a dedicated rifle. OR you can get an extra barrel and have a Switch gun set up to shoot a wider range of bullets.
I mainly shoot the SMK's, RockyMtns, Predators and HATS when they come out. Any bullet that has a BC over .900 will be a monster down range.

So you have to decide on what bullet your going to shoot and build the rifle around that.

Dave

Dave, thanks and I understand...I don't mind building one or the other. If you had to do all over again, would you change your twist for the "monsters". And if so, what twist would you land on for the monster of monsters (keeping in mind the monster bullet would have to have to capacity to kill ELK at long ranges).
Perhaps this question is to early and I simply need to wait on the results of the NV shoot!!! Sorry for all the questions, my gun is going to be on hold until I come up with a twist that will handle these bullets..........

KZ.....

 

[kellyzier]

Dave, thanks and I understand...I don't mind building one or the other. If you had to do all over again, would you change your twist for the "monsters". And if so, what twist would you land on for the monster of monsters (keeping in mind the monster bullet would have to have to capacity to kill ELK at long ranges).
Perhaps this question is to early and I simply need to wait on the results of the NV shoot!!! Sorry for all the questions, my gun is going to be on hold until I come up with a twist that will handle these bullets..........

KZ.....

Does anyone know if ZA, HAT, GS and Lehigh have web sites that talk about their bullets???????????????????????????????????

 

[MontanaRifleman]

Does anyone know if ZA, HAT, GS and Lehigh have web sites that talk about their bullets???????????????????????????????????

GS and Lehigh do....

GS Custom Bullets - Designed in South Africa - Proven on the toughest game on the planet.

Lehigh Bullets - Custom Match Bullets Homepage

My guess is the ZA and GS bullets will dominate the shoot.

 

[noel carlson]

Kelly,

Neither the ZA375/7.0-W, nor the 6.5, was designed for hunting. While they are both frangible, and probably "legal", they cannot be magazine fed, nor could they be expected to penetrate in a linear fashion. More likely, you would destroy a very large amount of meat sans a perfect shot.

The ZA375/6.0-W is suitable for taking game in my opinion, because it avoids both of those limitations.

The Sierra seems to be right at it's design limit in an 8" twist. If your objective is to maintain compatibility with a ZA, only one question remains; Will a ZA375/6.0-W stabilize in an 8" twist. We already know the answer to that... it will. The ZA 375/6.5-W may as well. We will know that prior to the Las Vegas test.

Best,
Noel

 

[Black Diamond 408]

Kelly,
I have built two 375's for my personal use, the first one was to test a McGowan
12 twist barrel. It shot the 350,s great, but the longer bullets were not so stable.

My second rifle has the Gain Twist experiment, i wanted to move into the higher BC
bullets that are coming out, remember the standard twist for the cheytac is 11.5 and
that shoots the Hookers good and they are a high BC of .945 plus the SMKs at .770
I do a lot of R and D here with barrels and twists and new wildcats, some work some dont.
I have tried most twist rates but when you start dealing in the extreme BC bullets your
going to be stuck with one bullet type or make.

Long range ... well the SMK has enough energy to kill an Elk past 2400yds, the 370gn RockyMtn
will have even more and these are legal hunting bullets. So in my opinon if your building a rifle your going to hunt with then get a barrel that will handle these bullets. If you push these bullets to 3200fps and over spin them you will see poor results. It takes quite a while to get a
gain twist barrel from Bartlien. I would like to try a Gain twist in somthing like 20 to 10 exit, Just for the Jacketed bullets.

 

[noel carlson]

Dave,

I think your focus on projectile adaptability/flexibility, in a hunting rifle, pretty much reflects what I have been able to gather from the hunting community.

I took the cue by moving to the ~6 caliber PDT core projectile. It will be interesting to learn the extent to which increased specific gravity reduces the rpm requirement. I have a suspicion that the ZA375/6.0-W will return to the 11.5" twist specification of the Hooker... but with a considerably higher BC.

Las Vegas will be telling.

 

[Black Diamond 408]

Noel,
I am looking forward to trying the 6 and 6.5's in my barrel. The Vegas Shoot should be
very interesting to say the least. It will be amazing to see the amount of data that is
obtained.

Dave

 

[Black Diamond 408]

Here is a comparison of some 375cal bullets that we have been talking about.

From Left to Right...

1. Sierra 350gn SMK "Jacketed"
2. Rocky Mountain 361gn Alum tipped "Jacketed" VLD
3. Predator 347gn Brass solid
4. GS Custom 355gn Copper solid
5. ZA 6.5cal length Copper solid 400gn
6. ZA 7.0cal length Copper solid 420gn

375 Snipetac shell casing

Dave

 

[MontanaRifleman]

Great pic Dave. I thought the GS bullets were coated with a black moly? Is that an older bullet or was it ordered without moly? Or did it just come that way?

-Mark

 

[Black Diamond 408]

Mark,
They might offer them coated but these are the latest manufacture. I just got them in
a couple weeks ago.

Dave

 

[edge]

What is the usable water capacity of that case?

Thanks.

edge.