375/408 Banded Solids Test

[Augustus]

Kelly, the 375 test rifle was a standard 375 Chey. The 431 gr you speak of has long since been discarded in favor of a 422 gr with a different tail. With this class of bullet 2900 is attainable out of the standard case.

I hate to be the bearer of bad news but your quest for a magic twist rate to take advantage of the full range of bullets available is wishful thinking. The use of the tungsten core may help but that remains to be seen.

I once had a little spotted bitch that was a coon tracking machine, I never saw a dog that had as much talent as she did, her only problem was that she was really weak at the tree. My hunting buddy had a dog that was a treeing machine but he didnt track worth a flip. We decided we would raise a litter of pups out of them and they should be tracking, treeing machines. Well, when the pups came along they were the most worthless pieces of hound flesh ever I see. They would not track or tree a lick. Sooo, the moral of the story is.... Well, you figure it out.

 

[kellyzier]

Kelly, the 375 test rifle was a standard 375 Chey. The 431 gr you speak of has long since been discarded in favor of a 422 gr with a different tail. With this class of bullet 2900 is attainable out of the standard case.

I hate to be the bearer of bad news but your quest for a magic twist rate to take advantage of the full range of bullets available is wishful thinking. The use of the tungsten core may help but that remains to be seen.

I once had a little spotted bitch that was a coon tracking machine, I never saw a dog that had as much talent as she did, her only problem was that she was really weak at the tree. My hunting buddy had a dog that was a treeing machine but he didnt track worth a flip. We decided we would raise a litter of pups out of them and they should be tracking, treeing machines. Well, when the pups came along they were the most worthless pieces of hound flesh ever I see. They would not track or tree a lick. Sooo, the moral of the story is.... Well, you figure it out.

Augustus, great analogy...Thanks!

 

[Black Diamond 408]

I did some testing today with an array of bullets in my 375 snipetac with the Bartlien gain twist barrel. Initial sight in was set yesterday at 100yds. Then i moved to 535yds and re sighted.

Here are a few results

Retumbo powder, vel. 3130fps
350 smk bullet at 535yds
Group size 4" average didnt test at long distance
------------------------------------------------------------------------

Predator 350gn banded solid
Retumbo powder, vel 3158fps
535yds
Numerous groups from 1.350" to 2"

1125yds
Same load
20.5 moa added from 100yd zero
3.5" to 5" groups
10mph cross wind, variable speeds
No vertical stringing
seated to touch lands
--------------------------------------------------------------------------

GS Custom 355gn banded solids vel 3140
535yds
5-7" groups
1125yds
13" group
Only tried one powder and one load.
--------------------------------------------------------------------------

370gn Rocky Mountain bullet vel 3050fps *jacketed bullet*
535 yds
5-8" groups

1125yds
Missed target, only tried one load, more testing to come.
-------------------------------------------------------------------------

So far the Predator bullets are giving the best results in this barrel and twist rate.


Here are a few photos i took while out checking the target.

This is my mini sno kat, its the only way out to the target.

Looking back to my shop and shooting bench, 1125 yards at the red line.

One of the Predator bullet test targets, 1125yds 3.5" spread
Bullets seated into the lands. Note the cardboard is in front of steel plate, bullet fragments ripped the paper.

Last Predator bullet test on steel plate, 1125yds. 5" spread
Changed the seating depth .010 off the lands

Initial testing shows this bullet likes to be jamned into the riflings.

Dave

 

[Master Diver]

Dave,

Thanks for posting your results. It seems you had quite a nice day in the snow.

Cheers,

Master Diver

 

[Black Diamond 408]

After the nice day yesterday for shooting today brought a different story. The wind was up and cloudy with intermitent snow showers. I set up the vid camera to see if i could capture bullet strikes on the 535yd steel plate. I should of done this yesterday. I only fired three shots as the wind and cold made it not fun. The first vid Part 1, shows the last two shots, part 2 is the ride out to the target to see the bullet strikes. You can see the bullet trace after each shot, then the slap of steel. The steel is catapiller track sections welded together, it is very heavy and the bullet makes a very loud POP when it hits.

YouTube - Shooting 375cal Snipetac rifle/part 1

YouTube - 375 snipetac shooting, part 2

I am shooting my 375 Snipetac rifle, bullets are the brass 350gn Predators.

 

[Topshot]

Are these .375 cal Predator bullets the same as the .338 calibre ones? ie the front section is smaller and rides the lands?

I had trouble loading them in my .338 Edge as if you load them too deep they fall into the case as the bands are a different diameter.
They seem to shoot OK though.

 

[Master Diver]

GREAT shooting under these harch conditionsgun)
Seems Predator bullets got it right with this design.

Cheers,

Master Diver

 

[Black Diamond 408]

Top Shot,
I talked to Steve Damron from Research Dynamics here in the US, they are addressing the
top band issue.

Dave

 

[kellyzier]

Kelly,

The 431 grain version was a very early ZA375 design that had stability problems when fired at a MV greater than 2,600 fps. This was remedied to some extent by tail revision, which added an additional 150 fps from the same 8" twist.

A 1: 6.5" twist stabilizes the 421 grain, 7.0 caliber, to it's maximum velocity of 2,950 fps from a CheyTac case. The 400 grain 6.5 caliber ZA can be driven to 3,100-3,200 fps from the CheyTac. We have not tried am AM loading.

Both are capable of sub-half minute groups out to 1,500 yards, but we are looking for better data collection at the upcoming Las Vegas test.

Best,
Noel

Noel,
I am going to take someones suggestion here and order a second barrel for the longer solid bullets for my 375 snipe tac. Beacuse of lead times on barrels, I am going to take my chances and not wait until the NV shoot. Who would you suggest for the barrel maker and what twist would you reccomend for these 400 and 421 gr solids??

I've seen some strings here talking about standard twists from 1 in 8...all the way down to 1 in 6.75 ???

thanks in advance
kz

 

[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.

Agustus,
As I told Noel today, I can't wait for the NV shoot to order my second barrel. It's really for expiremental purposes. I would like to order a barrel designed to shoot the 7 cal solids in my 375 chey tac. Based on your data here, Im going to need a 5.5 twist. In your opinion what barrel would be best?

The standard twist 1 in 5.5 or a gain twist to 5.5? Also, what would the gain twist start at to meet your "less deviation" suggestion?

thanks,
kz

 

[Augustus]

Kelly, this is just a suggestion and others with first hand knowledge may disagree. Based on what I have seen so far, I would go with a 9-5.5 for the seven cal solid copper. I shot several of these from a constant eight twist and the bands held up fine. They stabilized nice in a 13-6.5 up to 2700 with around 1/2 min accuracy, the groups started opening up past this point with this barrel. The case is capable of pushing the sevens to 2900. I believe the 9-5.5 barrel will acheive 1/2 min with the solid copper sevens. Again, proceed at your own peril and know you are walking on unplowed ground. Bartlein is about the only game in town and they told me they were around 8 months behind. While we are talking LR rifles. I just got my 338/408 standard case with a 29 in. barrel yesterday. This rifle will eat anything, frankly I have never seen anything like it. During the load work up all shots fired were under 1/2 min. The load I settled on was 144 gr. of 50 BMG at 3200 with ES in the single digits. The firt LR target was 1224 yds. The dope was dialed in according to Horus Atrag. It was nearly dark and I fired 2 rds. They both rang the steel and hit just under 3 in. from each other exactly as the puter predicted. You are about to have some fun.

 

[kellyzier]

Kelly, this is just a suggestion and others with first hand knowledge may disagree. Based on what I have seen so far, I would go with a 9-5.5 for the seven cal solid copper. I shot several of these from a constant eight twist and the bands held up fine. They stabilized nice in a 13-6.5 up to 2700 with around 1/2 min accuracy, the groups started opening up past this point with this barrel. The case is capable of pushing the sevens to 2900. I believe the 9-5.5 barrel will acheive 1/2 min with the solid copper sevens. Again, proceed at your own peril and know you are walking on unplowed ground. Bartlein is about the only game in town and they told me they were around 8 months behind. While we are talking LR rifles. I just got my 338/408 standard case with a 29 in. barrel yesterday. This rifle will eat anything, frankly I have never seen anything like it. During the load work up all shots fired were under 1/2 min. The load I settled on was 144 gr. of 50 BMG at 3200 with ES in the single digits. The firt LR target was 1224 yds. The dope was dialed in according to Horus Atrag. It was nearly dark and I fired 2 rds. They both rang the steel and hit just under 3 in. from each other exactly as the puter predicted. You are about to have some fun.

Augustus,,,
You mentioned "the case is capable of pushing the sevens to 2900", were you talking about the standard 375 chey tac? Am I correct in assuming that the 375 snipe tac can push the sevens to 3150 fps??

By the way, Im sure you will love your new 338, I hear it's an amazing shooter!!

 

[kellyzier]

Augustus,,,
You mentioned "the case is capable of pushing the sevens to 2900", were you talking about the standard 375 chey tac? Am I correct in assuming that the 375 snipe tac can push the sevens to 3150 fps??

By the way, Im sure you will love your new 338, I hear it's an amazing shooter!!

Augustus,
And just to be clear, do you think the 9---5.5 twist barrel will stabilize the 7 cal to 3150 fps ??

 

[Augustus]

My 375 is a standard case and 2900 is attainable, it is MAX. My 375 barrels are 30 in. The Snipe-Tac should push it faster but 3150 is probably being a little optimistic. As far as the seven being stable at 3150 from a 5.5 exit twist, I simply dont know and I will bet nobody else on the planet knows. If you order the barrel you will probably be the first to answer the question.