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.375/416 Barret?

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Unread 02-09-2010, 09:14 AM
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Re: .375/416 Barret?

I am going to read up on frontal ignition. These cases are so big that it may be doable. I have sort of come up with an idea of how it could work, but am not sure wheter my idea is feasible. Would plug threaded into the case head be safe? I was planning on threading it into the case head from the inside of the case and having a shoulder on the plug larger than the threads. How strong is a 50bmg primer? Would it blow the plug out and down the barrel?
I admit that I know just enough to be dangerous.....but dangerous at ever extending distances.
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Unread 03-26-2010, 11:09 AM
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Re: .375/416 Barret?

Fiftydriver, eddybo, Dave,

I'm glad to see you guys posting on the subject, and this thread is a great read. It appears many of us are on the same quest right now, as Dave knows. We (GS Custom Bullets) were just recently asked to design an ultra long range .375 bullet for two guys doing this very thing. One is using a 375 Snipe-Tac and the other a special 375/50 conversion. As you all know, the powder is the limiting factor.

In the case of the 50 conversion, we ran into two configurations that worked well, so far, and the guys in Australia can confirm this. One is limited around 150 grains real case capacity and was designed by the SMc crew, Superior Ballistics Inc. Those guys know what they are doing when it comes to powder burn efficiency. Thing is, their case design actually promotes a faster burn, which is not really what we are after here. They did however reach 3100fps with that case using H50BMG and ADI 2218, with the prior being 102% case fill! The other discovery they made is that if you use the US869 at higher pressures, around 70,000psi+, it burns better (and in a shorter barrel), then either of the two prior powders. It was actually the best performer for our specific use, but we declined because of the pressures...yes, we like to be safe, and the spent brass to extract...

They are however offering the case design to the market, if anyone cares to buy it from them. No real agreement was reached, so it's fair game.

The other design was very basic, much like your work, with it being a 416Barrett necked down and improved, while setting the shoulder back a little to get a .8"+ neck. This proved to be the ticket, so far. It's 177 grain useable capacity was just about right (I believe that was actually higher, but they might have rated that based off real powder charge cap, not sure). And the longer case neck worked great for this longer bullet and it looks like (statistical date reported from SBI) the longer case neck will greatly improve throat life, as well as the GS Custom bullet design does, so this is a great combination for the long haul (pun intended).

The dark side of this story is that it is being loaded by a private company that uses custom powders I have no access to. The reported maximum is said to be 3,400fps with the design bullet, 415 grains, and a 34" barrel. And, to thicken the plot, I have heard VV is coming out with N570...

The bullet is finished and the first small order is on it's way here for me to see this thing work first hand. The gentleman with this 375/50 should have it all lined up for us to load up and shoot to see the true potential of this bullet first hand. Interesting thing is it's basically the same design as the 338 295 grain bullet that has been shipped all over the world since 2004. It's stable through transonic and accurate at these ranges, so I am dying to see how this turnes out. On Quickload at least, it shows the 415SP outrunning the 350LRBT (Jamison) bullet supersonic by 500 meters, worst case. So I cannot wait.

In my small and realistic opinion, I think what Dave is doing with the .688 case is a fantastic idea. It might end up being the best option for a so-called standard sized action (non-BMG). The case is also the base for the 577 T-Rex from A-Square. They are making their own cases, and I am hoping they have improved their quality in this area to make the case feasible for use at 65,000psi., and consistent. Expensive to say the least though.

I must add though that I have magnum-itus as much as any guy here does. And I cannot get enough of the stuff we are doing here. Eddybo, rock on man! Just let me know if I can help with anything as it is my passion as well, aside from work. I've been toying with this for over 2 years now.

Forward ignition is the right idea, I believe. You would be best off making a small reamer to open up the primer pocket and allow a SS or brass tube with a T-flare. The tubes can be rather simple and cheap, and VariFlame might be able to help you out with that (spoke to them a few years ago). Looks like they will outlast your brass many times over.

Fifty, If you are ever interested in trying the GSC 458 566SP bullet against the Lehigh/Predator bullets, give me a call. It has been extensively tested from a 460 Steyr with great results! GS CUSTOM USA - Contact


Last edited by Extremist; 03-26-2010 at 11:28 AM.
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Unread 03-26-2010, 05:37 PM
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Re: .375/416 Barret?

Extremist, what is forward ignition?
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Unread 03-27-2010, 12:39 AM
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Re: .375/416 Barret?

VV570 is available right now....I have 8 lbs ready to burn but have been busy building smaller rifles for buddies. I have a couple of bigger guns in line so I should get to burning a little over the next week or so.

I am waiting on my reamer very similar to what you described. I am glad for any info you can share, and will give you a call. Right now I am thinking a primer pocket reducer that has a tube for forward ignition would be the ticket. I am thinking it could seat in the BMG primer pocket and the tube will extend through the flash hole....have not figured out how I would deprime the cases if I do that. Still just in the thinking stages on forward ignition. I need to take a look at variflame, never heard of them.

If I had a reamer and a barrel I would be playing with this thing.
I admit that I know just enough to be dangerous.....but dangerous at ever extending distances.
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Unread 03-27-2010, 01:41 AM
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Re: .375/416 Barret?

Originally Posted by eddybo View Post
I have been pondering a .375 Cheytac or .375 Am as a big brother to my .338AM, but got side tracked a little. I do not know a thing in the world about the 416 Barret. It is bascically a .50BMG shortened and necked down to .416 from what I read on wickpedia, but with about 40 grs more capacity than the 408 based cases. It has me really wondering what a .416 case with minimal body taper and a sharper shoulder would do when necked to .375.
Here are my questions?

1. Downfalls of the .416 brass problems etc.?

2. Rocky Mountain RBBT bullets ? I have used a few in a buddy's 375 CT, seem to shoot okay any idea on performance on big game?

3. Reloading stuff? I have never dealt with .50 BMG sized cases. What am I going to need for trimming cases, priming them etc? What primers do they use?

4. I am thinking about a McMillan big .50 repeater action, any experiance?

5. Probably a Lawton 10 Twist .375 would get used since I do not plan on shooting solids. That sound about right as far as twist?

6. I know I will not make weight in some states as far as legal for hunting. How many states have weight restrictions?

7. Is this just a bad idea?

8. I know I will have to have a finish reamer ground and a reamer for a sizing die, anything else that I would need to get on order?

Any input is appreciated, especially contact info for anyone who has tried this.

I just posted my opinon on here tonight about using the edge or Lapua for an all around shooting and training gun and then the snipe tac or allan mag for an interim gun, but I didn't allude to my third gun the 416.

Backing up a bit, why not take your 338 AM and simply kick it up to the 375 AM or 375 snipe tac. I will refrain from my opinion on which 375 because of fall out on this web site, but either way, you have an easy and fairly cheap upgrade with your AM

On another note, Dessert Tactical Arms is on the verge of something really awesome with the 416-375...This caliber with the ZA or GS solids could very well be the cats meow in long range shooting to 3,000 yards.

I intend to build this rifle that will convert from a medium weight gun to a heavy weight for target shooting. Call Mike from and he can give you some ideas or talk to the guys from DessertTacticalArms. It sounds like once they develop this cartridge, we will have readily available brass for the 416-375

In summary, I have spent tons of time calling folks,, emailing folks and reading up on the 375. Several gun builders (dave viers n kirby allan alike) are leaning towards the 375. It has a lot of promise in my eyes and the parent case (408 chey tac) is an awesome middle of the road big cartridge.

The end of the road in my eyes is the 416-375.....Im currently building the 375 snipe tac...And waiting on dessert tactical arms...If they accomplish what Im hearing, my next step will be the 416-375......

This is just my opinion, and you know what they say....
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Unread 03-29-2010, 12:35 PM
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Re: .375/416 Barret?


How's the N570 working out? You got to let us all know! Hope it's as good as I think it will be!
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Unread 03-29-2010, 03:19 PM
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Re: .375/416 Barret?


I necked down one of my 416 Viersco Mag cases to 375 and ran a few capacity tests with
various powders. US869 180.gns, BMG-50 170 gns. This was measured from filling the case to the bottom of the neck. I made up a set of loading dies, bushing FL sizer and Sliding bushing seater die with Micrometer stem. Looks like the neck will end up just shy of .400 long.

I will have a set of reamers done for this in the following weeks. I will need to get a test barrel
ordered in 8 twist, 34" should be plenty long enough. I am thinking Brux for this one.


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