375-408 CheyTac (Kirby Alert!!!!!!) question

[wildcat]

Kirby, I was reading an artical by CheyTac Associates and they will be relasing the 375x408 CheyTac soon. What do you know about this, and are you thinking about adding the 375x408 Cheytac to the Allen Mag family. I am thinking you probably already thought about this, but due to poor bullet selection you decided to go with the 338 Allen Mag. I think I remeber you saying Sierra might be making a 350grn Match King, or that somebody was making a bigger bullet with better BC for the 338 caliber.

I was just curious. By the way, I am ready to send some MONEY /ubbthreads/images/graemlins/shocked.gif for my 338 Allen Mag project to get underway. I am just waiting for the e-mail, so we can get this project finally started.

Jake, A.K.A Wildcat

 

[triggerfifty]

Not Kirby, but I started promoting that cartridge. Others had made it first, such as Barney Lawton, Bill Shehane, etc. Cheytac only responded to the potential of that cartridge when I posted on my website and information about it. I was a former owner in the cheytac group, but walked when bad management took it over and is still driving it into the ground. Cheytac may be releaseing it in their line, but it is NOT their idea. Lately, they seem to be mastering the idea of idea stealing, then releasing a press release as if it's their own idea. I've built 3 of these 375 rifles, will release brass with a headstamp indicting credit in a different direction than Cheytac.

3 years ago, a couple of us in the company proposed the idea of 408 based cartridges and was laughed off. Now, someone wants to grab headlines by making it some novel idea. Not true. It is a great cartridge, destroys the .408 and yes, the 338/408 based guns. Supersonic range of the 375 is around 3000 yards, 2800 better than the .408.

Driving the 338 300 gr. matchking at 3300 fps still only yields 2200 yards of supersonic range. The 375 is 800 yards superior.

Humbly,
Trigger

SOE 375 Web Page

 

[wildcat]

I see that they (Chey Tac) are selling rifles such as M310 in single shot. What do you think about there rifles?

Wildcat

 

[1doug]

[ QUOTE ]
Driving the 338 300 gr. matchking at 3300 fps still only yields 2200 yards of supersonic range

[/ QUOTE ]


why would you load down the 338 -408 to what is abtainable with a 338-416 imp? the 338-408 will easily hit 3500 with the 300 grain mk

d-a

 

[triggerfifty]

On the M310. It's a fine rifle in .408 CT. The only fault i find with it is the bipod mechanism that is supplied with the gun. They use the harris short BR version. It's too near the center of the gun, with too much gun weight on top of it, makes it floppy and tough to manage.

I've modified a clients M310 rifle with one of the SOE bipod units.
SOE Products Page - M310 modifications

It's a very accurate rifle, barrel and action by Barney Lawton in Dillon, Montana, CT puts it together in idaho. They use a 29" barrel, and get a speed of about 2900 fps, with a supersonic range of 2200 yards. Good setup, bad bipod.

Dean

 

[triggerfifty]

[ QUOTE ]


[/ QUOTE ] why would you load down the 338 -408 to what is abtainable with a 338-416 imp? the 338-408 will easily hit 3500 with the 300 grain mk

d-a

d-a... The supersonic range is not much gained by adding velocity, it's more BC value based. The faster you drive a bullet, the faster it also slows down, and the SHAPE of the trajectory is what changes the most. Flatten out the rising branch of the trajectory, you get a steeper fall angle on the falling branch end of it. For long range work, in unknown distance conditions, you want a more even shape to the curve, hence speeds NOT exceeding 3050 fps or so. BUT, if you only intend to "work" in the front end of the trajectory to get maximum use of the "flat" trajectory, push up the speeds, and don't shoot past maximum ordinate range, which is about 65% of the range of the shot.

On the 338 Lapua using a 300 gr. SMK, at 3300 fps, you get a supersonic range of 2200 yards at sea level standard conditions. Drop the velocity down to 2900 fps, you get a supersonic range of 1970 yards under standard conditions. By hammering up the speed to 3300 fps of barrel eating speed, you only gain 130 yards of supersonic range.

Worse yet, your falling branch is steeper, making range determination much more demanding. High speed only means two things in reality:

1. Faster barrel burnout
2. Long range unknown distance shooting much more difficult past the maximum ordinate range of the shot.

As for your speed of 3500 fps, you are past the point of diminishing return. With that speed, your supersonic range is actually 50 yards LESS than at 3300 fps. The faster you push it, the faster it will slow down.

 

[1doug]

[ QUOTE ]
On the 338 Lapua using a 300 gr. SMK, at 3300 fps

[/ QUOTE ]

I bet you dont have to deprime those.

On your 375-408 are you using LRB bullets?


d-a

 

[bailey1474]

[ QUOTE ]
As for your speed of 3500 fps, you are past the point of diminishing return. With that speed, your supersonic range is actually 50 yards LESS than at 3300 fps. The faster you push it, the faster it will slow down.

[/ QUOTE ]

I'm not trying to stir up a hornets' nest here, but this just doesn't make a lick of sense. Given the same bullet and same conditions, all forces acting on the two will be equal. That extra 200 fps can't just dissapear and the slower bullet can't gain anything once it leaves the bbl. I'm no physicist, but this makes no sense to me.

 

[lerch]

OKay, you lost me here bud. Now I aint a smart man, but this just doesnt make any sense to me??????

 

[triggerfifty]

Air drag you mean? Push a jet up to the supersonic threshold, and chop the throttles, she WILL slow down **** fast. Same thing with a bullet, increased speed means increased air resistance = faster deceleration. You can't make up for BC with speed, the supersonic range does not gain much, it does a little, but not much.

Or are you talking about something else not figuring out?

 

[lerch]

I was really just echoing what Bill said. I just dont see how a bullet going 200fps faster would fall below the speed of sound 50yds closer if all other factors are equal????

 

[Fiftydriver]

Triggerfifty,

I am curious what numbers you are using as far as BC in your 338 comparision. From actual bullet drop in my 338 AM with the 300 gr SMK I need to use a BC of .810 to get the exbal ballistic model to match my actual bullet flight.

With 3300 fps and that BC you are still retaining 1100 fps at 2500 yards????

I load my 338 AM to a very mild level and get 3440 fps with that bullet. This load is still getting 1100 fps at 2600 yards.

Now I surely agree that the 375 has great potential but please tell me what bullet you are using to keep it super sonic out to 2900 yards. I would bet money its the LRB bullet with its BC right at or slightly over 1.000.

First off, thats the only bullet out there that will do this and you better hope to hell your rifle shoots it well because other then that there is no other options.

Sierra is coming out with a SMK in 375 which will be a great boon to that round but it is supposed to be a bullet in the 350 to 375 gr range. Given those bullet weights and even with the best VLD design, you will be looking at a BC still in the .8 range, very similiar to the 300 gr 338 SMK. Maybe slightly higher but nothing even remotely similiar to the LRB bullet which at this time I am not even sure if it is available to the public???? I got on their web sight the other day and did not see it available.

Then also your dealing with a solid VLD bullet design, not the greatest for big game hunting and in many states not even legal to use on game.

I think if you compare apples to apples your gap between the 338 and 375 will drop considerably. I am not denying that the 375 has alot of potential and perhaps more then the 338 rounds but with similiar bullet designs its not the huge gap you say it is in my opinion.

I have tested the 300 gr SMK alot at long range and out of the 338 Kahn which will get you 3150-3200 fps it stays very consistant out to 2000 yards. Once it goes past that they fly all over hell.

I have shot my 338 AM with the same bullet to 2500 yards and accuracy and consistancy are great telling me they are still super sonic and this load is right at 3400 fps.

Again, not wanting to pick a fight by any means, just want you to explain what bullet you are using in the 375 for this comparision?

Good Shooting!!

Kirby Allen(50)

 

[bailey1474]

The air resistance may be more on the faster bullet, but it still is starting faster. The slower bullet is going 3300 fps @ the muzzle. The faster will be going 3300 fps x # of yds down range. Now, all things are = except the faster bullet has a sizable head start. So, how does the slower bullet make up x # of yds??????

 

[Fiftydriver]

Just checked the LRB web site and there is no J40 listing for the 375 cal. I suspect these are listed in the law enforcement only area. Again, not easily attainable by the general public.

I think you are comparing the 338-408 with conventional bullets to a 375-408 with "super" bullets that are expensive as hell, hard to get and need specially designed barrels to get them to shoot well, just like the 408 CT.

How about you put one of them LRB J36 300 gr 375 bullets in that 375-408 of yours with a BC of 0.640 and see how it compares to a 338-408 with a 300 gr SMK. I suspect the 338 will spank it ballistically.

Again, not picking a fight. I fully agree on several of your points, such as:

-With the right bullet the 375 would be a superior round ballistically.

-The 375 should offer better throat life.

-The 375 should prove less finicky and less effected by changing temp conditions because of the higher expansion ratio.

BUT!!

You need the special bullets and barrels to get it to work as you are saying. This is my only point. If you put a 1.00 BC bullet in the 338 AM I would bet you still have 2900 yard reach super sonic.

I just find it interesting that you do not offer the bullet information that you are using in your 375 but you point out the 300 gr SMK in the 338 version.

Apples to Oranges my friend. If your going to make a fair comparision you need to keep the playing field even and use componants that we can all get. If not, its just interesting reading and thats about it.

Kirby Allen(50)