Long Range Hunting Online Magazine


Go Back   Long Range Hunting Online Magazine > Hunting > Long Range Hunting & Shooting

Long Range Hunting & Shooting Nightforce Optics


Reply

408 Cheytac Vs 338 AM?

 
LinkBack Thread Tools Display Modes
  #15  
Old 06-07-2007, 09:57 AM
Official LRH Sponsor
 
Join Date: Jun 2004
Location: Fort Shaw, Montana
Posts: 6,770
Re: 408 Cheytac Vs 338 AM?

As mentioned the main issue with the 408 CT is not a design problem but instead a bullet problem. It was designed around a solid monolithic bullet design that frankly is to finicky for any real widespread usefullness.

If the barrels bore is designed specifically for the solid bullets they shoot well and yes they offer some ballistic advantages over conventional lead core bullet.

BUT!!

If the bore is not matched correctly with the bullet diameter, accuracy often times is terrible.

Also mentioned is the terminal performance and legal issues using this type of bullet on big game. Some states simply do not allow it and Montana is one of them.

Performance wise, the 408 CT could have been a much better and more popular round then it has become. I would be interested now to see just how many 408 cases are sold every year to those using them for wildcats instead of the actual 408 CT parent round. I would bet its nearly 1 to 1 right now.

Had the 408 been designed around a lead core bullet of around 400 grains it would have been MUCH more forgiving over a wide range of different barrels. You may have lost some BC but accuracy is the key here much more then anything else. IF you can not hit what you shoot at, does not matter how flat it shoots!!

Comparing the 408 CT to the 338 Allen Magnum is a bit hard to do. Both have their advantages and disadvantages and they are really two different critters.

The 408 cas be loaded with a wide range of popular powders that will work well with its capacity to bore ratio. The 338 Allen Magnum on the other hand is best suited to only the very slowest powders. Luckily, there are some very good ones to choose from including H-50BMG, WC872 and VV 20N29. Of these, from my testing, H-50BMG is the most consistant options for long range precision. WC872 will work perfectly well but you will get velocity swings with temp changes, more so then with other powders.

VV 20N29 is a great powder but its expensive, very expensive and while you may get a bit higher load density and perhaps slightly more velocity, it is in my opinion not worth the cost increase over H-50BMG.

The most popular bullet for the 338 Allen Magnum is obviously the 300 gr SMK. It may be the most popular but I do not believe its the best choice for top performance. I just tested some prototype Wildcat bullets in 338 in my 338 Allen Magnum that weighed 266 grains and had a very sharp aluminum tip with a Rebated Boattail design.

Imagine a 50 cal Hornady 750 gr A-Max scaled down to 338 cal!!! This bullet is significantly longer then the 300 gr SMK while offering very similiar baring surface area. In my testing it looks like we should expect at least 100 fps and possibly 150 fps increase in top velocity potential over the 300 gr SMK.

Combine that with the higher BC which I estimate will be in the .850 to .880 range and it will be vastly superior to the 300 gr SMK which has an exstablised BC in the .78 to .8 range.

One flaw of the 300 gr SMK is that does not reliably expand at extreme range, that will not be the case with this new Aluminum tipped Wildcat Bullet. The tip will ensure expansion at any range. TO that point, in the 338 AM where velocity potential will be in the 3500 to possibly 3600 fps in long barrels, surviving impacts between 500 and 1000 yards poses another problem, bullet failure on impact.

Early prototypes were made with very light, match grade jackets. In some barrels they worked very well but not in others at these velocities.

The latest batch of prototype bullets are made of a dramatically heavier jacket and so far have proven much more up to the challange of the special strains of this monster 338 chambering. Not only that but the heavy jacket can only help with bullet integrity on impact as well. Now if I can talk Richard into making a bonded core version, we may have the ultimate bullet!!!

Because of the aluminum tip, these new bullets are basically the same length as any mono solid VLD bullet design would be but with the advantage of being much more forgiving with bore diameter, ability to use conventional load data, ability to expand terminally and all with basically the same weight as a solid as well.

Still, there are disadvantages to my 338 Allen Magnum. Mainly, throat life. It is obviously limited compared to the 408. It is for that reason that I am working hard on my 375 Allen Magnum at this time.

I have access to the new 350 gr SMK when it comes out but feel this bullet will not offer the ballistic potential I want in my 375 Allen Magnum. As such, Richard Graves will be making an aluminum tipped bullet option in 375 cal as well as soon as his dies get in to build them. With a bullet in the 370 gr range with an aluminum tip, it should match the ballistic performance of the 338 cal version.

With the larger bore of the 375 Allen Magnum, you get several benefits:

1. Longer barrel life. Not sure how much longer but I would be amazed if we did not get an additional 500 rounds of accuracy life.

2. Ability to use much faster burning powders which also help on throat life to some degree but mainly just give us more powder options to use.

3. The larger bore will be much more efficent and as such will not be wedded to 32-33" barrel lengths as minimums. I suspect a 30" barrel will get out of a 375 Allen Magnum what a 33" barrel will get out of my 338 Allen Magnum. Shorter barrels mean stiffer barrels!!!

4. Just easier to load for. Taking a 408 CT to 375 is much easier then going all the way down to 338 cal.

With the correct bullets, I think the 375 Allen Magnum will be the most potent ballistic option yet, but we are waiting on bullets. The 350 gr SMK will not run with the 300 gr SMK in 338 cal. It is head and shoulders above the current batch of 375 cal bullets but it will not get us what we are looking for in comparision to the 408 and 338 Allen Magnum.

As far as loading dies, they are available through me and I will also be offering 375 Allen Magnum dies here soon as well. I am also working on offering formed cases to my customers as well but still a few weeks out on that option but its coming.

Good Shooting!!!

Kirby Allen(50)
__________________
Kirby Allen(50)

Allen Precision Shooting
Home of the Allen Magnum, Allen Xpress and Allen Tactical Wildcats and the Painkiller Muzzle brakes.

Farther, Faster and Flatter then ever before.

Web Page: www.apsrifles.com

allenmagnum@gmail.com
Reply With Quote
  #16  
Old 06-07-2007, 03:18 PM
Bronze Member
 
Join Date: Jul 2005
Posts: 30
Re: 408 Cheytac Vs 338 AM?

Kirby,
Thanks for the info.
How long is the .375 out?
Give me a number so I can talk with you about building me a AM?
Thanks
Reply With Quote
  #17  
Old 06-08-2007, 07:25 AM
Official LRH Sponsor
 
Join Date: Jun 2004
Location: Fort Shaw, Montana
Posts: 6,770
Re: 408 Cheytac Vs 338 AM?

The reamer is here so we can make a 375 AM anytime you want. Only hang up currently is bullet availablility. THe final design of the 350 gr SMK should be ready any time but the Wildcats will be out a ways into the summer I am sure.

Send me an e-mail at the below address in my signature and we can chew the fat and I will get you my contact numbers.

Kirby Allen(50)
__________________
Kirby Allen(50)

Allen Precision Shooting
Home of the Allen Magnum, Allen Xpress and Allen Tactical Wildcats and the Painkiller Muzzle brakes.

Farther, Faster and Flatter then ever before.

Web Page: www.apsrifles.com

allenmagnum@gmail.com
Reply With Quote
  #18  
Old 06-11-2007, 07:06 AM
Bronze Member
 
Join Date: Jul 2005
Posts: 30
Re: 408 Cheytac Vs 338 AM?

Sent you an e-mail.
Thanks
Reply With Quote
  #19  
Old 12-05-2012, 11:51 PM
Bronze Member
 
Join Date: Nov 2012
Posts: 51
Re: 408 Cheytac Vs 338 AM?

Kirby,
Breathing new life into this forum after several years, what's the word on the Al-tipped bullet?

I am gearing up to build a .375 CheyTac and my builder is encouraging me to neck down to the .338.
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes


Similar Threads for: 408 Cheytac Vs 338 AM?
Thread Thread Starter Forum Replies Last Post
375-408 Cheytac nochmehr Rifles, Bullets, Barrels and Ballistics 8 12-06-2012 12:06 AM
Doe Day with the Cheytac JUDD Deer Hunting 24 12-17-2010 02:19 AM
Anyone try these in an automatic rifle:338 Lapua, 375 Cheytac, 408 Cheytac, 505 Gibbs WildcatB Rifles, Bullets, Barrels and Ballistics 1 02-17-2009 03:41 PM
408 cheytac dj300ack Reloading 3 09-10-2008 07:05 AM
375 cheytac gunman123 Long Range Hunting & Shooting 6 01-28-2007 09:46 PM

Current Poll
Have You Ever Backpack Hunted?
YES - 62.14%
965 Votes
NO - 37.86%
588 Votes
Total Votes: 1,553
You may not vote on this poll.

All times are GMT -5. The time now is 08:27 PM.


Powered by vBulletin ©2000 - 2014, Jelsoft Enterprises Ltd.
Content Management Powered by vBadvanced CMPS
All content ©2010-2014 Long Range Hunting, LLC