.338 Allen Magnum...WOW!

[Fiftydriver]

Don't have answers to all your questions but here are a few I do have.

1. Barrel whip.

DO not use carbon wrapped barrels to control barrel whip. I have tested this several times to prove it to customers. Take an all steel barrel and a carbon wrapped barrel, clamp each in the chuck of a lathe or in a padded vice by the first two inches of the breech, then hang 10 lbs of weight off the end of the muzzle with a dial indicator on the muzzle, see which barrel flexes the most, it will not be the all steel barrel unless your comparing a HUGE wrapped barrel to a very small contour all steel barrel. Same contour barrels, the all steel is by far more resistant to flexing and whipping. Carbon wrapped barrels have their purpose but its often misleading about what those are. Carbon fiber, pound for pound is stronger, stiffer and lighter then steel, problem is, if you take a 5 lb steel barrel compared to a 5 lb carbon fiber barrel, the carbon fiber barrel would be so huge in diameter it would not be usible for a rifle barrel. A bit misleading.

2. extreme barrel length vs velocity results in 338 calibers

I have alot of data on this as well, I have tested my 338 Allen Xpress and 338 Allen Magnum with barrels up to 40" in length. For example, my huge 338 Allen Magnum with its "Up to" 150 gr powder charges, will still only gain single digit FPS per inch over 36". In something like the 338 AX which is very comparible to your 338-378 in performance, you will be looking at 5-6 fps velocity gains, not worth it and you will likely pay the price in barrel rigidity. For my 338 Allen Magnum, I do not recommend any barrel length over 36". In all honesty, 34" is really the most practical as there still is not much worthwhile velocity gains over 34". For the smaller 338 magnums, its really not worth it to go much over 32" in barrel length. Just not enough velocity gains to make it worth while.

Have never tested the gain twist barrels on my wildcats so can not offer anything meaningful there.

The design of the desert tactical rifles would make it a challange to build using manual machines. It may be possible but would take more time then I have at the moment so would have to decline such a project.

You want to top the 338-378 Wby with a 280 gr Barnes at 3180 fps. A single shot 338 Allen Magnum with same bullet in a shorter 30" barrel length would likely still break 3300 fps. In a 32" barrel length you could push a 265 gr Barnes LRX to +3500 fps and a 280 gr LRX to 3400 fps......

 

[dworrel]

I ampresently using a custom 338-378 Weatherby shootin th 280 gr barnes over a stout load of h570 powder. 3138 fps through several chrongraphs. Great load and caliber. My next rifle I am much considering, if Kirby could build a 338 on a Desert tactical arms bull pup chassis to allow for a barrel of 36 to 40 inches and maintain a standard length rifle. If I do this I am very worried about "Barrel whip". Would having a carbon wrap that is done in Montana on the last 50% of the barrel help with this? How bout a Bartlien Progressive twist rifling tube on it? Kirby,,,your thoughts? What a flat shooter to surpass the MK5 chassis and 338-378 Weatherby!

Mark Gordon at Short Action Customs has built several custom barrels for me for my DTA SRS. The standard chassis will take up to 338 Lapua. He does a great job. All have been shooters. He generally uses Bartlein barrels.

I am currently doing a 6.5 SAUM barrel for mine with a 28" barrel that will be shorter than most rifles. Love my DTA.

You could do a 34" barrel in a 338 Lapua based caliber. Should work fine. He would be the guy to do it.

Short Action Customs | Your Foundation for Precision

 

[Wachsmann]

So after reading some of these post I seen another 338 or maybe a 375 which I though was built maybe on a 416 barret case. Is this case larger than the 408, or is the barret case just a remodel of the 50 cal with some work done to the brass. I think I read it would hold something like 186 grains of powder which is freakin wild to say the least. Also does the 338 edge produce more volicity with the 300 grain pills than the AI or Kirby version of his AX or are they all within 100 fps of each other? Just curious.

 

[Fiftydriver]

The Barrett case is MUCH larger in capacity then the 408 CT case, BUT, it can not be loaded as high in chamber pressure so the end result is surprisingly similar to the wildcats based on the 408 CT, usually less then 100 fps difference. Add to this, the Barrett requires a 50 BMG class receiver and rifle platform whereas the 408 CT based rifles can be built in much lighter and smaller platforms.

All things equal, the 338 Edge will get you 2900 fps on average with a 300 gr berger out of a 30" barrel length.

The 338 AX will get you into the 3050 fps range with same barrel length and bullet. There are some special throat designs that can bring the edge up to the performance of the 338 AX and 338 AI but those same throats can also be used on the 338 AX and 338 AI to give them an additional boost in performance so that is why I said, if all else is equal, the 338 AX and AI will be roughly 125 to 150 fps faster then the Edge.

 

[Farooq Ansari]

I had the distict priviledge of not only seeing a .338 AM this weekend, but actually got to shoot it! WOW! was this one impressive beast! A J Peacock stopped on his way back from his easter visit to his family and brought the AM along. It was a beautiful day with no wind so naturally we had to burn some powder. we both shot sighters on the steel @ 650 yds and the gun was right on the money after him not having shot it since last elk season. we then moved out to milk jugs @ 800 yds.....not a problem....2 dead jugs.....he then wanted to check his windage just to be sure and shot my hanging plate over on the edge. this is a peice of 3/4" cast steel that is called a mucking plate in a mine.....the AM shot right thru it at 800 yds! my 6X284 barely even scratches it!

this is the first Kirby Allen build i have had the pleasure to see/shoot, and i want you to know that it is a work of precision shooting art..... thanks for the fun AJ.......aj

Really very impressive at that range

 

[mark fox]

I am the owner & designer of a cartrage named the .285 tyrannos. it pushes the 180 gr vld at 3654 fps the cartrage hold 27.5 grs. more powder than the 338 lapua. I will soon be testing it on the new 195gr berger. should be around 3500 fps. will soon know. With a few points shy of .800 b.c. transonic should be around 2900 yards. I am the father of 12 other cartrages all very nasty.

 

[Savvyup]

Sounds impressive, can you start a thread and tell us some more?

 

[jonthomps]

Older thread but a great one. Awesome info. What a round - makes me wish I lived back in CO where I could exploit it's capabilities!

 

[Fiftydriver]

Since that article, we have started using some faster barrels and better brass so we are not getting the same level of performance with even longer brass life or if you want, you can up the throttle a bit and get more performance with same brass life.

 

[royinidaho]

Since that article, we have started using some faster barrels and better brass so we are not getting the same level of performance with even longer brass life or if you want, you can up the throttle a bit and get more performance with same brass life.

Hey! Whatdaya mean 'faster barrels'?

I'm all kinds of interested in that kind of talk. I'm tired of going through so much brass.

 

[Fiftydriver]

Been testing some Krieger and Bartlein barrels.

Last three Bartlein barrels I have developed loads in for the 338 AM averaged 50 fps more velocity with same brass life in a 30" barrel length compared to the standard 32". Stepping up to a 32" barrel averaged close to 100 fps more.

Kreigers are very similar. Have a new one to test that will be interesting, new design for the XHS.

Now, some of this is from using the new Bertram brass as well which is simply stronger brass then the old Jamison brass. The combo has been very positive however. Add to that the harder cut rifled barrels are lasting around 10-15% longer as well from early testing.

Only 6 barrels tested so far but that is enough to give a pretty good idea that they are a bit faster and do not pressure up as quickly.

Have also redesigned my XHS barrel contour which is supporting the chamber better.

Always tweaking as we go along!!!

 

[ishootkittens]

By all means keep tweaking until it is perfect. Maybe then everyone will stop flamming the 408 based cartridges. The more I research them the harder it is to find positive feedback on them, yet the more interesting these cartridges become to me. I do have some questions on barrel/case life. I'm aware that it's "all according to how you shoot it", but do you have any figures to give us on normal barrel life or case life? Thanks!

 

[Fiftydriver]

The reason most of the bad press is out there is because most that use them, use these chamberings in the wrong situations. MOST hunters and long range shooters have NO NEED for a rifle like this. So they get one and try to use it for all of their long range shooting when in reality, these are highly specialized weapon systems that have a narrow usage window if used correctly.

I have hundreds of potential customers contact me every year wanting one of these rifles and when I talk with them a bit to find out exactly what they want this new rifle to do, about 9 out of 10 go with a more conventional rifle and chambering such as my 338 Allen Xpress.

Many just do not understand what these big chamberings SHOULD be used for and try to use them for an everyday long range rifle system.

I tell my customers that these rifles are designed to be used for those that want to start hunting at 1000 yards and out from there. Yes they work great in the +700 yard ranges but for these ranges, its really a waste of time, money and barrel life. As mentioned there are much better platforms for use from the 0 to 1000 yard ranges.

Also, those that want a rifle that they can test and test and test are not going to be happy. If someone has a case of "TINKERITIS", that being someone that is always on the hunt for a better, PERFECT load, do not go for these rounds, you will not be happy. If you want a rifle that will get you 1/2 moa hits at long range and are happy to set your rifle up and do more practice then load tweaking, and actually have a use for a rifle in this class, you will be very happy.

Main issue with these rifles has been brass and getting a bullet that will handle their performance levels. Most of those issues have been worked out over the past 10 years so they are getting pretty good now. New barrels are also helping with these rounds.

 

[ishootkittens]

I see, I appreciate that quick response. Will that 338AX allow me to take game from 2000+ yards? I really would like to find a caliber that really lays the hammer down but still have useable barrel life and doesnt break the bank when I pull the trigger. I thought maybe the 338AM was the answer to that question but everyone seems to be pointing elsewhere. Thanks alot