CheyTac 338 Lapua Brass

T

Triggerfifty

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Jun 1, 2005
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#1
Shooters, this is a non-aligned professional bump for CheyTac's new 338 Lapua brass, made by Jamison International. I've tested this brass and saw some of the high pressure testing done on these cases. They are superior to anything out there. Including Lapua's brass.

Jamison has a solid handle on the 338 Lapua as well as 408 CT and 375 CT brass. Here is a link to the JI site.

Trigger

Jamison International 338 Lapua brass
 
#2
Re: CheyTac 338 Lapua Brass

That's good to know. Earlier Jamison brass wasn't so good, but the newer stuff I've been running through my .408 has been the best brass I've seen for that caliber, getting anywhere from 10-14 loads out of it.
 
#3
Re: CheyTac 338 Lapua Brass

I'd like to know how they got the case to hold 158gr of water.
grin.gif
 
#4
Re: CheyTac 338 Lapua Brass

Corey,

I wondered that also, good point, and made a call to Terri at JI. She faxed me the C.I.P European drawings it was made from. On that drawing, it states "C.I.P. Maximum 158 gr. water". That was where the reference came from.

I don't know how to attach it here, but will be glad to scan and email, or fax to anyone that does. Three pages total, or just the one page referencing this.

djd
 
#6
Re: CheyTac 338 Lapua Brass

You can almost buy 2 boxes for the price of one Lapua brass. 10 - 14 reloads is very great, I think, for a caliber like the 338 LM.
 
#7
Re: CheyTac 338 Lapua Brass

Includes one ice bullet. Sorry I had to do that
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: CoryT</div><div class="ubbcode-body">I'd like to know how they got the case to hold 158gr of water.
grin.gif
</div></div>
 
#8
Re: CheyTac 338 Lapua Brass

I'm a confused. Their site also says that their 375 CheyTac brass has a water capacity of only 151 grain of H20. Is this accurate??

Parent Case 408 CheyTac

Bullet Diameter .375 in (9.53 mm)

Neck Diameter .3757 in (9.54 mm)

Rim Diameter .6420 in (16.31 mm)

Rim Thickness .065 in (1.65 mm)

Case Length 3.0400 in (77.00 mm)

Case Capacity 151 gr. H20 (9.79 cm³)

JeffVN
 
#11
Re: CheyTac 338 Lapua Brass

Like I offered before, I have the C.I.P. European document. Anyone want to post it here?

The only thing I can figure, is a difference in measuring points between C.I.P. and SAAMI/ANSI spec.s for measuring water capacity and <span style="font-weight: bold">where it's measured from</span>.

The C.I.P. drawing also says: <span style="font-weight: bold">".338 bullet displaces 22.69 grains per inch."</span>

I think that explains it.

djd
 
#12
Re: CheyTac 338 Lapua Brass

Email it to me bro I will post it up here for everyone if thats what you want!!
 
#13
Re: CheyTac 338 Lapua Brass

Bobby,

I may not be doing it right, but I checked the water capacity of my cases. I was getting an average 161.5 in the stock case and 173 in my "improved" version. I averaged several cases as there was as much as .75 gr variation in half dozen cases.

I am filling my case to the brim of the neck and leveling it to eliminate any bulge from surface tension. Is this the proper method or should I be filling the case only to the base of the neck?

Gotta plead ingorance here, but at least I keep good notes.
 
#15
Re: CheyTac 338 Lapua Brass

Understood.

I doubt I get more than 160 gr of Retumbo in there but my info was not aligning with the Jamison website when I went to it. Now you have me wondering how much Retumbo this thing will hold.

I will let you know when I check it out.
 
#17
Re: CheyTac 338 Lapua Brass

NotaGuru,

Thought you might be interested, my casing will hold 160 gr of Retumbo when filled to the base of a projectile. It will hold 168 full. It would not be a compressed load but it would be zero airspace.

I won't be putting 160 gr Retumbo loads in anytime soon so do you have any recommendations for a slightly slower burning powder option that I might tinker with that would come close to capacity charges?
 
#22
Re: CheyTac 338 Lapua Brass

Dogtown,

You mention getting 10 - 14 loads out of your cases. What is the failure at that point? Are they splitting at the neck, fracturing above the rim or what is the typical cause of their demise?

I ask as I have experimented with fire forming 2 different ways for my .375 CT Imp. One is load a round and let it conform to the chamber, which by the way was recommended by NotaGuru and works well and the rounds were accurate. The other way is to put a reduced charge in (20 gr of Unique) top off with cream of wheat, and put a tissue plug in.

The interesting part is that they form very differently. Long story short, the bullet technique shortens the case by .015 and the reduced charge technique forms the case without shortening it. The bullet technique "borrows" the material from the neck for the form and the reduced charge method apparently stretches the body of the case.

I may pick one method over another depending on how the case fails at the end of its useful life. Your experience is greatly appreciated here, thanks.
 
#23
Re: CheyTac 338 Lapua Brass

Guys from what i've seen in the development of these founds is that the limitation isn't from the brass flow, it's from the work hardening process of firing at higher pressures and the brass eventually becoming brittle. I've seen split necks etc., yes, but as you resize them, the brass gets harder and harder, making the resizing process tougher and tougher. Of course, if you're only neck sizing, the issue isn't as bad. But we full resized because ammo will go through different guns.

Trigger
 
#24
Re: CheyTac 338 Lapua Brass

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: NotAGuru</div><div class="ubbcode-body">N170 50bmg and us869 are about the only slower you could try. MarkS i believe tried some of the 24n41 and was getting hang fires. </div></div>

24n41 and 50bmg are pretty much the same as far as burn rate goes and you can pretty much substitute one for the other for BMG loads.
 
#25
Re: CheyTac 338 Lapua Brass

Thanks Triggerfifty,

I assumed as much. I annealed my brass prior to fire forming. I did this because the brass seemed inordinately hard and I knew the fire forming would exascerbate the problem and shorten my case life. I was trying to run it on an expansion mandrel for neck turning and it had so much springback that I could'nt turn the case on the turning mandrel.

I can shoot 2 to 4 firings (depending on load) before I need to push the shoulder back so my intent was to neck size only in between to extend brass life. My brass is custom to my gun so I am not compelled to full length size until I have headspacing issues.

My intent here is to monitor work hardening (how the brass resizes is a good indicator of this) and re-anneal when necessary. I believe as long as the annealing is done properly it can be repeated several times. I believe most people overheat brass when annealing and inadvertantly burn out some of the alloying metals which degrades the brass.

I will post the results of my reloading from time to time.
 
#26
Re: CheyTac 338 Lapua Brass

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: C.K</div><div class="ubbcode-body">
24n41 and 50bmg are pretty much the same as far as burn rate goes and you can pretty much substitute one for the other for BMG loads. </div></div>

So does that mean they have the same ignition properties?
 
#27
Re: CheyTac 338 Lapua Brass

So what is the real internal volume of the Jamison 338LM brass ? Lapua´s own brass is around 115-116 grains when filled to the brim (no bullet) and the case is measured after firing but before FL sizing.
 
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