Long Range Hunting Online Magazine


Go Back   Long Range Hunting Online Magazine > Rifles, Reloading, Optics, Equipment > Rifles, Bullets, Barrels and Ballistics


Reply

New .338 lanches a 300gr Sierra MK at 3500fps?

 
LinkBack Thread Tools Display Modes
  #1  
Old 02-14-2002, 09:32 PM
Platinum Member
 
Join Date: Jun 2001
Location: Palmer, Alaska
Posts: 2,539
New .338 lanches a 300gr Sierra MK at 3500fps?

Who wants the next level LRH cartridge? The latest and greatest are few and far between with the longrange large calibers and reaching a climax in possibilities I think. We all know the advantages that the added velocity would mean in wind etc. so....... What's it going to be that could reach the 3500fps mark with the 300gr Sierra MK and shoot very accuratly probably between 3400 and 3450fps in a 36" barrel? Can we make this baby happen? What's your Idea?
__________________
Brent Moffitt
Reply With Quote
  #2  
Old 02-14-2002, 09:57 PM
Platinum Member
 
Join Date: May 2001
Location: Pennsylvania
Posts: 1,757
Re: New .338 lanches a 300gr Sierra MK at 3500fps?

Hello Brent

The 338/416 Rigby Imp will turn up 3310 FPS if I don't care about loading the brass more then 2X and that's with a 37" barrel.
I have more case capacity but, not the powder available to use it. That could be a major problem in larger cases too.

I think the 3400FPS is VERY feasable as I saw a freind of mine take his 338/416 IMP to 3350 FPS without any pressure signs but, he had a 40" barrel.

So you see, you may not have to go too much bigger in case size to reach that 3400 FPS mark. I'm quite sure a slower burning powder and a 40" barrel will do it with the case I sent you witch has at least 8.5 to 10 grains more capacity then the 338/378 Weatherby case.

What action would you put this case or larger one on????

I have the Hall "G" on mine and it works fine. The BAT would be a fine one as would the Rock McMillen action.

I'm sure it can be done (3400 to 3450FPS) but, is it really needed? That 300 gr bullet floats so flat and accurate at just 3200 FPS it scares you. It's like it don't want to come down. Check out the ballistics on it at that speed and then go to 3310 fps.
The BC seems to run out at .797 as far as actual fire from the drop charts.

You can always get more speed with longer barrels and bigger cases, to a point.

Keep us informed as to your progress.

Darryl
__________________
Darryl Cassel
Reply With Quote
  #3  
Old 02-15-2002, 02:26 AM
Platinum Member
 
Join Date: Jun 2001
Location: Palmer, Alaska
Posts: 2,539
Re: New .338 lanches a 300gr Sierra MK at 3500fps?

I'm doin the dirty deed, as some say about using the Rem. 700 for the Rigby cartridge. I won't be loading it up too hot though, I want accuracy and long case life here. I've heard all the arguements for and against by now and can't say who's right or wrong. I do know, all those in favor have built many not just one or two, they are all accurate and have handled pressures that even ruined cases.

I bought a Rem. 700ADL chromoly steel in 300WM ($395.)for fun until the 40" SS barrel gets here. $150. for the Choate stock. I'm kinda going the least expensive way I can with this one. The big Ruger action I have will work for the .408 Cheytac based .338 if I go to a larger case desighn. I can't afford a custom action right now so this will have to do. I have an Oehler 43 so I won't be guessing as to PSI being developed.

I think the shoulder will be moved forward .050" to give about 140gr capacity up another 5gr. The taper in yours is .024" from base to shoulder. The reamer Dave, my smith has is .577" at the shoulder having .014" taper. That will gain some capacity, how much I don't know.

I compared trajectories on the Oehler BEX program at 2975, 3200, 3300 and 3500fps, and what's gained at 3300 over 2975 is about what is gained from 3300 to 3500fps. Not as much as I thought but a substantial amount.

Also on those two 338/416 Imp cases, one was perfectly tapered on the inside from .015" thick at the neck to .055" at the base, the other one was not. It went to .028" thick 2/3rds down from the shoulder and then sharply back to .020" thick then sharply back to .030" then onto .055" at the base. I measured them with an RCBS Casemaster dial indicator.

I wonder which case would hold upto the heavy loads longer, the Weatherby or the Rigby. I assume the brass is just as strong as Norma makes both. The thing I like in the Rigby is it would seperate further up the case upon failure, I see this as a good thing. The Weatherby seems to get thin just ahead of the belt, I see this as a bad thing as there is nothing left to seal off the gas behind it if it lets go, the Rigby has 1/3rd of the case behind the seperation left to seal things off.

BTW the case I measured at 134gr water capacity was the good thick one. OAL was 2.925".

Oh Darryl, when you load yours HOT (3310fps) what is the first thing to go in the case, primer pocket, seperation 1/3rd up or just too damn tight anymore to chamber.

Later
Brent
__________________
Brent Moffitt
Reply With Quote
  #4  
Old 02-15-2002, 07:59 AM
Platinum Member
 
Join Date: May 2001
Location: Pennsylvania
Posts: 1,757
Re: New .338 lanches a 300gr Sierra MK at 3500fps?

Brent

When they expand, they get to tight to chamber and the primer pockets loosen up.

No seperation as you would see in other cases such as the 378 Weatherby.

Good Luck
Darryl
__________________
Darryl Cassel
Reply With Quote
  #5  
Old 02-15-2002, 09:23 AM
Silver Member
 
Join Date: May 2001
Location: NC
Posts: 352
Re: New .338 lanches a 300gr Sierra MK at 3500fps?

Brent,
Just a FYI to you. With a .577 diameter at the shoulder yes you will gain case capacity but that is really shallow taper and could cause extraction problems even without pressure loads. The rule of thumb that is normally used for minimum taper on a case is .008/in of taper. Anything less then that you normally end up tapping your bolt handle to get cases out of the chamber. If your smith already has the reamer, then I assume he's already chambered up some barrels. Ask him to make sure there are no problems that he is aware. There are no hard and fast rules here, only guidelines, so maybe you'll be ok.

Also when you got 134gr of H20 with that case how exactly did you measure it? Just curious. I normally measure the case as fired, with a primer cup upside down, and fill even to the mouth of the case. Just comparing notes really. I've got (2) 338-378 Weatherby cases that I measured and they held 135.? and 136gr of H20 and they aren't improved at all and came out of a tight BR chamber.

Steve
Reply With Quote
  #6  
Old 02-15-2002, 02:34 PM
Platinum Member
 
Join Date: Jun 2001
Location: Palmer, Alaska
Posts: 2,539
Re: New .338 lanches a 300gr Sierra MK at 3500fps?

Steve, I was comparing a case of my brothers in 338/378 which was 126gr water and a case of Darryls 338/416 Imp that was 134gr water. Derricks has a tight neck chamber and was not sized, Darryls was sized already so what it was when fire formed I don't know. Both had primers inserted upside down and a drop of soap to break the surface tension of the water (keeps it from rising above the case mouth). Both case were weighed before and after on a powder pro RCBS digital. I only weighed one case each and Darryls was definatly larger even though they looked very similar besides the shoulders. With what you say Steve I will check a few more of the 338/378's to see if it's a low one.

Steve, any idea of case capacity in the improved 338/378 Weatherby? I'm guessing 140gr or so unless they neck down 460 brass to keep the necks long and then would they increase the case OAL even more also?

Dave went hunting to Argentina yesterday, so I can't ask him about the taper issue for two weeks now. Darryl, will you measure a fired case of yours and see if there is a little less taper in those cases to make me feel a little better for now, maybe your sizer is a bit tighter than the reamer was.

Ok I must say I am tossing around the idea of using the 338/378 case as is for a few reasons, the one Derrick has with the tight neck really shoots awesome. He has dies mounted in a Dillon 550 head that I can bring over and mount and use in mine for now. We can shoot the same ammo in a pinch if needed. His load development MAY help mine $$$$.

I haven't had problems with brass on my 416wby yet, my 378wby showed a few hairline cracks above the belt on a few cases but I don't know how old those cases were, they came with the gun and were pretty used. I have come to learn by measuring belts on these cases where a load is getting stiff and killing case life, Cases aren't cheap.
__________________
Brent Moffitt
Reply With Quote
  #7  
Old 02-15-2002, 06:52 PM
Silver Member
 
Join Date: May 2001
Location: NC
Posts: 352
Re: New .338 lanches a 300gr Sierra MK at 3500fps?

Brent,
I'll double check the (2) 338/378 cases I have. Going by memory today. So I'll make sure but I'm positive they were in the mid 130's. I use the drop of dish soap also and right even with the top of the mouth. The sizing of the cases will make a +-1gr difference roughly, but not the 10gr difference we're seeing right now.

Steve, any idea of case capacity in the improved 338/378 Weatherby? I would have to lay it out in AutoCAD and measure the volume increase. Will let you know. Roughly though my 338 Lapua Improvd is a 7% increase, and that shoulder was moved forward .050" and sharpened slightly. The diameters are very similar so that would be a rough guideline to go by.

Nothing wrong with the 338/378 as long as your familiar with and aware of the belt issue with the Norma brass. You can always cut off part of the old chamber and rechamber later on to what ever you want. In the meantime you would be shooting a very potent case in the 338/378 and having a ball with the benefits you already noted.

Keep in touch with what you find out about the H2O volume of your brothers cases.

Steve

[ 02-15-2002: Message edited by: Steve Shelp ]
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes


Similar Threads for: New .338 lanches a 300gr Sierra MK at 3500fps?
Thread Thread Starter Forum Replies Last Post
338, 300gr Sierra, box of 500, Jay Buchanan Reloading Equipment and Components 0 09-18-2009 01:54 PM
300gr. Sierra MK's soren Rifles, Bullets, Barrels and Ballistics 1 03-08-2009 03:58 PM
338-300gr sierra new shooter Rifles, Bullets, Barrels and Ballistics 3 12-17-2008 10:22 PM
338 RUM with 300gr Sierra Matchkings? idaholonggunner Reloading 0 11-04-2007 11:50 PM
WTB 300gr Sierra MK's Brent Guns For Sale 5 03-28-2002 07:48 PM

Current Poll
In the last 12 months, what was your longest rifle kill on big game?
0 to 200 yards - 25.95%
1,531 Vote
201 to 400 yards - 32.12%
1,895 Vote
401 to 600 yards - 23.09%
1,362 Vote
601 to 800 yards - 10.00%
590 Votes
801 to 1,000 yards - 3.92%
231 Votes
Over 1,000 yards - 4.92%
290 Votes
Total Votes: 5,899
You may not vote on this poll.

All times are GMT -5. The time now is 12:12 PM.


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