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375-408

 
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  #36  
Old 08-14-2012, 08:14 PM
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Re: 375-408

[QUOTE=Joel Russo;684626]Very well put Kirby, you beat me to the punch. Damn you..

SORRY!!!
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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.

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  #37  
Old 08-14-2012, 08:21 PM
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Re: 375-408

One more thing to consider on any build that will be using the 408 CT for a parent case. You should have a MINIMUM thread diameter of 1.185" and a barrel shank diameter no smaller then 1.350" diameter to at least 1" past the end of the throat of the chamber.

This is MINIMUM.

In fact if your using a button pulled rifled barrel, this can be CRITICAL and your chambering reamer had better be designed properly. Why...... Well, let me explain, if you use a button pulled rifled barrel, it will be relatively soft in comparision to say a cut rifled barrel. If you use an improved chamber that has to little body taper, you will have extraction issues, especially when the brass gets a bit older.

NEVER go smaller then 1.185" thread diameter for a Chey Tac based chambering just to be on the safe side. Remember, along with the bolt thrust issue, the chamber pressure also pushes on all sides of the case. The 408 CT has DRAMATICALLY more case baring surface to the chamber so that 65,000 psi is applied to a much larger area, harder for the barrel to contain.

The main reason you need at least 1.185" of steel around the chamber at the threads and the shank needs to be a minimum of 1.350".

Trust me, I have played with many chambering reamers and barrels to find out these are the minimums you need to use. Now ovbiously, even larger diameter threads are better and there is nothing wrong with a barrel shank larger then 1.350.....

I am pretty sure that the MRC does not have a thread diameter that large.
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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
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  #38  
Old 08-24-2012, 01:31 PM
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Join Date: Nov 2011
Location: Tucson AZ
Posts: 224
Re: 375-408

might want to also consider LAZZERONI caliber 9.53 (.375) Saturn for the big 350gr SMK ,,,,, I am building our own prototype now with custom 11 twist poly barrel ,,,,, see Long Magnum Cartridges and Lazzeroni Rifles ,,,,,,,
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  #39  
Old 09-15-2012, 02:59 PM
LR3 LR3 is offline
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Re: 375-408

Kirby and Joel. Given the above discussion I would appreciate some advice. My problem is I love shooting my 375 Allen Magnum and now I ve put about 500 rounds through it it and shooting out to 2400 yards it does great. If anything its getting more accurate but that may be I m shooting it better. But, Kirby the fire formed rounds I bought from you for it are now getting a little tight and difficult sometimes to extract. My first question is when should I give up using them and should I order some more fire formed ones from you? Should I cycle them through the chamber as empty cases to check them before reloading? Secondly, I have a Gibbs 505 loaded with 144gr reloader25 with barnes tsx 525 at 2270 fps. As you know one reason the 505 is liked in Africa is because of the low pressures particularly in the heat. But it is stiff and needs a good pull to extract. Do you think the pressures may be to high? Looking forward to comparing the 338 am you are building for me with the 375am. Interesting Joel you find the 338 is more accurate and that both of you dont find solids after multiple shots not that accurate. Very interestin discussion. Thanks.
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  #40  
Old 09-15-2012, 06:29 PM
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Join Date: Jan 2004
Location: Blackfoot, Idaho
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Re: 375-408

Quote:
Originally Posted by LR3 View Post
My problem is I love shooting my 375 Allen Magnum and now I ve put about 500 rounds through it it and shooting out to 2400 yards it does great. .
I'm smiling really big here. This is where I was with my 270 AM. My 375 AM is, as my wife would say, being savored. It's by far the most fun shooting gun I have (only have 4). Only 25 shots thru her and we are dialed in like we've been dancin' for decades.
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  #41  
Old 09-16-2012, 07:12 AM
LR3 LR3 is offline
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Join Date: Feb 2009
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Re: 375-408

Roy. Be careful - Soon your wife may say it s me or the gun!! :-) Mine just bought me a new blue tooth Kesterel and Nomad so I cannot complain.
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  #42  
Old 04-28-2013, 07:03 AM
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Join Date: Aug 2009
Posts: 30
Re: 375-408

Quote:
Originally Posted by Fiftydriver View Post
One more thing to consider on any build that will be using the 408 CT for a parent case. You should have a MINIMUM thread diameter of 1.185" and a barrel shank diameter no smaller then 1.350" diameter to at least 1" past the end of the throat of the chamber.

This is MINIMUM.

In fact if your using a button pulled rifled barrel, this can be CRITICAL and your chambering reamer had better be designed properly. Why...... Well, let me explain, if you use a button pulled rifled barrel, it will be relatively soft in comparision to say a cut rifled barrel. If you use an improved chamber that has to little body taper, you will have extraction issues, especially when the brass gets a bit older.

NEVER go smaller then 1.185" thread diameter for a Chey Tac based chambering just to be on the safe side. Remember, along with the bolt thrust issue, the chamber pressure also pushes on all sides of the case. The 408 CT has DRAMATICALLY more case baring surface to the chamber so that 65,000 psi is applied to a much larger area, harder for the barrel to contain.

The main reason you need at least 1.185" of steel around the chamber at the threads and the shank needs to be a minimum of 1.350".

Trust me, I have played with many chambering reamers and barrels to find out these are the minimums you need to use. Now ovbiously, even larger diameter threads are better and there is nothing wrong with a barrel shank larger then 1.350.....

I am pretty sure that the MRC does not have a thread diameter that large.
UP.
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