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300 Tejas

 
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  #22  
Old 04-10-2010, 02:42 PM
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Re: 300 Tejas

On average, a 338 Edge will get you around 2850 fps with a 300 gr SMK in a 30" class barrel. This is on average. Some slower barrels will be in the 2800 fps range, some fast barrels will get you 2900 fps and yes there are a very few fast barrels that when loaded to very top end pressures may get you around 2950 fps. In all honesty, I have seen this with one rifle in the several dozen rifles I have chambered in this caliber.

I have also built many custom 375 RUM rifles with 28 to 30" barrels and yes, the 375 with the same weight bullet will get you higher muzzle velocity then the 338 caliber shooting same weight bullets, BUT, not dramatically more. Where a 338 Edge will get you 2850 fps average velocity, the 375 may get you another 100 fps tops with same weight bullet.

Now if you figure you get a very fast barrel and your pushing the load to top practical pressures around 65,000 psi for RUM brass, its totally possible to see a 375 RUM get you 3050 fps with a 30" barrel.

Now improving the shoulder to a 50 degree angle will get you VERY LITTLE measureable powder capacity increase on the RUM case simply because the RUM parent case is pretty darn square already with min body taper, a simple shoulder anlge increase will likely increase powder capacity less then 2 grains. That amount on a cartridge that has a +100 gr powder capacity is very minimum and will result in very little velocity increase when loaded to the same appropriate chamber pressures.

Certainly we should not be attacking anyone for any reason, it is certainly their choice to do what they want with their rifles but my concern is when someone posts velocity results on a public forum with some members or guests that may not have alot of experience and they think that if a 375 Tejas can get 3200 fps with a 300 gr bullet, They should easily be able to get 3100 fps with a standard 375 RUM with same bullet. This is simply not wise to atempt.

My main concern is that everything does not always go perfectly. There is always a risk of getting a piece of brass that may have a flaw or is weaker then they should be, put in a 70K pressure load and bad things can happen quickly. Anyone that has had a case fail in a modern high pressure rifle learns very quickly that there are no advantages to pushing a case harder then its design limits.

Lately I can not believe the amount of talk about smaller chamberings coming very close to matching the performance of 408 CT class wildcats in 338 and 375 caliber. From someone that has alot of experience with all of these large class chamberings, I worry that many are running the ragged edge. My concern is more a safety issue then anything else.

Hell, I have customers that are breaking 3450 fps with my 338 AM with 300 gr bullet weights when the load I recommend them to use is right at 3300 fps. Its just human nature I guess but it is not what I recommend and I use these things every day of the year.

Nothing more or less, I just know from testing MANY, MANY rifles in this class that these velocity levels are WAY over even what the exceptionally fast rifles in these chamberings are producing and that should trigger red flag warnings all around.

If your only getting one or two firings on your brass cases, your WAY over pressure and you better hope and pray that you do not run across a weak case or you to will quickly realize how unpleasant this combo can be. It is really no fun at all.
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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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  #23  
Old 04-10-2010, 04:33 PM
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Re: 300 Tejas

Yep I can truthfully report that a 300 SMK can be driven from a standard 338/408 case using a 29 in. barrel and reach 3492 fps. I did it once but I wont do it again. Just because something is possible does not mean it should be done.
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  #24  
Old 04-11-2010, 01:35 AM
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Join Date: Apr 2007
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Re: 300 Tejas

Quote:
Originally Posted by Fiftydriver View Post
Certainly we should not be attacking anyone for any reason, (quote clipped)
I agree! This forum has impressed me as a group of professionals that are interested in furthering their knowledge towards LRH. There's plenty of other internet forums that practice a different technique on info/folks that challenge the norm........LRH isn't like those, and we should take the extra effort to keep it that way.

We don't know the specifics on this case yet....and throat design, barrel twist rate and groove/bore diameter, along with his barrels individual personality, could account for a velocity variance from the "norm".

I must admit though....it does seem fast

So we all can learn....

Is there a reamer print you could post?
What COAL?
Brass life at these velocities?

Thanks!
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  #25  
Old 04-11-2010, 02:26 AM
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Join Date: Sep 2008
Posts: 327
Re: 300 Tejas

The important point is there is no other data on LRH for the 375 tejas, (which is basically an edge AI anyway) This is why we need to keep whatever data gets posted on this subject HONEST.

i apologise if my comments were a little antagonistic, but in the interest of safety this unrealistic data must be questioned and moderated which was my intent.
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  #26  
Old 04-12-2010, 05:24 PM
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Join Date: Jun 2007
Posts: 3
Re: 300 Tejas

I have known Brad Stair for quite a while now and have five guns that he built for me, and have found his work to be very good and his load data to be pretty much on the money. I dont have a 300 or a 338 but am in the process of having a 375 Tejas built. He has been making this series of cartridges from 404 brass since before RUM brass was available. These rounds do have minimal body taper and sharp shoulders. Im not aware of problems of brass life if you dont overdo the pressures. He guarantees half min accuracy. He also has a line based on the 408 and the 50 BMG. If you need to verify or clear up anything call Brad. He is very informative and easy to talk with. His number is 801-394-0331. Thanks for your time Richard
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  #27  
Old 04-12-2010, 07:29 PM
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Re: 300 Tejas

I don't think anyone is questioning the rifles quality or the builders ability to make a fine rifle. In fact, if this 375 Tejas is actually getting 3200 fps with a 300 gr bullet weight, the rifle most certainly has been build correctly to handle this pressure.

The concern is not with the rifle or chambering, its with the performance claims as they are WAY over what is conventionally thought of as standard or even high velocity for such a chambering.

It would be like one of my customers reporting they are getting 3200 fps with my 338 Allen Xpress(lapua based) with a 300 gr SMK. If I say this, I would respectfully and VERY QUICKLY get all over them saying that would be very unsafe to push this chambering to that level of performance.

Some feel they can just increase powder charge until they see pressure signs. Well in a properly built rifle, they will not see obvious pressure signs until they are well over pressure. We have to use a bit of common sense here. You can not get X fps without Y pressure and Z bullet time in the bore. Certainly other aspects will effect final velocity output but a throat design will not get you 300 extra fps over a standard throated rifle of the nearly identical chambering.

We all need to remain respectful but we must also bring up concerns when we run into them. All of us from time to time need to be throttled back a bit for our own good, me included.
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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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  #28  
Old 04-13-2010, 01:36 AM
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Join Date: Aug 2008
Location: washington utah
Posts: 189
Re: 300 Tejas

my brass has been fired twice at these pressures and the primer pockets are still tight. Brad told me his load is a 260 gn accubond at 3400 fps but he couldnt remember the exact load off the top of his head. my load starts with 105 gns of 7828ssc 300 hornady boat tail at 3105 fps and tops out at 111gns at 3200 fps. my other load starts with 100gns of rl25 with 350 smk at 2835 fps and tops outwith 108 gns at 3005 fps.
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