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Drop in Velocity?

 
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  #8  
Old 01-21-2005, 11:03 PM
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Re: Drop in Velocity?

Brian B,

My comment about the 30-378 was only referring to the price of brass and what you get for your money. The 30-378 will outperform the Warbird and do it with slightly cheaper brass but my point was, much better quality Norma brass.

I totally agree that in a 26" barrel, anything including the 300 RUM and larger is really to much case for the appropriate powders to be used. Now bump up to a 28" barrel and the RUM and Warbird will start running hard, as will the 30-338 Lapua. Get a 30" barrel and the 30-378 comes into its own as it can actually put that 120 gr case capacity to use.

I have run my old 300 RUM side by side to a 30-378 Sako, both with 26" barrels. Both loaded to top acceptible pressure levels meaning that the addition of two more grains would start openin gup primer pockets on each load.

Both used the 180 gr Ballistic Silvetip. The 30-378 churned up 3490 fps, the 300 RUM hit 3420 fps. That was like you said with 15 grains less powder.

Velocity, like sex, SELLS!!!

Lazzeroni knows this very well, thats the only reason he is in business still.

I see this nearly every day taking with customers about my Allen Magnums. Especially the 257 AM. I tell them that it will drive the 130 gr Bonded Core FBHP with its B.C. of .550 to an honest 3650 fps and they just look at you.

Tell them it will drive a 115 gr ballistic tip to 3800 or a 100 gr BCFBHP to near 4100 fps and they light up like a christmas tree.

I will show them the pencil length 156 gr ULD rebated boattails for teh 257 AM with their B.C. of .820 and they simply ask how fast will it go. When I reply in the 3200 to 3300 fps range they just look at me and reply big deal, my 300 Win Mag will drive a 150 gr pill faster then that.

At that point I know if they are going to compare a .820 B.C. bullet at 3300 fps to a .420 B.C. bullet at the same velocity, it will just be a waste of their time and mine as well to try to show them the advantages of a fast moving extremely high B.C. bullet.

Again, velocity sells like hotcakes and out to 500 yards extreme velocity does work well I will admit as long as the bullet will handle the strains. Problem is, many extreme velocity rounds will not reach the grade for extreme range accuracy.

I am with you, far to many get hung up on velocity these days.

Good Shooting!!!

Kirby Allen(50)
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Kirby Allen(50)

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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

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  #9  
Old 01-21-2005, 11:30 PM
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Re: Drop in Velocity?

Thanks again for taking time to help me with this.

I looked back in my journal and my aol for the X bullet was 3.632 I found the most consistant ES was at 3.575 AOL. at 3729 FPS.

By the way I do not understand ( on the shorter then full length Warbird case ) What do you mean. I trim my brass to 2.790. Maximum case length is 2.810 is this what you are talking about.

I have also seen some post about tightning the action bolts to 65# when I take my actioned barrel out of the stock should it be tightned to a specific torque when I place it back in the stock.

Brian was talking about the heavier bullets. If I were going to rebarrel my rifle would you change the twist rate to something other than a 12 twist.to shoot the 180 grain at 3550 fps. And what if I used a 30 in barrel.

I loved the Rosie thing Point taken. Thanks Brian
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  #10  
Old 01-22-2005, 12:01 AM
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Re: Drop in Velocity?

Bcraft1111,

What I ment by "shorter then standard" is that a standard full length magnum runs 2.850" in case length. The big magnums like the 30-378 and Rigby will run 2.910" long.

I did not realize the Warbird was actually 2.800" long. Still it is shorter then the standard 2.850" standard magnum length brass allowing even more room in a conventional length Mag box.

The X bullets generally need to get a run at the rifling to have any consistancy at all. Most often an X bullet seated to close to the rifling will result in pressure variations that show up in velocity spreads.

This is really the opposite compared to a conventional bullet design. Unfortunately, while the velocity spreads may decrease with a longer jump to the rifling with the X bullet, often the group size increases.

For a pillar bedded rifle, 65 in/lbs is the correct torque. For some composite stocks this is to much and they will get springy.

This is far to much for a traditional wood stock, even a properly glass bedded stock as this amount of pressure will compress the wood significantly.

I would recommend contacting Lazzeroni and finding out what torque specs they recommend for their rifle. If it is pillar bedded, I would use 65 in/lbs.

If you do decide to rebarrel, the 1-12 twist will actually stabilize a 200 gr Accubond, I have seen it at 200 yards. The rifle was printing 1 1/4" groups at 200 yards. Not great but not bad either.

Still, I would go with the standard 1-10 twist simply because it give so much great flexibility in which bullets you can use. There is no doubt the 1-10 twist barrels would stabilize any bullets up to a 220 gr Sierra MK or 210 gr Berger VLD even in the coldest temps.

They also shoot the lighter bullets extremely well if you choose to do so. I am in total agreement with Brian about the use of heavy bullets in this class of round. Once you get to the point where you can get 100 gr of powder under a 30 caliber bullet, there is no point in using anything less then 180 gr bullets and yes, the 200 gr bullets are even a better balance for the Warbirds case capacity.

My brothers rifle shot the 200 gr Accubonds very well with Retumbo and topped 3200 fps easily with this bullet. I believe he was puching 3300 fps with top safe loads.

As far as barrel length, that is a personal preference. I like long barrels on my big game rifles and especiially my extreme range rifles. But I hunt in very wide open big country here in central Montana where a long barrel is more of an advantage then a disadvantage.

If I were building myseld a rifle like around the Warbird, I would use a #7 contour Lilja 3 groove, 1-10" barrel and flute it with the large diameter .312" 50 BMG style flutes with a finish length of 30".

This would give me the stiffness of a .825" diameter muzzle but with the weight of a relatively slim #6 contour. Properly set up I would imagine you would be getting +3600 fps with the 180 gr Accubond and groups would be in the 1/2 moa range or less.

Better yet, you could drive the 200 gr Accubonds to 3400 fps and with a quality brake such as the Holland Quick Discharge brake, recoil would feel about like a 308 Win in a heavy rifle.

That is just what I would do but again I like the feel of a 30" sporter rifle as all my shots are off bipods or bags. No offhanding for this kid.

Have a good one,

Kirby Allen(50)
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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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  #11  
Old 01-22-2005, 12:56 AM
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Re: Drop in Velocity?

I thought I understood that in the magnum calibers that every inch you add or take off a barrel takes or adds 50 fps, So where does it stop being efficient. why not a 32 in barrell or even 34.

I called Jarret and talked to Jay Jarret and he said that in there signature rifle in 300 jarret they only use a 25 in barrel and that used all the powder and got all the velocity they could get out of it 3450 with a 165 grain. I do not quite understand this. Is there a trade off somewhere in this approach to barrel length.

Oh by the way I did call Lazzeroni about 3 months ago about the action screws and they said just tighten them up. I asked if the needed to be tightened to a certian torque and the answer was " just make sure they are tight" I was just getting a second oppnion.

Thanks for the Info.
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  #12  
Old 01-22-2005, 12:00 PM
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Re: Drop in Velocity?

Bcraft1111,

From teh testing I have done, what I have witnessed from actual velocity testing with the same load in different barrel lengths is that a round of this size will generally gain around 20 to 22 fps per inch of barrel added after 24" out to around 28". From there on out you will gain about 18 fps per inch.

In a round like the 257 STW and my 257 Allen Magnum which have case capacities in the 85 gr and 100 gr range on the very small .257" bore, you will see around 35 to 40 fps gained goign from a 26" barrel out to 30".

It simply has to do with the expansion ratio of the round and the length of barrel you are using. A round like the 257 AM has a very low expansion ratio so it will gain more velocity per inch of barrel then say a 257 Wby with its higher expansion ratio.

Your Warbird has a pretty low expansion ratio but not exceptionally low for a 30 cal round. For thsi reason this round will not get a huge velocity gain per inch of barrel.

The big 338 mags are even worse in this aspect. They will generally only gain 20 fps or so at the most per inch of added barrel.

Heavier bullets will gain more velocity in long barrels then light bullets will, simply because they use slower burning powder.

I certainly will not question anything that one of the Jarrets say about their rifles but I will say that by todays standards the 300 Jarret is a relatively small 30 cal magnum. Basically identical to the 300 Wby with its 85 to 90 gr capacity compared to the RUM with its 100 to gr capacity, the Warbird with its 105 gr and the 30-378 with its 120 gr capacity.

SO of all these it will gain the least amount of velocity per barrel inch and it is far better suited to a 25" barrel then either of the others.

These numbers are not a given by any means, more like an average. Some barrels will produce slightly more, others slightly less per inch.

If your looking to gain 50 fps per inch of barrel you will be disappointed I am afraid.

The way I look at it, the 300 RUM and the Warbird, in real world rifles using real world bullets are damn near ballistic twins when each are loaded to the same chamber pressure in same length barrels. They also will gain about the same velocity per inch of increased barrel length.

I assure you that if you took a 300 Jarret and chambered it in a 38" barrel, you would most assurely gain anywhere from 75 to 100 fps over the 25" barrel length so, yes, they will keep gaining velocity, even out to 36" or so of barrel length.

Jarret rifles are built for extreme accuracy, well all custom rifles are built for this but the best way to get extreme accuracy is with the stiffest barrel you can use. That translates into either a shorter barrel or a heavier contoured barrel. The Jarret rifles are designed to be relatively light weight and as such they use shorter barrels to get keep their barrels stiff.

Again, accuracy is far more important then extreme velocity.

Good Shooting!!!

Kirby Allen(50)
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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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  #13  
Old 01-24-2005, 10:12 PM
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Re: Drop in Velocity?

Fiftydriver

I was wondering if you were able to find the recipie for the 180 accubond and retumbo for the warbird.

Thanks for your help.
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  #14  
Old 01-25-2005, 12:34 AM
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Re: Drop in Velocity?

Bcraft1111,

I dod not forget, my brother has been out of town the last couple days. Supposed to be back tomorrow. I have a message for him to contact me with his load data.

I will get it to you as soon as I get it.

Sorry for the wait.

Kirby Allen(50)
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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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