6.5 ulta mag

shawn68

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Nov 26, 2006
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seattle
I found some info about a 6.5-300 ultramag. The guy is calling it the 6.5 ultracat. Does any one have any thoughts about this wild cat? I kinda have a thing for overbore cats. I know the 6.5-284 and 6.5-06AI have a great reputation, but they just are not SEXY enough. I dont want to jump on the wsm band wagon either. Any thoughts? Any body tried necking down the 338 Lapua? Im looking for 140 at 3500fps or better.
 
There is a guy that posted on this board a few years back that used a 300 Wby necked down to 6.5. Its one fast flat shooting cannon. Barrel life is very short.

There were a few guys at Williamsport using the 300 Wby necked down to a 6.5 as well. I'm sure if you search the boards someone is using the "6.5 ultra".

AG
 
I have a 6.5-300RUM. I love mine. It shoots a Barnes 120XLC at 3850 fps. I have not tried any other bullets in mine because the Barnes shoots one hole groups at a 100yds and 3/4" groups at 300yds. I think the speed of the 140gr that you are looking for is reasonable.


I have killed two deer with mine and it performed awesome! This past weekend I was able to do a little long range shooting at 750yds. I was shooting at a life size deer target and even though the wind was blowing harder than I would had liked and this being the first time I have tried shooting anything past 300yds, I got one 3" group a 1/2" off the deers nose. After that I adjusted for the wind and hit the deer in the shoulder and neck, I was pretty happy /ubbthreads/images/graemlins/grin.gif.
 
Shawn68,

The 6.5mm RUM is about as large a powder capacity as you can use and still be somewhat practical in the results. My 6.5mm Allen Mag is based on a blown out, improved 338 RUM case so it is shorter by 90 thou then what a 6.5-300 RUM would be but its capacity is basically the same.

I went with the shorter 338 RUM case so that it would give me the same capacity but in a shorter case allowing me a better OAL for a repeating round.

Our current 6.5mm AM has a 30" Lilja 1-8 twist and it is my wifes long range rifle. We are using a relatively mild load to get a legit 3540 fps with the 142 gr ULD RBBT. This is only a temporary load as I have some prototype 168 gr ULD RBBTs coming from Richard Graves of Wildcat Bullets to test in this big 6.5mm.

As others have said, it is also my opinion that anything lighter then 120 gr of bullet weight is really a waste of time in this type of round. The 120 gr X bullets are a pretty good choice as they are much longer then a conventional 120 gr 6.5 bullet and will obviously like the velocity potential.

I still feel that for long range consistancy, nothing helps these large capacity small bore rounds like alot of bullet weight.

Simply put, with todays powders and bullets, this is a practical chambering, just do not use it for a varmint rifle or you will be rebarreling it every season!!! /ubbthreads/images/graemlins/grin.gif

As a big game rifle, they will last many seasons easily.

Good Shooting!!

Kirby Allen(50)
 
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Im looking for 140 at 3500fps or better.


[/ QUOTE ]

If that is all you want, the 300 RUM with a 155 AMAX or Scenar is capable of delivering 3600 FPS+ with good BC's. I have personaly tested the scenars at over .500

The benefit here is barrel life. The bbl life with the 6.5 RUM will be incredibly short. The 300 is short enough.
 
Yeah but with good cleaning practices and practical shooting, "let it cool down", cant some one dictate how long the barrel will last. Or are you guys thinking that it would be hard to stay on top of the throught erosion?
 
[ QUOTE ]
Yeah but with good cleaning practices and practical shooting, "let it cool down", cant some one dictate how long the barrel will last.

[/ QUOTE ]

To some degree, yes. To a much larger degree, no.

You can abuse a 308 and still get about 5000 good shots through it and still maintain 1 MOA accuracy. You can pamper a 300 RUM and you will still feel lucky to get 1 MOA after 800-1000 rounds. The more the powder and smaller the bore, the shorter the life of the barrel. Its just the nature of the beast!
 
Thats why we get someone to make 168 gr ULD RBBT in 6.5mm for us crazy fools and drive them to 3300 fps. I suspect their BC from bullet drop will be in the .85 to .875 range, vastly superior to any 30 cal bullet out there save the Wildcats in the real heavy weight variaty and then recoil increases dramatically and velocity potential drops quickly as well.

I fully agree that the 30 cal RUM is a much more user friendly idea, I have one of the very first 300 RUMs to make it into Montana, has over 1500 rounds through it and my brother in law and his family used it this fall to take several deer out to 450 yards with great accuracy. Probably around moa but still getting 3400 fps with a 180 gr Ballistic Tip.

Still, its always fun to really rip a 6.5mm bullet out there fast!!! /ubbthreads/images/graemlins/grin.gif We do not always need to be practical, good thing or I may be out of a job!!!
/ubbthreads/images/graemlins/grin.gif

Kirby Allen(50)
 
Hi just go with either i would look at having Kirby build you a 6.5 Allen MAg as he will be able to help you with every thing. The only advantage with the full length case is get 7mm Ultra Type S Bushing Full length die from redding and use a smaler bushing to suit the 6.5 neck and you have a sizing die then get a 264 Win Mag Competition seating die and run the reamer into it and you wil have true match grade dies. I would also get a fast twist barrel and use the heaviest projectiles you can. Also look around for the old 155gr Sierra 6.5 MatchKings they were extreemly accurate and if you can find them they are worth their weight in gold in large magnum cases. I actualy havd a coustomer here that is looking at mabe a 6.5 Ultra aswell.

Cheers Bill
Australia
 
[ QUOTE ]
I suspect their BC from bullet drop will be in the .85 to .875 range, vastly superior to any 30 cal bullet out there

[/ QUOTE ]

By using published BC's, yes. I shoot a Lilja 27.25" 12x in 300 RUM and the 178 AMAX. Published BC is .495 I zero my rifle in at 300 yards (dead zero) and she drops right at 34" in starndard air density at 600 yards. This is rediculously flat. Sure it works out to a BC of .495, on the G7 drag function. If you calculate that with the G1 function, its over 1.000. Oh and did I mention that is at 3100 FPS muzzle velocity?

Unfourtunatly, I dont get the same results with my 308. I dont even get quite the published BC even using the G1 function. It is also unfortunate that this particular bullet is not well suited for big bears or moose or elk. It is a good deer sized critter bullet though.

The point is, sometimes paper ballistics just dont cut the mustard.

Please dont get me wrong, the overall ballistic capabilities of the 6.5 RUM are truly amazing. This is in no way intended to be an agument. Just pointing out some of the natural phenomenons that sometimes occur in this art.
 
[ QUOTE ]
Hi just go with either i would look at having Kirby build you a 6.5 Allen MAg as he will be able to help you with every thing. The only advantage with the full length case is get 7mm Ultra Type S Bushing Full length die from redding and use a smaler bushing to suit the 6.5 neck and you have a sizing die then get a 264 Win Mag Competition seating die and run the reamer into it and you wil have true match grade dies. I would also get a fast twist barrel and use the heaviest projectiles you can. Also look around for the old 155gr Sierra 6.5 MatchKings they were extreemly accurate and if you can find them they are worth their weight in gold in large magnum cases. I actualy havd a coustomer here that is looking at mabe a 6.5 Ultra aswell.

Cheers Bill
Australia

[/ QUOTE ]


Cool info. Is the allen the blown out necked down 378?

I was wanting to stay away from belted mags
 
Hi the 6.5 Allen mag is a 338 Ultra mag necked to 6.5 and improved to Kirby's design and the 7mm Alen Mag is the 338 LApua Case with the same modifications as the RUM case. They are not belted rounds so if you like the 6.5 Ultra it is easier with dies but the allen mag will have a shorter case with the same capacity and allow a projectile to be seated out longer with the same magazine length they both have the same performance but diferent advattages aswell take your pick and Kirby or Shawn could make you a great rifle in either calibre. IF you choose a diferent gunsmith make sure they specilise in magazine fed magnum long range rifles as their is a diferent approach to asembling them to a target rifle in single shot format.

Cheers Bill
Australia
 
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