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Overbore?

 
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  #1  
Old 08-25-2004, 09:02 AM
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Location: Texas
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Overbore?

I need some help. Is overbore reduced with slower powders and heavier bullets? How do I get the best long range performance out of my 300 RUM?
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  #2  
Old 08-25-2004, 02:57 PM
 
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Re: Overbore?

I think that now days everybody has their defination of overbore. I think that alot of this term has to do with barrel length , I mean if your only shooting a 22" barrel and you want a big 30 cal I don't think that you gain much velocity over the 30-06 ,even with some of the big boys shooting almost twice the powder.

Hey Fifty , about that 25stw reamer you have , what sort of velocity are you getting with a 26" tube ? I was thinking about rechambering a 25-06 to one of the fast 25's maybe a 257Wby or the 257stw
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  #3  
Old 08-25-2004, 03:11 PM
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Re: Overbore?

The best way to max out your RUM for LR performance is to use the longest barrel and the heaviest bullet.

For me, that is a 35" barrel and 240gr MK. At 1000m, this bullet arrives with ALOT of energy. I am sure that with enough elevation, 2000m would be within reach.

Might be a bit extreme but gives you an idea of how to get the most performance from all that powder burnt.

Jerry
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Old 08-25-2004, 03:32 PM
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Re: Overbore?

Just some added info to help me achieve the best performance. I have a Remington 700 BDL SS with a 26 inch barrel in the 300 RUM. I purchased this rifle to help me "reach out and touch" the large bucks in Northwestern Oklahoma. Sometimes the range is extreme with no cover to get closer. I managed a kill a buck at 425yds with my 30-06, but it shot like a rainbow and required two hits in the vitals. Any help is appreciated.
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  #5  
Old 08-25-2004, 05:50 PM
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Re: Overbore?

"Overbored" is really a subjective term whose traditional meaning has changed over time. Here is my definition:

A cartridge is "overbored" if a maximum charge of the bulkiest appropiatepowder still leaves an air space between the top of the powder charge and the bottom of the seated bullet.

With that in mind - who cares if a cartridge is overbored? My "overbored" 7STW is incredibly accurate and really has the abilty to reach out and touch something. In short, it makes me happy. [img]images/icons/smile.gif[/img] [img]images/icons/smile.gif[/img] [img]images/icons/smile.gif[/img]

VH
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  #6  
Old 08-25-2004, 11:56 PM
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Re: Overbore?

TomVan,

The term "overbore" was started back inthe day when the best and basically only slower powders on the market were 4350 and 4831.

THe term overbore was started when a case, which was larger then the standard at the time was used but could not provide any real velocity advantage over existing rounds using the available 4350 and 4831.

The common thinking was that they were not real useful as they provided very little advantage over smaller cased rounds.

The 25-06 was thought to be very overbore for its bore size.

Today, with the large array of slow burning powders, this term means very little to the extreme performance experimentor.

The way to get the best long range performance out of the 300 RUM is to use bullets at least 180 gr and heavier is better with powders starting with H-1000 and slower.

Good Shooting!!!

Kirby Allen(50)
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  #7  
Old 08-26-2004, 12:46 PM
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Re: Overbore?

Tom, you really need to define your ranges. Odds are you will not be shooting over 600yds. Around here, that is short range.

If so, the best combo of bullet will be in the 165 to 180gr class. The standard stuff. As long as you watch your impact velocities, the SST, MK, ballistic tips and similar bullets will work just fine. Impact vel must not exceed 3000fps so shots should be at least 150yds away.

If most of your shooting is inside 200yds, first off you don't need this cannon, however, you will have to consider a premium bullet like the Barnes or Failsafe so that bullet failure is eliminated. Downside are these bullets do not expand well at long range and low impact velocities.

You will need to do a bit of balancing there.

For the type of hunting you are suggesting, performance in the 300WM range would be more then adequate. You can download the RUM and use just about any bullet you want.

Personally, I limit my muzzle vel to 3000fps or so. That way I can take a shot at any range. I just use the heaviest, highest BC bullet that fits this performance, then limit max range based on impact vel, accuracy and energy.

Good luck with your hunt...

Jerry
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