Long Range Hunting Online Magazine


Go Back   Long Range Hunting Online Magazine > Rifles, Reloading, Optics, Equipment > Rifles, Bullets, Barrels & Ballistics

Rifles, Bullets, Barrels & Ballistics Applied Ballistics


Reply

barrel length vs. powder usage

 
LinkBack Thread Tools Display Modes
  #1  
Old 12-14-2013, 06:23 AM
Bronze Member
 
Join Date: Dec 2013
Posts: 58
barrel length vs. powder usage

Want to put new barrel on my 7 mag and would like to start load development with Hodgdon Retumbo because I have plenty. Do I need a 26" barrel to completly burn the max load of 70 plus grains, or will this slow powder burn up in a 24 inch?
I have found load data using 140 grain bullet and Retumbo, it will be a compressed charge if I end up at max load but the barrel length is not specified.
Reply With Quote
  #2  
Old 12-14-2013, 08:21 AM
Bronze Member
 
Join Date: Oct 2011
Location: Moss,Tn.
Posts: 37
Re: barrel length vs. powder usage

I don't own a 7 Mag. but, I've loaded some slow powder and I'd probably get the 26" barrel. I'm assuming that this rifle will be a long range rifle and not be in the woods. The longer barrel won't really be a hindrance. You might get decent velocities from your loads. Hope everything works out.
Reply With Quote
  #3  
Old 12-14-2013, 08:33 AM
Gold Member
 
Join Date: Feb 2012
Posts: 816
Re: barrel length vs. powder usage

personaly i think retumbo is to slow for the 7mag with any barrel lenght. Ive loaded the 7 rem mag for 20 years and have allways had my best luck with powders like hodgdon 4831, imr483 and 7828 and re19 and re22. Any slower then these powders and your not going to gain velocity your just going to use more powder.
Reply With Quote
  #4  
Old 12-14-2013, 07:35 PM
Bronze Member
 
Join Date: Dec 2013
Posts: 58
Re: barrel length vs. powder usage

Quote:
Originally Posted by lloydsmale View Post
personaly i think retumbo is to slow for the 7mag with any barrel lenght. Ive loaded the 7 rem mag for 20 years and have allways had my best luck with powders like hodgdon 4831, imr483 and 7828 and re19 and re22. Any slower then these powders and your not going to gain velocity your just going to use more powder.


What barrel length are you loading? According to my burn rate chart that lists 97 different rifle powders with number ,1 being fastest and 97 being slowest, R-22 is number 89, IMR 7828 is number 90, ad H-4831 is number 85. All the powders you listed are relatively slow burners.
Retumbo is slower at number 94 which is why I wondered if it could be used in a longer barrel.
With the powder shortages these days and the fact that I am the proud owner of like 24 pounds of Retumbo, I wanted to keep my options open.
This does not mean I am dead set on using this ( have 2 other rifles that eat it happily ), I run several powders for load development always but if a 26 inch barrel is necessary in an effort to have this powder as a good option, well it's worth it, however if I am spitting into a fan, then he extra 2 inches of barrel is not worth it.
I was always of the thought that a slow powder in a long barrel would produce better velocities, but that doesn't make me right.
Reply With Quote
  #5  
Old 12-14-2013, 08:02 PM
Edd Edd is offline
Platinum Member
 
Join Date: Jan 2011
Location: Tulsa
Posts: 1,159
Re: barrel length vs. powder usage

Barrel length doesn't matter but bullet weight does. I'd use H1000 for medium weight bullets.
Reply With Quote
  #6  
Old 12-14-2013, 08:17 PM
Silver Member
 
Join Date: Sep 2009
Location: South Dakota
Posts: 410
Re: barrel length vs. powder usage

I'm using RL33 with 180gr bergers out of my 25" barreled 7mm Rem Mag, and I'm sending them at a confirmed 3105fps.

I wouldn't bother using it with anything smaller than the 180s though, because with the 168s, I run out of case capacity and am only running them at 3030.

Regardless, that's a hell of a lot of speed from a 180 and 25" barrel.

You're right that sending MORE powder through a SHORTER barrel you may not get a complete powder burn, with those lighter bullets...but it works just fine with the heavies.
__________________
"We do not rise to the occasion...we fall to the level of our training."
Reply With Quote
  #7  
Old 12-14-2013, 09:20 PM
Gold Member
 
Join Date: Feb 2008
Posts: 523
Re: barrel length vs. powder usage

I just don't know if my results will 'track' in another cartridge, but they are very similar in capacity and barrel lengths and compare well.
I have had magnum rifles in 24", 26" and 28", and too be honest there is really very little to be gained by trying a very slow powder to increase performance, chances are that you will only get less barrel life and an extra 100fps is not anything to write home about.
I also found that whatever powder produced the highest velocities in the shorter barrel, also produced the highest velocities in the longer barrels, so I don't feel that trying a super slow powder will achieve much, but I have to say that I have had my best results in a few cartridges to date with RL25 and Retumbo, which run very similar charge weights and produce very similar velocities in equal barrel lengths, quite a bit faster than some traditional powders, so it just may be that it isn't too slow for your application. Either powder have produced the highest velocities in the following chamberings, 25-06, 264WinMag, 270WeatherbyMag, 300WinMag and 300WeatherbyMag. I have never owned or loaded for a 7RemMag, sorry.

Cheers.
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes



All times are GMT -5. The time now is 01:03 AM.


Powered by vBulletin ©2000 - 2014, Jelsoft Enterprises Ltd.
Content Management Powered by vBadvanced CMPS
All content ©2010-2014 Long Range Hunting, LLC