Long Range Hunting Online Magazine


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


Reply

Why are there fast bbls and slow bbls

 
LinkBack Thread Tools Display Modes
  #1  
Old 09-23-2011, 01:01 AM
Platinum Member
 
Join Date: Apr 2004
Location: Reno Nevada
Posts: 1,513
Why are there fast bbls and slow bbls

Some bbls of equal lengths can shoot same identical load at different speeds ,why ? I have a 7mm wsm that shoots nearly 7mm STW speeds . Just today shooting 168gr Berger VLDs with bullet touching the lands 69.2 grs of Re#25 I was able to average 3250 FPS. No complaints of course just wondering why ? Its a 26" Brux bbl. 70.5grs of WXR pushed a 139gr SST at 3500 fps ( 3 Shots) but 100 yd group was greater then 2 MOA. 168 gr VLD shot under 3/4 MOA at 130 yds.
__________________
How does it profit a man if he gains the whole world but loses his soul?
Reply With Quote

  #2  
Old 09-23-2011, 07:47 AM
Platinum Member
 
Join Date: Feb 2007
Location: Townsend, Montana.
Posts: 7,904
Re: Why are there fast bbls and slow bbls

Yes, I do believe that some barrels are faster than others of equal length and twist. With in reason of course. But I think there are more chrono errors than anything fooling people. I have seen chrono's lie to me and by quite a bit. So I feel the difference in barrel speeds can be significant, but not 200 fps like some believe. I have also seen data showing some bullets of the same weight being way fster than others of equal weight. Again, I am not saying the shooters are fibbing, but rather their chrono is a lying little cuss.

Jeff
__________________
Reply With Quote
  #3  
Old 09-23-2011, 09:02 AM
Gold Member
 
Join Date: Nov 2010
Location: Colorado, Front Range
Posts: 555
Re: Why are there fast bbls and slow bbls

How the chamber was cut will also play a role. Custom rifles with tighter chambers have less brass expansion keeping the gases behind the bullet. I have a .223AI that shoots on avg. 300fps over factory or book loads. When I had this gun built I was told It would give 100-200fps more over a standard .223. Broz is correct on the chrono, try running through a friends also.

Jon
Reply With Quote
  #4  
Old 09-23-2011, 09:12 AM
Platinum Member
 
Join Date: Jan 2005
Location: OK
Posts: 2,145
Re: Why are there fast bbls and slow bbls

I have a pro crony that is long in the tooth and thought it was giving me bad numbers, and it may have been during bad lighting shooting sesions.

So I bought an alpa crony and set them up back to back,(during good lighting conditions. The alpa read on average 35fps faster than the pro, and very consistantly at 35 fps high.

But when bullets had low ES both cronys showed it, and when they had high ES both cronys showed it. So there acraccy that way was spot on.

Low batterys and bad lighting will play hell on them the pro crony gives you terrible number spreads and the alpa just says error.

as what was said before, chamber dimensions, lot of powder, lot of barrel steel,
land and groove configuration, bore and groove dia. all these and more can have an effect on velocity, and if the conditions are stacked in favor one way or the other a considerable velocity difference can be seen.
Reply With Quote
  #5  
Old 09-23-2011, 11:43 AM
Platinum Member
 
Join Date: Apr 2004
Location: Reno Nevada
Posts: 1,513
Re: Why are there fast bbls and slow bbls

Well that's was very informative. I know in the directions for my chronograph it was stated that if the screens are just 1/16th off they'll give a false reading. Yesterday I also shot my 22 mag and 44 mag through chronograph and it was spot on. BUT I'm still etching my head over performance with 139gr SST 70.5 grs of WXR produced 3x 3500 fps ? That's screaming fast ,but the accuracy was ( If I fired a few more shots) would of looked like a buck shot pattern. They don't make WXR any longer.
__________________
How does it profit a man if he gains the whole world but loses his soul?
Reply With Quote
  #6  
Old 09-24-2011, 07:10 AM
Gold Member
 
Join Date: Feb 2008
Posts: 519
Re: Why are there fast bbls and slow bbls

Quote:
Originally Posted by Iron Worker View Post
Well that's was very informative. I know in the directions for my chronograph it was stated that if the screens are just 1/16th off they'll give a false reading. Yesterday I also shot my 22 mag and 44 mag through chronograph and it was spot on. BUT I'm still etching my head over performance with 139gr SST 70.5 grs of WXR produced 3x 3500 fps ? That's screaming fast ,but the accuracy was ( If I fired a few more shots) would of looked like a buck shot pattern. They don't make WXR any longer.
I think you might be surprised to find that WXR was and is plain old RE22 just with a different label attached by Winchester, the loads are interchangeable.
Reply With Quote
  #7  
Old 09-24-2011, 12:29 PM
Platinum Member
 
Join Date: Apr 2004
Location: Reno Nevada
Posts: 1,513
Re: Why are there fast bbls and slow bbls

Yes that's what I heard .
__________________
How does it profit a man if he gains the whole world but loses his soul?
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes


Similar Threads for: Why are there fast bbls and slow bbls
Thread Thread Starter Forum Replies Last Post
Sav/stevens factory bbls and stock goose Gun Parts - Stocks, Barrels, Actions, etc. 2 12-08-2010 10:27 PM
WTB: 30"+bbls. in 6.5,7mm,.30 & .338 cal. for Rem. GEG Guns For Sale 6 02-13-2009 02:40 AM
New Pac Nor 300 Weatherby bbls msalm Gun Parts - Stocks, Barrels, Actions, etc. 1 01-21-2008 09:51 PM
Cleaning solvents for our BBLs Iron Worker Rifles, Bullets, Barrels and Ballistics 1 01-19-2008 10:51 AM
wts for best offer:Browning BPS w/ 2 bbls & Ruger mkll 30/06 pdhunter Guns For Sale 1 03-16-2005 07:11 PM


All times are GMT -5. The time now is 02:27 PM.


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