The Firing Line Forums

Go Back   The Firing Line Forums > The Skunkworks > Handloading, Reloading, and Bullet Casting

Reply
 
Thread Tools
Old August 16, 2012, 07:46 PM   #26
HShack
Senior Member
 
Join Date: February 5, 2009
Location: Lexington, SC
Posts: 105
"Don't be intimidated going to long range. If you can shoot around 1/2 minute, you're better than a lot of us."

Well, so far I CAN'T shoot a 1/2" group. To me, 3 shot groups mean little; at least 5 are necessary. Several times I have had a promising group started then here comes that flier. I think my heartbeat is the biggest problem as the crosshairs move at least 1/2 moa. I also need a scope with a finer crosshair.


By the way, how is the word "VARGET" pronounced- is the "G" soft as in "gee" or hard as in "get"? Haven't been able to find any locally yet.
__________________
Shack
HShack is offline  
Old August 16, 2012, 07:51 PM   #27
allaroundhunter
Senior Member
 
Join Date: May 6, 2012
Location: Southeast Texas
Posts: 1,670
Haha, it is pronounced "Var" mint / tar "get"
allaroundhunter is offline  
Old August 16, 2012, 08:10 PM   #28
4runnerman
Senior Member
 
Join Date: January 16, 2010
Location: Minnsota
Posts: 2,832
As other posted go with a 175 SMK. Mine is awesome with 43.2 gn RL-15 and 175's 2.81 COL. You will be very hard pressed to get a 175 up to 2800/fps.
__________________
NRA Certified RSO
NwCP- Performance Isn't Optional
4runnerman is offline  
Old August 16, 2012, 11:12 PM   #29
HShack
Senior Member
 
Join Date: February 5, 2009
Location: Lexington, SC
Posts: 105
"You will be very hard pressed to get a 175 up to 2800/fps."
__________________

Looks like 2600 fps will stay supersonic at 1k.
__________________
Shack
HShack is offline  
Old August 16, 2012, 11:23 PM   #30
HShack
Senior Member
 
Join Date: February 5, 2009
Location: Lexington, SC
Posts: 105
Big jump...........

Looks like that 155 gr. A-Max has to jump .145" to get to the lands. That don't sound good......

Doesn't appear that can be helped much even with reloading since COL is so limited by bearing surface requiements.[and ejection port dimensions].

Sounds like a custom barrel is in order.......
__________________
Shack
HShack is offline  
Old August 17, 2012, 06:54 AM   #31
4runnerman
Senior Member
 
Join Date: January 16, 2010
Location: Minnsota
Posts: 2,832
Sorry HShack- I was thinking one mile again. Need MV of 2830 or something like that. I have shot mine at 1000 yards many times already. Got a 6MMBR 2 weeks ago and have not shot the 308 since.
__________________
NRA Certified RSO
NwCP- Performance Isn't Optional
4runnerman is offline  
Old August 17, 2012, 05:39 PM   #32
Bart B.
Senior Member
 
Join Date: February 15, 2009
Posts: 4,985
Interesting stuff about long range with different bullets out of the .308 Win.

http://www.border-barrels.com/articles/art1.htm
Bart B. is offline  
Old August 17, 2012, 09:55 PM   #33
Unclenick
Staff
 
Join Date: March 4, 2005
Location: Ohio
Posts: 10,314
Bart,

I note that if the author of that article had used the G7 BC championed by and measured for the 190 grain Sierra to be an average of .270 by Bryan Litz, the predicted 1200 yard velocity would have been 1089 fps. That's closer to the measured 1076 fps than any of the suggested BC alternatives in the table. Or at least, it is under Army Std. Metro conditions. Carmichael's conditions for the measured velocities aren't provided.


Quote:
Originally Posted by allaroundhunter
While the 155s might hold tighter groupings at 100 and maybe 200 yards, I would put money on them being out shot by 168s and 175s when you push them further than that.
If two bullets have the same exact BC at all velocities and the same muzzle velocity and (less significant) the same gyroscopic stability factor, they will fly in the same amount of time to any given distance, thereby giving gravity and wind the same amount of time to act on them. For that reason the drop and wind deflection for both will be the same, regardless of them having different diameters or weights. Gut intuition incorrectly suggests the heavier of the two bullets will be blown less easily by wind, but gut intuition doesn't catch that the difference in weight is already factored into the BC by the way it's calculated. If they weren't going to drift the same amount in the same wind at the same velocity, they wouldn't have the same BC.

The 155 grain Palma bullet (#2155) used in 1992 is not the same one now labeled "Palma" by Sierra (#2156). The original one is now referred to simply as a 155 gr MatchKing. The newer 155 is longer and more aerodynamically efficient so it has a higher BC. Indeed, its BC at top velocities is up with that of the Sierra 175 gr SMK (#2275), though it drops off faster with loss in velocity. But because you can get it up to higher velocity at the start, it's got a very slight theoretical advantage at 1000 yards from a 24" gun barrel.

The only area of concern I see with the newer design is that it's bearing surface is very short; about 3/4 of a caliber. This shouldn't be a problem for Palma shooters soft seating against a tight throat, but for magazine fed guns and longer throated chambers it doesn't give you a lot of room to play with seating depth and it makes getting the rounds seated concentrically of greater importance as the short bearing surface won't self-straighten in the bore as well as a longer one does.
__________________
Gunsite Orange Hat Family Member
CMP Certified GSM Master Instructor
NRA Certified Rifle Instructor
NRA Benefactor Member
Unclenick is offline  
Old August 17, 2012, 10:22 PM   #34
FiveInADime
Senior Member
 
Join Date: January 25, 2012
Posts: 368
I just have to say, if you need to take a 1000 yard shot on a target you just need to learn how to stalk in closer to them. It really ain't all that hard, I mean they're stationary for cryin' out loud. Besides the .308 is questionable for humanely poking a hole at that distance.

Sent From My Galaxy S 4g Using Tapatalk
FiveInADime is offline  
Old August 17, 2012, 11:18 PM   #35
allaroundhunter
Senior Member
 
Join Date: May 6, 2012
Location: Southeast Texas
Posts: 1,670
Deleted
allaroundhunter is offline  
Old August 17, 2012, 11:23 PM   #36
Bart B.
Senior Member
 
Join Date: February 15, 2009
Posts: 4,985
Unclenick mentions:
Quote:
The 155 grain Palma bullet (#2155) used in 1992 is not the same one now labeled "Palma" by Sierra (#2156). The original one is now referred to simply as a 155 gr MatchKing. The newer 155 is longer and more aerodynamically efficient so it has a higher BC. Indeed, its BC at top velocities is up with that of the Sierra 175 gr SMK (#2275), though it drops off faster with loss in velocity. But because you can get it up to higher velocity at the start, it's got a very slight theoretical advantage at 1000 yards from a 24" gun barrel.
Those of us working up the first loads for Sierra's original 155 (no. 2155) talked about better shaped ogive would probably give that weight bullet a better chance at 1000 with 26 inch barrels that were popular in high power match rifles at the time. One former Nat'l Champ used a 26 inch barrel with the 2155's (loaded a bit warm) in late 1991 and said they were decently accurate at 1000 yards, but his saving grace was the 6600 ft. altitude at the NRA Whittington Center where they were fired. At Camp Perry for the Nationals, its 580 foot altitude's denser air would probably slow that bullet down to much for supersonic flight not far past 800 yards. The new Palma bullet is a big improvement over the old one.
Bart B. is offline  
Reply

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 02:49 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
This site and contents, including all posts, Copyright © 1998-2014 S.W.A.T. Magazine
Copyright Complaints: Please direct DMCA Takedown Notices to the registered agent: thefiringline.com
Contact Us
Page generated in 0.08315 seconds with 7 queries