Long Range Hunting Online Magazine


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


Reply

preasure problems with 7 ultra

 
LinkBack Thread Tools Display Modes
  #1  
Old 06-14-2009, 04:56 PM
Bronze Member
 
Join Date: Mar 2008
Location: South Dakota
Posts: 54
preasure problems with 7 ultra

Hey

I was doing some load workup this last week and found the one. The load 180 berger vld 84 grains of retumbo fed 215 primers. fired and annealed rem brass. The load gave me 3283 avg with a average diff of 8 fps and gave me .25 moa at 600. The brass was handling it very well no signs of excessive pleasure at all and i couldn't have been happier. I went out with my brother Friday evening and had problems with over pleasuring cases. It was only about 65 degrees when we were out and only about 10 warmer than it was when i did the load workup. so temp shouldn't have been the problem. All cases had a had a normal going through neck and mouth cleaning and partial neck sizing, primer pockets also cleaned. the powder scaled out to the 10th of a grain and from the same jug.
bullets were all set out to the same leignth. the bullets are just touching the lands.

I don't know what i am doing wrong to cause such a big diferance in preasure. Would it be the barrel the brass of something i am overlooking.
also the problem wasn't continious with three over preasuring and the next round not and several more after that and back and fourth. I put 12 rounds down range that nite and kept the shots spread apart to keep the barrel cool.

any thing else to look at would be greatly appreciated.

thanks
chris
Reply With Quote
  #2  
Old 06-14-2009, 05:07 PM
Silver Member
 
Join Date: Oct 2006
Location: Oregon City, OR
Posts: 481
Re: preasure problems with 7 ultra

Was the over preasure rounds the first in the string or say shot 3 or 4. I have seen over heating the ammo by letting it "cook" in a hot chamber for to long before firing. If its hot I would not let it sit in the chamber for more than 5-10 sec, if its been longer, eject and load a new round.

Just a thought...

Same lot of powder?
same lot of Bullets?

Willys
Reply With Quote
  #3  
Old 06-14-2009, 05:32 PM
Platinum Member
 
Join Date: Jan 2004
Location: Blackfoot, Idaho
Posts: 8,041
Re: preasure problems with 7 ultra

hartman99,

Need a little more description of the over pressure symptoms.

I have a load of US 869 and 7828ssc that are very consistent from a very low temperature to about 65 Degrees F. The pressure sign is the click on bolt lift. After the click extraction is normal.


If I shoot at 70 or above it takes two wacks up and one wack back with "tool" to extract the case. The case is then ruined due to expanded primer pocket.
Reply With Quote
  #4  
Old 06-14-2009, 08:34 PM
Platinum Member
 
Join Date: Feb 2004
Location: Pennsyltucky
Posts: 2,623
Re: preasure problems with 7 ultra

i once had a 7 ultra. had the same problems you're describing. took it apart and built a 338 edge. all my problems went away and couldn't be happier. a 7 ultra is just way too much overbore for me. in my opinion, just touching the lands is probably your problem. with that much overbore, a very small thing can turn into a biggy. get em away from the lands and see if you're not more consistant.
Reply With Quote
  #5  
Old 06-14-2009, 08:46 PM
Platinum Member
 
Join Date: Jan 2003
Location: The rifle range, or archery range or behind the computer in Alaska
Posts: 3,503
Re: preasure problems with 7 ultra

I had a 300 RUM barrel with the same problem. After about 65 rounds down the pipe, I started seeing huge pressure increases. It got worse every day. I would back off powder and things would still be hot. Turned out it was a VERY cooked throat. This cause a lot of friction and subsequently increased the pressure.

The 7mm RUM will cook a throat even faster.

Sorry for the bad news.
__________________
Quote:
Originally Posted by Broz View Post
Please just answer one very simple question. Why would anyone shooting long range load a low BC , low SD 168 gr offering in a 300 win???????

My answer to this is. The only reason is to make the 7 RM look good. There is no other reason.

Jeff.
Reply With Quote
  #6  
Old 06-14-2009, 08:57 PM
Platinum Member
 
Join Date: Apr 2005
Location: Alaska
Posts: 3,342
Re: pressure problems with 7 ultra

How many rounds have been fired down that barrel?
Reply With Quote
  #7  
Old 06-15-2009, 01:21 AM
Bronze Member
 
Join Date: Mar 2008
Location: South Dakota
Posts: 54
Re: preasure problems with 7 ultra

there are just at 200 rounds down the tube, the pressure signs were heavy bolt lift, trouble extracting the case, extractor marks and cratered primers. I am doing a cast of the chamber tonight to do some measuring. I have also heard that if the neck of a case is too long that will cause problems with pressures. the cases measure 2.860 to 2.870 and thinking if i get them down to 2.845 or so may help but will have to wait to see for the weather to cool down.

thanks

Last edited by harfman99; 06-15-2009 at 01:38 AM.
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes


Similar Threads for: preasure problems with 7 ultra
Thread Thread Starter Forum Replies Last Post
whats a better round 338 ultra mag or 300 ultra mag? pdbsa Rifles, Bullets, Barrels and Ballistics 27 05-02-2012 11:01 AM
Problems getting a tight group on my 300 Rem. Ultra Mag bowhunter1001 Rifles, Bullets, Barrels and Ballistics 13 07-24-2011 11:36 PM
Help identify preasure signs ? dustybrown Reloading 12 02-01-2010 03:06 AM
problems with a .338 Win mag PaTony Rifles, Bullets, Barrels and Ballistics 3 08-24-2009 09:59 PM
Problems with IOR 2.5-10 X 56. Wiktor Long Range Scopes and Other Optics 4 10-31-2004 12:00 AM

Current Poll
Are you on Facebook?
Yes - 46.77%
1,086 Vote
No - 19.25%
447 Votes
No, but I may join - 1.77%
41 Votes
No way, are you kidding? - 35.96%
835 Votes
Total Votes: 2,322
You may not vote on this poll.

All times are GMT -5. The time now is 11:28 AM.


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