Strange high speed from Obermeyer barrel

James Jones · #1 04-24-2006, 08:25 AM

I did some load development for a new 300Win mag I have , it s Sako L691 action barreled with a 25" 1-11 twist Obermeyer barrel. I worked up a load for the 190gr Breger VLD's and ended up with 81grs of H-1000 with a velocity of 3206fps avarage !!! the bullets were seated into the lands .005" and the brass is once fired neck sized Lapua lit by a CCI-BR2 primer.
Their are no pressure signs on the case at all the primmers took seemingly the same pressure to pop out as any other load and the I even miced the case just above the belt and it showed only .002" expansion over the unfired cases.
I checked the velocity against two other rifles that have a known velocity and they are the same as when I worked them up. This is a compressed load and the bullets are seated into the lands which to me would think that the pressure would be higher faster.

I know that some barrels are a little faster than others and that the 5R barrels are a little faster than conventional barrles but damn this seems a little over what it should be , I was hoping for 3000fps.
This is the only Obermeyer barrel I have ever delt with and to say the least I'm amazed with the speed and the accuracy which the groups for this load are just under 1" at 300yds.

Anybody have any ideas on what could be causing this.

sambo3006 · #2 04-24-2006, 03:06 PM

Do these bullets have a long bearing surface? That could contribute to high pressures along with seating into the rifling. If you are getting that high of vlocity, your pressures almost assuredly have to be high as well. Hogdon lists 81 gr of H1000 as max with 180 gr and 79 gr as max for 200 gr. so you are a grain or so above the book max for a 190 gr loaded to SAAMI length. Of course, every bullet will produce different pressures based on shape, but if I had to guess, I would say again that your pressures are probably too high. I would think that 3000 to maybe 3100 fps would be achievable with your bullet in that cartridge at safe pressures.
I'm sure you will get some more input from others who have more knowledge than me, but hope this helps.

James Jones · #3 04-24-2006, 05:06 PM

Sambo3006 , thats exactly what I was thinking the Berger VLD's don't have to long of a bearing surface less then a SMK , the jackets are thiner and I'm pretty sure that the lead is softer.
I would surely assume that I'm way over pressure with this velocity but I'm not getting any signs out of it at all.

I don't know it has me baffeled , I'm gonna back off a full grain as the accuracy and ES was about the same just a little slower, but still alot faster than expected

Jimm · #4 04-24-2006, 07:17 PM

Dang JD,

The lottery falls in your lap and you are ........complaining [img]/ubbthreads/images/graemlins/laugh.gif[/img]

Take it like it comes , oh yeah , say your thanks when it goes your way ! [img]/ubbthreads/images/graemlins/grin.gif[/img] [img]/ubbthreads/images/graemlins/laugh.gif[/img]

Jim B.

Meister · #5 04-24-2006, 07:27 PM

5R strikes again... Gotta love those Obermeyer sticks!

Carbonman · #6 04-24-2006, 11:51 PM

Boots Obermeyer barrel's have as small as a .299 bore and .3075 groove. The tight bores really squirt them out.

James Jones · #7 04-25-2006, 04:31 AM

I know that a tighter bore can help with the velocity but man that seems a little high

DOn't get me wrong , I'm not complaining about the extra speed , it just has me concerned , the physics say that the pressure has to be higher, but thier are no signs of it

I'm gonna back down the load and test several other bullets soon so see if the slugs could be the issue