CHRONO RESULTS...308WIN....PUZZLING

[sargeny1]

Hi all...finally got myself a chrono - rcbs - seems to work fine..last week tested my handguns...no surprises...

Yesterday .... Ed Brown Marine Sniper..308Win..24" KREIGER BBL..built in 2000...jewell trigger and Swarovski 4x16.....ALWAYS shot no larger than .5"....OK..

Load # 1 Varget 44gr. cci br2..Nosler 165gr. Partition..Lapua Case once fired...2.810" OAL
High 2677fps Low 2659fps Avg 2666fps ES 18 SD 8

Load #2 Same as above BUT 45gr Varget:
5 shot group >>>!!
High 2745fps Low 2745fps..Avg 2745 es 0 sd 0...!!!?????

Load # 3 Same as above BUT 46gr Varget...a MAX Load in Nosler #6 Manual....

High 2811fps Low 2782fps Avg 2798fps ES 29 SD 12...

Max Load seems High in pressure...primers starting to flatten a little..and I can see chamber reamer marks halfway around the cases just above the pressure ring.....

I DID NOT shoot these loads for accuracy...just FPS...
I'm close to the speeds in the Nosler manual...and am just wondering about that 45gr load....maybe I hit a sweet spot..??? The recoil was very mild and the rifle came straight back and the crosshair stayed dead on the the 100yd aiming spot....temp was 72deg...sunny...all groups were 5 shot and I allowed the rifle to cool thoroughly between ALL shots....
I was hoping for a little more velocity from that 24" Kreiger bbl. but I guess 2745fps is not tooooo shabby...???????

What say ye learned gentlemen...????

Thanks..
Pete :roll:

 

[DrMike]

Your velocities seem in line with what I would anticipate. All of your loads give good SD. It is entirely possible that your results on the 45 grain load is an artifact. However, it is possibly still a good load, even if further testing reveals a bit of a spread in velocities. I'd likely focus on that load, shooting another series with ten rounds to get a true reading of both velocity and accuracy. Good data and your loads demonstrate excellent technique with great consistency. Congratulations.

 

[martineta]

Got my attention. Might have to pick up a lb of Varget.

 

[CatskillCrawler]

Those velocities seem to be just right for .308Win and a 165gr bullet. That is a rather remarkable string of consistency. I'm enjoying the added insight a new chrony adds to your range sessions too.

I've found Varget to be very consistent in 7mm-08's so your results don't surprise me . Good stuff it is.

 

[rjm158]

I've had great results using Varget in every caliber based on the .308 case (except 338 Federal but that's a rifle problem.) It's also worked pretty good in some of the long action calibers like 30-06 with light bullets.

Ron

 

[Guy Miner]

Very similar velocity to what I'm getting from my 24" Krieger .308 Win and Varget.

BTW, for about 12 years, and several barrels, I've been using 45 grains of Varget with 165 & 168 grain bullets.

Guy

 

[SJB358]

I can't find much other than RL15 that rivals Varget in accuracy and speed in the 308 with 150's and 165's. I get around 2900 out of the 150's and 2750 or so with 165's. Your speeds seem to be right in line. Scotty

 

[FOTIS]

Load #2 chrony results seem questionable to me. I never had that happen. However the actual velocity range does sound good.

Varget is a great powder.

 

[DrMike]

I've actually had (on two occasions) three-shot loads that gave identical readings. However, upon subsequent testing, the spread was revealed to be greater than zero. That is why I would argue that the results are an artifact in this instance. It is always possible that the reading was flawed and he only got one reading out of the test shots, in which case a Chrony (at least) would indicate a velocity with a SD of zero. From the standpoint of a chronograph, the first shot is always perfect.

 

[.300RUM]

I would shoot 2 more 5 shot groups with load #2, I would bet my left thumb that it comes up with a greater spread. In any case, varget is great, if the accuracy for any of those at the velocity you want is not to your standards, you might also try Ramshot BigGame, one of my very good friends has a load of BigGame that shoots 165's about 2800-2850 fps, and his rifle likes it alot.

 

[Oldtrader3]

That is what is known as a "degrees of freedom issues". The sample size is too small to find the full expected range of variability but it is there. It may take a few more shots to find it, maybe as many as 30 bullets but it is there somewhere.

 

[ElmerThud]

It's great to achieve a minimal extreme spread and really what everyone looks for, especially of the load that works producing a good tight group.
The books are there for indications and remember the manual figures are determined following exacting & consistent procedures in a lab.
Your own readings are for you, with your rifle and loads.....but not necessarily to laboratory standards. It's clear that without an identical setup to the lab. - you can't exactly match the data from your own load.
So, as long as the velocities are sufficient, providing the terminal energy to do the job whether target shooting or hunting specific game, IMO a tight group comes first, then check the velocities (& hope they're good for purpose, otherwise it's try agin time).
Cheers, ET

 

[Oldtrader3]

True, Elmer, but you should observe variability as reflected by a standard deviation number which may not be the same as the derived lab number for a large sample but it shoild be a positive number that is not zero, none-the-less. There is no such thing as zero distibution with a bullet being fired by slightly different loads shot from a rifle which are flying at 2700 fps. The SD number although relative, is also a useful tool for analysing the predicted spread of velocities between loads which often indicates a higher accuracy potential with that load.

 

[Larry in SD]

With my 20" Remington Model 700 SPS (SPS Sporter shortened to 20") I ended up loading 45.0grs. of Varget with 165gr. Nosler Ballistic Tips (and Partitions) as the load of choice. My .308 didn't like 150's at all.

My average velocity for 25 rounds over the chronograph for the Ballistic Tips was 2612 FPS from the 20" Barrel and 2620 FPS for the Partitions from the 20" Barrel. I'd have to pull my sheet to check what the extreme spread and standard deviations were.

Larry