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

How many shots in that number 2 string?

Wow id go out and buy a lotto ticket, what are the odds of that happening?

I dont even own a chronograph, but I do know that must be pretty rare.

A minimum of 7 shots is recognised as being the minimum for confidence in the results. ten shot test strings are standard with SAAMI. A 3 shot test string just gives you a taste of what may be. A 5 shot test string gives you an idea. Best to use 10 shot test strings to be sure.

I use Varget with my 175 MK match loads in my 26" barreled M70 Target with a schneider barrel. I use 45 gr in WW Palma cases and 44.5 gr in LC Match cases. It is not uncommon for me to have several shots in a 10 shot string to be the same velocity with the 2' screen spacing of my M35P Oehler. However when I use the 4' spacing a better picture of actual velocities is given. A 10' spacing gives the best results but is more of a PITA to set up and use. With the 10' spacing each "count of the crystal used in chronographs is less that 2 fps in the 2650 - 2700 fps range. With the 2' spacing each count is is close to 7 - 8 fps. Thus with the shorter spacing of the RCBS chronograph and only a 5 shot string it is very probable that the exact velocity of all 5 shots of the 45 gr Varget load were not exactly 2745 fps. Probably close but not exact.

Your velocities are in line with what to expect from your 24" barrel and the short screen spacing of the RCBS chronograph with the 5 shot test strings shown.

Larry Gibson

Test this again a few more times and let us know what the results are.

If the load is good I'd guess you will get SD's in the single digits again.

When I see 5 shots all reading the same, it usually means the chrony only read one shot...

quote:

Originally posted by Antelope Sniper:
When I see 5 shots all reading the same, it usually means the chrony only read one shot...

Yup! How many shots actually registered on the chrony? While I don't have an RCBS unit, there should be a routine to scroll thru the velocity of each shot in a string. I'd bet that, for some reason, it only registered one shot. Redo the entire load with 10 shots & write down each vel. reading as well.
Bear in Fairbanks

Thats what I was thinking that it onle read the frist one.

like lots of interesting facts, many people see them and reject them.

does your chrony error if it miss reads?

and yes, you can have LESS vel with more powder.. and can REPEAT it over your chronograph.. but poeple will argue with their own eyes