Sticks Wrote:I am shooting a 18" Barlitien, which is stabilized at 2475 for ELD, Amax, and SST (123gr).

jackwagon Wrote:Thanks Sticks. Is your barrel a 1:8 twist also?

grayfox Wrote:Barrels can and do differ, I have 1 18"-er that's fast (the Amax and SST's run 2510 in mine) but the Hdy Black runs slower, I don't know why but that's what it is.
So the chrono is really worth it to you. Especially if you want to reload.
Just a thought.

grayfox Wrote:To get real good data... might as well admit it... try to get a chrono. I know there are several but I use a magnetospeed and it's been super.
And range-friendly and sun/clouds-INsensitive.
Barrels can and do differ, I have 1 18"-er that's fast (the Amax and SST's run 2510 in mine) but the Hdy Black runs slower, I don't know why but that's what it is.
So the chrono is really worth it to you. Especially if you want to reload.
Just a thought.

VASCAR2 Wrote:What part of Indiana are you in Jackwagon? I live close to Vincennes Indiana only on the other side of the river. I have a PACT chronograph and a Friend has a Magnetospeed chronograph.

Sticks Wrote:Yes it is



Best advice here. A simple Chrono will run you $99 or so, then you will have accurate info on what your rifle does with each ammo. Extrapolating data from other users with the same barrel length, twist, and hopefully the same mfg as yours will get you close, then you can dial it in shooting long range (500y or more).

J.Boyette Wrote:@jackwaggon,

Typically 50fps per inch is the normal measurement for going up or down for barrel est...

VASCAR2 Wrote:When I've chronographed factory 123 grain A-Max it averaged 2464 FPS out of a Brownell's 18" Grendel II chamber (Satern/Liberty barrel) 1:8 twist on a 70 degree day. The Hornady 123 grain SST Factory averaged 2490 the same day with Magneto Speed Chronograph.

Here is a picture of the velocity curve LRRPF52 has posted from the Grendel handbooks.

Klem Wrote:What you could do that is more precise is shoot groups at your 750yd range and note the drop.

Zero for 100 and then record the drop for each 100 beyond that. Or, if ammo and time is a factor shoot a few groups at 300 and 700yds. Then play around with Strelok to predict the velocity by matching the actual drops to a particular velocity. Normally we determine velocity first and use that to predict drop at various distances. This way you are doing it the reverse.

Kestrel's with Applied Ballistics have a feature where you enter the chronographed velocity, shoot at a known distance and notice the difference between the predicted drop and actual drop. Then return to the kestrel and enter this difference to fine-tine your velocity. This is because all chronographs come with a margin of error. The Chony I use states it can be up to 5% error. Add to that any further error from the way it is set up on the day and it's unlikely the chronograph is going to exact. 5% of 2,500fps is 125fps which is a fair error and might explain why your bullets don't land exactly where your ballistics program says they should land. I don't know if Strelok has a similar feature to Applied Ballistics and maybe someone else can chime in here.

But...the other guys are right, you will need a chronograph at some stage if you ever want to do meaningful load development.

Klem Wrote:'3-hr drive each way', that's dedication.

What did you have to dial to get on 500? And where did it land relative to the Point of Aim?

jackwagon Wrote:Klem, the Strelok app says 3.92 MRAD /70.55''/ 39.2 clicks I dialed this in initially but never saw any signs of impact, instead of wasting ammo I went back to zero on the scope and held at the 4 mil mark ( SWFA 10X42) so none of my hits were dialed. When I held at the very tip of the triangle at 4 mil mark I was hitting every time. Precision...probably not, acceptable to me...yep