Chronograph DO i NEED ONE

[finnbear270]

chrony

Just yesterday I took my chrony to the sand quarry to check zero the foxing rig, & find out what the Sako .270 is doing with it's current load, figures were averaging 33fps short of 3000 with the .270 using a Nosler 130grain partition over 59.5 grains H4831 in Nosler custom brass with cci large rifle primer, groups achieved off the top of the truck, not bags, were five shots into a two p piece @ 100 yds, so the rest of the brass will be loaded out the same,Tikka M595 .223 foxing rig has been used for a long time with it's current load and been found very accurate bearing out Vihtavuori's claims for an accuracy load, this load has been found to be interchangeable in this rifle with 40grain Nosler bt/Hornady 52grain Amax/Hornady 50grain molyVmax, 24.8grains N133, cci small rifle primers, lapua match or Lapua .223 brass & also some mixed brass, 3400 fps was very consistent showing around 9fps variation, six round groups were all touching with poi set at 1.5 inches high @ 100yds. All in I think a very good use of a saturday afternoon.

 

[Muir]

Nice! I like it when a load performs well. I do a lot of chronographing as I calculate ballistic coeffecients of all the bullets I use, as well as testing of some ammunition for commercial outfits. It often seems like a waste of a good bullet to just send it over a screen into paper, but you can learn reams.

An interesting thing to do is to start off at 5% below minimum (powder allowing) and work your way up slowly towards maximum while chronographing. You will be at MAX for your rifle when adding powder shows no significant gain in velocity. Since the pressure/velocity curve is just that; a curve, you can expect the velocity increase to slow as you reach maximum effeciency. There are many commercial, over-bore cartridges that will show insignificant velocity gains throughout the upper end of recommended charge weights for a given powder. If you analyse this data with the eye towards effeciency, you can choose whether or not putting another 2.5 grains of powder is into a case is worth 125 fps; saving powder and wear on the brass, barrel and breech. Making a "Charge Weight/Velocity" graph with each powder and bullet weight is an interesting thing to have around on a cold winter night when you're reviewing your data. Just my ramblings...~Muir

 

[wise man]

chorie

all right . the best thing to do if your in to reloading . Yes its a must to know what your load is doing i will not boar you with that. Get you and a coulp of mates thats in to loadind and throw in to help with the cost. All yous can share becouse you will only need that chromie one or two times . just a wee bit a thawt.

 

[Muir]

Aye! An the firse un tha puts a bullet thru the thing buyes the next! ~Muir