ORIGINAL: gleason.chapman
ORIGINAL: jaw3
Is there a source that recommends velocity for a given weight/type bullet.
If I load a 330 gr Harvester sabot with 90 gr 777 I get about 1550 fps.
If I load a 280 gr Harvester sabot with 90 gr 777 I get about 1650 fps. I'm just starting this quest for
velocity, ft-lbs accuracy quest, but wonder if the increase charge is worth the extra vel or should the
defining fact be when the group starts to open?
Any thoughts?
Regards,
You need to know the ballistic coefficient of the bullet. Usually on the manufacturer's web site or "Google is your best friend". Example lets do 330g Harvester on their web site, here it is:
http://www.harvestermuzzleloading.com/index.php?view=article&catid=3%3Asaber-tooth&id=3%3Asaber-tooth-load-data&option=com_content&Itemid=4
You can see by the load data that 10g of powder is getting you only 50 more fps, approximately. The
Saber Tooth is shaped like a XTP, so I think it is going to have a ballistic Coefficient like a 330g XTP
http://www.nfa.ca/nfafiles/cfjarchive/ballistics/bcchart.doc#C45
which is .180 for the 300g XTP, so drop the values .180, 330 and 1550 in a balistic program and sight in at 145 yards for about a 3" high at 100.
Here is a Screencast on how to run a ballistics program:
http://screencast.com/t/NGC51UoF2Sg
Chap
Chappie"s Guesstimate of BC is very very close if you were shooting them at 2100 FPS!
, I will take the time later to transfer a post from another site to here where I shot the 330's with 2 different charges and used a crony at the bench and backstop.
Using "load from a disc" BC calculator based on known velocity at the bench and 103 yard distance the BC for a load that averaged 2110FPS at the muzzle was .180/ then normalized by conditions at the time it was shot to a BC of .178.
Using the same program but with a Muzzle velocity average of 1715 FPS the BC was .197/ normalized by conditions to .195.
Yes it is a known Fact that the BC of a projectile changes with Velocity, take a look at Seirra's web site they list the BC at 4 different velocity's for some of their projos!
IMHO you are shooting 2 of the finest Hard cast Boolitzs ever made to cleanly harvest anything on this Globe.
Tell us about your Rifle, will it shot BH209? My 22" Knight T-bolt crony's 1778 FPS average with 105 grv of BH209.
IMHO 1700 to 1800 will be the best velocity to shoot these wide Metplat Boolitzs.
but you can't go wrong at 1550 to 1650 either! the BC will be higher, You don't need hyper velocity with a properly designed Boolit.
The Fellow that actualy made the molds for these Bullets (Veral Smith ) told me that a striking velocity of 1500 would be a ideal, and let you eat right up to the Boolit hole. to drive them faster would just ruen a lot of good eaten. The folks that shot these out of Pistols find that 1000 to 1275 FPS is egualy deadly. It is also known that to drive them to fast causes a diminishing return on results.
IMHO, The Boolit you have described is in it's perfect shape before it leaves the muzzle. It has been said that Craig Bodington loves to find a bullet with a nice mushroom and long shank. Well, the WFN/LFN Hard Cast Boolit, is just that! Cast Boolit Shooters already know that there boolit is just what Craig likes, only it started life that way and doesn't have to go threw some uncontroled varying medium to make it such. A nice Mushroom is nothing but a wide metplat. IMHO The Boolitzs you have choosen are perfect for all occasions. they already meet CB's perfect bullet criteria and they woun't change shape because they are Hard cast, as they travel threw any game animal. They will just work like CB's perfect Boolit.