6 dasher velocity by the inch

[robbor]

Are there any charts out there that show dasher or br velocity for barrels cut down by the inch???

 

[expiper]

I have never taken one specific Barrel and cut it off and shorten it repeatedly to give you a direct answer to your question but I do have 6BR Barrels from 20 inches to 30 inches in length and 2 inch increments. The 20-22 and 24 inch barrels are all either 14 or 13 inch twist,, the 26-28 and 30 inch barrels are all 8 twist,,,, I have shot the same bullet and powder combination in all of these various length barrels, and whatever worked great in the short barrels also worked great in the longer Barrels, even though there was a velocity difference .... I have used various 65 and 68 grain Bullets and Vita Vouri 133 and also LT 32 powder..... I used Powder charges that worked good in the short range Barrels and got excellent accuracy out of the long range Barrels also and from the shortest barrel to the longest barrel, I got about 150 ft./s increased velocity and the corresponding accuracy for the intermediate Barrels was Progressive as it should have been..... so you can do the math it increased approximately 15 to 20 ft./s per inch of barrel length more prevalent in the shorter barrel and then there's a Barrels got longer the LT 32 gained about 20 ft./s per inch...... this caused me to draw a conclusion that seems to be counter to what the popular theories are of velocity nodes giving ultimate accuracy. I feel as though it's a pressure node that we're looking for to give good accuracy...... once the breach pressure is high enough to burn the powder cleanly no matter how long the barrel, and even if the velocity increases as it should, the accuracy stays there.... you hear people say the magic velocity for a true Benchrest rifle should be around 3350 ft./s with a 68 green bullet and this is true but the same bullet with the same powder charge at 3500 ft./s in a longer barrel is still supreme accuracy, so it must be the pressure and the clean burning of the powder that gives the good accuracy rather than X amount of feet per second,,,,, I hope this gives you food for thought and I also have answered your question...... Roger
PS,, when warm weather comes back this spring I plan on shooting 105 grain bullets in all of the various Barrel links however, I realize the 14 and 13 twist barrels won't stabilize these bullets but I would get an idea of the muzzle velocity no matter how inaccurate they might be because of the slow twist.....

 

[charlie b]

You can make up a chart using data from Quickload or GRT. Just put in the load data. Change barrel length and write down vel.

GRT for 6BR, 105VLD, 29.2gn N540, 2.33oal

bbl vel
32 2938
30 2905
28 2868
26 2828
24 2782

 

[Frankm]

I ve often wondered too whether nodes are more pressure related nodes vs velocity related nodes ….