what is wrong, strange accuracy problem

[artemistrad]

Hi, today I tested two loads for my 5,6x50Rmag.
First load 27,5grain Benchmark in RWS cartridge and 50gr Barnes TTSX bullet
Second same setting but 28grain Benchmark also bulletjump by both was same!!

The first load, nice grouping
Second load big spreading but for all more then 10inch lower then the first load???? How can that be? What's wrong? How can a half grain more charge give les speed and so dramatically spread??? Is the bullet not taking the lands? Still the holes in the paper were nicely round! Who can help me,what is happening here???

 

[Reloader222]

In my opinion the second load combination has a much lower velocity and due to this this bullet did not stabilize well enough to give you a good grouping. Do you perhaps have a chronograph to measure the speed?

 

[artemistrad]

Hi, thanks for your reply! No I have not the possibility to measure the speed!!

 

[artemistrad]

I know that this load is very much to the top max possible!

 

[Dosh]

Arte, the most accurate load sometimes is a bit below the max. Your load of 27.5 grains indicates a lower charge was more accurate. Since you have no means of measuring velocity, experiment with charge weight first and seating after. Veel Guluk

 

[artemistrad]

Thanks, will work on that lower load. Misschien heb ik geluk!? Gr Mark

 

[MagnumManiac]

In my experience when more powder gives less velocity and big dispersion in bullet impact, the max pressure has probably been exceeded.
The other reason that the bullet impact changes is due to barrel harmonics, the lower impact shows that the accurate load was exiting the bullet at the top of the barrel whip, and the inaccurate load was exiting at the bottom of the barrel whip.

Just my theory.

Cheers.
gun)

 

[FearNoWind]

Well, Arte, I'd say you've already gotten lucky. If you're grouping well with the lower powder charge there's no reason to push the envelope. Faster is not always better.

 

[dkhunt14]

The second load may be faster. If the gun is sighted in at a certain distance and you shoot a faster load it will go lower because the trajectory is flatter. If you have a rifle with a scope and it is sighted in at 100 and you shoot a faster load it goes lower with no scope change. Matt

 

[artemistrad]

Hi Matt, can believe that by a big load difference but not by 0,5grains...and then 10" lower? gr Mark

 

[dkhunt14]

What yardage are you shooting at? Is the gun scoped? I am not familiar with that cartridge. But faster loads at short range shoot lower, because they are flatter. That does sound like a lot. Matt

 

[artemistrad]

Hi, the gun is scoped, and sighted in at 100meter. The cartridge is between a .223 and .22-250 so a very fast cartridge. Gr mark

 

[artemistrad]

Well experimenting some time now, different loads and different bulletjump's no accuracy that's acceptable. If there are some suggestions, please be welcome! Maybe my gun never will be accepting the ttsx-bullets.

 

[just country]

Morning. Barnes bullets pushed at top velocities some times foul barrels. I shoot the same bullet in my 22-250 AI. I shoot 27.5grs of tac powder. I increases the powder charge .5grms. and the bullet went crazy. I backed off the charge and bullet went back to .250. The depth of the bullets to the lands and grooves definitely effect the barnes bullets. I also shoot the 55gr. Nosler Black bullets. very good bullet. Barrel Harmonics could play a roll in the crazy accuracy. I am not being a SA but check the scope mounting. Thank u for listening.gun)