6.5/.284

[Newt]

loading 54 grains of H4831SC, Lapua brass, fed 210 primers,new 27" Hart barrel. Why am I consistently chronographing only 2480 fps ???

 

[280man]

good question have you ever had any problems with your chrono? My Hart barreled 6.5x284 seems to be right inline with what is considered "normal" speeds

 

[cliffe]

double check that scale! i just started trying h 100v at 49 gr. ave. speed 3006. was shooting h4350 at 47.5, ave. speed 2844. 54 gr. of h4831 seems like alot of powder.

 

[Rtheurer]

51.5 of 4831SC gives me 2940fps in this Broughton 30" The last barrel gave me 2970 with 52.4 of 4831SC and a 30" Rock Creek

The Broughton Before was 53gr 4831SC 2987fps

Somthing is not right, Chrono or scale or somthing.

Might want to barrow some stuff from a freind to double check things.

RT

 

[RichAllen]

You got some good advice, get another chron.
54 grains of 4831SC is about 2 grains more than the biggest load i've ever heard of used in 6.5x284

I'm not questioning your knowledge about the load just the amount of grains. I'm using 50.5 grains getting 2940 fps,unfired brass) and 3025 using 51.5 grns,fire formed).

 

[JohnRodriguez]

I use 51.3gr of H4831sc and get 2933fps out of my savage 12F-class. when I first started cronied my loads, I was not sure if muzzle blast was affecting my readings so I did some 200 yard readings and was getting 2650fps readings which is consistant for my load. you might try doing a 100 or 200 yard readings and working a backwards with a ballistic calculator to figure out your muzzle velocity.

 

[BarryL]

I hit some serious pressure signs at 52gr. so something is definatly wrong there. 51.8 is my sweet spot with H4831sc, Fed210M, Lapua brass and Sierra 142's and if I recall Im at 2940fps with a 26 1/2" 1-8 1/2 twist.

 

[243Mendoza]

You got some good advice, get another chron.
54 grains of 4831SC is about 2 grains more than the biggest load i've ever heard of used in 6.5x284

I'm not questioning your knowledge about the load just the amount of grains. I'm using 50.5 grains getting 2940 fps,unfired brass) and 3025 using 51.5 grns,fire formed).

I think it depends on your chambering. A friend uses 53-54 grs of 4831SC and gets 2950-3000fps.

 

[cliffe]

hey, whatever happened to newt??? wonder if he got that problem resolved??? hey steve, he said he was shooting 54 gr. of h4831sc and only getting 2480fps.alot of powder to me, for 2480 fps. don'tcha think. cliffe

 

[BarryL]

I would be curious to find out how things went. Im going to guess an inaccurate scale but I do think on a very short barrel excess powder could just burn out the end before serious pressure signs appeared. Or a very sloppy chamber.

 

[243Mendoza]

hey, whatever happened to newt??? wonder if he got that problem resolved??? hey steve, he said he was shooting 54 gr. of h4831sc and only getting 2480fps.alot of powder to me, for 2480 fps. don'tcha think. cliffe

2480fps is VERY low. Maybe a typo and he meant 2840fps which is still low but within the errors mentioned below:

1)I'd check the chrono as other people have said
2)make sure the the powder is H4831SC
3)check the balance with check weights
4)check the bullet seating depth
5)check the throat for wear