6.5 CM 123SMK at 3000fps, chrono error?

[SquarePizza]

I loaded up some 123gr SMKs over 39.0 grains of IMR4895 today and chrono'd them at 3019fps out of my trg 22 with a 24" barrel. Hodgdon's data states 2896fps from a max load of 39.2 grains of 4895.

Could my loads really be going that fast vs the published data?

Chrono is a basic competition electronics at 20feet or so. In the past the speeds I have gotten were expected/in range with published data and mostly confirmed by my recorded DOPE. This new load is the only time i've had cause to question my findings.

 

[TheOE800]

My 26” AINA Bartlein shot factory 130gr at 2900fps, just as a datapoint.

 

[mick243]

Hogdons data reflects the result they got from their test barrel and that particular powder lot on the day they tested…. Maybe they had a slower than average barrel and yours is faster than average, maybe they tested on a colder day, maybe maybe maybe…. Take velocity data from reloading data guides with a grain of salt….

 

[beetroot]

My 24" CTR will do 130s at 2925fps

 

[Doom]

Typically test data performed to SAAMI specs will be higher than those experienced in typical commercial rifles. Custom chambers can change that. I would shot that load again and see what speed you get assuming you haven’t seen any pressure signs.

 

[Cascade Hemi]

I loaded up some 123gr SMKs over 39.0 grains of IMR4895 today and chrono'd them at 3019fps out of my trg 22 with a 24" barrel. Hodgdon's data states 2896fps from a max load of 39.2 grains of 4895.

Could my loads really be going that fast vs the published data?

Chrono is a basic competition electronics at 20feet or so. In the past the speeds I have gotten were expected/in range with published data and mostly confirmed by my recorded DOPE. This new load is the only time i've had cause to question my findings.

Yes it is possible. Your chronograph is also telling you your load and rifle combination is generating a lot more pressure than what was used for the load data. Match your velocity to the same data velocity and that will be your correlated pressure. QL says you're around 66kPSI. I would back down your charge weight until you match the velocity you were expecting.

 

[308sako]

My 24" CTR will do 130s at 2925fps

24" Wiseman barreled Sako sporter: 123 A-Max / 44.0 grains of Winchester 760/Hornady brass/Federal 210 = 3099 ft/sec

YMMV of course this load was worked up to incrementally and what is safe in my system could possibly blow yours to hell so do your homework.

 

[SquarePizza]

I see zero signs in the federal brass or CCI primers of pressure. There is no difference in the brass between 37.5grains 4895 and 39.0grs.

37.5 gives me 2860fps, but has a larger extreme spread and standard deviation than the hotter 39.0

At the end of the day though, I may go with the 37.5 simply because IMR4895 is a little more temperature sensitive than I am used to with varget, and I don't want heavier loads heating up too much during a PRS match.

 

[Cascade Hemi]

You chronograph is your pressure sign. Velocity is a byproduct of pressure.

 

[Twitchy]

Using Peterson brass, SRP, RL16, 123g ELDs, I was able to get them upwards of 3200ish in testing. I used them closer to 3050 for matches. This was out of a 29" barrel.

I've also used 142g SMKs at 2900ish out of the same barrel.




I've been known to "push the limits" with my reloading sometimes.

 

[918v]

I see zero signs in the federal brass or CCI primers of pressure. There is no difference in the brass between 37.5grains 4895 and 39.0grs.

What about the primer pockets? Did they get looser?

 

[Heffo]

All good I’ve had 3050fps with 123s 26” barrel and 43.6gr H4350.