Need help. Not getting advertised velocity.

[Evilaviator]

RRA AR15 National Match 20" with Wylde cut chamber
WW new brass
Remington 7 1/2 BR primers
Sierra 77gMK
22gr Varget
Seated OAL 2.250
200/300yd load
Five shot string velocities:
2420
2421
2443
2451
2489
ES 69
SD 25.1

The other test was with a Sierra 80grMK loaded with 23.5gr of Varget and set to jump .005 The data from that was:
2604
2627
2660
2587
2593
ES 73
SD 26.6

This is a brand new rifle testing brand new loads. From what others have been posting, seems like I am down a few hundred fps from what everyone else is getting for the 77gr Sierra magazine length load. The 80gr Sierra load doesn't seem to be that far off. The only thing that I can figure is that my CED M2 is inaccurate.

Any suggestions or probable causes for the low velocity readings on my 200/300yrd load? Is 2700fps the number I should be shooting for?

BTW, right or wrong i worked up to these loads from Glen Zediker's recommendation. He's advertising @2650fps for these loads.

 

[Queequeg]

Re: Need help. Not getting advertised velocity.

It appears you could get more oomph by adding powder as the Hodgdon manual lists max Varget load for the 80 gr SMK at 25 grains of Varget at a listed 2869 fps and 51,000 psi.

Are you getting any pressure sign from the present loads that would prevent you from continuing to work up?

 

[Evilaviator]

Re: Need help. Not getting advertised velocity.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: queequeg</div><div class="ubbcode-body">It appears you could get more oomph by adding powder as the Hodgdon manual lists max Varget load for the 80 gr SMK at 25 grains of Varget at a listed 2869 fps and 51,000 psi.

Are you getting any pressure sign from the present loads that would prevent you from continuing to work up? </div></div>

No that will be my next step. But it seems that most across the course shooters are using 23.5gr varget for their accuracy loads. I'm not too disappointed in my 600yd numbers. Its my 200/300yrd magazine length load that has me scratching my head. Seems like should be seeing closer to 2600fps from that.

 

[mattmcg]

Re: Need help. Not getting advertised velocity.

Sounds like you are trying to develop the best load for your rifle based upon reading other people's loads on the 'net. Bad idea.

Stick to the fundamentals. Find a recipe in one of the major reloading manuals starting with a minimum and give it a try (as you have done). Then start increasing the load in .5 grain increments (or .3 depending upon your level of patience) until you witness signs of over pressure. Then back off in .2 grain increments until you settle in on an accurate load that you're happy with. Once complete, log it and load it!

 

[mattmcg]

Re: Need help. Not getting advertised velocity.

And since you mentioned that your CED M2 might be giving erroneous results, figured I would pass this info along as well. I have on certain occasions seen the M2 read too low if I have the device too close to the muzzle of the rifle. When this happened, I just move the CED out another two foot or so and problem solved.

Not sure why this is the case but am thinking that perhaps gasses or burnt powder are being read by the device causing the lower readings. Might be worth a try also although it sounds like you need to work up your loads as well.

 

[Pthfndr-CA]

Re: Need help. Not getting advertised velocity.

You should be able to go to 23.5-24.0gr for the 77s.

24-24.5 for the 80s. I use 24.5 of RL15 for my 80gr loads, no problems at all even when it's 100 degrees.

 

[BHP9]

Re: Need help. Not getting advertised velocity.

Run the reloads over the chrono using a bolt gun.

 

[Grump]

Re: Need help. Not getting advertised velocity.

22 grains of Varget under a 77-gr HPBT is LIGHT, and your velocities are right where I would expect them to be.

I was running 23.5, but I don't have my notes handy. Been clearing out other parts of the garage, so the reloading stacks are buried.

 

[Sig685]

Re: Need help. Not getting advertised velocity.

22gr Varget for 77SMK IS very light. Varget likes to fill cases; I find it's more consistent towards the top end.

For the 77SMK, I go easy on the powder at 24.5 gr Varget. MV: 2740FPS.

For the 80gr in my LR load, I load more Varget. MV: 2850fps.

Edited to remove the 80gr load. I take extra steps to control the pressure and this is an above max load. I'm not sure this is something you do.

 

[Evilaviator]

Re: Need help. Not getting advertised velocity.

Ok range update. Worked up some more loads for the 77 and 80gr SMK.

77gr SMK:

OAL 2.255
24.0gr Varget
Avg Vel 2644
ES of 15.0

Very nice load. Didn't bother going higher than 24gr. No pressure signs that I could tell.

80gr SMK

.010 jump
25.0gr Varget
Avg Vel 2730

No signs of over pressuring with this load. Only shot two rounds of this charge because I honestly thought the rifle was going to start spitting primers. Seemed like the 24.5gr was the best for this bullet. It yielded 2680fps with ES of 7. Also, I would feel very comfortable knowing that I have a cushion staying in a safe load zone.

Im trying to decide if 25.0gr for the 80gr would be ok, but to be honest im kinda worried about pushing it higher than that to see where I start getting pressure signs. Seems to me from what I've been reading all over the place that 24.5 is a sweet spot.