That first cartridge you shoot may not clear the barrel, but you could probably set up the chrono in the house and be fine until you hit 3 grains of powderThey're all spendy
I'm gonna load up some 77 TMKs with Staball match in .5gr increments to around 24gr and see what velocity I get and where pressure is then try a group of 10 and see what happens.
Will post results later.
Here’s the load I settled on, work up slowly, it’s above max.
77 TMK
Lc brass
CCI 450
25 gr Staball Match
2.28 COAL
Approx. 2800fps, drops verified at 500
18” Suppressed Tikka
I think it’s all the same year, but I’m not entirely sure. I found a bag of new American Eagle 556 brass at a lgs last year and it’s all LC head stamped. It’s on its second firing.Do you have one year of LC or mixed?
Just something to watch out for, and maybe you already know this, but when the velocity drops as your working up a load: In this case that slight decrease from 25 grains to 25.2, it is often a warning sign that there is about to be a spike in pressure. I also saw what others mentioned about slightly flat primer and very slight cratering.Here's my results with match. Helps being able to shoot at the house right now.
loaded inside on a chargemaster lite and checked with an RCBS 502 scale so take listed weights for what their worth.
Loaded up 22 to 25gr. Had what looked like a slightly flat primer at 24.4g but it looked pretty comparable to some other loads so I kept going. With no other signs at 25gr I went back inside and loaded another at 25gr then 25.2, 25.4, and 25.6.
T3x with an 18.5" barrel, and a magnetospeed sporter strapped to a supressor with the sensitivity turned all the way up.
For reference I get 2710 with 24.3g of N140 and a 75gr ELD-M.
I'm guessing either Hodgdon load is extremely conservative, or the LC brass and Tikka being able to shoot 5.56 fine are letting me go over book max? I'm fine with ~2700 fps (I'd probably stop at 25 or 25.2 maybe...). Would anyone keep going though just to find max or would you guys stop there. I'm not extremely experienced so I'd rather not push it too far.
Just something to watch out for, and maybe you already know this, but when the velocity drops as your working up a load: In this case that slight decrease from 25 grains to 25.2, it is often a warning sign that there is about to be a spike in pressure. I also saw what others mentioned about slightly flat primer and very slight cratering.
FWIW, you ain't gonna blow up your Tikka with that load.I probably missed slight cratering at 25.6gr. At 25gr it doesn't catch my nail but it's hard to tell.
Based on that I'd probably back off to 24.5gr which would put me in the 2650fps range. At my elevation that's 1800fps around 400-425 yards.
L to R
24.3 N140 w/ 75 ELD-M -- 22gr Match 77TMK - 25gr Match 77TMK -- 25.6 gr Match 77 TMK
Danke.It’s max, so work up.
23.5 gr, CCI400 primer, R-P brass. I load really long, 1.940” BTO. That’s just barely touching the lands.
2915 fps
Edit to add, 24” barrel.
P
So... I was out last night shooting my RSS at 600 yds. 4.5 mils ended up being my come up for that distance. When I got home I started fiddling around with the ballistic calculators on Hornady's website (they're free, and I'm cheap). When I use the standard bc calculator I end up with a velocity of 2725fps. When I use the 4dof calculator with their profile for the 77 tmk I end up with a velocity of 2850. My question is which one do I believe? Most of the data from both calculators is within 0.2mils but that seems like a fairly large swing in velocity. My load is 25gr of leverevolution, 77tmk, federal 5.56 brass, federal 205 primer. Based on what I've seen here and elsewhere I'm more inclined to believe it's 2725fps especially since my barrel has been chopped to 20". What do you guys think?
I kind of figured it was something like that. I think I used a .410 bc as sierra's website lists different bc's for different velocities and I half ass guessed where the bullet would spend most of its time at that range.4dof produces wild outputs on non Hornady bullets. A .420 G1 BC works correctly.
Is this a compressed load?Here’s the load I settled on, work up slowly, it’s above max.
77 TMK
Lc brass
CCI 450
25 gr Staball Match
2.28 COAL
Approx. 2800fps, drops verified at 500
18” Suppressed Tikka