Non variable background:
Rifle: CZ 550
Caliber: .308
Barrel: 26″ heavy
Optics: Leupold Varix-II 3×9
Stock:H-S Precision Kevlar, barrel floated
Rings: Steel CZ
Todays variables:
Temp: 58 degrees
Weather: overcast, some wind
Distance: 100 yards, shooting seated from bench using ammo box as rest
Load data:
Cases: Rem. once fired, fireformed and neck sized, trimmed to 2.010″
Bullet 1) 30 rounds using Speer 165 gr. BT SP
Bullet 2) 10 rounds using Nosler Ballistic Tip 165 gr.
Powder: 41.5 gr. IMR 4895 run through a Redding BR3 measure
Primer: CCI LR
OAL: 2.807″ with Speer, 2.812″ with Nosler
I measure from the two most distant holes in the paper, inside edge of one to outside edge of the other (which averages to a center-to-center measurement) in fractions. For figuring mathematical averages Im converting them to decimal.
| Group # | Four shots | Three shots (omit flyer) |
Comment |
| 1 | 1.875″ | 0.75″ | |
| 2 | 1.25″ | 0.50″ | |
| 3 | 2.25″ | 1.25″ | Horizontal stringing |
| 4 | 1.125″ | 0.50″ | |
| 5 | 2.25″ | 0.938″ | |
| 6 | 1.75″ | 1.625″ | Nosler load |
| 7 | 1.75″ | 0.50″ | Nosler load |
| 8 | 1.25″ | 0.75″ | |
| 9 | 1.75″ | 1.50″ | Horizontal stringing |
And, just for fun:
Average 4-shot group using Speer: 1.37″
Average 3-shot group using Speer: 0.884″
Average 4-shot group using Nosler: 1.75″
Average 3-shot group using Nosler: 1.0625″
Yes, hardly scientific since the sample groups were different in size, I know….
Some of the horizontal stringing, esp. group #3, came when I shifted my grip and rest.
If youre doing the math, that leaves four rounds unaccounted for. I took two Noslers and two Speers and shot them at the steel tanks at 300 yards. Missed the first two until I recalled that I needed to holdover about a foot..at that point they rang quite nicely.
Im annoyed at the flyers. I thought they were from being the first rounds off the magazine but that wasnt it. Im betting the problem is me. Im going to order upo someLapua brass, some Fed BR primers and some Sierra MK’s and see where it goes from there. I also want to try some Varget and and some BLC-2. I think this rifle has good potential, it just needs to be played with. At this point it has about 140 rounds through it. Also need to go through it an make sure all the screws are tight….that horizontal stringing pisses me off.
This is advice based on something that I’ve read rather than something that I’ve learned from experience, so take it with a grain of salt.
You might want to vary the charge weight in your loads and see if that impacts accuracy at all. It might help account for barrel harmonics. It’s probably easier just to point to a link than try to explain it:
Here you go.
Barrel harmonics are addressed in Browning’s BOSS system (which was later added to other rifles) which put a threaded counterweight on the end of the barrel. Worked great, just dont see to many of them around any more. Cryotreating is supposed to help with harmonics as well by relieveing stresses in the metal. One of the reasons Dan Wesson revolvers, by the way, are so accurate is because by virture of their barrel attachment system the barrel is in ‘traction’ and therfore cant vibrate very much, if at all.
Believe me, I know alot about reloading. What I’ll do is probably switch everything (primers, brass, etc) over to the higher-end stuff (Lapua, Nosler, etc) and start doing the maddening half-grain increments. Trial and error, mostly.
Believe me, I know alot about reloading.
That’s the impression I get, which is why I’m reticent to give advice. I know a lot about a lot of things, but I have a hard time acquiring experience as quickly as I acquire knowledge. Thus the disclaimer, “this is what I’ve read”.
Some folks use Federal Gold Medal Match brass as a cheaper alternative to the Lapua brass.
As far as addressing Barrel harmonics are concerned, I have some interesting ideas that I’d like to play with, but unfortunately, I need a machine shop for the purpose. I’d really like to try experiment with a barrel tensioned with some ultra-high modulus carbon fiber. There’s some stuff out that’s about 3-4 times stiffer than the IM7 that Remington uses in their production barrels. It’d be cool to play with other kinds of stiffening devices as well. I have an idea for a strut of sorts that might prove to work well, but then there’s still the need to machine a prototype to test it.
On the topic of reloading, do you have any recommendations for a single-stage press? I do intend to get a 550 or 650 at some point for high-volume stuff, but I’d like to get a single-stage for one-off business. They seem to be out of fashion lately, so I can’t really get a handle on what’s decent. My father had a Rockchucker back in the day, but I was five years old then and I don’t really remember how well it worked out for him.
I do NOT know a lot about reloading, but it certainly looks like you’ve dealt with all the major variables. According to theory, what you’re getting is the best you can get out of that rifle at this early stage of life, barring rifle mods.
As for the stringers, a machine rest would tell the tale…it’s not something I’d expect from you, based on the groups you’ve been getting. Could be they’ll just go away with more rounds through.
For a single-stage press, which every reloader should have, the RCBS RockChucker is the standard. Dont get the smaller RS-series, Partner, or other smaller one. Get the RockChucker. If you plan on loading some seriously mondo big stuff (.50 3-1/4 Sharps, .50 BMG, .378 Weatherby, etc) a larger press with more leverage is very nice to have in which case RCBS’ AmmoMaster is a good choice.
a few thoughts
Varget, Great stuff, super nice velocities, a right bitch to measure. BLC2 measures well, accuracy and velocity perfect…is hyper sensative to to humidity, temp and elevation. perfect for bench, not good in mountain country.
try ramshot tac powder. fast, stable, great velocities adn fairly clean burning. http://www.ramshot.com. it is a bonus that it is a local company for you. If you have a 26″ barrell try about 42.5gr for a 168gr bullet as a starting load. The military is using 43.5 grains pushing a 168 Hornady AMAX for SR-25 sniper rifles.
Thanks. It looks like I can get one Rock Chucker Supreme for under a hundred dollars at Midway or Midsouth. I think I’ll probably do that. The only question now is whether I should do that before or after the Dillon.