Terrible ES/SD. Advice?

DaveMachine

DaveMachine

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Here's the situation. I'm trying to do load development for a new Tikka CTR in 6.5CM with approx. ~150 rounds through but the velocities I'm getting all over the place. I don't have my numbers in front of me but most of my loads are anywhere from 50-60 ES. It has occured to me that maybe the new rifle/barrel could be the cause but I'm unsure.

I'm using:
RL-22 and IMR4350
Hornady 140gr BTHP and Speer Impact 140gr
Sig brass and Peterson LRP brass (not mixed! everything is from the same lot)

F/L sized using Lee dies.
Powder thrown using RCBS chargemaster. Scale is given approx 30min to warm up and then calibrated. Scale is level, no open windows or breeze.
Cases are chamfered and deburred.
Bullets are seated using Lee bullet seater.

Velocities are measured using a Chrony.

The funny thing is, the loads don't shoot terribly at 100m but the velocities vary quite a lot from shot to shot. I'm not the world's greatest reloader, but usually my reloads don't give me such erratic velocities. What I'd like advice about is what I should be looking at to tighten up the velocities.

Code: 
IMR 4350 - Speer 140gr Impact
[TABLE="width: 640"]
[TR]
[TD="width: 64"]Chg[/TD]
[TD="width: 64, align: right"]1[/TD]
[TD="width: 64, align: right"]2[/TD]
[TD="width: 64, align: right"]3[/TD]
[TD="width: 64, align: right"]4[/TD]
[TD="width: 64, align: right"]5[/TD]
[TD="width: 64"][/TD]
[TD="width: 64"]ES[/TD]
[TD="width: 64"]SD[/TD]
[TD="width: 64"]Avg[/TD]
[/TR]
[TR]
[TD]A - 40.5[/TD]
[TD="align: right"]2427.493[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD="align: right"]0[/TD]
[TD="align: center"]#DIV/0![/TD]
[TD="align: right"]2427.493[/TD]
[/TR]
[TR]
[TD]B - 40.8[/TD]
[TD="align: right"]2444.882[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD="align: right"]0[/TD]
[TD="align: center"]#DIV/0![/TD]
[TD="align: right"]2444.882[/TD]
[/TR]
[TR]
[TD]C - 41.1[/TD]
[TD="align: right"]2496.063[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD="align: right"]0[/TD]
[TD="align: center"]#DIV/0![/TD]
[TD="align: right"]2496.063[/TD]
[/TR]
[TR]
[TD]D - 41.4[/TD]
[TD="align: right"]2543.307[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD="align: right"]0[/TD]
[TD="align: center"]#DIV/0![/TD]
[TD="align: right"]2543.307[/TD]
[/TR]
[TR]
[TD]E - 41.7[/TD]
[TD="align: right"]2534.449[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD="align: right"]0[/TD]
[TD="align: center"]#DIV/0![/TD]
[TD="align: right"]2534.449[/TD]
[/TR]
[TR]
[TD]F - 42.0[/TD]
[TD="align: right"]2568.898[/TD]
[TD="align: right"]2622.375[/TD]
[TD="align: right"]2604.659[/TD]
[TD="align: right"]2650.262[/TD]
[TD="align: right"]2610.892[/TD]
[TD][/TD]
[TD="align: right"]81.36483[/TD]
[TD="align: right"]29.50805[/TD]
[TD="align: right"]2611.417[/TD]
[/TR]
[TR]
[TD]G - 42.3[/TD]
[TD="align: right"]2611.549[/TD]
[TD="align: right"]2628.937[/TD]
[TD="align: right"]2615.486[/TD]
[TD="align: right"]2644.685[/TD]
[TD="align: right"]2586.286[/TD]
[TD][/TD]
[TD="align: right"]58.39895[/TD]
[TD="align: right"]21.69997[/TD]
[TD="align: right"]2617.388[/TD]
[/TR]
[TR]
[TD]H - 42.6[/TD]
[TD="align: right"]2637.795[/TD]
[TD="align: right"]2695.866[/TD]
[TD="align: right"]2668.635[/TD]
[TD="align: right"]2615.486[/TD]
[TD="align: right"]2631.89[/TD]
[TD][/TD]
[TD="align: right"]80.38058[/TD]
[TD="align: right"]32.09024[/TD]
[TD="align: right"]2649.934[/TD]
[/TR]
[/TABLE]

Code: 
RL22 - 143gr ELD-X
[TABLE="width: 640"]
[TR]
[TD="width: 64"]Chg[/TD]
[TD="width: 64, align: right"]1[/TD]
[TD="width: 64, align: right"]2[/TD]
[TD="width: 64, align: right"]3[/TD]
[TD="width: 64, align: right"]4[/TD]
[TD="width: 64, align: right"]5[/TD]
[TD="width: 64"][/TD]
[TD="width: 64"]ES[/TD]
[TD="width: 64"]SD[/TD]
[TD="width: 64"]Avg[/TD]
[/TR]
[TR]
[TD]B 42.5[/TD]
[TD="align: right"]2452.756[/TD]
[TD="align: right"]2414.042[/TD]
[TD="align: right"]2401.247[/TD]
[TD="align: right"]2371.063[/TD]
[TD="align: right"]2365.157[/TD]
[TD][/TD]
[TD="align: right"]87.59843[/TD]
[TD="align: right"]35.45995[/TD]
[TD="align: right"]2400.853[/TD]
[/TR]
[TR]
[TD]C 43.0[/TD]
[TD="align: right"]2469.816[/TD]
[TD="align: right"]2431.43[/TD]
[TD="align: right"]2469.816[/TD]
[TD="align: right"]2463.255[/TD]
[TD="align: right"]2467.192[/TD]
[TD][/TD]
[TD="align: right"]38.38583[/TD]
[TD="align: right"]16.36149[/TD]
[TD="align: right"]2460.302[/TD]
[/TR]
[TR]
[TD]D 43.5[/TD]
[TD][/TD]
[TD="align: right"]2550.853[/TD]
[TD="align: right"]2524.934[/TD]
[TD="align: right"]2525.262[/TD]
[TD="align: right"]2500.328[/TD]
[TD][/TD]
[TD="align: right"]50.52493[/TD]
[TD="align: right"]20.62911[/TD]
[TD="align: right"]2525.344[/TD]
[/TR]
[TR]
[TD]E 44.0[/TD]
[TD="align: right"]2587.598[/TD]
[TD="align: right"]2534.777[/TD]
[TD="align: right"]2491.47[/TD]
[TD="align: right"]2542.323[/TD]
[TD="align: right"]2471.129[/TD]
[TD][/TD]
[TD="align: right"]116.4698[/TD]
[TD="align: right"]45.66064[/TD]
[TD="align: right"]2525.459[/TD]
[/TR]
[TR]
[TD]F 44.5[/TD]
[TD="align: right"]2596.457[/TD]
[TD="align: right"]2590.223[/TD]
[TD="align: right"]2563.976[/TD]
[TD="align: right"]2542.323[/TD]
[TD][/TD]
[TD][/TD]
[TD="align: right"]54.13386[/TD]
[TD="align: right"]24.96081[/TD]
[TD="align: right"]2573.245[/TD]
[/TR]
[TR]
[TD]H 45.5[/TD]
[TD="align: right"]2685.039[/TD]
[TD="align: right"]2698.163[/TD]
[TD="align: right"]2656.824[/TD]
[TD="align: right"]2679.134[/TD]
[TD][/TD]
[TD][/TD]
[TD="align: right"]41.33858[/TD]
[TD="align: right"]17.25277[/TD]
[TD="align: right"]2679.79[/TD]
[/TR]
[/TABLE]

ES/SDs worse than i recalled.
 
Last edited:
I have had issues like you describe when i put my budget chrony too close to the muzzle - i now put it roughly 12-15ft away, and have had no issues since.
 
Did you do a charge ladder? I'm using H4350 and 143 ELD-X in my CTR, so sort of similar. Some charges will produce ES of 50+ but it should be possible to get to single digit SD and ES<20 without too much effort. Make sure you're using a single lot of powder.

There are many many ways to do this, but if you're chasing ES/SD numbers this is how I like to do it. Load a range of charges in 0.3 grain increments. Just do one each and go until signs of pressure or published max or whatever you're comfortable with. Measure the velocities and graph them (velocity on y, charge weight on x). You don't really need to graph it, it's just easier to see. You'll see a couple of potential nodes where the curve flattens out and velocity is stable. With only 1 shot per charge this won't tell you for sure where a node is, but it will show you for sure where a node isn't. Pick a flat area of the curve to focus on and this time load up 3 each in 0.1 grain increments. I usually only do 3 different charges at this stage (so 9 shots total). Measure velocities and pick the most consistent. You'll eventually want at least 5 shots to measure your ES/SD numbers but that method works well for me. Only once I can remember I picked an area on the initial plot that didn't turn out to be a real node. If you do this enough times across various lots of powder the lot to lot variation becomes obvious.
 
Are your primers seated all the way to the bottom of the pocket, with at least a 0.002" of crush?

Maybe consider adding an expander mandrel to your process, just to help even out the neck tension a little better.

Also, try to make sure you're not bumping your case's shoulder back too far. Even though tikkas have a spring loaded ejector pushing the case forward, and it shouldn't matter because of that, I found my tikka's es went down a bit once I sized my cases more appropriately for my chamber.
 
How are your groups? I’d be suspicious of the chronograph reading…maybe? Also, are you verifying your loads with a balance beam scale (just to rule out an issue with the digital scale)? Also, pressure will rise a little as your barrel gets fouled up, but not to the extent you’re seeing - might be a good idea to slow down and allow cooling between shots. I’ve seen my Tikka start acting up when the barrel starts getting hot.

Neck tension could be a culprit too. Have you measured or skimmed (as necessary) that sig brass? The Peterson should be very consistent right out of the box.

That’s all I can think of. Good luck and I hope you’re able to sort it out. That rifle should be very accurate and consistent.
 
DaveMachine said:
Trimmed to 1.955"
Click to expand...

6.5 CM case length should be between 1.910" minimum and 1.920" maximum.

Unless you have a seriously non-standard chamber, you're .035" over max trim length.

That's not to say you CAN'T use 1.955" if the chamber will allow it, but it's not the standard dimension.

The danger with overly long case length is the end of the case gets pinched in the freebore (beyond the chamber) and the bullet won't release cleanly. This will cause an over pressure condition.

Could very well also result in wildly erratic velocities from shot to shot.

Hopefully it's a typo.
 
You mention full length sizing and seating the bullets with the dies. Do you measure any of these as you are going along, or just set the die and assume that all the new rounds are going to be the same coming off the full length dies and seating dies?

I use a forster press, anneal brass between firing, and still get the off pc I run through the full length die to get it the same. Same thing with the seating die, and I use a whidden die. I have found that when I anneal between each firing, full length size without the expander ball, then use a mandrel die to set neck tension I get the most consistent overall length on finished ammo. But I also measure each round, and make sure I'm within 0.001" of each other using my measuring equipment, which itself can be problematic as well.

I use a redneck chrony. Shoot tight groups at 100m and then move out with the load up to 1000m. If I can hit the 18" gong with 45 rounds out of 50, I think I have something good going on with the process of my reloads. Going out to 1400m is on another level after that, and I am working on what I am inconsistent with to get proficient to that longer range.
 
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