Help Me Understand My Data

slowelk

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I am brand-new to reloading and shooting data collection. I am shooting a factory Tikka T3x 6.5 CM with a 21.5 inch barrel, and capturing data with a Magnetospeed v3. These strings were shot yesterday, it was 60 degrees, and about 50% humidity, and I let the barrel cool completely between groups.

Load 1 H4350 - Velocity
2,603Average 2,594.8
2,606S-D 13.0
2,594Min 2,573.0
2,598Max 2,606.0
2,573ES 33.0
Factory 147 ELD-M String 1 - Velocity
2,523Average 2,530.6
2,521S-D 21.0
2,510Min 2,510.0
2,534Max 2,565.0
2,565ES 55.0
Factory 147 ELD-M String 2 - Velocity
2,538Average 2,531.0
2,532S-D 24.6
2,565Min 2,497.0
2,523Max 2,565.0
2,497ES 68.0

First thing - all of these groups were sub-moa at 100 yards, with the Load 1 string at .59MOA. Next, I can't make heads from tails with what velocity is doing. With Factory String 1 I thought it could be a result of the chamber heating up, but then Factory String 2 went the opposite direction. Handload string was using Peterson LRP virgin brass. OAL matched factory at 2.8#.

Can you guys help me make sense of the velocity changes? I understand velocity spread may not show itself at 100 yards, but the weekend before I was shooting the factory loads out to 1,000 and was 3/3 at 1,000 FWIW.
 
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mvrk28

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No big shock that your factory velocities are all over the place.

In terms of lowering your SD on hand loads, need a little more info about the equipment and process to shrink that number.
 
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slowelk

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No big shock that your factory velocities are all over the place.

In terms of lowering your SD on hand loads, need a little more info about the equipment and process to shrink that number.
I'm using a cheap RCBS press, die, and powder measure, hornady electronic scale, 40.5gr of H4350. What else do you want to know?

I'm very underwhelmed by the velocity with powder slightly over book max.

I thought it was odd that the first two shots of each string were very close, and then the gaps grew significantly. Is there anything with that?
 

bruceleroy

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Dec 29, 2015
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I dont think your factory numbers are strange at all. As stated, your process should be looked at to see if there are any areas that can be improved. Mine did that then I bought an electronic scale/dispenser. Now my SDs ar below 10 in my Grendel and my 308.
 

JakeSCH

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Check your formulas for Max / Min / ES.

How big was your target at 1000 yards? Your factory ES of 60 would produce ~1.5 MOA difference. However if you look at your first 3 shots in all 3 attempts, your ES was much smaller (30 or less).

I bet if you took 5 shots at 1000 you would see the same trend. And I agree, its factory ammo. That is why companies only guarantee sub moa on factory ammo to 100 yards.
 
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slowelk

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Check your formulas for Max / Min / ES.

How big was your target at 1000 yards? Your factory ES of 60 would produce ~1.5 MOA difference. However if you look at your first 3 shots in all 3 attempts, your ES was much smaller (30 or less).

I bet if you took 5 shots at 1000 you would see the same trend. And I agree, its factory ammo. That is why companies only guarantee sub moa on factory ammo to 100 yards.
Copy/paste error on those, they are fixed now. Target was 18" round.
 
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slowelk

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The reason is decided to load more rounds at 40.5 was because it was the most accurate of my ladder. As I increased over 41, things really widened up. Should I mess with OAL next?

If anyone wants to develop a load for me and is near Missoula, MT let's talk :) time and mental energy are not things I have much excess of.
 

mvrk28

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The reason is decided to load more rounds at 40.5 was because it was the most accurate of my ladder. As I increased over 41, things really widened up. Should I mess with OAL next?

If anyone wants to develop a load for me and is near Missoula, MT let's talk :) time and mental energy are not things I have much excess of.
My recommendation would be to NEVER use OAL as a means of measurement for any reason other than to check if the loaded cartridge will fit in your mag. The measurement you want to use is CBTO, or Cartridge Base to Ogive. To measure this you will need a comparator tool and a caliper. The reason you do this is because the meplat of most bullets is very inconsistent, and everything from meplat to ogive will never make contact with the barrel. So if one bullet has a longer meplat and one has a shorter meplat, you will have different amounts of "jump" between each cartridge. Consequently, you're also changing the depth the bullet is seated internally which will change your pressures and can affect your MV.

I would be willing to bet you could shrink your SD's with a couple small modifications to your process.

1. Measure CBTO and not COAL
2. Remove the expander ball from the RCBS die, add a Sinclair Expaner Mandrel to the mix so you can set your neck tension.
3. Upgrade your scale to something more accurate.

This is where I would start, just my 2 cents.
 

Cahunter805

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Like stated not surprised by the factory data.
Regarding your hand loads.
Was this new brass or fired brass?
Did you prep the brass at all?
What primer are you using?
 

briscoetab

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I’ll second what @mvrk28 said. I have used a RBCS electronic scale in the past and then went to a RBCS beam scale. Have not used a Hornady scale but many people said the RCBS scales would not work for them at all. Both worked ok for me, the biggest issue was just watching for drift with the electronic scale and being very careful of vibration and wind currents on both of them. If I did that the scales worked ok but would have to check the electronic scale every 10 or so loads and rezero or recalibrate. So while they will work they are very annoying and you have to be careful.

Definitely get a set of bullet comparator gauges to measure ogive to bullet base and headspace space gauge for resizing brass. They are fairly inexpensive and super invaluable for reloading.

I have only messed with up to the 143 ELD’s in the 6.5cm. I would expect a little more speed, probably up in the 2700-2750 range without really pushing it hard. I have had to go almost 3grains pass book max to find the actual max for my 6.5cm but be careful if you are doing that, watch for pressure signs and make sure if you live somewhere it gets really hot to check load in higher temps for pressure signs as well. Don’t know how much experience you have but if it’s not too much only do this with help or advice with someone who has experience. I think I am around 2 grains above book max on the load I use.

Last thing, how new is the rifle? It may take a little time to smooth that barrel out with a little copper and for it to settle in. It may pick up a little speed as well after 100-200 rounds.
 

wind gypsy

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Your results are typical and those kinds of velocity spreads are likely a good indicator of what you should expect. A lot of the internet single digit SD reports you see come from peoples select 3-5 shot groups, luck, very involved load processes, or chamberings that make it easier like 6br variants or 6.5x47.

Shorter barreled 6.5 creeds are going to be pretty slow unless you hotrod the piss out of it or use a stiff charge of rl17 / rl26.

Don’t get too wrapped up around the numbers if you’re hitting at 1000.
 
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slowelk

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Thanks for the replies everyone. There are some terms thrown out there that I need to look up, sounds like I need some better gear too.

To answer some questions that came up:

new brass, I did no prep after reading that some of the premium brass didn’t need prep. CCI 250 magnum primers.

rifle has 177 rounds through it as of yesterday. I think a better scale might be the first order of business.

Other questions:

What are reasonable expectations for standard deviation and extreme spread? If you could assume that charge weights were precise, what else contributes to velocity variation?

I’d really like to get 2,700 FPS out of this combo. That isn’t asking too much is it? I read over on snipershide that due to Peterson’s lower case volume, it actually produces lower muzzle velocities due to lower average pressure, despite higher peak pressure. Is there any truth to that?
 

briscoetab

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Thanks for the replies everyone. There are some terms thrown out there that I need to look up, sounds like I need some better gear too.

To answer some questions that came up:

new brass, I did no prep after reading that some of the premium brass didn’t need prep. CCI 250 magnum primers.

rifle has 177 rounds through it as of yesterday. I think a better scale might be the first order of business.

Other questions:

What are reasonable expectations for standard deviation and extreme spread? If you could assume that charge weights were precise, what else contributes to velocity variation?

I’d really like to get 2,700 FPS out of this combo. That isn’t asking too much is it? I read over on snipershide that due to Peterson’s lower case volume, it actually produces lower muzzle velocities due to lower average pressure, despite higher peak pressure. Is there any truth to that?
I would have to run/look up some numbers just to make sure about the velocity. My statement earlier was off the top of my head about the 2700-2750fps and honestly I haven’t really been doing any major load work up this past year so my mind maybe a little rusty on actual numbers.

Charge weights are one of the major contributors to velocity variation but all of the following are just as important: seating depth, neck tension and case sizing. There are some other factors but those are probably the major ones and for the most part you do not necessarily need high dollar equipment to control them, you just need to be consistent in you reloading routine.

You don’t really need to do any case prep on your brass other than possibly chamfer and deburing and that is just to help with bullet seating and not damaging the bullet as you seat it. There is a rabbit hole of brass prep you can go down and most of the improvements are minimal if not non-existent in my opinion and experience.

You may get slightly better consistency on the second firing of you brass because it is formed to your chamber and hopefully all of it is pretty much the same. You need a headspace gauge to measure your fired brass because that is what you should base your sizing off of for best results.

Honestly if you can keep that SD and ES your max your in good shape. Those are not bad numbers. Like stated above you can improve those numbers but it will take quite a bit more time and/or better equipment. I am probably getting close to $4000 in reloading equipment and when I am serious I spend a good bit of time in the reloading room but I have cut back on some of my steps to speed up the process and haven’t really saw a regression in results yet.
 

wind gypsy

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I’m not familiar with folks using magnum primers in creedmoor type case capacities but even in modest magnums it’s common to get lower velocity spreads with standard large rifle primers than with magnum primers. I’d try fed 210m or cci br2.

you should get a little more velocity with rl16 and still have temp stability. RL 17/26 will get you more yet but be more temperamental.
 

mvrk28

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Thanks for the replies everyone. There are some terms thrown out there that I need to look up, sounds like I need some better gear too.

To answer some questions that came up:

new brass, I did no prep after reading that some of the premium brass didn’t need prep. CCI 250 magnum primers.

rifle has 177 rounds through it as of yesterday. I think a better scale might be the first order of business.

Other questions:

What are reasonable expectations for standard deviation and extreme spread? If you could assume that charge weights were precise, what else contributes to velocity variation?

I’d really like to get 2,700 FPS out of this combo. That isn’t asking too much is it? I read over on snipershide that due to Peterson’s lower case volume, it actually produces lower muzzle velocities due to lower average pressure, despite higher peak pressure. Is there any truth to that?

If you want to push them fast, I'd suggest RL26. I am running a lighter charge than what I've seen others doing in my 6.5 CM. I'm at 47 gr with a 124 gr Hammer Hunter (they actually weigh about 126). I'm right around the 3000 fps mark out of a 22" barrel.

In terms of SD there are a few factors that will effect it,

1. Accurate charge weight
2. Consistency in seating depth
3. Neck tension
4. Primer seating

The above are in no particular order other than primer seating because it does effect your SD but not nearly as much as the other three. If you are at the point where you are analyzing your primer seat pressure, you are probably already in the single digit SDs and just chasing a number to brag about to your friends.

If you are getting a new scale, I'd look at the Frankford Arsenal intellidropper or the RCBS Chargemaster Lite. You get a lot more than just a scale, it just makes the whole process a lot easier. I went with the Chargemaster 1500 a couple years ago and it's great, but looking at the performance of some of the more affordable units gives me a little buyers remorse.
 

JakeSCH

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Jun 14, 2020
Messages
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The guys above hit it dead on. Headspace is extremely important, so i would definitely get the money for one of the gauges.

Accuracy > Velocity, however consistent velocity is accuracy at distance.

I would add to try and use imperial dry lube (dip it in a couple times, wipe off outside before you add gun powder). That step along dropped my ES and SDs. Depending on the brass, deburing flash holes may have a significant impact.

I also run a cheap homegeek jewel scale from amazon in combination with a RCBS beam scale. Consistency is most important...and when using two scales helps identify if the digital scale is drifting.

I am getting a SD of 6 and ES of 13 in my 6.5 PRC shooting sub 0.3 MOA. I am primarily a hunter who picked up reloading to improve my skills, so that is better than I will ever need.

Lastly, is your barrel really 21.5? I thought Tikka only had 20" and 22.4" barrels? A shorter barrel will reduce velocity compared to manuals, which typically use 24" for the 6.5 CM. If you really do want velocity, try one of these powders (RL16, Hybrid 100V, StaBall 6.5)

Best thing about reloading is that there is no rush, take your time and learn / tinker. Let the obsession burn!
 
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slowelk

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Good advice above, thank you. I’ll need to read that other thread on lubing necks. Is the hornady headspace gauge the way to go? I see a lot of good stuff on rl16, but it looks to be hard to find.

It really is 21.5” because I cut it and added a brake, and in 10 months or so I’ll have a suppressor.
 

HiMtnHntr

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No surprise, as mentioned, to get a wide velocity spread with factory ammo. Handloading, and tweaking various things, will shrink the gap, but you will typically see a bit of a spread of velocity even with handloads, in my experience.
 

Brendan

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My experience with new brass is limited compared to some, but neck tension has been all over the place. I have been running it through an expander mandrel, chamfering and deburring, then using imperial dry lube on inside of the necks and bullets. Even better if you shoot all your virgin brass 1X before you start load development.
 

Don Qui Puncher

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If you want to push them fast, I'd suggest RL26. I am running a lighter charge than what I've seen others doing in my 6.5 CM. I'm at 47 gr with a 124 gr Hammer Hunter (they actually weigh about 126). I'm right around the 3000 fps mark out of a 22" barrel.

In terms of SD there are a few factors that will effect it,

1. Accurate charge weight
2. Consistency in seating depth
3. Neck tension
4. Primer seating

The above are in no particular order other than primer seating because it does effect your SD but not nearly as much as the other three. If you are at the point where you are analyzing your primer seat pressure, you are probably already in the single digit SDs and just chasing a number to brag about to your friends.

If you are getting a new scale, I'd look at the Frankford Arsenal intellidropper or the RCBS Chargemaster Lite. You get a lot more than just a scale, it just makes the whole process a lot easier. I went with the Chargemaster 1500 a couple years ago and it's great, but looking at the performance of some of the more affordable units gives me a little buyers remorse.
Is that load compressed? I’m .02 off the lands with 140 hornAdy and bergers and start to compress at 46, I do the stupid toothbrush and buzz it down but still crunching, 47 is compressed big time. I’m 2760 with the Hornady I haven’t chronod the bergers yet. RL 26 and lapua small primer
 
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