Great Groups crazy chrono numbers

[Poconolg]

I went to the range yesterday and shot 8 5 shot groups. I shoot a Rem700 in 22-250 with a Lilja barrel, Jewel trigger and Sightron scope. I use a Pact Chrono. I neck size my brass and weigh each charge, 34gr A2520 with Bib bullet seated .010 off the lands. The 8 groups were .4 .3 .3 .22 .31 .46 .65 this was at 100 yds. Good groups. Strange thing is that my ES went from 56 up to 215 and my SD was never below 55 most of the time about 150. To me looking at those numbers I should not have had such good groups. Two weeks ago I shot a group that was .12 with similar numbers. I use a caliper to measure outside edge to outside edge and then subtract .224 to get center to center of the 2 holes that are the farthest apart. The group that was .12 I measured a few times to confirm the size. What is going on with these crazy chrono numbers. I am not complaining because I would rather have good groups than good numbers, but I was just wondering.

 

[HTSmith]

I'm betting you have a Chrono issue. Those are crazy big ES's, even for sloppily loaded ammo.

 

[chop house]

borrow a magnetospeed

 

[Poconolg]

I take my time and make sure each round is the same. I anneal, check case length, inside neck ream, neck size, weigh each powder charge and measure each round ogive to base to within .002. Neck tension is .002, I use the Redding bushing dies with the micrometer on top.

 

[Big Mc]

I went to the range yesterday and shot 8 5 shot groups. I shoot a Rem700 in 22-250 with a Lilja barrel, Jewel trigger and Sightron scope. I use a Pact Chrono. I neck size my brass and weigh each charge, 34gr A2520 with Bib bullet seated .010 off the lands. The 8 groups were .4 .3 .3 .22 .31 .46 .65 this was at 100 yds. Good groups. Strange thing is that my ES went from 56 up to 215 and my SD was never below 55 most of the time about 150. To me looking at those numbers I should not have had such good groups. Two weeks ago I shot a group that was .12 with similar numbers. I use a caliper to measure outside edge to outside edge and then subtract .224 to get center to center of the 2 holes that are the farthest apart. The group that was .12 I measured a few times to confirm the size. What is going on with these crazy chrono numbers. I am not complaining because I would rather have good groups than good numbers, but I was just wondering.

Your Chrono had a bad day. That,s the first thing i would look at. It would be great if you could get a loner. Just my two cents Tommy Mc

 

[Coyotefurharvester]

New batteries, chronograph as far from muzzle as possible. Level and stable.

 

[Webster]

I went to the range yesterday and shot 8 5 shot groups. I shoot a Rem700 in 22-250 with a Lilja barrel, Jewel trigger and Sightron scope. I use a Pact Chrono. I neck size my brass and weigh each charge, 34gr A2520 with Bib bullet seated .010 off the lands. The 8 groups were .4 .3 .3 .22 .31 .46 .65 this was at 100 yds. Good groups. Strange thing is that my ES went from 56 up to 215 and my SD was never below 55 most of the time about 150. To me looking at those numbers I should not have had such good groups. Two weeks ago I shot a group that was .12 with similar numbers. I use a caliper to measure outside edge to outside edge and then subtract .224 to get center to center of the 2 holes that are the farthest apart. The group that was .12 I measured a few times to confirm the size. What is going on with these crazy chrono numbers. I am not complaining because I would rather have good groups than good numbers, but I was just wondering.

ES of 251 impossible. Chrono problem. Was it a bright sunny day. Do you have sun screens. My sun screens don't help because the sun is at an angle and the light comes in on the bullets under them. I have an old Oehler model 33 it uses the same exact detectors as the newer model 35. I usually got funny numbers between 1-3 in the afternoon. Good numbers any other time. Even an ES of 56 seems big. A SD of 150?

 

[boltfluter]

Find a friend with an Oehler 35 and compare numbers. Then retire the Pact and pick up a used 35. Many available on here from time to time at great prices.

Paul

 

[LCazador]

Get a friend to help you out with say a Labradar unit to confirm readings. Sounds like a bad day for your chrono.

 

[KMart]

Like Webster said, probably sun position or in and out clouds.
ES AND SD MEAN NOTHING IF YOU ARE SHOOTING GOOD GROUPS AND THEY ARE REPEATABLE.
Extra points are not given in a shoot for the low ES or SD. The deer, ground hogs or prairie dogs can not tell the difference.

 

[itchyTF]

Try adding an infrared led strip for lighting.

 

[STOMP442]

Like said above, it sounds like you are having a chrono issue. Spend the $150 on a Magneto Speed. It will be the best $150 you have spent in a long time. That being said, let the target tell you what the rifle likes. Obviously you are having some issues with yours because of the wild numbers but I think people get to caught up in the numbers rather than the results on paper.

 

[HTSmith]

I take my time and make sure each round is the same. I anneal, check case length, inside neck ream, neck size, weigh each powder charge and measure each round ogive to base to within .002. Neck tension is .002, I use the Redding bushing dies with the micrometer on top.

I wasn't saying you were being sloppy--quite the contrary it appears. What I was trying to say was that even badly loaded ammo should do better than the ES's you are seeing. Agree that groups trump ES, but that Chrono has to be off somehow. One good option is to go bust some whistle pigs and forget the chrono.

 

[MislMan]

Quit using a chrono and concentrate on your groups and shooting form. Work on consistency and wind reading.

 

[DiffEQ]

Your groups suggest a "node" in the middle.

The 8 groups were .4 .3 .3 .22 .31 .46 .65 ....

Load up 10 each of the .3 .22 couplet and see how they group at 300.
Range report!

I made a light bonnet for my Chrony Beta and although it was much better, it still missed a few. Bought a magneto and have never looked back.

 

[rogina]

I take my time and make sure each round is the same. I anneal, check case length, inside neck ream, neck size, weigh each powder charge and measure each round ogive to base to within .002. Neck tension is .002, I use the Redding bushing dies with the micrometer on top.

I have shot a lot of 8# kegs of aa2520 and it shoots great but the sd was never better than 20. Your numbers are crazy.

 

[RegionRat]

To me looking at those numbers I should not have had such good groups

Yes and no. A 100 yard group with a poor velocity statistic is a possibility for some situations and only adds to the suspense of what you will find.

My guess is like the others... I think your chrono numbers are suspect.

The point of my post is to say you can not tell what the velocity stats are by looking at a 100 yard group size, good or bad.

With your situation, using a Lilja bbl in 22-250, it is possible to have poor velocity stats and good 100 yard groups. A good rig can stay inside half MOA at 100 yards shooting a huge ES just depending on the harmonics of the bbl and gun. When the bbl section is relatively heavy, a good rig can print small with a very wide range of velocity at 100 yards.

In a situation like this, the math on a typical 22-250 trajectory that assumes the bbl is infinitely rigid would allow for less than 0.3" change at 100 yards just due to velocity. When you consider that no rig is infinitely rigid and that luck plays a role in small group samples, it is completely possible to print small groups at 100 with a good rig using poor velocity stats. That said, I do really still agree it is more likely that your situation is due to the chronograph issues. ETA: That same ES becomes a full minute of vertical difference at 600 yards, or roughly 6" of vertical just due to velocity and much easier to interpret.

I would borrow a LabRadar and shoot at least 10 rounds and see what comes. If the velocity numbers look very different from your optical chrono, I would try a little distance to make sure the muzzle blast pressure wave isn't getting to the sensor before the bullet passes the second sensor. That sort of issue can cause lots of noise in an optical chrono. If you can also shoot the string before lighting conditions can change, it also helps avoid the errors with sky screens.

If you cannot get over a tie breaking chronograph, the obvious way to see if those velocity numbers are really that bad is to put it on paper past 300 yards. The vertical due to the speeds will leverage themselves and make it much easier to interpret the results.

 

[ckaberna]

The target tells the truth.

 

[SSL]

I went to the range yesterday and shot 8 5 shot groups. I shoot a Rem700 in 22-250 with a Lilja barrel, Jewel trigger and Sightron scope. I use a Pact Chrono. I neck size my brass and weigh each charge, 34gr A2520 with Bib bullet seated .010 off the lands. The 8 groups were .4 .3 .3 .22 .31 .46 .65 this was at 100 yds. Good groups. Strange thing is that my ES went from 56 up to 215 and my SD was never below 55 most of the time about 150. To me looking at those numbers I should not have had such good groups. Two weeks ago I shot a group that was .12 with similar numbers. I use a caliper to measure outside edge to outside edge and then subtract .224 to get center to center of the 2 holes that are the farthest apart. The group that was .12 I measured a few times to confirm the size. What is going on with these crazy chrono numbers. I am not complaining because I would rather have good groups than good numbers, but I was just wondering.

Play with your lighting. If too bright (direct sun) you might want to shade the sensors better. Too much shade...try removing the sun shades.
I had a problem with my old Chrony giving erratic readings. Soled it by carefully cleaning the sensors and then covering them with a strip of clear packing tape. Settled the readings right down. Strange things can happen with chronos. I even had a day where everything I shot was reading far faster than they could possibly be traveling. Turned out I hadn't unfolded my Chrony completely. Felt like an idiot.

 

[Poconolg]

I cannot shoot past 100 yds because that is all the range I belong to has. I ordered an Oehler 35P yesterday.