Es?

[Fla shooter]

Just started reloading and work up a load that shoots 3/4 to 1/2 moa just got chronograph today shot 5 rounds 2911,2916,2938,2868,2909 . Is this to much of a spread ??? 7mm 69.5 retumbo 180berger cci250

 

[7stw]

Just started reloading and work up a load that shoots 3/4 to 1/2 moa just got chronograph today shot 5 rounds 2911,2916,2938,2868,2909 . Is this to much of a spread ??? 7mm 69.5 retumbo 180berger cci250

You really only have one there that is a little off from the pack, the one that is 2868. Sometimes those will show up, for no explainable reason. It can be the brass is " tired" the barrel is hot, cold, or something you may never figure out. How did the load shoot on paper? Best thing to do is shoot it some more, and compare. If the load is grouping well, and you are not shooting super long distance, don't worry about it. That is actually pretty good speed.

P/ S, consistentcy is KEY.

 

[Fla shooter]

Im gonna try 168bergers should pick up some speed I think

 

[Fla shooter]

Shot 168's with the same recipe as the 180's grouped .436 with four n a pulled the last one only being .723 !es was 2968,2948,2954,2950,2960

 

[7stw]

Shot 168's with the same recipe as the 180's grouped .436 with four n a pulled the last one only being .723 !es was 2968,2948,2954,2950,2960

That is not bad, but speed could come up a little, or leave it alone. Are you shooting a five shots at once, or are you waiting after two shots? Just curious.

 

[Mikiedem]

What kind of chronograph?

 

[Fla shooter]

Shooting all five take a few secounds to reset chony !i bumped it up to 70. Of retumbo n it dropped to 2883 to 2860! Cant figure why it dropped

 

[Fla shooter]

Chrony

 

[backwoods83]

H4831sc or H1000 with CCI BR2s or Fed210m's works better with 162 hornady's or 168 bergers, I have a H4831sc 210m recipe that runs 3056fps avg with a spread from 9-13fps, depends on conditions.

 

[Mikiedem]

Chrony is not known for consistent accurate readings, hence the cost. I was using one and after the constant error I bought a CED. The same load I was shooting over the chrony would have ES of anywhere from 25-70 fps, the CED typically 8 fps. But for the 7mag, I would switch to a faster powder than retumbo.The fact that you added .5 more and fps dropped could be barrel is not long enuff to burn it all before its out the barrel. RL22, H4831 are good a choice. Just my 2 cents

 

[7stw]

ThE reason I asked about how many shots and how close, is that barrel heat will play a part of your SD, and ES. As the barrel heats, it flexes more, and sometimes gets tighter and will effect speed/ pressure.

 

[jsthntn247]

Fla hunter, you havnt mentioned what caliber this is for. Also you need to work the load up properly if you expect to know why it does a particular thing with a small increase in charge. Retumbo is slow burning and if you don't have a 26" or longer barrel, you are probably getting incomplete powder burn which cause velocity to do funny things and causes unexplained fliers. I suggest starting 4 grains under book max and loading 3 each in .5 gr increments. Shoot these over a chrono at 100 yards in round robin and post the results. This is known as OCW method and has worked well for me. Taking a stab and praying that someone's else's load will work in your gun almost never works.

 

[rscott5028]

ThE reason I asked about how many shots and how close, is that barrel heat will play a part of your SD, and ES. As the barrel heats, it flexes more, and sometimes gets tighter and will effect speed/ pressure.

I'm not sure if I agree with your causality.

Chamber temperature heats the cartridge and cartridge temperature does most certainly affect MV. If you ever let a cartridge sit for long in a hot chamber, that shot will likely print high.

As to the OP... Your sample size is way too small. You need to shoot/record a lot more samples to be statistically significant. If you're happy with group sizes, then keep shooting. If you question the consitency of your chrony, then shoot longer ranges. Groups don't lie.

-- richard

 

[Fla shooter]

I have worked up a load I started with 68.5 n worked on seating depth with 5 shot groups then went all the way to 70.5 @.5each 5 shots and @ 69.5 was the best accuracy ! Went to 1000 yds this weekend n shot 5 under 8 inches I was suprprised n happy ! I just got tbe chony this weekend did not have it for load work up ! If I do my part it will shoot 1/2 moa @ 100 yds