Thread: What's going on here??

Mate tested his 308 load today and had this happen.
First 5 shots consecutively and last 3 were fired 10 minutes later. What would explain the drop in speed? First 4 being pretty close together obviously.
Components are norma brass, 2206h, 168eldms and fed LR primers.
Any help would be greatly appreciated

100m (first 5)
200m (last 3)

First ones shot while the sun was out
Last three were shot under cloudy conditions

you have 136 ftps extreme spread....what is the issue???? unless your shooting for gnats nuts at 600 yards you do not have an issue.
do they group ok??? yes= no problem
ducking as dannyb reaches for his jandles again.

the last 3 are 94 fps apart...again where is issue???

What sort of chrony was used?

so 8" drop at 200 yards....either group is very dead deer= what problem??/

He is worried about the spread in speed. 16" bushpig with the chances of shooting out to 400m when he hunts south island.
Re chrono the drop for the last 3 works out to the speed on the chrono but could that cause an issue shooting out towards 350-400 if his speed is a bit crook?

hold the line caller...will consult manual and reply.....

bear with.... have data for 165grn ballistic tip so in ball park. his will be slipperier so slightly better,
2400fps 2.8 high hundy-31.6 at 400 -64.1 at 500
2300fps 3.1 high at hundy-35.1at 400 -70.3 at 500
bboth sighted for 200yard zero,
so 4" difference at 400 and 6" at 500 yards.....so if aiming for fat part of shoulder,it would be dead. at worst slightly low of high but still dead.

speeds given are 100fps apart same as his load data from chronicgraph...

Ok so I should tell him to relax basically.

168grn nosler solid base
2500fps at muzzle, at 400 yards-29.4
2400fps at muzzle ,at 400 yards-32.5
2300fpsat muzzle, at 400 yards-36.0
7" with a 200fps difference in speed

yes and sight the friggin thing in couple of inches high at hundy.....makes heap more sense.

Greetings,
That is a pretty wimpy load, about 3 grains under max by my estimate. I note that the drop works out by estimate so it is possibly not a chrono error but I wouldn't rule it out. I would recomend working up closer to max and re testing. Sometimes light loads are not as good as those closer to max even with AR2206H. It would be worth sitting down and making a list of what changed from 100 to 200 metres. I don't thik I have ever seen that much velocity difference in AR2206H loads other than with very light loads.
Regards Grandpamac.

PS I assume that 40.5 grains was the charge. If not what was it?
Regards GPM.

Leaving bullets sitting in the sun for 10 min. would do it

The barrel cooled down. Test it: Shoot three rounds, one every ten minutes so the barrel cools down in between, and I am betting they will be the similiar speed as the last three.

Make it go faster. You're letting down .308's everywhere. My .30/06 is laughing his cake hole off.

I don't think it liked spicy loads from memory