Ballistic coefficient of AA Express pellets

no avatar
Cantankerous One
Posts: 16
Joined: Wed Jan 04, 2017 11:19 pm

Ballistic coefficient of AA Express pellets

Sat Jun 24, 2017 5:07 pm

Anyone know the BC of AA Diablo Express pellets please?

Thanks
EV2 Mk4 .177
TX200 Mk3 .177
TX200SR Mk1 .177
Ultimate Sporter (R) .177
HW100T .177
HW100BP .177

no avatar
gary martin
Posts: 815
Joined: Thu Feb 19, 2015 8:21 pm

Re: Ballistic coefficient of AA Express pellets

Sun Jun 25, 2017 8:32 pm

these pellets are rebadged JSB Express, Chairgun gives them the same BC as the regular 8.44g but these published values are really just a guide. The same pellet shot from a different barrel can give a different value. to get a true value you would need to work it out yourself. you will need two chronos, one at the muzzle and the other at a known distance, from the two readings it is then possible to get the true value.

no avatar
Archer50
Posts: 200
Joined: Mon Jun 20, 2016 5:06 pm
Location: Perth

Re: Ballistic coefficient of AA Express pellets

Mon Jun 26, 2017 9:12 am

I don't know how accurate you need the figures to be, but if you want to calculate the true BC for your gun and can't get hold of two chronos, you can get a useful approximation by measuring your POI at a longer distance - say 60 yards, and using ChairGun. I don't know about AA Express, but I have tested AA Field 8.4's and JSB Exacts with my S400 and HFT 500 and found that the AA pellets had roughly the quoted BC (0.021), but the JSB's had a much lower rating - around 0.016, so you can't assume that AA Express = JSB Express for BC.

Here are some figures averaged from 20 shot strings from my S400 off a bench rest indoors, with a Combro on the gun, a Caldwell 35yards down range and a paper target at 45 yards. 45 yards wasn't really enough for the POI drop to give accurate figures, but you'll see what I mean. The most interesting thing for me, was that the test confirmed what I had already found from ordinary shooting. Although the AA pellet left the gun significantly slower than the JSB, it was travelling faster down range, with the difference being noticeable in real life from about 40 yards on.

AA Field
Nominal BC = 0.0210
Velocity at muzzle = 748 fps
Velocity @ 35 yards = 605 fps (81%)
BC calculated from velocity = 0.0206
POI @ 45 yd = -2.40 inch
BC calculated from POI = 0.0203

JSB Exact (batch 44)
Nominal BC = 0.0210
Velocity at muzzle = 774 fps
Velocity @ 35 yards = 593 fps (77%)
BC calculated from velocity = 0.0163
POI @ 45 yd = -2.48 inch
BC calculated from POI = 0.0156

Of course, for most purposes you can just scrounge a few pellets and see how you get on with them ;)

Hope this helps.

Alan

no avatar
Cantankerous One
Posts: 16
Joined: Wed Jan 04, 2017 11:19 pm

Re: Ballistic coefficient of AA Express pellets

Mon Jun 26, 2017 1:07 pm

Thanks Archer and gary for the info and advice.

KRs
Tony
EV2 Mk4 .177
TX200 Mk3 .177
TX200SR Mk1 .177
Ultimate Sporter (R) .177
HW100T .177
HW100BP .177

Post Reply

Who is online

Users browsing this forum: No registered users and 13 guests