Donation

Target Shooting Matches, Discussion & Events > The Long Range Club

Altaros long ranged shooting and equipment

<< < (5/5)

rsterne:
I assume the V40 velocity is in fps measured at 40 metres from the muzzle?.... What is the altitude of your range, or is that taken into account in the 1022 mBar pressure?....

Bob

Altaros:

--- Quote from: FastJ on June 07, 2023, 05:27:01 AM ---Cool

What is pn for lw blank?

--- End quote ---
unfortunately I don't understand the question (I don't know what the abbreviation pn is)

To Bob,
yes it can by 40m from muzzle, I have a European LabRadar which has limited transmitter power and at longer distances the .22 may no longer measure correctly. I used absolute pressure from my weather station. Regarding the BC, this barrel does not give the maximum BC with these bullets, since the stability is at the level of 1.3, so below 1.5, which partially worsens the BC of the bullets . For full stability a 1:10 twist would be better.

rsterne:
Jari (FastJ) wanted the part number for the LW blank you used....

I noticed that the first few shots at 1000 yards were quite low, and you ended up with significant holdover.... That may be because you are using the G1 drag model, which is not very suitable for airgun slugs.... The RA4 drag model (intended for .22LR bullets) is a better match, and Miles Morris has just released his new "SLG1" drag model, based on calculations for my 2.5 calibre long BBT's.... These drag models are included in George Conway's ballistics apps, available at....  https://gpc.fotosoft.co.uk/  ....

I use his "Easy BC" and "MERO" apps, which have a wide assortment of drag models built in.... The problem with the G1 drag model for your slugs is that they have much less drag than the G1 from 800-1100 fps, particularly between 900-1000 fps.... While this gives a nice BC, then when you use the G1 model to predict drop at extreme ranges, it underestimated the velocity loss, resulting in you needing holdover.... As an example, using the new "SLG1" drag model by Miles Morris for the data in your last video changes the BC to only 0.17 (remember, that is only a number), but increases the predicted drop by 8 feet (abour 2.5 metres), which would appear to be closer to what your slugs actually did at 1000 yds.... Just something for you to play with.... Some of your competitors have changed over to using the RA4 drag model, which is a better fit for airgun slugs than the G1....

Bob

Altaros:
Hi Bob,
unfortunately the LW website is down, but it is a barrel blank .223 755mm long, OD: 10mm, they only have one of this type and diameter..

I have been using only the G7 function for many years ( ATP slugs have BT and the G7 function suits me best so far) . G1 is useless for shooting over 300m, but understandable for most when comparing BC.
At this distance, even a minimal change in wind from direction 6 or 12  or a small change in temperature or muzzle velocity make realative big change on impact (MV changes permanently as the barrel gets dirty and a 1fps difference is already noticeable at 1000 yards).

I added a new video with the start of the premiere. This is the shooting on the second day after the first video.


I was just on the edge with the pressure in the battle, so the muzzle velocity started to decrease and thus the position of impact.

Navigation

[0] Message Index

[*] Previous page