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UKV - The Place for Precision Rifle Enthusiasts


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About phoenix

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    Advanced Member

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    Thermal and night vision foxing , plus some rabbit control and the odd bit of roe deer stalking

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  1. Lines per millimetre, or more accurately line pairs per millimetre, is a resolution measurement system that has its genesis in old analog tubed NV systems. When applied to digital imaging systems (NV or thermal) it doesn't really produce a sensible number. If you want to know the the size of the smallest thing a digital imaging system can detect at (say) a distance of 100m), then simply divide the pixel size by the focal length of the objective lens and multiply the answer by 100 So, in the case of the Helion 2 XP50 pro, the pixel size is 17 microns, the focal length is 50mm.
  2. What you are calling positive and negative is known as white hot and black hot in thermal terminology and it is what it says. In white hot mode, hotter objects appear white and in black hot mode, hotter objects appear black There are also various colour modes where a temperature (or small range of temperature) is displayed as a specific colour. This colour presentation looks very clever and attractive to those who are not au fait with thermal imagers, but in reality, white hot and black hot provide a much more detailed image than any of the colour modes because the number of col
  3. No apology needed -there's nothing wrong with differences of opinion based on knowledge and experience. BTW, I agree, the Helion 2 XP50 pro is is a different league from any other spotter I've ever used Cheers Bruce
  4. A bit long and rambly in places but it might help some people Cheers Bruce
  5. Thanks for the replies. I've recently built an induction annealer and have also found a cheap portable hardness tester that allows me to measure the hardness of the brass at the neck of the case before and after annealing to ensure that the hardness has dropped to near the same as it is for new (annealed) brass. in a couple of days there will be a YouTube video showing the annealer and hardness tester . I'll post a link when it goes live Cheers Bruce
  6. Do you full length size before or after annealing? Cheers Bruce
  7. I recently asked Reload Swiss for loads based on RS52 and RS 60 for 69g Sierra TMK bullets in a 1 in 9 twist 22-250 In each case they stated that the burning rate could vary by as much as +/- 10% between different powder lots Reload Swiss use Quickload for their recommendations I have a 1kg of RS60 so loaded up some cartridges and fired them over the magnetospeed and then adjusted the burning rate in Quickload so that the QL MV prediction matched the measured MV. The difference in the nominal burning rate and the adjusted burning rate was only 2.3%
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