EdGun Pellet Velocities & Batch Variation in 177 w/Groups

Working to get my EdGun velocity down in order to minimize group sizes out to 55 yards. It seems the more velocity I have the more pellet picky the EdGun becomes.

I did some testing indoors at 35 yards (the most I had at the time) and found that even same brand and lot pellets give different groups. I went through about half the tins of pellets I had in no particular order and documented the groups so I can pick the tins that work the best for competition.

All groups were shot in the high 890’s and low 920’s in terms of velocity. I wasn’t 100% pleased with the results, i’d like to see 0.25″ ctc groups at 35 yards minimum and got a couple just under 0.40″.

These were 10 shot groups.

AA= AirArms 10.34 grain, tins are marked “A”, “B”, “C”, etc so I don’t go mixing tins during a shooting session and I can go back and use a particular tin for competition.
JSB= The latest red/white non-batch marked tins from PA, 10.34 grains, tins marked alphabetically.
JSB 000009= Are the older JSB pellets, 4.52mm head size, marked by batch and head size from 2009, tins marked alphabetically.

Anything under 0.60″ is deemed acceptable, anything over 0.75″ is considered “fucked” and used for velocity testing. I plan on doing this with the EdGun, Cricket and my USFT.

You can see the JSB 26009, 4.52mm head size batch has the most variation, from 0.40″ to 0.84″ between tins (this holds true for both the EdGun and the USFT).

The newer JSB tins are the most consistent with the EdGun (not so with my USFT) and the AA tins are in the middle (they work the best for my USFT).

The worst by far was the JSB 4009 batch with a 1.17″ group.

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I wanted to ultimately get my velocity into the 860’s for the EdGun and the Cricket so I did some fiddling and velocity work. The Cricket was not cooperating (see other post about Cricket hammer spring adjustment) so I did the EdGun. I turned out the hammer spring adjustment one half turn and got velocities from 870 to 850 in a 70 shot string.

The velocities were jumping around a bit so I decided to do some spread sheet work with the various velocity tests I have done to date. Firstly the regulator needs to be turned down, if the velocity was around 920fps I would get a perfectly flat 175 shot string.

What I found interesting is that as the velocity is reduced the spread (difference between the highest and lowest velocities) is reduced but what I call the “jump” (max spread from shot to shot) increases.

In order to get the velocity under 1000fps (sent from the factory as such) I had to cut down the hammer spring (cut 1/8″ off). I’m thinking that because the regulator is set for a higher velocity that the more I lower the velocity the more issues the hammer is having against the valve pressure.

Looks like i’ll have to open her up and tickle her innards here sooner rather than later. 😆

I’ll be doing some more indoor pellet testing Saturday with the lower velocity (I may try to get it up closer to 880) before the match Sunday. I plan on using it for the California State Championships for the last weekend in September.