Brocock Concept Elite S6 .177 tuning for slugs

Forums PCP Airguns Brocock Concept Elite S6 .177 tuning for slugs

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    Franklink
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    (This is entirely my own gun and my own experimentation, completely unrelated to the reviews that I do for Airguns of Arizona)

    I've had this sweet little Concept S6 for 3 or 4 years. Unregulated. Traditional LW choked barrel.

    A couple of years ago I messed with the length of the adjustable hammer to get it shooting JSB 10.34s at about 870fps, for just a bit over 17 foot pounds. Hammer length was 2.256inches for that fpe. It really liked a couple old boxes of Crosman Premiers that I had at the time and I think I remember it doing about 850fps with them. It was really really accurate with those pellets. And when they ran out I went to the JSB 10.34, which it did ok with, but wasn't ever too incredibly accurate with them. With either pellet it got 6 good magazines (24 shots) with an ES under 30fps on a fill from just a bit under 150 bar down to 100bar. And that's where it's been for over 3 years.

    It has mostly sat for the last 2 or so years, just not being used much.

    Enter NSAs 12.5gr slugs. 

    I saw Nicks announcement and decided to buy some for a fun experiment: see if I can bump the fps on that ole unused Brocock and then I'll have a .177 slug shooter. Not sure what I need a .177 slug shooter for, but the gun isn't being used for anything else, doesn't love any ammo that I currently have on hand so why not. 

    I took some baseline chrono readings…..only 680fps with the 12.5gr NSAs from the same 17fpe settings mentioned above. Okay, open it up to get to that adjustable hammer. I decreased the hammer length to its minimum length of 1.92inches, so reduced the hammer length and therefore travel by about 0.336inches. So roughly 1/3rd of an inch.

    Figuring that would increase my required starting pressure, I filled it to 240bar and headed to the garage for some chrono work. Yeah this required burning up some slugs, but there's no other way to figure out fill pressures on an unregulated gun.  

    This is how it looked.

    The chrono analysis is for the shots in red. Looks to me like about 4 magazines, 24 shots from about 200 to a bit under 150 bar.

    Decided to try that again, only filling to 200 bar this time and this is how that one looked.

    Looks like I'm good for just a hair under 22fpe, and it's still doing a solid 4 mags (24 shots). I don't think this gun was ever designed to be a power house and I suppose I could put a heavier hammer spring in there or some preload but I'm betting that transfer port is going to be the limiting factor on how much power I can get. I also suspect that the shot count is going to go down if I try to go that route. 

    I think I'll leave it here and do some accuracy testing this weekend. 

    That stated 0.07BC sounds pretty cool. 

    I've also got high hopes for the accuracy results from these slugs from this gun. I've suspected that it is a slightly oversized bore, since it did so well with those old boxed Crosman pellets that seem to run big. Generally it seems that trying to squeeze slugs down too tight of a bore doesn't result in anything good. 

    Crossing my fingers that it'll shoot them accurately. Whether it does or not, it should be a fun little experiment. 

     

     

     

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    mercado
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    👍nice didn't know that those guns could be bump higher in power…I loved mine but sold it .. for the lack of power..n could not find anything about tuning that gun..such awesome little guns..

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    Franklink
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    Doing a little shooting with the slugs right now.

    Full disclosure: the 75 is cherry picked out of a couple 5 shot groups at that distance. The 30 and 50 are not cherry picked. 

    Still shooting, and honestly looks more like 1.5inch groups average @75. 

    This is a "hunting trigger" and I'm only using a 4-12×40 scope , with a sleeping bag in a compression bag as my rest.  

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    Franklink
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    Five, five shot groups at 75. 

    Not horribly impressive, but better than I expected. I'm sure with a decent rest, some more magnification, and either clicking or a reticle that allows something better than, "oh that looks like about halfway between those hash marks" it could do better. 

    Overall pretty pleased, it'll get shot at some pdogs as-is. 

    • This reply was modified 1 week ago by Franklink.
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