My Best Group Ever – 0.23" at 55 Yards with Brocock Bantam

Forums PCP Airguns My Best Group Ever – 0.23" at 55 Yards with Brocock Bantam

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    DrPutz
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    I was testing out my new-to-me Bantam that I have been working on tuning.  I recorded a 0.23″ 5-shot group at 55 yards, HFT style on bucket and sticks in a light breeze with snow fall (see second sheet target #13).  I think that I now have it tuned well enough for Field Target this spring.

    I wanted to see how many shots I was getting at a 190 bar fill: 90 good ones down to 150 bar, then 5 or so with an apparent POI change (plus 10% air pressure loss due to temp changes). Anyway, I was testing out the 13.43g .177 JSB Monster MK2’s to see how they shot.  Attached are the two pages of groups – I had two 0.53/0.53″ groups, several at 0.7″ to 0.8″, plus one 10-shot group at 0.85″.  I nearly fell off the bucket after that the 0.23 because I could see how good it was.  My fingers were so cold that I could barely feel the trigger and load the pellet (all hand loads).  Note that I did not adjust the POI, since I wanted to see how it changed over the fill pressure. 

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    shutik
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    Very nice shooting, you have capable gun for sure.

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    Element
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    Very nice shooting! What have you done to tune the Bantam?

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    Glem.Chally
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    Excellent group, that’s a beauty 

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    dirtbikerick
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    Congrats, feels great when everything comes together huh.

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    Skip-in-WV
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    Excellent. 

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    Hynzie
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    ahahh beautiful group congrats ,,,now you have a heck of a challenge to match or beat it ,,congrats man and under those  weather conditions even better,,do you  know what your getting for a fps ,,,,PAT

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    whitefox545
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    Congrats Dan!!  Great Job with the Brocock, Is that Keith’s rifle that he shot last season?  Look’s like you will be a real contender this spring!!  See you soon!  Jeff Little  McMurray Pa.

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    DrPutz
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    My current tune is roughly 801 fps (at the bottom end of the shot count where this group was taken) with the JSB Monster MK2 13.43 gr for 19.14 fpe:

    • I opened up the transfer hole to 0.133 (3/4 of .177), but not the barrel or the power adjuster.
    • I kept the much lighter valve spring (.026″ wire diameter spring 1″ long).
    • 0.054″ hammer spring, due to the higher speeds from the transfer port opening.  Now easy to cock, which is what I wanted.
    • The hammer screw is 0.062 above the inner hammer top.

    The MK2’s are about 10 to 15 fps slower than the original Monsters – probably due to their tight fit.

    I don’t believe this is Ketih’s old gun, as his was black – this is the poplar version.  I am working on adding a rail for a adjustable hamster/rest for Open FT Class.

     

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    minagenral
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    Awesome shooting! Are these groups with unsorted pellets? Either way nice groups

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    DrPutz
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    These were straight from the the tin, unmolested. It has been too cold and windy of late to do any further testing. I am waiting on a new batch from Pyramyd to try this spring on field target. 

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    intenseaty22
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    Excellent! Nice shooting. 

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    sonny
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    nice shooting!

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    whitefox545
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    Hi! Dan,  Just wondering how much difference you are seeing as far as drop at 55 yards as compared to the 10.34 JSB heavy’s?  I have been shooting the 13.34 JSB’s this winter indoors as I am unable to find any 10.34 with a head size of 4.52  that are actually what is marked on the can,  both of my Air Arms rifles group WAY better with a head size of 4.52 or 4.53 but I cannot find any (and I have tried many different vendors) that are what they say they are on the tin. I did buy good many tins of 13.34 JSB’s from A.G.O, that were ALL 4.52 as marked on the tin but I am on my last tin. 
    I haven’t been shooting outside with them as of yet because the weather as you know has not been conducive to good testing and I am a bit apprehensive about how much more the 3 grain difference will make at distance for site spread (ark of the pellet). as compared to the 10.34’s out to the 55 yard distance that we shoot for field target, It could make range finding much more critical at the longer distances!!  It seems like such a little amount but is actually a little over 20 percent of the total weight.  Just wanting to know your thoughts on this as I only have a little over a years experience with this stuff!!
                                                                                                     Jeff Little  McMurray Pa.   P.S. Can’t wait to see the new ranges!!!

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    Centercut
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    I have Keith’s old Bantam .177. It’s very interesting the old Monsters at 840 FPS are all over the place. They tighten up at 815, but not great, and certainly not better than the 10.3 or H&N 10.6. Now I need to try the new Monsters.  ;)   PS. The speed drops about 110 FPS from 10.3 to 13.4. And yes, it will definitely make ranging much more critical at 40 to 55 yards. 
    Mike

    • This reply was modified 2 months ago by Centercut.
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    whitefox545
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    Centercut,  You got a good gun there from Keith!! I know as I shot with him a couple of times last summer!!  Great guy also!!   As far as the J.S.B.’s I have only shot the old style 13.34’s at thirty yards indoors so far, they shoot real well for me there but they Do have a 4.52 head size !!! and if I do shoot them for field target I will have to shoot them at a max. of 818 fps to stay under the 20 f.lb. limit for hunter class, I think they are shooting around 840 F.P.S. now but I will slow them down for testing.  Thank’s for your info !!  I wish I could find 10.34’s in my head size 4.52 or 4.53 but no luck sense last spring , seems as though the last big container that came into the States after the shortage (when you couldn’t find any in stock any were last year) I have not been able to get any tins with the size pellets that are marked on the tin from any of the vendors and BELIEVE ME I have tried most of them!!!  I almost wish I had not started to weigh and sort head size as before I did I just thought it was me when I got flyers!!  I found out that size DOSE matter at least in my two Air Arms barrels!!  I am actually having a barrel custom fitted to one of my receivers to try to get a barrel that will eat the smaller head size pellets!!  Got my fingers crossed but who knows !! I may be wasting my money!!!        Thank’s again!!  J.L.
                                                      Sorry !!  didn’t mean to get the thread off course!!

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    Centercut
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    Anytime. For the Bantam the old Monsters are ok, just not as good as the 10.3s. I did find that the H&N 10.6 were every bit as good as the JSB 10.3s. I have a post where I shot those 3 at different speeds at 52 yards. The only thing I’ve yet to do is try the 10.3 and H&N at just under 900 FPS. Right now Medium in the Bantam is about 925 with the JSB 10.3. I’ve been told by a very experienced guy at my club to try them at 895 FPS and my groups would tighten up even more. 

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    whitefox545
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    I also bought a few tins of H&N 10.65’s and while they were marked as 4.52 head size almost all of them were 4.49 and 4.50 but I will say they were much more consistent as far as the weight was concerned!!  all were within 4 tenth’s of a gram with the JSB’s being all over the map as much as 1 and one half grains apart!!  I have found at least for my rifles at our maximum distance of 55 yards the weight means a whole lot less than the variance in the head size dose!  at least with my guns!!  If shooting at longer distances I’m sure you would see more of a poi change with the weight variance!  with different head size you will see a change in speed also, as much as a 10 fps change between 4.49 and 4.53. 
     I don’t know why they even put head size on the tins if they don’t have the Q.C. to accomplish it!!  Thank’s again Centercut!  J.L.

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    chasdicapua
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    Now that’s a righteous 55 yard group!  .42 MOA, well done. 

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    DrPutz
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    So there was a few questions about the drop of the JSB 13.43 vs 10.34 – got me curious.  I shot a few different distances tonight to produce the curve below.  The weather was FINALLY cooperative, no wind and warmer temps.  I will have to plug this in to figure out BC.  Note that the 13.43’s were shot at about 805 fps and the 10.34’s at 870 fps – keeping under a 20 fpe FT limit and under 870 fps for stability.  I had some wild flyers, best group was 0.45″ at 55 yards with the monsters.  I tried Barracuda Matches, but they were terrible, though I think they cleaned the barrel, as the subsequent JSB groups were better.

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