GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: Nomadic Pirate on August 30, 2015, 10:15:00 PM
-
So I received some samples from Tom to test.
he sent me .250 and .251
(http://i34.photobucket.com/albums/d124/NorthShoreLB/DSCF1663_zpssvyvmzjp.jpg) (http://s34.photobucket.com/user/NorthShoreLB/media/DSCF1663_zpssvyvmzjp.jpg.html)
It's a very nice looking bullet indeed
(http://i34.photobucket.com/albums/d124/NorthShoreLB/DSCF1664_zpsjth58egx.jpg) (http://s34.photobucket.com/user/NorthShoreLB/media/DSCF1664_zpsjth58egx.jpg.html)
I did some quick 50 yards preliminary test with my 80 FPE Storm that has a Career barrel on.
(http://i34.photobucket.com/albums/d124/NorthShoreLB/DSCF1666_zpsfgnhnt4x.jpg) (http://s34.photobucket.com/user/NorthShoreLB/media/DSCF1666_zpsfgnhnt4x.jpg.html)
(http://i34.photobucket.com/albums/d124/NorthShoreLB/DSCF1667_zpscjnlkt9n.jpg) (http://s34.photobucket.com/user/NorthShoreLB/media/DSCF1667_zpscjnlkt9n.jpg.html)
The bullet of course don't fit the Mags so a single shot tray had to be used.
(http://i34.photobucket.com/albums/d124/NorthShoreLB/DSCF1665_zpsiomto34y.jpg) (http://s34.photobucket.com/user/NorthShoreLB/media/DSCF1665_zpsiomto34y.jpg.html)
It was a quick test, not shooting several groups and picking them
(http://i34.photobucket.com/albums/d124/NorthShoreLB/DSCF1668_zpsdvnpswzx.jpg) (http://s34.photobucket.com/user/NorthShoreLB/media/DSCF1668_zpsdvnpswzx.jpg.html)
My very 1st shot I pulled ( completely my fault), after that I shot two 6 shots groups refilling after I shot the 1st with the .251s
(http://i34.photobucket.com/albums/d124/NorthShoreLB/DSCF1669_zps9ii076io.jpg) (http://s34.photobucket.com/user/NorthShoreLB/media/DSCF1669_zps9ii076io.jpg.html)
(http://i34.photobucket.com/albums/d124/NorthShoreLB/DSCF1670_zpslmaeuedb.jpg) (http://s34.photobucket.com/user/NorthShoreLB/media/DSCF1670_zpslmaeuedb.jpg.html)
(http://i34.photobucket.com/albums/d124/NorthShoreLB/DSCF1671_zpsmoo1k1me.jpg) (http://s34.photobucket.com/user/NorthShoreLB/media/DSCF1671_zpsmoo1k1me.jpg.html)
First Impressions ?
Having quickly shot 2 groups I would say that this bullet is definitely one to look into further.
-
Wow 58 grain .25s! That's some smack down! I've used 52 grain .25s with incredible success. Can't wait to see what 58 grains does to a pigs head!
-
So we can contact him through the email on the package? I've been looking for some heavy slugs for my talador!! ;D
-
Very nice slugs Manny.
How do you think they will work in a Sumatra ?
Just wondering.
Dave
-
Manny arent those the same design as the .250 BBT slugs? They look awful similar.
-
Hopefully Tom will chime in with answers, I sent him a PM telling about this Thread
-
Yes, They are the Bob's BBTs. I have been working with Tom to get these slugs made. I'm very excited that they are done. Here is a link to a post I had on my build. http://www.gatewaytoairguns.org/GTA/index.php?topic=90710.msg900227#msg900227 (http://www.gatewaytoairguns.org/GTA/index.php?topic=90710.msg900227#msg900227)
I just did preliminary testing. But I went ahead and ordered 500 of the 251. I think I can shoot much better groups than I did. I'm getting used to the recoil of my gun specially after all I have been shooting lately is my AA MPR FT at 12 fpe.
-
I also noticed more recoil than shooting the 43gr EunJin, that
s why that very 1st shot got me :)
Yes, I'm sure I'll shoot better groups too if I sit on that bench and concentrate :)
-
hey you guys
as to the design of the slug
it is not an exact copy of the .250 50grn bbt but a modded copy of the .257 60 grn bbt
yes you can contact me via the email on the business card pictured in the post
have a little patience i can not get on the computer to reply till after 5 cst
little more info on these i can size them .250/.251/252/ working on a .253 size die now the come as cast at .254
i cast with an alloy that is conductive with air guns
if you have any more questions feel free to ask here or send me an e-mail
thanks mule
-
Hi Tom,
I just wanted to say it's good to have you here on GTA. I'm glad (and shocked) to see another Laurel resident on the forums :) I saw that you do gunsmithing in addition to casting. I do a little of the former as a hobby when I'm not at work or doing something with my wife and five boys. In fact I'm planning a .25 cal PCP conversion this winter that may be worthy of your slugs.
Anyway I wanted to say kudos on the results Manny is getting with your slugs. If there is anyone who can put them to good use, Manny is the guy who literally brings home the bacon.
-
I have to thank Tom for working with me finding the molds and then producing the BBT .25 58s. In my eyes, he went out of the way to do research for the mold and get it made. He has been a pleasure to deal with and when it was all set and done, putting out a great product.
Thank you
Daniel
-
hey you guys
as to the design of the slug
it is not an exact copy of the .250 50grn bbt but a modded copy of the .257 60 grn bbt
yes you can contact me via the email on the business card pictured in the post
have a little patience i can not get on the computer to reply till after 5 cst
little more info on these i can size them .250/.251/252/ working on a .253 size die now the come as cast at .254
i cast with an alloy that is conductive with air guns
if you have any more questions feel free to ask here or send me an e-mail
thanks mule
Here is my take on bullets versus pellets. I was interested in BC of pellets and started looking for approximations online and came up with, say the JSB pellets, around .025 to .035. This particular bullet we're looking at here at worst is going to be over .1. So though the JSB might leave the barrel at say close to 900 fps and generating about 45 foot pounds. The Eun Jin at 43 grains generates probably close to 60 foot pounds, and the .58 grain bullet, say at 725 fps maybe 65 foot pounds. So, for the sake of trajectory, you're an 2 inches high at 30 yards and 1 inch low at 55 with a 50 yard zero. The Eun Jin, I'm guessing is going to be in the low end of BC maybe at best a .02... at 800 fps is almost 4" high at 30 yards and an inch low at 55.
Enter this little bullet, and I'm sure my .1 estimate is off by some, because cast bullets of similar are .115 and climbing... but .1 it is less than 2" high at 30 yards and the same 1" low at 55. Very similar to the exact Kings in my guesstimates. However, let's just use our zero range, 50 yards, for comparison of a shot on an animal so we know we'll hit it ;D. Retained energy at 50 yards.... is 72% for the 58 or 48 pounds. For the 43 Eun Jin, in my figgering... 22% and only 13 or 14 pounds. For the JSB about the same.
Ok... too far? Lets come to 25 yards... it's 55% for JSB and the Eun Jin so roughly 26 and 28 pounds respectively. For Hunting fur of over say 25 pounds, I can't think of a reason to not shoot this 58 grain bullet EVER if you can hit something with it accurately and routinely... the concern I have my Sam Yang and it's similar bullet... 25 yards... I'd shoot anything.... can I at 50? Testers will tell... ;D
Back to this bullet.... already I can tell you that at 50 yards you have at least 60% or more retained energy, closer to 70% I'd venture and trajectories better than a pellet... accuracy, accuracy, accuracy... if the bullet works at these velocities and twist... and I was a HUNTER.... well you know my thinking....
Thank you Mule....
Aloha... 8)
-
hey to all you guys
just want to thank you for the good words
i have had some people contact me about the possibility of casting some slugs in the 45 to 50 grain range in 25 cal
if i get enough interest in this it will be possible
let me know what you think
-
So I would guess that you reduced the diameter of the 63 gr. .257 cal bullet down to 0.250".... That would reduce the weight about 3 gr.... That would place the length at 0.515" if you didn't reduce that in proportion.... If you also shrank the length in proportion to the diameter, down to 0.500", then the weight would be about 58 gr.... Either way, it should work just great, although it will no longer fit in the MRod magazine, like the 52 gr. does....
The 63 gr. in .257" has a recommended twist of 14", so a 58 gr. at 0.250" would be similar.... However, I think those estimates are conservative.... What twist rate are you running?....
Bob
-
I have a TJ .25 14" twist and should be able to propel the 58g up to 940-960 fps but I'm going to still around 840 to keep my shot count up.
I need to do some shooting a figure out the BC of the 58g slugs
-
bob
i reduced the overall diameter to .254
and some of the other diameters a little not much/// not in the shop right now so can't get to the drawing for the actual specs
shortened it about .002 if i remember right
the slug drops from the mold at an average of 58.4 grains
mule
-
Ahahhh, Isn't the GTA great ?
Minds from different backgrounds coming together, bouncing idea off each others and picking tidbits to enlarge product avaiability/selection in this fast moving segment of today's airgunning world.
GTA is arguably the best overall Airgun forum around by a good margin.
-
I figure I would post this here too.
Today I measured the ballistic coefficient of the BBT .251 58.4 grain.
I took 5 shots at each distance.
Gun filled to 2600psi
At the muzzle: 838 fps avg - 91.1fpe
27 yards away: 825 fps avg - 88.2 fpe
the BC came out to be. .2308
I have no idea if this is right or not. I use used chairgun to calculate it. It Seams a bit high but does are the number.
It seems high to me