My highest 25 LBT FPE so far or so I thought
These energies are in the 134 to 179 FPE range if my chrony is correct.
I was filling to very high PSI levels, I dropped down to 3200 PSI and got the lower group by filling between shots.
I seems the higher the velocity the tighter they group. Also bear in mind that these groups were shot with a 2×7 Burris that is Parallaxed at 100 yards.
This is with the barrel I prepped yesterday with my hillbilly lathe and Airarcher valve parts, hammer and hammer spring and Tagdaggers rear bushing which replaces the power wheel and rear bushing.
They are also noticably higher, 110 FPS, than what the barrel was giving with the added one inch of choke. I suspected that swaging bullets with air was a velocity theif.
Regards,
Roachcreek 😳 😳
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I have posted about the LBT lead that has to be cut in and how it ruins King accuracy.
Yesterday I detuned the 17 inch LBT carbine, being as I now have a 23 inch rifle that shoots 1030 FPS I wanted something a little more tame to shoot around the house here.
So I wanted something in the 25 ACP level, 750 to 800 Range and set my carbine up thusly:
Stock valve parts, medium weight hammer spring and 95 grain hammer. I set the top hat at .070 and the PW is on 3 fill was 3000 PSI.
Velocity over my now hopefully repaired chrony was a long string of 770 to 780 FPS for the LBT’s. For shits and grins I fired Kings over the box and got 980 FPS.
I am in a scope bind right now, having two AF rifles and two FX Royales and only two scopes. The Leupold VXIII is getting M1 knobs on it and I have a 3200 5×15 Tactical coming in tomorrow, so bottom line I had to rob the 2×7 Burris off of the 23 inch LBT. Which is okay because it will live on the 17 inch LBT, and the fancy long range Leupold will go on the 23 inch LBT to take advantage of its long range accuracy and flat shooting abilities.
But I digress once again. I had to sight in. So I set a target up at 40 yards, zeroed my scope on the laser I have mounted, checked the zero at 15 yards with LBT’s and then with Kings, both shot one ragged hole.
I found that interesting.
So I shot at 40 yards, and got it roughly zeroed, and decided to try a King group to see how they shot at 980 FPS, now bear in mind in the 23 incher or even the 17 set up for hyper velocity makes these Kings go way over super sonic and that combined with the loose lead, that resembles a Astroglide lubed, 65 year old mother of 6 with a grin 😆 , makes them shoot for shit.
But the rifle grouped 5 Kings into .9 inches, not the best, but not too bad in a fix if your out of LBT’s. Then I shot a cleaning shot thru the barrel with one LBT and then shot a group to see how they grouped at that range. It put 5 shots just under .5 inches and 1.25 inches higher than the Kings.
So I found out at lower velocity if 980 FPS can be considered lower velocity, it has with Kings the accuracy to shoot squirrels at 30 yards, I guess that would compute to spiringer accuracy with Kings, and at 25 ACP velocites it is a real tack driver.
It also makes the 25 LBT neighborhood friendly at that level.
I have now cast and shot perhaps 3 thousand LBT bullets, I am getting the mold figured out nicely and have the rifles shooting where I would like them. I figure at the price of Jerry’s slugs I have paid for all the LBT casting equipment, maybe three times over.
Regards,
Roachcreek
Some people where asking me about where to get the 250Bar bottles from, so here is a link for 280cc,400 & 500cc.
Lead is a mineral resultant from fully decayed Uranium ore. Wash your hands when you’re done.
Nice groups.
Hoot
You need to have a slug that is bigger than your barrels inside diameter, enough so that you will displace a little lead when you push it into the barrel.
One way is to take a Jerrys slug and tap it on the end so that it expands and has to be forced into the breech end of the barrel with somethng on the order of a brass punch and a small hammer. You might want to put a little lube on it also.
Once it is in the breech end of the barrel completely, push it in halfway down the barrel with a cleaning rod, then stop, put your rod in the muzzle end and push the slug back out the breech.
If you push it completely thru and out the muzzle, the barrel choke will size it down a few more thousands and you don’t get a true reading.
In example, my groove diameter is .2549, my choke is .251. That differnce was why I did not get good or consistant accuracy until I cut the choke off the barrel.
Now with my LBT slugs, the slugs will not go into the breech end, so I had to open up the breech end of the barrel to get them to fit. Once you cut a lead in, Kings will fit very loose, accuracy with Kings will not be good. So this is a bullet specific barrel alteration,
That is why Jerry’s slugs are a bargain if they shoot in your rifle.
But I digress, what your trying to accomplish is to have the bullet completely fill the rifling grooves when your slugging the barrel. A airgun cast bullet will not expand upon ignition like they will in a powder burner, and if the slug is oversize for your barrel, swaging it down using air power will rob you of power, so the ideal situation is to have the slug .0001 over your groove diameter. This means .0001 over the maximum measurement of the slug you slugged your barrel with.
Again with mine my barrel is .2549 so I size to .255 which is .0001 over groove diameter.
For those of you who do not know this or are confused, think of it this way, bore diameter is the diamerter of the barrel before rifling is cut, groove diameter is the diameter measured at the bottom of the rifling cuts or valleys. ie, a 308 Winchester is called a 30 caliber, meaning the bore is .30 but the goove dameter is .308. What your after when you slug is the groove diameter.
I measure the slug length wise at its maximum width to get the correct groove diameter.
Pellets skirts will expand to the bore when fired or so some think. Jerrys slug work well because he has those small rings that enable you to push the slug into the breech end and they form to the rifleing well due to their small bearing surface. It is a great design because it will work in different diameter barrels.
Regards,
Roachcreek
K now what’s the best way to slug the barrel
You can always buy the 250BAR bottles from the UK, they are the same thread size, that way you can fill to 3600 PSI if needed.
😯 😯 😯
gearhead,
I cast them out at .256 and size them to .255 for my barrel that I have slugged at .2549.
RC
I’m just wondering what are the LBTs sized at?
Unless you cut a lead in breech, they will not chamber, but if you do I still owe you a big favor for that scope wheel, just let me know.
If after doing it you change your mind you only loose 3/8 inch of barrel length, or at least on a Condor you only loose that much.
RC
Still impressive with that length barrel. I have filled to 3400 psi with my Logun tank for the .308. It is same tank just a little shorter. I’m going to machine my 24″ unchocked barrel and put it in it’s own frame just for slugs and see how far I can push the fps and fpe wig Jerry’s slugs. Want to sell a few of those LBT’s
No I filled to 3400 PSI. Which makes my ass pucker up.
The lower group was fired at 3200. I get three shots that are almost identical in FPS, well 1021 to 1030 FPS from 3400 to 3200.
BUT I DO NOT GET 1135, or 1185, that has to be a chrony error.
I sighten in at 100 yards just now, and then shot on my metal clad target at 150 yards.
And I did it twice, the drop each time was 16 inches.
16 inches is exactly what Handloads.com says I should get at 1030 FPS with a 56 grain bullet with a 100 yard zero, and unlike HCairgun, Handloads.com has alsways been right on for me.
This is 132 FPE.
So with egg on my face, I have to admit that perhaps it is time for a new chrony.
Regards,
Roachcreek
If you filled to 3600-3700 might be right. When I made 167 fpe it was with 3200 psi. I know if I want to go any higher it is going to take more psi. I have a 4500 psi tank so I can work my way up to 3800 psi and see what happens. Suprised you can get that much air through a stock sized condor stem. My stem is .250 ID. Nice job.
me too… but give us all a time before you post so we can watch!
… oh ya… add the m-rod forum to that list as well 🙄
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Roach, what if you made a little pellet seater out of a chunk of oak or something to push those kings past the lead and into the rifling, wouldn’t this take care of the flappy gap lead and regain the precision of the kings by having them seated squarely in the lands?