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Thread: 55 gr. Bob's Boattail HPs in .25 cal at 110 FPE

  1. #1
    Boolit Buddy rsterne's Avatar
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    May 2013
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    55 gr. Bob's Boattail HPs in .25 cal at 110 FPE

    I have a hot .25 cal Disco that is a genuine 100+ FPE gun, so I pulled it off the wall today to try some velocity experiments with different size bullets.... I have some 50.4 gr. FN BBTs (NOE 250-51), and also some 58.3 gr. FN (NOE 250-60), plus the HP versions as well.... I tried them as cast (0.250" nose / 0.252" drive band), and they were hard to chamber in my TJ's .25 ACP barrel.... so I sized some of each down to 0.251", 0.250" and 0.249".... I tethered the gun at 2950 psi (it is modified for 3K plus) and both bullets picked up a lot of velocity between as cast and 0.251", gained more at 0.250", and then lost about 10 fps at 0.249", presumably from a small amount of blowby….

    The 58.3 gr. FN were well over 900 fps, so I thought I would tune the gun for the 55.0 gr. HP version of that bullet, sized to 0.250".... Mean looking little devil....



    I maxed out the preload and hit 993 fps (120 FPE), and then backed it off a turn and got 965 fps.... At that setting, off the tether, I got 2 equal shots and then a 3rd at about 940 fps, so I backed the preload out a bit more and ended up with 3 shots off tether of 956, 963 and 945 fps (111 FPE average) within a 2% ES.... Tethered, of course, it shoots 956, within a few fps.... which will give me a good platform to test these HP bullets.... The gun is loud, and not very efficient.... but at 110 FPE it should really lay a smackdown on a Marmot.... 8)



    This is a penetration test of the 55 gr. BBT HP in soap at 110 FPE.... The nose came apart.... penetration of the base was 95 mm (3.75")….

    Bob

  2. #2
    Boolit Master HARRYMPOPE's Avatar
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    what kind of groups are you getting and at what distance?
    “When people have tried everything and have discovered that nothing works, they will tend to revert to what they know best—which will often be the tribe, the totem, or the taboo.”
    ― Christopher Hitchens

  3. #3
    Boolit Buddy rsterne's Avatar
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    Sorry, lots of snow here still.... Hope to be able to answer that question in a couple of months....

    Bob

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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check