New .257 (and .224) Cailber Bob's Boattail Designs
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New .257 (and .224) Cailber Bob's Boattail Designs
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Topic: New .257 (and .224) Cailber Bob's Boattail Designs (Read 8543 times))
rsterne
Member 2000+fps Club
Bob and Lloyd
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Real Name: Bob
New .257 (and .224) Cailber Bob's Boattail Designs
«
on:
February 06, 2015, 01:52:38 PM »
I am rather surprised that nobody has asked Veral at LBT to make up molds for my Bob's Boattail's in .257 cal using the pattern he has for the .250 cal. 52 gr.and stretching it.... Perhaps now that he will have a second pattern with a longer ogive radius (the one from the 7mm) somebody might take the initiative.... Understanding just how flexible his manufacturing system is might help....
Veral uses a "tracer lathe" which bores the profile in the mold by following a pattern (like a giant pantograph) that is (at least) 10 times the size of the bullet.... For my Boattails he uses three patterns, one for the nose (which is overlength), one to produce the bearing area with the grooves (of which he has many of different lengths to vary the weight) and one for the boattail (which we had custom made, and is about twice as long as was required for the initial 52 gr.).... Since the pattern is only one side, he can tell the lathe how far out from the center to make the cut, and therefore change the caliber, up to about .50 cal in fact.... Therefore the basic pattern can produce bullets of virtually any length (and weight) and any caliber.... Here are just two possibilities in .257 cal to show you the versatility of this mold making system....
The bullet above is simply a stretched version of the 52 gr., made to the .257 cal (or whatever your specify).... The mold number would be
#25-63-BST
.... The one below uses the new longer ogive nose profile from the 7mm 94 gr. and has the boattail extended slightly...
The mold number for this mold would be
#25-79-BST
.... In both cases, I would suggest that you print off the drawing and send it to Veral with your order form, and with the diameter and alloy you plan to use, so that there is no confusion as to which ogive pattern to use.... The twist rates shown are the suggested twist rate from the Kolbe Twist Calculator and takes into account the reduced stability of the boattail, and I have every confidence that the bullet would be stable using those.... However, people are having success using my BBTs in slower twist rates, so the Twist Calculator may be overcompensating for the boattail, possibly because it is a rebated design.... Therefore they may well work in a slower twist than shown, only trying them would tell you for sure....
If you want a longer (heavier) or shorter (lighter) version of either of the above, you can order that as well, by changing the middle number in the mold number.... For example, if you want a 70 gr. it would be
#25-70-BST
.... and a 90 gr. would be
#25-90-BST
.... For either of those two weights, I would suggest basing the design on the 79 gr. with the longer ogive nose, and sending Veral that drawing, while specifying clearly the change in weight you require....
One other thing.... If you want a .224 cal boattail, that can be done as well.... Here is a drawing for one such design....
The bullet above uses the original nose ogive and boattail patterns, but reduced slighty in length to produce the appropriate diameter Meplat and Base, and give a good bearing length as well.... It would be ordered using mold
#22-41-BST
.... I hope this post will help clarify just how flexible LBT's mold making system is.... and the wide variety of Bob's Boattails that can be made from the few patterns Veral has made....
Bob
Logged
Coalmont, BC, Canada
🇺🇦
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since! 🇺🇦
Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).
airgunnertoo
Plinker
Posts: 107
Re: New .257 (and .224) Cailber Bob's Boattail Designs
«
Reply #1 on:
February 06, 2015, 03:25:48 PM »
I am sitting here waiting for a .25 marauder to be delivered. is there a size that could be made for it with out needing a lathe to rechamber the barrel? I would like to cast ammo that has decent accuracy.
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YEMX
GTA Senior Contributor
Posts: 5900
Semper Gumby
Real Name: Tom
Re: New .257 (and .224) Cailber Bob's Boattail Designs
«
Reply #2 on:
February 06, 2015, 03:58:35 PM »
The 25-63-BST is for the TJ 25-20 barrel, correct? .250 bore, .257 groove, w/a 1:14 twist?
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Silver Spring Md
rsterne
Member 2000+fps Club
Bob and Lloyd
GTA Senior Contributor
Posts: 26926
GTA Forums Person of the Year 2017
Real Name: Bob
Re: New .257 (and .224) Cailber Bob's Boattail Designs
«
Reply #3 on:
February 06, 2015, 04:45:45 PM »
The original version of the .250 cal, the 52 gr., will work with the MRod's 15.5" twist, but it may not chamber well, and I'm not the guy to ask, never had an MRod.... You need to ask in the PCP Gate what success others have had.... Alternately, BillG is now swaging bullets that WILL chamber in an MRod, he is advertising in the Hobbyist Gate....
Yes, the #25-63-BST is intended for the TJ's 25-20 barrel with a 14" twist.... The 79 gr. is likely too long, but only trying it would prove that one way or the other.... It would definitely work in their 25-35 barrel, which has a 10" twist....
Bob
Logged
Coalmont, BC, Canada
🇺🇦
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since! 🇺🇦
Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).
PakProtector
GTA Senior Contributor
Posts: 2890
yes
Real Name: Douglas
Re: New .257 (and .224) Cailber Bob's Boattail Designs
«
Reply #4 on:
February 08, 2015, 12:31:59 AM »
Thanks for the .224 Bob. I assume this is as long as the 14" TJ Hornet liner will stand, yes?
BTW, with some creative relief of the 25 cal Marauder magazine, it should swallow the 63 gr comfortably; my .224 has no issue with .500-long .224's.
cheers,
Douglas
«
Last Edit: February 08, 2015, 12:34:06 AM by PakProtector
»
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Ann Arbor, MI, USA
My most valuable friends are the ones who will tell me I am wrong.
More valuable still are the ones who go to the trouble of making me see it.
rsterne
Member 2000+fps Club
Bob and Lloyd
GTA Senior Contributor
Posts: 26926
GTA Forums Person of the Year 2017
Real Name: Bob
Re: New .257 (and .224) Cailber Bob's Boattail Designs
«
Reply #5 on:
February 08, 2015, 02:04:09 PM »
The recommended twist for the .224 cal, as shown on the drawing, is 12".... I have no idea how it will work in a 14" TJ's, but since most of the other BBTs seem to work in a slower twist than recommended it wouldn't surprise me.... Heck, I've been told the original 70 gr. BBT in .30 cal works great in a Smooth Twist, so go figure !!!
Bob
Logged
Coalmont, BC, Canada
🇺🇦
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since! 🇺🇦
Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).
PakProtector
GTA Senior Contributor
Posts: 2890
yes
Real Name: Douglas
Re: New .257 (and .224) Cailber Bob's Boattail Designs
«
Reply #6 on:
February 09, 2015, 08:38:07 AM »
I am in the market for another .224 mold. It is rather a toss up between the BBT and the WFN from NOE...with a bit leaning to the heavier, larger meplat-ed NOE. All this overshadowed by the slowly progressing .308 which will absolutely be consuming the bigger BBT fodder, likely out of a 2x2 4-cav running 95 and 110 gr cavities.
cheers,
Douglas
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Ann Arbor, MI, USA
My most valuable friends are the ones who will tell me I am wrong.
More valuable still are the ones who go to the trouble of making me see it.
rsterne
Member 2000+fps Club
Bob and Lloyd
GTA Senior Contributor
Posts: 26926
GTA Forums Person of the Year 2017
Real Name: Bob
Re: New .257 (and .224) Cailber Bob's Boattail Designs
«
Reply #7 on:
February 09, 2015, 02:17:24 PM »
You could also request a larger Meplat on the LBT mold, which would shorten the overall length and weight just slightly, while allowing a slower twist.... Shortening the nose 0.020" would increase the Meplat to 70% (instead of 60%) and reduce the twist requirement by about an inch....
Bob
Logged
Coalmont, BC, Canada
🇺🇦
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since! 🇺🇦
Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).
KnifeMaker
GTA Senior Contributor
Posts: 8224
yes
Real Name: Michael
Re: New .257 (and .224) Cailber Bob's Boattail Designs
«
Reply #8 on:
February 11, 2015, 08:43:33 PM »
Humm! Now this is getting interesting! Wonder how having it hollow pointed would effect the twist requirements. (weight -vs- length for twist)
Knife
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Central Texas
rsterne
Member 2000+fps Club
Bob and Lloyd
GTA Senior Contributor
Posts: 26926
GTA Forums Person of the Year 2017
Real Name: Bob
Re: New .257 (and .224) Cailber Bob's Boattail Designs
«
Reply #9 on:
February 11, 2015, 10:54:27 PM »
In theory you should need a slightly faster twist rate for a HP.... but the only way you can input that information into a Twist Calculator is to figure out the Specific Gravity, using the weight and volume, and use that.... Unfortunately, a HP bullet's SG isn't evenly distributed, so doing that will predict too fast a twist rate required.... The true answer lies between what you would calculate for a solid and for a HP.... When you consider that it seems like the predicted twist rates for the Boattails are a bit too fast, it becomes a matter of "try it and see" if you want to use a slower twist....
Bob
Logged
Coalmont, BC, Canada
🇺🇦
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since! 🇺🇦
Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).
KnifeMaker
GTA Senior Contributor
Posts: 8224
yes
Real Name: Michael
Re: New .257 (and .224) Cailber Bob's Boattail Designs
«
Reply #10 on:
February 13, 2015, 12:13:16 PM »
Thank's for the Reply Bob!
I am testing a Lyman 257420 mold here that is on loan from Tofazfou. It has one standard cavity, and one HP cavity. Work done by Eric at HP mold Services. there is a little over a 3 grain difference in weight with my alloy.
So far, both exhibit excellent accuracy. At 80 yards, a .22 LR hull isn't safe at all! LOL!!! A Squirrel's noggin isn't safe at all. I feel a pot of Dumplings coming on!!!
Knife
«
Last Edit: February 14, 2015, 01:10:09 AM by KnifeMaker
»
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Central Texas
rsterne
Member 2000+fps Club
Bob and Lloyd
GTA Senior Contributor
Posts: 26926
GTA Forums Person of the Year 2017
Real Name: Bob
Re: New .257 (and .224) Cailber Bob's Boattail Designs
«
Reply #11 on:
February 13, 2015, 12:45:30 PM »
Sounds like my 257420.... but mine has a bigger HP cavity, there is a 7.4 gr. difference.... 73.4 down to 66.0....
Bob
Logged
Coalmont, BC, Canada
🇺🇦
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since! 🇺🇦
Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).
KnifeMaker
GTA Senior Contributor
Posts: 8224
yes
Real Name: Michael
Re: New .257 (and .224) Cailber Bob's Boattail Designs
«
Reply #12 on:
February 14, 2015, 01:14:29 AM »
Tell me about it Bob. Is it work by Eric, Yourself? How's the accuracy? I know Eric made some with deeper HP's but he wasn't thrilled with the accuracy if I remember our conversation right.
I have two NOE molds here. Thinking of having one of them HP'd. One is only 60 grains after decking. But I can't help but wonder if having it done would make the bullet too light for the 1-14" Twist in the .257
Mike
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Central Texas
TheBullsEye
Marksman
Posts: 491
No
Real Name: Jake
Re: New .257 (and .224) Cailber Bob's Boattail Designs
«
Reply #13 on:
February 14, 2015, 01:24:58 AM »
Do i have this straight that he will produce a mold and sell it to your for your personal casting needs correct ?
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La Farge, Wisconsin
Gamo Coyote .177
FX Dreamlite .25
rsterne
Member 2000+fps Club
Bob and Lloyd
GTA Senior Contributor
Posts: 26926
GTA Forums Person of the Year 2017
Real Name: Bob
Re: New .257 (and .224) Cailber Bob's Boattail Designs
«
Reply #14 on:
February 14, 2015, 01:17:36 PM »
My HP conversion was done by Erik.... beautiful work.... Look at the destruction of the large HPs when testing in melt-and-pour soap....
I don't think you will ever have a problem with stability on a flat base 60ish gr. .257 in a 14" twist regardless of the size of the HP cavity.... Not so sure about the Boattails, though, combining that with a large HP may run into problems....
Most of the custom mold makers will make molds to your requested diameter, taking into account the alloy you plan to use and how much it shrinks.... Certainly Accurate and LBT do, I don't know about NOE, never dealt with them....
Bob
«
Last Edit: February 14, 2015, 01:20:01 PM by rsterne
»
Logged
Coalmont, BC, Canada
🇺🇦
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since! 🇺🇦
Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).
Tofazfou
Expert
Posts: 1676
yes
Real Name: Cedric
Re: New .257 (and .224) Cailber Bob's Boattail Designs
«
Reply #15 on:
February 14, 2015, 03:41:49 PM »
WOW BOB! How fast at the muzzle are those travelling?
Is that about 2.5"-3" of penetration then MASSIVE EXPANSION.....lol?!
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California
KnifeMaker
GTA Senior Contributor
Posts: 8224
yes
Real Name: Michael
Re: New .257 (and .224) Cailber Bob's Boattail Designs
«
Reply #16 on:
February 14, 2015, 11:05:11 PM »
Bob, the 60 grainer fp NOE would come in closer to 55 grains. That's why I worry about it. It will still have an area similar to a gas check base.
Very explosive expansion! In a varmint bullet, this is very desireable. In a game bullet, this would be considered bullet failure. Each type has it's uses.
Problem Coon's here would be rapidly dispatched by such a bullet. Wouldn't use it on much of anything larger. Any bone hit could lead to complete failure.
Knife
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Central Texas
rsterne
Member 2000+fps Club
Bob and Lloyd
GTA Senior Contributor
Posts: 26926
GTA Forums Person of the Year 2017
Real Name: Bob
Re: New .257 (and .224) Cailber Bob's Boattail Designs
«
Reply #17 on:
February 15, 2015, 12:19:14 AM »
All were shot at 130 FPE.... HPs are large, great for varmints, not suitable for bigger game....
Upper from right is 77 gr. RCBS Cowboy HP, penetration 113 mm
Lower from right is 66 gr. Lyman 257420 HP, penetration 110 mm
Upper from left is 87 gr. RCBS Cowboy FN, penetration 255 mm (already went through 1 complete 9" block)
Lower from left is 73 gr. Lyman 257420 FN, penetration 265 mm (same)
In the same soap, a .22LR 40 gr. solid HV (140 FPE) penetrated 277 mm.... 36 gr. HP (135 FPE) penetrated 136 mm.... So we're pretty much at .22LR performance with an airgun in .257 cal....
Bob
Logged
Coalmont, BC, Canada
🇺🇦
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since! 🇺🇦
Airsenal:
1750 CO2 Carbine, .177 Uber-Pumper, .22 Uber-Carbine, .25 Discovery, 2260 PCP 8-shot Carbine, 2260 HPA (37 FPE), 2560 HPA (52 FPE), XS-60c HPA in .30 cal (90 FPE), .22 cal QB79 HPA, Disco Doubles in .22, .25 & .30 cal, "Hayabusa" Custom PCP Project (Mk.I is .22 & .25 cal regulated; Mk.II is .224, .257, 7mm, .308 & .357; Mk.III is .410 shotgun and .458 cal), .257 "Monocoque" Benchrest PCP, .172/6mm Regulated PCP and .224/.257 Unregulated, Three regulated BRods in .25 cal (70 FPE), .30 cal (100 FPE) & .35 cal (145 FPE), .257 Condor (180 FPE).
YEMX
GTA Senior Contributor
Posts: 5900
Semper Gumby
Real Name: Tom
Re: New .257 (and .224) Cailber Bob's Boattail Designs
«
Reply #18 on:
February 15, 2015, 01:00:10 AM »
That's impressive!
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Silver Spring Md
Tofazfou
Expert
Posts: 1676
yes
Real Name: Cedric
Re: New .257 (and .224) Cailber Bob's Boattail Designs
«
Reply #19 on:
February 15, 2015, 03:14:45 PM »
Very Nice Bob. That's the good thing about Eric too, he will do pins to whatever specific dimensions you want. Your pin did exactly what you wanted it to do.
I've tried shallow pins and super deep pins and small and big calibers. The deep pins always fractured upon 2-3" of penetration but accuracy wasn't there. Either the bullet was off balance during flight or the large and deep HP was catching a ton of air. Not sure which but this was also with a 457 bullet in HP form. Once i trimmed the pin down, accuracy improved a ton.
But i stuck with pins that were pretty much down to the fattest part of the OGIVE or right before the top "Bearing groove/crimp groove". This allowed deep penetration with excellent expansion while allowing the base/rear of the bullet to keep driving on and the bullet retaining orig. weight.
I just let Eric do his HP thing...........lol
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California
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New .257 (and .224) Cailber Bob's Boattail Designs