.30 cal Boattail Airgun Bullet Designs

[rsterne]

I've been playing with boattail designs for a while, looking at their subsonic BCs, which are significantly better than a flat based bullet.... Anyway, here is what I came up with for the .300 cal barrels that Sean is supplying.... It's a 70 gr. in solid form, and would be about 65 gr. as a hollowpoint.... and has a Stability Factor of 1.5 at 900 fps in our 26" twist barrel (increasing below that).... The subsonic BC is supposed to come in at 0.16....

http://i378.photobucket.com/albums/oo221/rsterne/Bullet%20Casting/300calAirgunBoattail70gr_zpsf8c47a60.jpg (http://s378.photobucket.com/user/rsterne/media/Bullet%20Casting/300calAirgunBoattail70gr_zpsf8c47a60.jpg.html)

While I was at it, I did another design, slightly heavier, for the commonly available .308 cal barrels.... It's 79 gr. as a solid, and about 73 gr. as a hollowpoint, and will have lots of stability in any barrel 20" twist or faster.... It will just fit into a .30 cal MRod magazine.... The subsonic BC should be 0.19....

http://i378.photobucket.com/albums/oo221/rsterne/Bullet%20Casting/308calAirgunBoattail79gr_zpsf8dc7f83.jpg (http://s378.photobucket.com/user/rsterne/media/Bullet%20Casting/308calAirgunBoattail79gr_zpsf8dc7f83.jpg.html)

I have been in contact with Tom at Accurate Bullet Molds, who make custom molds that are CNC bored in either aluminum, brass, or iron, and in 1 through 5 cavities.... You can use any of the bullet designs in his online catalogue at.... http://accuratemolds.com/catalog.php .... You can even order a mold with different cavities, which is my plan, I will be getting an aluminum mold with one of each of the above bullet in it.... I have submitted the drawings to him, and I'll let you know when they are in the catalogue.... I'm really looking forward to testing these new designs....

Bob

[JeffinNZ]

Bob, do you lube them for the airgun?

[longbow]

I was about to ask which 30 cal. but see you have MROD mentioned. That's the Benjamin Marauder right? I haven't seen a .30 cal. version. Do you have an after market barrel on it?

I have been toying with the idea of a big boy's air gun in something from .25 cal. to maybe 9mm. I want a big bore airgun but not one so big it gets very few shots per charge. .30 kinda tickles my fancy but I do not see many available and only expensive guns in .30 cal.

I have looked a bit and have several airgun sites saved but am still finding new sites and info.

I like your boolit design and I like .30 cal... what can you tell me?

Thanks,
Longbow

[rsterne]

Normally no lube, although some do....

I have a Disco Double that I reworked the valve and hammer, made a custom breech to accept the MRod magazines and Sean Pero and I had a mandrel made for .300 cal barrels to fit the new JSB pellets, which are smaller than the standard .308 cal used for PB bullets.... The valve mounting screws are larger so that I can run 3000 psi, and the gun shoots over 100 FPE with 50 gr. pellets.... I wanted something heavier, hence this bullet design.... Here is a photo of the gun, not yet finished, some parts still in the white....

http://i378.photobucket.com/albums/oo221/rsterne/30%20cal%20Disco%20Double/IMG_3527_zpsc4058736.jpg (http://s378.photobucket.com/user/rsterne/media/30%20cal%20Disco%20Double/IMG_3527_zpsc4058736.jpg.html)

The stock is a Boyd's Blaster in Forest Camo inletted by Norm at DiscosRUs that I finished with 7 coats of Watco Oil, and the barrel has a carbon fibre shroud and a Hatsan air stripper fitted.... The magazines are modified by Lloyd at AirGunLab (who makes the Disco Double Kit) from a .25 cal MRod with a .30 cal 7-shot insert, and I can tune the gun for 1 magazine at 107 FPE or 2 magazines at 85 FPE by turning a single screw....

The barrels Sean has are 1/2" OD x 25" long, they are 0.293" land and 0.300" groove, with a 26" twist, hammer forged CrMoly, and are available as a blank (in the white) or with any stage of machining and finishing done you wish, including choking, cutting the chamber, leade, ports, crown, even lapping.... The barrel is capable of MOA with either the 46 gr. or 50 gr. JSB pellets (ie FX or Daystate).... Sean will also be making the breeches, valves, and hammers, and he can be contacted at seanpero@gmail.com

Bob

[detox]

www.Accuratemoulds.com has a couple designs listed for .357 caliber.
http://www.accuratemolds.com/bullet_detail.php?bullet=36-090A-D.png

[MT Chambers]

HMMMMM.......I wonder how that would work in my Wolverine??

[rsterne]

Yeah, the .357 molds at accurate are a stretched EPP/UG designs and one with an added gas check shouder, even longer....

The .30 cal design of mine is the proper size for the Wolverine, which is NOT .303 cal (that was an advertising gimmick), it's .300 groove diameter to match the JSB pellets.... I would think it should work fine....

Bob

[melloairman]

HMMMMM.......I wonder how that would work in my Wolverine??
The 36-090A-D proved to be inaccurate past 30 yards in several AR including my Corsair . In the 45 caliber it is a very accurate bullet .Marvin

[Blammer]

I think NOE already has some air gun bullet moulds.

http://noebulletmolds.com/NV/index.php?cPath=30&osCsid=nt6njqsu0viul6j0pt02u0acp6

may want to check it out.

[melloairman]

I think NOE already has some air gun bullet moulds.

http://noebulletmolds.com/NV/index.php?cPath=30&osCsid=nt6njqsu0viul6j0pt02u0acp6

may want to check it out.
In most cases there is no need for a AR specialty mold . Unless it is a caliber such as the 25 . Were molds for PB are far and few between . Or if your rifle can not push a standard weight bullet fast enough to maintain accuracy for 50-100 yards were most shoot . If you look at the Netherlands AR championships . Were PB are heavily restricted and most shooters go with AR . You will see that most of the top contenders use off the self molds like RCBS, Lyman and Lee . And these shooters are really into AR because the government will not allow much more . Marvin

[rsterne]

After a couple of very pleasant emails back and forth with Tom at Accurate Molds, I got an email telling me that the new boattail airgun bullet designs have been added to the catalogue as numbers 30-070A and 31-079A.... They are on the first page of the catalogue, so they are easy to find.... I went through the extremely simple order process on their website, and I was able to order one cavity of each design in a single aluminum mold block (which uses 6-cavity Lee handles).... The mold was $100 plus $15 extra to have two separate designs, and the shipping fee was a startling low $5.00.... The turnaround time is 3 weeks, so in about a month I should have it in my hands....

I'm really excited about the opportunity to get a custom bullet mold at no extra cost, and in such a painless manner.... My hat's off to Tom for all his help, and his excellent website....

Bob

[rsterne]

I received the mold from Tom, beautiful job....

http://i378.photobucket.com/albums/oo221/rsterne/Bullet%20Casting/IMG_3856_zps7cc7d72d.jpg (http://s378.photobucket.com/user/rsterne/media/Bullet%20Casting/IMG_3856_zps7cc7d72d.jpg.html)

.300 cal 70 gr. on the left, .308 cal 79 gr. on the right....

http://i378.photobucket.com/albums/oo221/rsterne/Bullet%20Casting/IMG_3865_zps7b3d763f.jpg (http://s378.photobucket.com/user/rsterne/media/Bullet%20Casting/IMG_3865_zps7b3d763f.jpg.html)

First 500+ bullets....

http://i378.photobucket.com/albums/oo221/rsterne/Bullet%20Casting/IMG_3873_zps35b0868f.jpg (http://s378.photobucket.com/user/rsterne/media/Bullet%20Casting/IMG_3873_zps35b0868f.jpg.html)

.300 caliber, 70 gr....

http://i378.photobucket.com/albums/oo221/rsterne/Bullet%20Casting/IMG_3881_zps834e3469.jpg (http://s378.photobucket.com/user/rsterne/media/Bullet%20Casting/IMG_3881_zps834e3469.jpg.html)

.308 caliber 79 gr....

http://i378.photobucket.com/albums/oo221/rsterne/Bullet%20Casting/IMG_3890_zps49acaa7c.jpg (http://s378.photobucket.com/user/rsterne/media/Bullet%20Casting/IMG_3890_zps49acaa7c.jpg.html)

They both fit in the MRod magazine and function perfectly....

http://i378.photobucket.com/albums/oo221/rsterne/Bullet%20Casting/IMG_3897_zps5a3bbf0b.jpg (http://s378.photobucket.com/user/rsterne/media/Bullet%20Casting/IMG_3897_zps5a3bbf0b.jpg.html)

Chrony testing and indoor targets look good.... but proper accuracy testing will have to wait until next spring....

Bob

[detox]

Linotype alloy will fillout that little mould cavity perfectly. Pellets will be a little lighter in weight also (19 bhn)

I wonder how well pure tin will cast?