Wildcatting: Sticky Business
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- Last updated: 15/05/2017
I love to play around with things and a chat with a hunting pal of my brother’s, Mark Zowek in America, brought up an interesting suggestion. Rather than go for maximum velocity, go completely the other way and see how low you can go? I have gone about as far as I can with sub-sonic .308 bullets regarding velocities, backward loadings, fragmenting projectiles, sabots and patched bullets. Mark suggested I try some 3D printer projectiles! I don’t have one, so why not try forming bullets using hot glue in standard lead bullet moulds?
As bizarre as it is, the kit needed is so easy to source and dare I say fun to use. The easiest part was the hot glue gun. These are available from any hobby store but I just typed it into Amazon and had 20-30 to choose from. You don`t need the most expensive, mine cost me £14.99 and that came with 50 extra hot glue sticks. What you want is a glue gun of sufficient size to heat quickly and deliver a smooth constant supply of molten material with as few air bubbles as possible.
The next piece of kit necessary is some form of bullet mould. I choose three differing .30 cal lead moulds from Lee Precision. These are well made, available in many perfect sizes, shapes and bullet weights and are quite frankly very cheap!
What you need now is practice and for further testing additional projectiles added to the mould to add weight or to change the bullet form in the shape of air gun pellets or buck shot. Case wise, any matched .308 cases are fine and you only need to neck size, but set up the dies to slightly crimp for correct ignition.
Propulsion wise, this is a primer-only proposition and so I used magnum CCI 250 primers for a good consistent flame. RWS 2500, Federal GM210Match or Fiocchi Nickel are equally good and from the results show differing primers can make a big difference to velocity.
Sticky fingers, or burnt ones are more apt; the procedure is very easy:-
■ Plug in hot glue gun and allow it to reach operating temperature and then insert the glue stick until you get a steady stream of molten glue.
■ Prepare Lee moulds by removing light packing grease with hot water and then dry.
■ Close the Lee mould tightly by pressure to both wood handles and position sprue cutter over the holes, this model was a double cavity, which speeds things up.
■ Place the nozzle of the hot glue gun directly into the mould’s orifice in the sprue plate and squeeze the trigger to start to fill.
■ Keep it tight over the hole to fill the bottom of the mould and then slightly cant the nozzle to allow trapped air to escape.
■ This is repeated for the second mould, assuring to keep the flow of hot glue constant.
■ Steps 5 and 6 are trial and error; you with find your own way to fill 100%, it took me at least 20 goes before I had synthetic projectiles with no or very few small bubbles.
■ After the hot glue is in the mould, place into a fridge to cool rapidly. Release of the pressure of the handles on the mould is fine, as the hot glue sets quite quickly.
■ Cool for 10-15 minutes.
■ Cut off the excess glue (sprue) from the top of the mould by moving the sprue cutter open and then open the mould to release two lovely new ‘jelly bullets’.
I had three moulds as stated; the round ball I left as it was, as it was the two conicals that interested me. The first C309-150-F moulds 150-grain bullets in lead but in glue they come out at 14-grains! The second C309-200-R produces 200-grain lead and 20-grain synthetic. This is light and why a primer- only propulsion is necessary, as a powder charge can cause the bullet to rupture, although I did do it but that’s another article if I am allowed back into the kitchen!
I also thought to give the synthetic bullets a heavier stature and also a ‘shuttle cock’ stability by adding an air gun pellet first into the mould and then the glue you had a heavy forward section. I used .309” cal lead balls, buckshot, .177, .22 and .25 air gun pellets as well as 30 cal airgun Emperor pellets.
I actually tried several differing primers, as they will make a difference. I also used weighed cases to minimise variation in the internal combustion chamber and neck sized with a set of Redding dies with varying neck bushes for a correct grip or neck tension. Also, a slight crimp was necessary to build up a small amount of pressure behind the slug that gave more consistent velocity.
I used a short barrelled RPA 308 at 14.5” to check they actually left the barrel! Friction and primary pressure to start bullet movement is always a bit hit or miss and I did not want to be picking out bits of glue from my barrel! I did not fit a moderator to start, as its quiet anyway, but more importantly I wanted to check the bullets were not tumbling.
I then switched to my trusty Tikka LSA 55 .308 win with a 21” barrel to check velocity, accuracy etc and then a few shots from the excellent 300 Blackout Schultz and Larsen. Here are the results:
RPA 14.5” 1 in 12 twist barrel.
First up, getting bubble-free bullets was nigh on impossible but those that had similar weights and bubbles in the rear section were grouped together for better accuracy. Firing was single shot only and from the short RPA 14.5” barrel gave next to no noise or report at all and at 10 yards accuracy at best was 1” with no crimp. Add a better crimp to the case and the accuracy was 1” at 15 yards at best. Nb. there were the odd fliers due to small air bubbles.
Velocity was low as expect from a primer-only ignition, with the biggest problem for velocity down the barrel, length or rifling land depth and width. Too much of either and I had a few phut and no shows and they had to be rodded out!
Velocities with the glue-only loads were 422-444 fps dependent on the primer used for the 14-grain bullet. The 20-grainer travelled faster due to better resistance and pressure build up from the longer, heavier design. However, accuracy was not as good as the 14! Adding extra weight via various air gun pellets helps with velocity, again more mass and momentum for the meagre gases from the primer to work on.
The trouble was getting a consistent bullet shape and accuracy was all or nothing! Velocity for the lighter 14-grainers ran at 422-444 fps for dainty 5.5 to 6.1 ft/ lbs energy. Still enough to penetrate a cardboard corrugated box and good fun for indoor practice.
Adding pellets and the increasing weight due to calibre increase upped the velocity and therefore energy levels, now you had between 10.9 to 28.2 ft/lbs for the 24 to 64-grain bullets from the 150-grain mould. Whilst from the 200-grain you had an increase for virgin bullets up to 8.4 to 9.7 ft/lbs and adding pellets for weights from 20 to 70-grains you then had a jump to 25.9 to 33.8 ft.lbs but accuracy suffered. I did try longer barrels but due to friction produced less velocity and no better accuracy.
Well, WHY? has to be the first question but it’s just fun and trying new things out and I still wanted an indoor short range plinker. With a moderator fitted all you could hear was the firing pin dropping! I think it proves it can be done and I would like to see what result you’d get using a 3D printer; probably more consistant.
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