Sorry for the long post, but thought I’d share some successes and post some further questions of the experts out there. This post explores my quest for an affordable 300 BLK subsonic hunting bullet, that can be safely used with a non-serviceable suppressor. I’ve gained a lot of knowledge in this forum, and I wanted to give some back (hopefully).
First, some background. When I started looking for acceptable subsonic hunting bullets, I quickly ran into a wall. There are basically two choices, Lehigh or Outlaw State, both of which are $1.00+ per bullet. I preferred the Outlaw State design, but after multiple email attempts to place an order with no response, I grew frustrated and decided I’d develop my own. I also investigated swaging my own j-word bullets, but figured out that would require significant investment for what is essentially a personal hobby, so I abandoned that route as well. Plus, I’m a tightwad, which I think was one of the requirements for joining the Cast Boolits forum.
Pretty quickly, I ran into two primary issues. The first is finding a technology that will withstand the pressures of firing and reliably feeding in the AR platform, but still expand at subsonic velocities on soft targets. The second issue, which was even harder to solve, was finding options that were safe to fire through a non-serviceable AAC-SDN-6 suppressor.
I started like most others by loading up 208 AMax’es or 220 Sierra RN’s. After a decent amount of testing and tweaking, I was able to get sub-1” groups at 50 yards with both designs. They will shoot 5 rounds with all of them touching. 100 yard groups are a tad over 1”. Velocity SD’s are typically 15 fps +/- for 10 rounds using WC 680 (mil version of AA 1680) with 100% cycling and bolt lock-back. Two critical items I found – I apply a heavy crimp, and I lightly tumble lube the j-words with 45/45/10. Those two things dropped my SD’s by more than half and greatly increased accuracy.
All is well, until it comes time to hunt with these rounds. To put it bluntly, they sucked. My style of shooting (mostly stalking) doesn’t always allow for pinpoint shot placement, so headshots on moving pigs with sometimes offhand shots isn’t feasible. I’ve gotten 100% run-offs on front shoulder shots (deadly with supers), and even raccoons run off more than half the time. Neither bullet is expanding (no surprise there) and doesn’t appear to be tumbling quickly enough to do the trick. In short, they’re not suitable or humane for anything but perfect headshots.
This pushed me to first consider modifying the j-word bullets to meet all of design goals. To date, I have finalized one design (j-words) and need help as I push forward on a cast boolit solution. My findings and questions are below.
300 BLK Subsonic J-Word Hunting Bullet Design – WARNING USE AT YOUR OWN RISK
My first fully successful design is using 220 gr Sierra RN j-words. After testing 3 different designs, I found the one that finally worked well.
To create it, I took a ¼” drill bit and carefully drilled off the exposed lead tip until just encountering the start of the jacket, leaving a shallow cup that I used to guide a #19 bit (0.166”) as I drilled out a 0.250” deep hollowpoint cavity. The #19 bit drills with only minor jacket removal and helps keep the HP centered (using the jacket as a guide) in my drill press. I drilled an undersized hole in a piece of 1”x4” with a split cut down the middle to allow me to squeeze the bullet and keep it from turning during drilling operations.
From there, I filled the cavity with flexible silicone caulk (Home Depot) and tapped a steel BB into the end of the cavity with a ball-peen hammer (several light taps). The #19 bit was chosen as it gave about a 0.005” interference fit between the jacket and BB and, together with the adhesion from the caulk as it dries, holds the BB is tightly in the cavity. Finally, I lightly skivved the outside of the jacket in four locations around the circumference of the bullet, and about as far down as the HP cavity. One note - leave the very tip of the bullet unskivved, as it will hold the BB more securely, a technique I figured out after taking the pictures in this thread.
To test the adhesion, I used a heavily crimped round in my inertial bullet puller, allowing rather aggressive hammering of the puller in an attempt to get the BB to come out of the cavity. I also used various other tools to attempt to pull the BB from the cavity, with zero success. I have fired about 100 rounds with zero issues. However, having the possibility of a loose BB in the barrel as it fires is going to be a problem, and you should thoroughly check your rounds before firing until you master the design.
CONSIDER YOURSELVES WARNED, USE OF THIS DESIGN IS ENTIRELY AT YOUR RISK AND CAN POSE SERIOUS HAZARDS IF NOT DONE PROPERLY. Hopefully enough said.
The point of the BB was to “recreate” the round nose of the bullet, which reduced fail to feed jams to zero in my guns, where a previous blunt open HP iteration was jamming every 2-3 rounds. Upon firing, the BB pushes against the column of flexible silicone caulk, causing very high pressures against the jacket walls, essentially exploding the HP cavity and leaving a 0.40-0.45” flat nose with about 180 grains of shank remaining.
Water testing confirmed the validity of the design, and results on raccoon-sized game has been emphatic. Where I was seeing 50-75% escapes with coons using 208 Amax / 220 RN unmodified, the BB design has been 100% DRT. I won’t post pictures here, but suffice it to say expansion was confirmed. I haven’t shot a hog with this design yet, so that question remains. Some pics…
EDIT 08/17/2014: Video of water testing above design. It's loud due to phone being right next to muzzle.
END EDIT.
The 220 gr Sierra RN j-word design is great and meets all of my criteria, but suffers from two issues. The first is the (lack of) availability of the 220 RN bullets. Recently, they’ve been very hard to get. The second is that, quite frankly, it’s a major PITA to make these bullets in any quantity. I have several friends that want them by the hundreds, and I just don’t have the time or patience for that. A third minor issue is that they’re still about $0.35 ea shipped, which isn’t bad, but the tightwad in me wants to do better. Which lead me down the road of Lead, so to speak…
300 BLK Subsonic Cast Hunting Bullet Design
I casted boolits as a kid under the close supervision of my Uncle, but hadn’t done it or had the equipment since then, some 35+ years later. It became apparent that maybe the best way to solve the problem was to go old tech and find a heavy cast boolit that would do the trick. So I broke out the CC and proceeded to spend a bunch of money on casting equipment, in order to save a bunch of money…?
Initially, I got discouraged due to the concerns of lead buildup in my suppressor and gas system from cast bullets. Gas checks might help, except they were problematic due to concerns of them coming off and remaining in the suppressor.
The technology that made it possible is the new PC’ing / Hi-Tek coatings. I’m currently using Gold Hi-Tek liquid coatings, and am having great success. During initial testing, I ran about 50 rounds through the gun, cleaned the barrel with my normal cleaning products, and was shocked at how little came out of the barrel (basically two powder residue patches and clean). I then examined the barrel and suppressor with my Hawkeye borescope. The barrel looked brand new, no deposits of any kind. Nice shiny barrel. The suppressor showed no difference before / after firing, with normal levels of residue deposits. The stuff works great.
I’m using this coating with the NOE 311247 PB mould, with and without hollowpointing. After two coats, I also lightly tumble lube with 45/45/10 to make sizing to 0.309 (from about 0.314 with Hi-Tek) very easy using a Lee push-thru sizer.
I have two problems that I believe are interrelated. I’m not getting the accuracy I’m looking for (1.5MOA or less) with a bullet hardness I expect will expand reliably. I recently tested various cast combinations for accuracy, and need some help from you guys interpreting the results. Here’s a picture of 50 yard groupings for four different cast designs:
Group 1, Upper Left – 12.5 BHN, 75:25 COWW/Pb equivalent 247 gr monolithic.
Group 2, Upper Right – Two-part bullet, 12.5 BHN Base, Pure Pb Flat nose. Water testing showed excellent “expansion”, normally in the form of a very bent nose. Adjusted the scope to left from first group to better center.
Group 3, Lower Left – Two-part bullet, 12.5 BHN Base, 50:1 Pb/Sn HP Nose.
Group 4, Lower Right – this is two 5-shot groups, one left of center, one right of center - 9.5 BHN, 98Pb/1% Sb/1% Sn HP monolithic.
The group 4 boolit is the one I really want to get working better so I can move on to water testing, but at about 3.0 MOA, it’s twice the grouping that I want. It seems pretty clear that the 9.5 BHN boolit is too soft, and is either not tolerating the 1:8.5 twist rate or can’t take the 20,900 psi load (per Quickload). Here’s the bullet, with the HP enhanced with a gentle twist of the Lyman Flash Hole uniformer…
Finally, to my question...
I really don’t want to have to cast softpoint bullets (groups 2 and 3 above) since they’re a major PITA and have a higher rejection rate than monolithic pours. Right now, however, it looks like I’m going to have to be closer to 12 BHN for accuracy and figure out a way to easily skive / weaken the HP of the cast bullet for reliable expansion.
Investigated so far: 1) Sizing down of the bullet when seated? Checked found 0.0005" diameter reduction (to .3085") with 9.5 BHN at base only (not driving bands), and no reduction on 12.5 bases using 0.001" neck tension with custom +0.002 oversize Expander 2) Leading? Nope, borescope shows clean as a whistle 3) Keyholing? I don't think so, as I don't really see evidence, and JBM Ballistics show a 2.65 Stability Factor.
Need to investigate: 1) Slug barrel to get true bore 2) hone out an extra Lee Sizer to 0.310" and see if increased diameter helps 3) 12.5 BHN HP Expanding? I'm thinking of water testing the 12.5 BHN HP's empty and with silicone caulk to see if I can get expansion and focus my efforts there.
I’m looking for some feedback to see if you guys have already been down this road and have some thoughts. If not, I’ll keep going and report back on my final solution. Thanks in advance for any input and enduring this booklet of a post.
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Originally Posted by popper
