3d Printed Shotgun Wads

[mikehill85]

I can't stress enough how important a strong and solid wad is for good results.
If possible, your sabot should match the cavity in the slug for best support, but the hot glue filler should work as well.
I ran into all kinds of trouble with my first injection molded wads - both the Brenneke clone and the sabot "Sleeve-Slug"

This is what the first sabots looked like after launch. The set-back had compressed the bottom to half the height:



This pic shows a recovered Brenneke taken apart. The indentions from the wad in the rim of the slug
vividly illustrates the forces involved during those critical first few milliseconds.
This wad was made from HDPE. (High Density Polypropylen) which is extremely tough.
Notice how the wad nose match the cavity in the slug for maximum support.



This is what a bunch of Brenneke looks like after being fired into a sand berm.
The one in front was shot through modified choke (notice the flattened ribs)
The rest were shot through a true cylinder barrel. (Diameter of both slug & wad is 0.73)



And this is what it looks like when you finally get every thing in working order
This five shot group was shot at 64 yards from a smooth bore.

Thanks for sharing. Thinking about the wads, I suspect I may know the reason for the poor release. The bottom part of the two part wad has a lip that sticks out at the bottom (see below). It may actually be grabbing onto the back of the sabot sections and also potentially sticking to the back of the slugs. I don’t remember seeing the bottom half of the two piece wad when I was checking for sabot pieces at the range. This could explain the crazy fliers. I have different shells which have one piece wads that I will try. Hopefully that will help.

[mikehill85]

I had another thought. Maybe some of the slugs are tumbling because of their velocity. The theoretical muzzle velocity is about 1160 fps. According to information I found on the BC of this slug, at 50 yards the velocity should be about 1034 fps. Maybe it is destabilizing as it goes subsonic. I'm not sure how sensitive to velocity/going from transonic to subsonic this slug is but even variations in the velocities from slug to slug could potentially be causing some to start out subsonic and remain subsonic and others to start out above the speed of sound and drop below it in short order.

Anyway, I think I'll take my chronograph to the range next time and see what the actual muzzle velocity is and if there is any correlation between "flyers" and muzzle velocity.

Any thoughts on this would be appreciated.

[longbow]

I have no personal experience with this slug but turbo1889 (used to be a frequent poster here) maintained that the Lyman sabot slug became unstable at transonic velocity when shot from smoothbore.

True or not?

Longbow

[mikehill85]

Some better groups this last time out. I added a nitro card in between the slug and the bottom part of the 2-part wad and bumped up the sabot diameter by 0.008".

I recovered a couple of the original birdshot wads the slug rides on (shown below). At first I didn't even recognize them because they were flattened but based on these drastically improved results with the addition of the nitro card and the appearance of the wads I think the wad was actually grabbing the back of the sabot before and stopping them from separating properly.

For my next batch of slugs I will use Winchester AA wads with the pedals cut off. I think these may support the slug better.

Original Wad


Wad After Firing


All shots were taken at 50 yards. All groups are 5-shot groups except for the last "cloverleaf" group, which is 3 shots.

1.9" 5-shot group


2.6" and 1.8" 5-shot groups


0.8" 3-shot group

[longbow]

That's looking better! In fact that's darn good!

Longbow

[mikehill85]

That's looking better! In fact that's darn good!

Longbow

If anything is wrong, it's probably my shooting. I've only been shooting since 2018. Yesterday there was a bit of a right to left crosswind too. Excuses aside, I'm happy with how things are starting to shape up.

[mikehill85]

I had one additional question I wanted to pose to anyone reading this thread with experience.

The last time I went out shooting I brought my chronograph. I only got about 10 shots off before an errant sabot piece hit the chronograph LCD and broke it. I have since purchased a replacement LCD which arrived today (it only took 2 days to get here from Poland and cost $13 total which is pretty amazing), I desoldered the old screen, replaced it with the new one and the chronograph is back in working order. I'm going to put acrylic guards in front of the screen and rear sensor before I go shooting with it next time.

My chronograph faux pas aside, I was getting very odd chronograph readings (~400-700 fps) and I'm wondering if anyone has any idea why. I'm thinking maybe muzzle blast was being picked up by the first sensor (in that case my chrony is too close to my muzzle). If it were picking up the wad, I believe my readings would skew on the high side.

[Cap'n Morgan]

Probably the muzzle blast - it will overtake the slug at the muzzle but quickly lose speed.
Increase the distance and aim high - it'll pick up those large slugs several feet, if not yards, above the chrony.

[mikehill85]

Thanks for the info. The fact it will pick up larger projectiles higher above the chrony makes sense. I will definitely shoot further above it next time I use it.

[mikehill85]

Update:

I went shooting today using shells with the Winchester AA12 wads as a base. The results were pretty decent I think (considering that I'm working with modified bird shot).

All groups are 5 shots at 50 yards

A 3.1" Group


A 2.0" Group


A 2.1" Group

[longbow]

Mike:

That's looking pretty good!

However, something you might want to try to see if groups tighten up even more is to go to a plastic gas seal and hard card wad column or as Ranch Dog did all card wad column. Cushion legs crush and it is unlikely the base of the seal is dead square with the muzzle when they exit. We know what happens to cast boolits when bases aren't dead square with the muzzle so I have to think that a hard card wad column will provide better support and likely will remain more square in the bore and leaving the muzzle.

Link to Ranch Dog's post:

https://castboolits.gunloads.com/sho...-Tail-Feathers

A consideration though is that if replacing the cushion leg with hard card wads I believe the reduction of volume at ignition (little crush compared to a cushion leg) that pressures rise. The effect seems more obvious with faster powders from the references I looked at. That would only apply if using a plastic gas seal to I think. Ranch Dog went with all card wads and from my experience there is a lot of blow by using all card wads so that should negate any pressure rise.

Anyway, using a hard card wad column for consistent support and square to muzzle base and a hull that fills the chamber might tighten groups up even more.

I have some slugs in shotcups with cushion leg cut off loaded over hard card wad column now. Just have to get some time to go shooting.

Longbow

[mikehill85]

Mike:

That's looking pretty good!

However, something you might want to try to see if groups tighten up even more is to go to a plastic gas seal and hard card wad column or as Ranch Dog did all card wad column. Cushion legs crush and it is unlikely the base of the seal is dead square with the muzzle when they exit. We know what happens to cast boolits when bases aren't dead square with the muzzle so I have to think that a hard card wad column will provide better support and likely will remain more square in the bore and leaving the muzzle.

Link to Ranch Dog's post:

https://castboolits.gunloads.com/sho...-Tail-Feathers

A consideration though is that if replacing the cushion leg with hard card wads I believe the reduction of volume at ignition (little crush compared to a cushion leg) that pressures rise. The effect seems more obvious with faster powders from the references I looked at. That would only apply if using a plastic gas seal to I think. Ranch Dog went with all card wads and from my experience there is a lot of blow by using all card wads so that should negate any pressure rise.

Anyway, using a hard card wad column for consistent support and square to muzzle base and a hull that fills the chamber might tighten groups up even more.

I have some slugs in shotcups with cushion leg cut off loaded over hard card wad column now. Just have to get some time to go shooting.

Longbow

I gave that idea a try, using only nitro cards instead of repurposing the original wad. Keyhole City today. To add insult to injury I found that my scope slid back in the rings...So there's nothing here even resembling a group. Let me know if it works out any better for you.

As a side note, the shells didn't reliably cycle in my semi-auto shotgun. I think this supports the idea that nitro-cards allow more blow by than gas seals.

It was well worth a try, in any case.

[mikehill85]

I got a new slug mould from Russia (the Svarog "Paradox" slug). It seems the wads are unobtainium so I have designed my own tail wad which repurposes the gas check from the Federal Two Part wad that came with the shells I bought. The tail wad is permanently attached to the slug with a wood screw through the end. I can't wait to test this bad boy out. It is bore diameter too so it should hopefully be accurate.

[longbow]

I think Blood Trail has that mould. You might do a search of his posts.

Kracken69 sent me some to try. They shot reasonably well from my single shot but are a bit undersize in the 0.733" bore.

Now I have the Mossberg Slugster with 0.729" bore. I have a few left so have to try them in the tighter bore.

I think you'll like them!

I'll be watching for a range report.

Longbow

[mikehill85]

Interesting. My shotgun also has a 0.733” bore diameter. Hopefully my rifled choke will help a bit. If not I guess I can try powder coating them.

[longbow]

Knurling will bring them up in diameter. I knurled some that Krackenfan69 sent but again, have not shot them in my single shot... they're loaded and waiting for me! Knurling takes them up to 0.735" or so, so they will have to swage to fit the bore.

I will try the knurled up slugs in the single shot and as supplied at 0.729" IIRC in my Slugster with 0.729"/0.730" bore.

Hoping to get out next week. I will post results and will be looking forward to your results as well.

Longbow

[mikehill85]

Knurling will bring them up in diameter. I knurled some that Krackenfan69 sent but again, have not shot them in my single shot... they're loaded and waiting for me! Knurling takes them up to 0.735" or so, so they will have to swage to fit the bore.

I will try the knurled up slugs in the single shot and as supplied at 0.729" IIRC in my Slugster with 0.729"/0.730" bore.

Hoping to get out next week. I will post results and will be looking forward to your results as well.

Longbow

Same here. I'll be interested to see your results. I should be going out shooting mine tomorrow.

I'm really enjoying the range these days. There are far fewer people due to the ammo shortage and most who are there are shooting 0.22s not AR-15s with the shortest barrel legally possible and a muzzle brake designed to shatter eardrums.

[mikehill85]

Update:

I had considered not posting this because quite frankly I am embarrassed and upset with myself but I thought I would anyway so hopefully others can learn from my mistake.

Well that was bad...I'm okay. My gun is okay and so is everyone else but I'm pretty pissed at myself. I guess I got too complacent with reloading. I figured that since this slug weighed nearly the same as the Lyman 525 Slugs I wouldn't have pressure issues. After I fired 5 shots I noted just the brass portion of one of the shells was extracted. I should have been checking all along and I'm posting this so others will know what not to do. If I had fired 1 shot, noticed the over pressure signs and stopped, I could live with that. That can happen if you're experimenting (although it's obviously still very bad), but the fact I fired 4 more before I noticed is really bad. Everything sounded fine, felt fine, etc., but I should have been checking for over pressure after every shot.

Weighing the slugs afterwards I found that with my 3d printed base wad the weight of the payload increased from 568 grains to 612 grains. I think this and the fact the 3d printed Nylon may not compress as much as LPDE is what lead to the obvious over pressure signs I got. I think not taking into account the weight of the wad was my biggest mistake. Anyway, lesson learned. I won't be using 3d printed wads for these slugs.

The fact myself and my gun weren't damaged hasn't been lost on me and I am grateful for that.

BE SMART! I WAS DUMB! DON'T DO THIS! DON'T BE COMPLACENT!



Clear Primer Cratering and Extractor Groove Extrusion. Yikes!


Several hulls are torn...One is missing everything but the brass. Yikes again!


The next two photos give you an idea just how raised the extractor mark is.

[longbow]

I've always gotten sticky extraction with over pressure loads... and yes it has happened more than once!

I am pretty carefull but sometimes things don't go quite as planned or expected.

The bulge into the extractor groove and sticky extraction are I think the first signs of over pressure and I believe that a load that does either is significantly over pressure.

The other is unexpectedly stout recoil!

Good that you and the gun are okay.

Longbow

[mikehill85]

I'm pretty surprised that an 8% increase in weight could increase the pressure so drastically. I never had any pressure signs like this before and they appear to be pretty extreme based on the shells and brass.

I am wondering if perhaps it is the fact that my wad went all the way up into the cavity of the slug where the lead is thin. Maybe when it fired the Nylon wad was pushed into the nose and caused the slug to obturate. That could certainly cause a very significant spike in pressure.

Anyway, this is the first time I've tried using a Nylon wad. I think the material/wad design may have had more to do with the pressure spike than the increase in weight. Obviously increasing the weight will increase the peak pressure but it seems to me the weight increase alone might not explain this level of pressure increase.

I actually found one of the slugs at the target with the tail wad still attached. It had the layer lines from the 3d print etched into it which might support the idea that the wad actually caused the slug to obturate. It was a bit hard to tell too much from the slug since it was pretty mangled but the holes in the target were circular so it was definitely mangled on impact.