Final Decision Made For AR15 Muzzleloader Black Powder Project Candidate.

[arakboss]

I have been tossing around different ideas for making a black powder muzzleloader on the AR15 platform. I have decided the easiest and cheapest way to accomplish this is to use my 350 Legend quick change pistol upper project. I have already proved the quick change barrel concept holds up to full house smokeless loads so I can move on with it.

Note to the risk adverse, this concept is not the safest method but I will take extra precautions where I can and still use this method.

The plan is to prime a once fired but chamberable case with a CCI41 primer. (extra margin of safety).

Chamber the primed case in the rifle. I have already experimented with chambering fired cases. They go in tight but they will chamber to full battery.

Flip the safety on.

Load powder charge through the muzzle as in normal muzzleloader. Maybe more gently as a live primer will be sitting under charge as it's tamped down. I will make sure my charge volume is more than enough to fill the 350 Legend case. This will assure that my projectile is resting tight on top of the powder column and not hitting the case mouth, leaving an air gap.

Load the projectile through the muzzleloader as in normal muzzleloader. Due to fast twist ratio of 350 Legend barrel, I will most likely be using coated conventional cast bullets rather than patched balls.

At that point the front stuffed AR15 is ready to belch lead, fire and smoke.

After firing remove case run a spit patch (bored buttered) or two through the barrel including chamber.

Load another primed case, rinse and repeat.

I will be using BP substitute and I am prepared to deal with fouling and corrosion issues. The quick change method of barrel mounting allows for easy barrel removal and the breech plug (350 Legend case + bolt) is removed after every shot. That will allow easy access to throughly and easily clean the barrel.

It's a cheapo 10.5 inch bear creek barrel. I doubt any tears will be shed around here if the barrel life is shortened from this use.

I will look for 36cal bp data to find some load ideas. Besides working over a live primer, what other safety concerns might you have using this method?

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[Yarome]

...what other safety concerns might you have using this method?

Verify your life insurance covers brain farts and premiums have been paid??

 

[arakboss]

Verify your life insurance covers brain farts and premiums have been paid??

I think it sounds more dangerous than it will really be.

 

[Yarome]

I think it sounds more dangerous than it will really be.

Probably not, but loading over a live primer... is it worth it?

 

[arakboss]

Probably not, but loading over a live primer... is it worth it?

I have loaded thousands of rounds over live primers

 

[arakboss]

Probably not, but loading over a live primer... is it worth it?

I am open to ideas on setting the primer last?

 

[Yarome]

I am open to ideas on setting the primer last?

Tap and install a nipple in your brass and use caps instead?

 

[RVTECH]

I will most likely be using coated conventional cast bullets rather than patched balls.

It may be difficult to find a cast bullet of the diameter when coated will allow for relatively easy loading yet be tight enough to engage the rifling to provide any accuracy.

Many years ago in an old .45 cal ML rifle I had I tried cast .45 ACP bullets in it and while I thought they were a fairly snug fit, accuracy was really poor.

 

[arakboss]

Tap and install a nipple in your brass and use caps instead?

That could work but the nipple would have to sit flush with the case head so the bolt would close on it. If you find a pic of such a modification please share it.

It's possible a berdan case with the right size anvil would allow a cap to be ignited. I will have to see if a cap will even fit in the small primer pocket.

 

[arakboss]

It may be difficult to find a cast bullet of the diameter when coated will allow for relatively easy loading yet be tight enough to engage the rifling to provide any accuracy.

Many years ago in an old .45 cal ML rifle I had I tried cast .45 ACP bullets in it and while I thought they were a fairly snug fit, accuracy was really poor.

I am not expecting great accuracy but you are right that could be an issue. I didn't have any significant problems with the muzzleloading of the 50 Beowulf projectiles so I think that will be easily overcome. Powder coated bullets are pretty slick but ride rifling well at the same time.

 

[Yarome]

That could work but the nipple would have to sit flush with the case head so the bolt would close on it.

It may be a possibilty to modify the hammer to accomodate some protrusion from the shell case(?)

Insert a round metal case "breech" into the bottom of the case to tap into. Basically a "nut and bolt" installation(?) Nipples have a flange that could be used to clamp into the brass base even with a slight inset.(?)

Combination of that and slight hammer modification?

Dunno. Would take some measuring and a bit of maths to see if it's even doable.

 

[arakboss]

It may be a possibilty to modify the hammer to accomodate some protrusion from the shell case(?)

Insert a round metal case "breech" into the bottom of the case to tap into. Basically a "nut and bolt" installation(?) Nipples have a flange that could be used to clamp into the brass base even with a slight inset.(?)

Combination of that and slight hammer modification?

Dunno. Would take some measuring and a bit of maths to see if it's even doable.

Your idea inspired this. I drilled out the small primer pocket to loosely accept a #11 cap. I left the hole shallow enough that the cap is sitting very proud. If I can get the bcg into battery without setting off the cap. It may go off when firing pin smacks it. I will slowly send the bcg into battery. I don't want to try it here in the condo but I will find a safe space to try it this week, stay tuned. It will be loose though so some pressure, flame, gases, fouling, etc are going to leak through the primer hole when firing an actual load.








If this idea worked and didn't have too much blow back (I will be surprised on both counts), I would have to have the muzzle pointed at the ground in order to insert the cap. Then slowly close the bcg on the cap before elevating the rifle again.

The advantage of this method would be that I could remove the extractor from the bolt and have the case stay in place for a few shots before cleaning. Then use a cleaning rod to pop out the case when I wanted to do a more thorough cleaning.

 

[arakboss]

Your idea inspired this. I drilled out the small primer pocket to loosely accept a #11 cap. I left the hole shallow enough that the cap is sitting very proud. If I can get the bcg into battery without setting off the cap. It may go off when firing pin smacks it. I will slowly send the bcg into battery. I don't want to try it here in the condo but I will find a safe space to try it this week, stay tuned. It will be loose though so some pressure, flame, gases, fouling, etc are going to leak through the primer hole when firing an actual load.

View attachment 1242818



View attachment 1242817


If this idea worked and didn't have too much blow back (I will be surprised on both counts), I would have to have the muzzle pointed at the ground in order to insert the cap. Then slowly close the bcg on the cap before elevating the rifle again.

The advantage of this method would be that I could remove the extractor from the bolt and have the case stay in place for a few shots before cleaning. Then use a cleaning rod to pop out the case when I wanted to do a more thorough cleaning.

I measured how proud the primer was and it is sitting .050 high above the case head. I suspect the #11 cap will squish down some when the bcg is put into battery. What is left sticking up should be whatever headspace there is. Hopefully the firing pin will ignite the cap instead of just pushing it further into the primer pocket.

 

[Yarome]

Hopefully the firing pin will ignite the cap instead of just pushing it further into the primer pocket.

That's a real possibility. And no detonation with a standard AR firing pin. Caps might be too much work to succeed and might include having to modify the bolt face and a whole can of worms to get it functional.

I would still try it, but not exactly optimistic. Reducing the cap depth itself might solve any issue with bolt locking, but that's a whole lot of work too and, again, still doesn't increase the odds of a detonation with a standard pin.

Your idea (primer) is the strongest bet for success, but still... it only takes once for your ram rod to become the projectile through your digits.

My advice, only do left handed loadings.

 

[arakboss]

That's a real possibility. And no detonation with a standard AR firing pin. Caps might be too much work to succeed and might include having to modify the bolt face and a whole can of worms to get it functional.

I would still try it, but not exactly optimistic. Reducing the cap depth itself might solve any issue with bolt locking, but that's a whole lot of work too and, again, still doesn't increase the odds of a detonation with a standard pin.

Your idea (primer) is the strongest bet for success, but still... it only takes once for your ram rod to become the projectile through your digits.

My advice, only do left handed loadings.

I am left handed, lol.

 

[arakboss]

That's a real possibility. And no detonation with a standard AR firing pin. Caps might be too much work to succeed and might include having to modify the bolt face and a whole can of worms to get it functional.

I would still try it, but not exactly optimistic. Reducing the cap depth itself might solve any issue with bolt locking, but that's a whole lot of work too and, again, still doesn't increase the odds of a detonation with a standard pin.

Your idea (primer) is the strongest bet for success, but still... it only takes once for your ram rod to become the projectile through your digits.

My advice, only do left handed loadings.

I have no idea why I was fussing with a #11 cap. It was an earlier idea I had to enlarge primer pocket and use a regular primer.

I might have went a little too deep with the primer pocket drilling as the primer is sitting below flush now but it pops in and out with ease. I will go ahead and test out both for fun but I would much rather use regular primers.

Photo below is of the same case that I drilled out for the #11 cap but with a small pistol primer inserted in it.

 

[osprey]

How many grains of holy black does a 350 legend hold full? I would try and fill a case to the top and put a thin wad over it to hold powder. Load bullet from muzzle with a rod with a stop on it so it seats bottom of projectile just shy of case mouth. Insert primed/powdered case and fire away. I am thinking this will e a pretty slow round due to not enough case capacity. Sorry if I missed the end goal but exactly what is the goal. Why not just load a cartridge with bp and seat bullet on it?

 

[arakboss]

How many grains of holy black does a 350 legend hold full? I would try and fill a case to the top and put a thin wad over it to hold powder. Load bullet from muzzle with a rod with a stop on it so it seats bottom of projectile just shy of case mouth. Insert primed/powdered case and fire away. I am thinking this will e a pretty slow round due to not enough case capacity. Sorry if I missed the end goal but exactly what is the goal. Why not just load a cartridge with bp and seat bullet on it?

I simply want to use an AR15 upper and lower in a muzzleloading bp configuration. No real agenda or goal beyond that.

Tomorrow I will dig out some Pyrodex and my bp powder measure to see what volume the 350 Legend case will hold. My guess is same as yours, not much. One advantage to my method is you can load as much powder as you feel is safe, as you won't be limited to what the case will hold. The case will only be there to serve as part of the breech plug system (along with the bolt) and to hold the ignition source.

I will probably try out loading some 350 Legend bp cartridges to. This set up will allow for loading either way. It can still be used for smokeless loads. It will be a jack of all trades firearm. I will try some bp shot loads in it as well. I expect the pattern will be very large unless I can find a choke tube that will counteract what the rifling does to the shot. That'll be another project for another time.

 

[osprey]

One thing I will add that may be of value to your endeavor. When using full bore projectiles, they must be soft enough to obturate in bore to give decent accuracy. I tried 300 gr .452 gold dots sized to .4515" in my converted Muzzleloader and they were quite inaccurate as they were too hard. Otoh, Parker BE bullets in 275 and 300gr sized to the same .4515" with the same powder charge as with the gold dots, showed fantastic accuracy as they are soft enough to obturate properly in bore.

 

[arakboss]

I have no idea why I was fussing with a #11 cap. It was an earlier idea I had to enlarge primer pocket and use a regular primer.

I might have went a little too deep with the primer pocket drilling as the primer is sitting below flush now but it pops in and out with ease. I will go ahead and test out both for fun but I would much rather use regular primers.

Photo below is of the same case that I drilled out for the #11 cap but with a small pistol primer inserted in it.


View attachment 1242834

I attempted to mock demonstrate this process of adding primer after charge is loaded, to my wife. I discovered that putting a primer in the case after it is chambered would be a very tedious task. It's not something I would attempt in the field. Therefore even though there is some risk in loading a charge over a live primer, that is the method I am going to use. I will rely on the other precautions (hard cup primer, safety on, etc) that I laid out in my original post.