MK 85 Early & later plungers

[gregdaws]

So, I recently picked up an early MK85 (blued with a laminate stock) with #11 ignition and an early style tapered plunger as in the left hand image. One issue that I have observed is what appears to be powder burn on the bottom of my scope right above the cap and I have a few questions.

• Does the later non tapered plunger (shown right) prevent the powder burn. Is it worth the investment ?
• Does the later plunger (shown Right) work with #11 caps or is it just FPJ, knight's site doesn't specify?
• I have seen wrap around scope covers that prevent scope damage, any idea where I could get something like that?

The gun seems to be in pretty much as new condition apart from some very minor rust issues and has what I believe is the original breech plug with the slot.

• The original breech plug has a brass liner and the replacements don't. Was there any advantage to the brass liner. (Just curious)

As always, any input would be appreciated.

 

[HC]

1 , no
2 , it looks to be a universal plunger (works with 209 primers & #11).
3 , no idea where to buy. Some people use tape to protect the scope.
4 , I’ve never seen the breech plug with a brass insert.

 

[retrieverman]

When you say brass liner, do you mean the #11 nipple that screws into the breech plug?

 

[michiganmuzzy]

Ive never seen a brass liner either. Knight made some LRP adapters out of brass, but they snap onto the Redhot nipples(they are reddish colored) and only work with the larger diameter hammer. Would love to see the liner you're referring to.
Knight made some velcro scope protectors, theyre discontinued i believe. Electrical tape works ok except for the adhesive left on the scope. GunSkins makes really good scope wraps that leave no residue. A piece of leather or suede from an old belt, jacket, or glove could be tied around the scope, right above the breech, too.

 

[gregdaws]

I’ll pull the BP from the gun when I get chance today or tomorrow and I’ll post a few pictures.

Essentially it’s identical to the steel plugs sold on Knights site except that it has the old fashioned slot instead of a hex head and has a machined brass liner that forms the chamber where the powder sits.

I hadn’t seen it before I picked the gun up but I found some for sale on eBay a when I went hunting for them.

Maybe it was Tony knight’s original design.

 

[michiganmuzzy]

I’ll pull the BP from the gun when I get chance today or tomorrow and I’ll post a few pictures.

Essentially it’s identical to the steel plugs sold on Knights site except that it has the old fashioned slot instead of a hex head and has a machined brass liner that forms the chamber where the powder sits.

I hadn’t seen it before I picked the gun up but I found some for sale on eBay a when I went hunting for them.

Maybe it was Tony knight’s original design.

Interesting, ive got a NIB mk that ive never pulled the plug out of. Maybe it has the same plug.

 

[gregdaws]

So, here is the stainless BP with it's brass insert.

 

[phalanx]

Wow, learn something new everyday on this site!!

 

[CRAW]

None of my MK-85 rifles have that BP

 

[flounder]

I have one that had a plug like that in it when I bought it used. I have some paperwork on it somewhere. Tomorrow, when I'm not working and the snow is flying here, I will try to find the paperwork and take a photo of it to share here.

 

[gregdaws]

I have one that had a plug like that in it when I bought it used. I have some paperwork on it somewhere. Tomorrow, when I'm not working and the snow is flying here, I will try to find the paperwork and take a photo of it to share here.

There was a guy selling them on eBay about 2 months ago as NOS knight BP’s.

 

[vaguru]

View attachment 31427View attachment 31428View attachment 31429View attachment 31430

So, here is the stainless BP with it's brass insert.

This breech plug is the Knight Magnum plug. They were an option back in 1990-91, maybe a bit longer. The idea behind it was the brass would seal against the barrel and then the nipple would seal against the brass liner. They work, increased velocity on average by 100-150 fps with the same load in "most" rifles. Was intended for use with real Black and Pyrodex. Had to use Magnum sabots due to the standards failing with the extra pressure.

The nipple for these plugs is a different size than the standard plug, 5/16-24 if memory serves, and his bored through. The brass liner is threaded into the steel plug housing. The vent hole is deep inside the brass liner to hold pressure and to keep it away from the cap.

I have 2 of these plugs and they are not interchangeable, fitted to one barrel. You can see the barrel contact in the right most picture, the ring on the out side of the brass is the "seal" with the barrel. The second pic shows a raised lip around the vent hole where the nipple "seals" against the brass.

As far as cap blast on the underside of the scope, doesn't matter which plunger, they both do it. Electrical tape around scope in that area is your friend.

Hope this answers your questions. If it were me I'd buy a standard replacement breech plug and nipple, much easier cleaning. Also with current BP subs the velocity gain is in the powder, not the plug.

 

[gregdaws]

Thanks for the explanation. I learned something this morning !!

 

[flounder]

 

[HC]

Thank you for sharing the details.

 

[gregdaws]

This breech plug is the Knight Magnum plug. They were an option back in 1990-91, maybe a bit longer. The idea behind it was the brass would seal against the barrel and then the nipple would seal against the brass liner. They work, increased velocity on average by 100-150 fps with the same load in "most" rifles. Was intended for use with real Black and Pyrodex. Had to use Magnum sabots due to the standards failing with the extra pressure.

The nipple for these plugs is a different size than the standard plug, 5/16-24 if memory serves, and his bored through. The brass liner is threaded into the steel plug housing. The vent hole is deep inside the brass liner to hold pressure and to keep it away from the cap.

I have 2 of these plugs and they are not interchangeable, fitted to one barrel. You can see the barrel contact in the right most picture, the ring on the out side of the brass is the "seal" with the barrel. The second pic shows a raised lip around the vent hole where the nipple "seals" against the brass.

As far as cap blast on the underside of the scope, doesn't matter which plunger, they both do it. Electrical tape around scope in that area is your friend.

Hope this answers your questions. If it were me I'd buy a standard replacement breech plug and nipple, much easier cleaning. Also with current BP subs the velocity gain is in the powder, not the plug.

Thank you so much for the explanation ! !

 

[gregdaws]

View attachment 31474View attachment 31475

Hey thanks for the info. That's a pretty cool piece of ML history ! !

 

[WV Hunter]

I learned something new as well! None of my MK's have ever had that.

And fwiw, for the OP... unless you plan to shoot 209's, the original plunger is much better. It has a flat face. The coned face will flare out your nipple over time. It was supposedly designed to use for both, but its really for 209's primarily imo. Using on #11's, musket caps works, but the flare will happen. #11 is the best in these, imho. The original 209 hammer had a huge cone on it. They made the cone much smaller in the current model in the later years.

Also, there is no stopping the blowback on these. If you plan to use a scope, make sure to wrap it with electrical tape or some sort of scope cover to prevent flash burn. Also wrap your BP with teflon tape, or use bp grease... to help cut down the fouling and prevent a stuck plug.

Good luck with your new rifle!