Advice on accurate load for MK-85

[Tannhauser]

In this thread I described the problems I had with my MK-85 reliably http://www.modernmuzzleloader.com/forum/viewtopic.php?f=13&t=30667. Thanks to advice in that thread, I solved the reliability issues.

Now I need to work up an accurate hunting load.

Here's a brief list of the loads I tried. All shooting at 50 yards off a rest.

Hornady 240 XTP, Hornady Green Sabot, 80 gr 777: Extremely tight in bore. Only shot two of these as it required two hands on a heavy duty ramrod to load this combination.

Nosler Ballistic Tip, Nosler Orange Sabot, 80 gr 777: Tight in bore, but loadable without extreme effort. About 3" groups at 50 yards.

Hornady 300 gr XTP, MMP 3P-EZ Sabot, 80 gr 777: Easy to load, requiring minimal effort to seat sabot. About 3" groups at 50 yards.

Hornady 300 gr XTP, MMP Black Sabot, 80 gr 777: Moderately difficult to load. About 3" groups at 50 yards.

CVA 235 gr Powerbelts, 80 gr 777: Desperation attempt :wink: Easy to load, minimal effort to seat sabot. About 3" groups at 50 yards.

I have some .44 and .45 Harvester Crush Rib Sabots on order.

I think I need to move up with my charge. Any advice from experienced Knight plunger gun shooters?

 

[Hornet22savage]

I think, but don't quote me some of the early 50 Cal's could have a 1:32 twist. If you are unsure try the tight patch ram rod trick to determine twist. If 1:32 you may need more powder.

 

[sabotloader]

In this thread I described the problems I had with my MK-85 reliably http://www.modernmuzzleloader.com/forum/viewtopic.php?f=13&t=30667. Thanks to advice in that thread, I solved the reliability issues.

Now I need to work up an accurate hunting load.

Here's a brief list of the loads I tried. All shooting at 50 yards off a rest.

Hornady 240 XTP, Hornady Green Sabot, 80 gr 777: Extremely tight in bore. Only shot two of these as it required two hands on a heavy duty ramrod to load this combination.

Nosler Ballistic Tip, Nosler Orange Sabot, 80 gr 777: Tight in bore, but loadable without extreme effort. About 3" groups at 50 yards.

Hornady 300 gr XTP, MMP 3P-EZ Sabot, 80 gr 777: Easy to load, requiring minimal effort to seat sabot. About 3" groups at 50 yards.

Hornady 300 gr XTP, MMP Black Sabot, 80 gr 777: Moderately difficult to load. About 3" groups at 50 yards.

CVA 235 gr Powerbelts, 80 gr 777: Desperation attempt :wink: Easy to load, minimal effort to seat sabot. About 3" groups at 50 yards.

I have some .44 and .45 Harvester Crush Rib Sabots on order.

I think I need to move up with my charge. Any advice from experienced Knight plunger gun shooters?

Actually I think any of those leads should have shot accurately for you. I shoot 3 different MK's and really do not see what you are getting. I do shoot hotter loads (110 T7) but I know if I were to drop the powder the gun would probably become slightly more accurate. Were I shooting paper for money I definitely would reduce the load.

The explanation of this might be in 'Barrel Harmonics' To me it sounds like you barreled action is not sitting the stock the way it should. Most often this problem is found in the barrel/barrel channel.

What type of stock does your rifle have wood or composite?

Have you checked to see if the barrel lies equally in the stock. With the symptoms you are reporting are reporting I am thinking there is unequal pressure on the barrel at various points along the channel.

One place to start might be with this general check that I wrote up several years ago. This was written basically addressing a DISC but could apply here also..

Checking the Fit of Knight stock


Rob, relieving the stickiness of that should be a really easy fix....

I wrote this up for a guy on Hunting Net the other day - i will repost it here. Look through it and see if it makes sense to you. I firmly believe the sticky stock will affect your accuracy...

Can i get a little info on making sure i don't have any stock to barrel issues? I have seen info on tv about how a free floating barrel helps and heard of different procedures of seating the barrel. I will be putting a new stock on my gun very soon (broke the original one), and don't want to have issues there.

I can share some information with you for sure... One thing to remember 'floating' a barrel is not the best for accuracy it is the ‘cheapest’ so that is why you see many companies floating barrels. Companies can not afford to spend the time (money) bedding a barrel to the stock properly so the best thing is to 'float' them. With a wood stock the temperature of the barrel on the wood will make the POI change unless they barrel is bedded in glass or some such feature. In a composite stock if the barrel were bedded into the barrel channel correctly the heat would not be a problem but the flexion of the forearm of the inexpensive stock create a POI shift - so the answer 'float' the barrel.

In your case... since I think you said you have a Knight and if you are getting a Knight composite stock you might not have any of these problems. When I put a barreled action in a Knight stock I set the action in the stock and start the lug screw in. Tighten it with the Allen wrench until it starts to pull the action down. Then stand the gun vertically with the recoil pad on the floor. Gently, and honestly i am not that gentle, tap the gun on the floor to assure that the recoil lug is all the way back in the pocket. Then tighten the lug screw up snugly to hold it all in place. Forgot to say make sure the ram rod is not in place.

When you have the lug screw in tight place the gun in a horizontal position and squeeze the nose of the forearm and the barrel together as tight as you can. If there is no movement – you’re done the barrel is seated on and in the barrel channel. Put the ram rod in and repeat the test. If the test is the same you’re done... go shoot it and give it a check for accuracy.

If during the squeeze test (ram rod removed) the barrel moves down into the stock or the stock moves up to the barrel... release the grip and note if the barrel moves (on its own) back to the original location. Everything should be good - the barrel is floating. Next repeat the test again noting where the barrel returns to. At this time grip the barrel and the forearm of the stock and pull them apart easily. If you feel the barrel stick at some point then you have a problem. If the barrel appears to lift slightly but when you release it - it returns to the original location and you feel no points of stickiness - you are good. Put the ram rod in and repeat the test.

During the squeeze testing if you felt some stickiness in the spring of the floating barrel you will then to do some very light sanding in the barrel channel to relieve the tight spot. You might be able to locate the tight spot by running a dollar bill under the barrel and between the stock to locate the tight spot. Do not sand any more than you need, in fact in my little world the thickness of a single dollar bill is the max thickness the barrel should be off the stock. I normal use a strip of white computer paper for this test it is thinner than a dollar bill - heck it might be worth more than the dollar bill also!!!

Hope this might help you... when you get your new stock and if I can help give a shout....

mike

Give it a thought see if any of this helps.

And to be really honest... I have not found that searching for a magic number of grains of powder or bullet makes much difference in hunting accuracy. More often it can be tracked back to stock to barreled action fit OR where the front rest may be placed on a stock while shooting. Even have the fingers tips on/over the barrel can sometimes effect POI.

 

[Tannhauser]

The rifle has a composite stock. I'll take a look at how the barrel sits in the channel. Thanks!

 

[sabotloader]

The rifle has a composite stock. I'll take a look at how the barrel sits in the channel. Thanks!

Actually for you the composite stock will be easier to work with. Heat has less effect on the composite material than it might have on wood.

Another suggestion... when you put the gun together tighten the lug screw lightly then stand the rifle vertical and tap the rifle lightly on the floor. This will move the action to the rear of the lug pocket. With the rifle still vertical - tighten the lug screw. This is a little thing but it might help???

 

[WV Hunter]

I shoot pyrodex rs in my MK's. A number of loads have shot really well... my recommendation would be to up your charge a bit. Most of mine shoot really well with 240-260gr bullets, with 90-100gr pyrodex. My go-to hunting load is 240gr/.429 speer deep curls w/green crush rib sabot over 100gr pyro and rws cap. Very accurate and an excellent hunting bullet. Try those XTP with the crush rib, very similar.

 

[1874sharpsshooter]

Mk's are great conical shooters also . 80 gr powder with a big chunk of lead worked good in mine

 

[LarryBud]

Lots of good advice here. I've had several MKs over the years and currently have a 50 with a wood stock

For me 70-85 grains of T7 3F and a big chunk of lead or 90-110 and a 300 grain saboted bullet ave always been good.

I suspect a stock / lug area fit problem. They just shoot too reliably when properly aligned.

 

[Hornet22savage]

Before I found this site I was shooting the Barnes TMZ 290 gr. with supplied yellow sabot over 2) T7 pellets out of my LK-93. Then I saw the light and switched everything. :lol:

 

[fliowa]

I have tried several combinations with my MK 85 but the most accurate load was with a 250 grain TC Shockwave with supplied sabot , 100 grains loose 777 ffg, and a Remington #11 primer. My MK is topped with a 3x9 scope. Taken plenty of deer in Iowa with that combo. Gun is sighted in at 3 to 3 1/2 inches high at a hundred yards.

 

[Dougs136Schwartz]

60 to 70 grains of FFF and Barnes 250 bullets shot very well with 2 MK 85s and multiple Woverines. All plunger guns.

I'm with Sabotloader this is not your load at 50 yards any of those combos should shoot better . I have fould that the older Knights did not like max loads . They may shoot good enough to hunt but I'm a accuracy freak. I would bet it's a stock issue .