MSD MIke
10-25-2016, 02:39 PM
For anyone that’s interested, here is my experience with the Marlin Micro Groove Barrel.
I have cast for my handguns and an old 03A3 with good success but had always had some reservations about the Marlin because of all the stories I have heard about the difficulty of using cast bullets in Micro Groove Barrels. My thought process was that if it worked in the Marlin then it shouldn’t be a problem in the Winchester with standard rifling. So I started with the Marlin. My goal on the initial test was not to look for real precision but to find a load that showed promise and didn’t leave any lead in the barrel. If I found something that seemed like it was going to work I would narrow down my powder choice and actually get a little more serious about load development. I don’t hunt so I don’t really care much about on target bullet performance beyond accuracy and it ability to shoot holes in plinking style targets. That and low recoil so it would be more fun than factory jacketed stuff.
Goal – Find a cast load with fairly low recoil that was accurate enough to shoot cans and stuff off hand out to 50-75 yard or so. Something I could shoot a decent volume of with no leading in that darn Micro Groove Barrel. If I found something that seemed to have potential I will pick a single powder and work with it.
Gun – El Cheapo 80’s vintage Marlin Model 336. Just like the bajillion others stuck in the back of people closets and safes. Due to my eyes not being very happy anymore I installed an old Weaver K4 I had laying around. It should be noted that the trigger pull is so heavy that you have to tie one end of a string around the trigger, tie the other end around a cinder block and push it off the table to get the gun to discharge. Of course I’m exaggerating but the trigger pull is HEAVY and will require some work before the gun can be shot to its accuracy potential
Caliber – 30-30 of course.
Bullet – Lyman 311041 with Hornady Gas Check. Supposed to be 173 Gr but drops at almost 180 with my alloy.
Alloy – Air cooled COWW, same stuff I use for everything.
Size – Bullets were sized to .310 for all loads.
Lube – 50/50
Brass – Mixed and untrimmed. For future load development I will pay more attention to brass. I roll crimped all loads in the crimp groove and it was apparent brass length was all over the place. The crimp varied a good deal from round to round.
Primer – Winchester Large Rifle for all loads
The test – Load ammo and shoot it at paper plates with a dot drawn in the middle. Gun was rested on a wobbly card table. 3-3 shot groups for each load. No chronograph on this trip. Just blasting to see how it worked.
Accuracy – I had shot the gun with the K4 and factory Remington Core Lokt 170 Grain ammo in the past and it shot about 2’’ at the same distance. Not spectacular but with a better rest, a better trigger and maybe a better shooter it would undoubtedly be more accurate.
Distance – 45 yards. I was shooting where I usually shoot handguns and that was as far as I could stretch it out. Fine for initial testing in my book.
All loads are listed in the Lyman Cast Bullet manual. None were maximum. I just picked a variety of loads to see what happened.
The Same Lyman 311041 sized to .310 with 50/50 lube was used for all loads
Loads-
7 grains Alliant Unique – Super Mild, grouped as well as the factory jacketed ammo but with POI 8’’ lower than all other loads. As an aside I also shot this load in my Model 94 and it hit so low I couldn’t raise the sight enough to use it.
16 Grains Alliant 2400 – Mild but with more pop than the Unique load. Noticeably more accurate than the 7 Grains of Unique. Groups were visibly smaller.
17 Grains IMR 4227 – Results pretty much mirrored the 2400 load but out of the 3 group I had one flyer that there was no explanation for. It went about 8’’ higher than all the others. I can usually call it if I pull a shot that bad but not this time. Not sure what happened on that one.
20 Grains IMR 4227 - I left this load for last thinking that if one was going to strip in the Microgroove rifling and lead the barrel this would be the one. While not as hard kicking as factory jacketed ammo it was getting to the point I wouldn’t want have 100 round plinking session with it. Results with this load were dismal. Occasionally you would get two that would hit close together but for the most part every round was a flyer. Some I couldn’t even keep on the paper plate. I figure I had done it now and had a mess to clean up when I got home.
So, since I made this a thread about Microgroove barrels and cast bullets I first want to tell you about clean up and what I found when I got home. I dropped the lever and pulled out the bolt so I could get a good view down the barrel. I nervously looked down the barrel and to my delight there was not even a tiny bit of lead fouling. The test was a total of 36 rounds from very mild to fairly stout. The rifle was allowed to cool a little bit between groups but probably not long enough. The bottom line is that if you are nervous about shooting cast in Microgroove barrels don’t worry about it. Just give a try, the worst that happens is you have to clean your gun. In my case the only thing in the barrel was some powder fouling that came right out with Hoppes. Actually easier than cleaning up after shooting jacketed. Before shooting cast I didn’t make any particular effort to clean out all the copper fouling, I didn’t use any super hard alloy, I didn’t slug my barrel and my bullet was sized at .310 just like many recommend for any 30 cal rifle. Just a standard cleaning and go shooting. So, other’s will have a different story but in my experience the Microgroove barrel is a non-issue.
A few observations.
Unique - Due to the fact I have and use a lot of Unique I will work a hotter load using unique. I found accuracy to be suitable but the POI was unacceptably low in my Winchester. Hopefully upping the charge will cure that and I can find a load that will work for the Marlin and the Winchester.
2400 – This was the best powder in this test. I find this really unfortunate because it is still very scarce. Once I pick something for the lever guns I want to buy a bunch and get to loading. I love 2400 in my handguns and despite its promise in the 336 I will probably reserve what I have for the revolvers. If availability improves or if I stumble on an 8lber it will be my go to.
IMR4227, 17 grains - This load seemed acceptable and due to the easy availability of 4227 I will work with it a bit more in the lower charge ranges.
IMR4227, 20 Grains – Not sure why the poor performance with this load. I initially though I was experiencing lead fouling in the barrel but that was absolutely not the case. Possibly a harder bullet would handle it better. I have a commercially cast bullet from the same mold that is much harder. I’ll give it a try to see if alloy hardness makes a difference. This load was hotter than I need for my type of shooting but I would like to know the reason for such poor performance just from a curiosity standpoint.
For the next test I will sort and trim brass to remove some of the variables. I will also have to do something about the trigger. Once I get that done I will get more serious and raise my standards to see if I can tighten up the groups. Never can tell when you’re going to have to waste a pesky pop can.
The most important result from this whole test was a good day in the desert shooting guns.
Thanks for listening,
Mike
I have cast for my handguns and an old 03A3 with good success but had always had some reservations about the Marlin because of all the stories I have heard about the difficulty of using cast bullets in Micro Groove Barrels. My thought process was that if it worked in the Marlin then it shouldn’t be a problem in the Winchester with standard rifling. So I started with the Marlin. My goal on the initial test was not to look for real precision but to find a load that showed promise and didn’t leave any lead in the barrel. If I found something that seemed like it was going to work I would narrow down my powder choice and actually get a little more serious about load development. I don’t hunt so I don’t really care much about on target bullet performance beyond accuracy and it ability to shoot holes in plinking style targets. That and low recoil so it would be more fun than factory jacketed stuff.
Goal – Find a cast load with fairly low recoil that was accurate enough to shoot cans and stuff off hand out to 50-75 yard or so. Something I could shoot a decent volume of with no leading in that darn Micro Groove Barrel. If I found something that seemed to have potential I will pick a single powder and work with it.
Gun – El Cheapo 80’s vintage Marlin Model 336. Just like the bajillion others stuck in the back of people closets and safes. Due to my eyes not being very happy anymore I installed an old Weaver K4 I had laying around. It should be noted that the trigger pull is so heavy that you have to tie one end of a string around the trigger, tie the other end around a cinder block and push it off the table to get the gun to discharge. Of course I’m exaggerating but the trigger pull is HEAVY and will require some work before the gun can be shot to its accuracy potential
Caliber – 30-30 of course.
Bullet – Lyman 311041 with Hornady Gas Check. Supposed to be 173 Gr but drops at almost 180 with my alloy.
Alloy – Air cooled COWW, same stuff I use for everything.
Size – Bullets were sized to .310 for all loads.
Lube – 50/50
Brass – Mixed and untrimmed. For future load development I will pay more attention to brass. I roll crimped all loads in the crimp groove and it was apparent brass length was all over the place. The crimp varied a good deal from round to round.
Primer – Winchester Large Rifle for all loads
The test – Load ammo and shoot it at paper plates with a dot drawn in the middle. Gun was rested on a wobbly card table. 3-3 shot groups for each load. No chronograph on this trip. Just blasting to see how it worked.
Accuracy – I had shot the gun with the K4 and factory Remington Core Lokt 170 Grain ammo in the past and it shot about 2’’ at the same distance. Not spectacular but with a better rest, a better trigger and maybe a better shooter it would undoubtedly be more accurate.
Distance – 45 yards. I was shooting where I usually shoot handguns and that was as far as I could stretch it out. Fine for initial testing in my book.
All loads are listed in the Lyman Cast Bullet manual. None were maximum. I just picked a variety of loads to see what happened.
The Same Lyman 311041 sized to .310 with 50/50 lube was used for all loads
Loads-
7 grains Alliant Unique – Super Mild, grouped as well as the factory jacketed ammo but with POI 8’’ lower than all other loads. As an aside I also shot this load in my Model 94 and it hit so low I couldn’t raise the sight enough to use it.
16 Grains Alliant 2400 – Mild but with more pop than the Unique load. Noticeably more accurate than the 7 Grains of Unique. Groups were visibly smaller.
17 Grains IMR 4227 – Results pretty much mirrored the 2400 load but out of the 3 group I had one flyer that there was no explanation for. It went about 8’’ higher than all the others. I can usually call it if I pull a shot that bad but not this time. Not sure what happened on that one.
20 Grains IMR 4227 - I left this load for last thinking that if one was going to strip in the Microgroove rifling and lead the barrel this would be the one. While not as hard kicking as factory jacketed ammo it was getting to the point I wouldn’t want have 100 round plinking session with it. Results with this load were dismal. Occasionally you would get two that would hit close together but for the most part every round was a flyer. Some I couldn’t even keep on the paper plate. I figure I had done it now and had a mess to clean up when I got home.
So, since I made this a thread about Microgroove barrels and cast bullets I first want to tell you about clean up and what I found when I got home. I dropped the lever and pulled out the bolt so I could get a good view down the barrel. I nervously looked down the barrel and to my delight there was not even a tiny bit of lead fouling. The test was a total of 36 rounds from very mild to fairly stout. The rifle was allowed to cool a little bit between groups but probably not long enough. The bottom line is that if you are nervous about shooting cast in Microgroove barrels don’t worry about it. Just give a try, the worst that happens is you have to clean your gun. In my case the only thing in the barrel was some powder fouling that came right out with Hoppes. Actually easier than cleaning up after shooting jacketed. Before shooting cast I didn’t make any particular effort to clean out all the copper fouling, I didn’t use any super hard alloy, I didn’t slug my barrel and my bullet was sized at .310 just like many recommend for any 30 cal rifle. Just a standard cleaning and go shooting. So, other’s will have a different story but in my experience the Microgroove barrel is a non-issue.
A few observations.
Unique - Due to the fact I have and use a lot of Unique I will work a hotter load using unique. I found accuracy to be suitable but the POI was unacceptably low in my Winchester. Hopefully upping the charge will cure that and I can find a load that will work for the Marlin and the Winchester.
2400 – This was the best powder in this test. I find this really unfortunate because it is still very scarce. Once I pick something for the lever guns I want to buy a bunch and get to loading. I love 2400 in my handguns and despite its promise in the 336 I will probably reserve what I have for the revolvers. If availability improves or if I stumble on an 8lber it will be my go to.
IMR4227, 17 grains - This load seemed acceptable and due to the easy availability of 4227 I will work with it a bit more in the lower charge ranges.
IMR4227, 20 Grains – Not sure why the poor performance with this load. I initially though I was experiencing lead fouling in the barrel but that was absolutely not the case. Possibly a harder bullet would handle it better. I have a commercially cast bullet from the same mold that is much harder. I’ll give it a try to see if alloy hardness makes a difference. This load was hotter than I need for my type of shooting but I would like to know the reason for such poor performance just from a curiosity standpoint.
For the next test I will sort and trim brass to remove some of the variables. I will also have to do something about the trigger. Once I get that done I will get more serious and raise my standards to see if I can tighten up the groups. Never can tell when you’re going to have to waste a pesky pop can.
The most important result from this whole test was a good day in the desert shooting guns.
Thanks for listening,
Mike