I bought a new 1894 Marlin a couple of months back and after slugging the bore discovered that it was .432", which isn't unusual at all.
I am the original owner of a 44 Magnum M1894, I purchased it for $173.25 dollars, May 1983 at a K-Mart in Texarkana Texas.
The microgroove barrels on these rifles were in a word: horrible. I sent the rifle back twice to replace, in my opinion, defective barrels. The first barrel clearly had some machining rings in the tube and both barrels varied in tube diameter. You could push a patch down the barrel and feel it stop and start as the barrel interior alternately grew larger and smaller. By the way, when How the barrel interior dimensions could vary so much when gundrilled is a mystery to me. Incidentally, back in the 80’s, discussing barrel quality with the factory guys , they verbally expressed contempt about the barrels at that time. I stopped sending the action back for barrels at the third microgroove barrel. While Marlin replaced two barrels for free, none of them were really better than any other and it was a futile experience and a waste of my travel time and shipping money.
For the first 18 years, I did not shot it much, basically because with those microgroove barrels, it would not accurately shoot lead bulleted pistol ammo. I do not cast my own, I purchase thousands of commercial cast bullets at gun shows, load them, and go shoot. The standard 240LSWC .429” lead pistol bullets would strip out at velocities greater than 1000 fps in a microgroove barrel. It was dismaying to compare 25 yard targets between the rifle and my pistols. Generally the pistol group at 25 yards was equal to or better than the rifle group with the same ammo. This was awful. Jacketed bullets however shot reasonable well, about 4 inch or less groups at 100 yards.
In 1999 I found out that Marlin was making new “Ballard” barrels. I called up the factory and discussed replacing the microgroove barrel with a Ballard barrel. The customer service representative, Mr. Tim Mooney, told me that it would cost $130.00 to get this rifle rebarreled. When I mentioned that I was firing .429 cast bullets, the gunsmith informed me that the rifle barrels were made to SAAMI specs which called out for rifles barrel interior dimensions of .431”. Marlin claimed that their specifications for the barrels were 0.431 ± .001”. Also the factory guys were very positive about the quality of these late 90’s era barrels. I asked the gunsmith to find me a good barrel made to the minimum dimension. The gun smith air gaged a number of barrels and claimed that none were on the low end, I got the basic understanding that the barrels were all .431 with very little dimensional variation. Well that shows that production processes had improved in 18 years.
Marlin had not changed the 1:38” twist of the microgroove barrels nor was the groove depth significantly deeper than the microgroove barrel. In my opinion the difference between a Ballard barrel and a microgroove is a bunch of lands. This is a mistake in my opinion as my Ruger pistol barrels had much quicker barrel twists and were much deeper grooved, and shoot cast bullets very well.
When I received the rifle back from Marlin I noticed that the gunsmith had inserted small strips of cloth tape on the front inside of the handguard. The handguard had always been loose and I believe that this was his attempt to take out some of the movement.
When I took this rifle out and shot it, it shot horribly with lead bullets or jacketed bullets. I was very unhappy at this point.
First thing I decided to do was some load development. The rifle did not like commercial cast bullets, the best groups came with H110 and I was using standard 240 JHP’s. Any brand. Group size with the best ammunition was unimpressive.
I decided to try to tighten things up in the hope that my group sizes would reduce. First thing I did was to soft solder the hanger bracket to the barrel. There is a bracket that keeps the fore end in place. The bracket fit into a dovetail on the bottom of the barrel. That dovetail was not very tight and the bracket would rotate/move within the dovetail. Using the copper pipe soft solder and fluxing paste with a blow torch permanently fixed the bracket in place. I only heated the bracket to the point where the solder melted. And then I took the heat off. I might have wrapped the barrel around that area with a wet towel to remove heat quickly. I did not want to get the barrel hot as I did not know if it was heat treated.
Next I decided to replace the cloth strips that the gunsmith put in the fore end with something more permanent. In the end I tightened up the fore end using Accur Glass gel. I poured gel over the cloth strips, in between the handguard cap, and the butt of the fore end. I wanted to take out any longitudinal and rotational movement between the fore end, its mounting pieces, and the front of the receiver. Overall it worked. The fore end is very solidly mounted.
Accuracy was improved but not as dramatically as glass bedding a bolt action. The rifle will shoot into four MOA at 100 yards. I am using a Williams rear and a post front.
I have noticed that pulling or pushing on the fore end greatly affects accuracy. Even though my fore end is quite tight and does not rattle it is possible to pull it and move it out maybe a card thickness out from the receiver. Groups moved left and right on the target by at least eight inches depending on whether the fore end is in or out.
I only have one other lever action, which is a 90's Marlin 336 in 30-30 and that rifle has a huge chamber and a throat cut so deep that the bullet has to jump two tenth's of an inch before it touches rifling. The best that rifle will do at 100 yards is two inch groups and at 200 yards the best groups start at three MOA and go up. This is with jacketed bullets. I have extensively tested the rifle with cast bullets and they will not hold on an 8.5" X 11" sheet of paper.
while I often read of posters claiming MOA and sub MOA accuracy with their lever actions, if the claimant shows a group, it is a three or five shot group. None of them has every shown a sub MOA ten or twenty shot group, so what those characters are doing is cherry picking the best out a bunch of low shot group targets and are only showing the clustering in a random set of data points. Call it the
Texas Sharpshooter fallacy. This is incidentally why the in print crowd considers three shot groups their gold standard. For one thing, the more shots you fire the larger the group you are going to get.
Until such time as Marlin changes the barrel twist, I have no desire to own another M1894 in 44 Magnum as the 1:38" twist is too slow. I want to be able to shoot heavier bullets in the 44 Magnum rifle. Also, my accuracy experience has been disappointing in the 44 Magnum and 30-30 Win as I wanted rifles that were better than 3 MOA or 4 MOA, though these things are used to harvest deer every year, at distances less than 100 yards, so I can't say they are not fit for purpose. But I want better accuracy and I want to be able to shoot cast bullets and get groups.