Maynard second model caliber size

[Steffo]

Hello,
I am trying to find out what size my second model Maynard should have.
I have tried the .515 size and it seems quite good, however I hear that it should take a .518 size.
Can the size get too big?
The .518 seems to be on the larger side, is there a risk that I break my Maynard if I try the .518 size?
Thanks in advance

[mgmradio]

I am using the Smith/Maynard bullet from the Eras Gon By mould. It drops at .520. The lodgewood loading tool sizes it down to .518. I use soft lead and it shoots sub MOA groups at 200m on paper and will knock down steel targets out to 400m.
My load is 35gr FFFG with a thin fiber wad then the bullet lubed with SPG. I can basically shoot this load all day with out cleaning, but usually swab the bore every 15-20 rounds.

[Steffo]

Thanks for the input,
My Maynard is quite fresh in the barrel and as said I shoot .515 bullets.
The .518 seems tight but is there a risk I break the gun if I try the .518 size bullet?

Regards
Steffo

[Lou Lou Lou]

No, the lead will give out before the gun

[Steffo]

No, the lead will give out before the gun
Thanks for input,
What would be the drawback of the .518 vs the .515?
Which would best fit the Maynard second model?

[mgmradio]

Have you slugged the bore ? If so what is the grove diameter? With a carbine you want a bullet at least.02 over size . The original civil war Maynards and Smith/Maynards were .520 diameter and will shoot just fine in your gun . I prefer the Smith style as it holds more lube .

[Hal]

I second the suggestion to slug your bore. They can all be different. My rule of thumb for cast bullets in a breechloader (even modern ones) is .0015" to .0020" larger than groove diameter. If you are not familiar with the practice of slugging a barrel, it would be best to read up on it and watch some videos. Essentially, you drive a SOFT and liberally OILED lead bullet/lead fishing weight/lead whatever, (GOT to be SOFT LEAD!!!) that is slightly larger than you expect the groove diameter to be, into a CLEAN and liberally OILED barrel with a brass rod. Then knock it back out in the opposite direction with a brass rod. Some people drive them all the way through. My opinion is that you are most concerned with the fit in the breech end, so I like to slug the breech end, maybe an inch or so past the throat. Then there are those guns that don't lend themselves very well to driving a slug in from the breech end, like say a Merrill or Burnside. A barrel can be larger at one end than the other. slugging the whole thing can reveal this, but then again, what can you do about it? Larger at the muzzle is not good for accuracy. If it's not the same all the way down, slightly smaller at the muzzle end is much preferable to the other way around, but I digress. when you get the slug out, then measure it with a micrometer (Ideal) or good quality caliper (Contrary to what some believe, I say is good enough). Even number of grooves is easy to measure. Odd number, not so much. Please do NOT take this as your only set of instructions on slugging a barrel. Read up on it before trying it yourself.

A chamber cast using Cerrosafe or sulfur is another method, but is more work and I personally have doubts about the accuracy of the measurement, especially with sulfur.

[ms3635v]

I have been shooting an original 2nd model Maynard for the past 35 years. I originally shot a Rapine mould bullet that casted at .520" then sized them to .518" with no problems. When Moose Moulds started making their Smith/Maynard bullet mould in .520", I bought one and continue to size the bullets down to .518" with no issues.