Bore size Maynard 2nd Model Questions

[musketnut]

I picked up a three point micrometer and was measuring a new to me Maynard 2nd model barrel.

Would anyone know if these measurements sound right or are within the acceptable range (normal)

Breech End
Lands .504
Grooves .515

Muzzle End
Lands .505
Grooves .518

If my measurements are correct I have come to believe from reading other threads that I should use a bullet that is approximately 2/1000ths larger than .518 which would be .520? Is that right?

Thanks for any and all help!! This forum is a gold mine for guys like me who are lone wolfing it.

[0556V]

I picked up a three point micrometer and was measuring a new to me Maynard 2nd model barrel.

Would anyone know if these measurements sound right or are within the acceptable range (normal)

Breech End
Lands .504
Grooves .515

Muzzle End
Lands .505
Grooves .518

If my measurements are correct I have come to believe from reading other threads that I should use a bullet that is approximately 2/1000ths larger than .518 which would be .520? Is that right?

Thanks for any and all help!! This forum is a gold mine for guys like me who are lone wolfing it.

Breech should be larger than the muzzle - check your measurements again. You can shoot a .520 but the breech is going to swage it down to .515 and I do not think the powder charge will give you enough bullet deformation to fill the .518 grooves better to have the muzzle smaller than the breech.

[Bruce Cobb 1723V]

If your measurement are true you should try and push a bullet down the barrel from the smaller end. It will be noticeably looser at the other end. You can do the same thing with a tight cleaning patch.

[Harry Gaul]

I am probably the only one or one of a few that feels that shooting an undersize bullet in a Maynard is a good thing. I have shared before my experiences with shooting a Maynard. I shoot an undersize bullet (510/511) in my Maynard with satisfactory results. In the past I shot an oversize bullet ( 515) and the first few shots were fine. As the fouling became apparent, the bullet would stick and then shoot out at some unknown velocity resulting in bullets hitting all over the place. When I switched to a smaller diameter, the bullet would exit at the consistent velocity at least through one relay. Remember the laws of physics. Two things ( fouling and bullet) can not occupy the same place at the same time. I am not a top shooter, but I do win my share of medals in my class at the Regional level. By going to a smaller bullet has it own set of problems. I made a video of how I keep a smaller bullet in a large brass case, but for the life of me posting on Facebook or this page has been and continues to be a problem. One of these days I will figure it out and post a video that I hope will help you and others.

True Blue and Diamond Hard,
Harry
3rd US
03626v

[Jim Brady Knap's Battery]

Way back in the days when I used a Maynard I shot 25 grs of 3f GOEX with an NEI .512 round nose bullet weighing 395 grs. Shot great and I busted bunches of birds and won more than a few individual medals. I was told many times that a 512 wouldn't shoot and that I needed at least a 515 and possibly up to a 520. I asked the advice givers to not say that in the presence of my Maynard because it was very happy with the load I was feeding it.

[Hal]

When you say lands and grooves, are you talking as directly measured from the barrel or as measured from a slug? If those are slug measurements, then it is larger at the breech, which is a good thing.

As for shooting undersized bullets, who am I to question empirical evidence, but undersized bullets are the recipe for leading a barrel.

[Jim Wimbish, 10395]

With lead bullets, the conventional wisdom is .001 to .002" over bore. This has always worked for me. Now I have gotten away with jacketed bullets that may be undersized by .001" or so, but never with lead bullets. Undersized lead bullets, particularly in pistols, will produce awful leading. You want a barrel that will squeeze the bullet down, not open up. For example, the original progressive depth minie rifling still in use has grooves that are deeper at the breech than at the muzzle.

Hard fouling is a lot more of a problem than soft fouling. Typically, you will get hard fouling toward the end of longer barrels. This is not normally a problem with a 20" Maynard but may be a problem with the 26" barrel. Normally you deal with this by cleaning between relays and using a bullet that carries enough lube to keep the fouling soft for the duration of the time that you are shooting. I shoot a 26" 36 caliber Maynard and I am able to shoot without fouling becoming an issue by having a properly sized bullet (.001" over) that has two lube grooves. This particular barrel has a gain twist, which is also supposed to reduce fouling. I clean all of my breech loading guns with a nylon brush between relays and only brush my muzzle loading barrels with a nylon brush if I notice hard fouling toward the end of the barrel, which is rare. It is easy to tell with muzzle loaders when fouling is becoming an issue since the gun gets harder to load.

[John Bly]

Undersize means smaller than the groove diameter of the barrel with a breech loader and smaller than the bore in a muzzle loader. It works with the minie bullet because with the hollow base it expands into the grooves to make a seal. Undersize bullets in a black powder breech loader can work if they are dead soft. The black powder explosion is like hitting the back of the bullet with a hammer thus expanding it into the rifling. Undersize hard bullets can cause leading because the hot gasses blowing past the bullet melt some of the lead and deposit it on the barrel surface.

I once made a 50 cal Maynard barrel 30" long at a customer's request. I shot it before I delivered it and I got hard fouling toward the end of the barrel. I figured that is why Maynard barrels are 26". I shoot my 1st model with 24 grains of 1 1/2 Swiss with a 375 grain bullet and I shoot an entire skirmish without cleaning. It's at it's best when hot and dirty. 3 wet patches are all that's required to clean it at the end.

[Hal]

As Jim and John mentioned, an undersized bullet will get what is referred to as "Gas Cutting". If the bullet does not make a good seal to the barrel, the combustion gasses will try to bypass the bullet. As they do, they cut particles of lead from the bullet and deposit them onto the inner surface of the barrel out in front of the bullet. Lead likes to stick together, so as the bullet passes these deposits of lead, even more of the lead can be worn off the bullet as it passes and then even more lead is stuck to the inside of the barrel. And so it goes. Obturation can make an undersized bullet fill the gap, but not always, and it is against conventional cast bullet wisdom to rely on it.

[John Holland]

John Bly - Great load information for your 26" barrel, what lube do you use?

[ms3635v]

I have been shooting a 2nd Model Maynard for 35+ years. I cast my bullets in a Moose Mould that drops bullets at .520" then I size then to .518" and I have never changed the bullet diameter size in all of those years. I use 35 grains of GOEX 3F. This powder/bullet combination consistently produces excellent accuracy.

[Jim Wimbish, 10395]

Most shooters I know use around 23 grains of Goex 3f in the 50 cal. Maynards with a 360 grain bullet in a reduced capacity case. I shot 26 grains for many years but have since reduced the charge. If you use the full capacity cases, you will need 30 grains of 3f Goex. My Maynards like a 516" bullet which is .002" over for my 26 inch barrels. There is a heavier 410 grain bullet that some shooters are using at 100 yards, but you really don't need it for 50. I get by with the 360 grain bullet at 50 and a 100. As for lube, I make my own with shortening or Crisco, bees wax as needed to keep the lube from getting runny, and a touch of lanolin to make the lube stick to the bullet better. Lube is not exactly rocket science.

[Hal]

VERY interesting. So my question would be -- would more lead be deposited on the barrel interior by combustion blow-by than would be left by friction of a fully involved bullet passing down the barrel........

Yes. Go here:

http://castboolits.gunloads.com/

There is a world of information about cast bullets, alloys, leading, etc. These guys will tell you that "Fit is king."

Small bullets are the number one cause of leading. Some people get leading and think their allow is too soft. If the bullet is already too small and you harden the alloy, you get even less obturation and an even worse fit in the barrel. The gas cutting I mentioned is due more to erosion than the heat of the gasses. Think water jet cutting machine. It's not the heat that cuts the steel. It is the high pressure water (well, and some abrasive most of the time). I'm sure that heat does play a part though, but probably more so due to the heat caused by the erosion and friction than the heat of combustion of powder. It doesn't act long enough to have an effect. Kinda like moving your finger through a candle flame.

If you are using a small bullet and getting good results and no leading, then by all means, keep doing what you are doing. If you are getting leading, look closely at bullet fit first.

[John Bly]

John Bly - Great load information for your 26" barrel, what lube do you use?

I use SPG lube in My Maynard. Thanks for asking. I also use a .030 card wad between the powder and bullet. This helps seal the bore from the hot gasses and wipes the bore from the previous shot.

[John Holland]

No....Thank you for the reply!