What diameter are the average .50 caliber barrels

[ETipp]

I suppose this can vary with specific rifle, but what is the average diameter for a .50 caliber? I am referring to the riflings.

When measuring the barrel on my New Englander my measurements with a dial caliper I'm seeing is .491 on average.

The Optima I have here is measuring .499

Hawken measures .494

Measured a PowerBelt as a reference and its showing .498

Just cast some Maxi Balls out of pure lead and they are 5.05

Does this sound right for the New Englander. Considering a .491 rifling and a .505 bullet that seems like a big difference.

 

[GUN NUT]

are you measuring the lands or the grooves a 50 should be just that 0.50

 

[ETipp]

are you measuring the lands or the grooves a 50 should be just that 0.50

The riflings, which are considerably different. My concern is on my New Englander.

However, the grooves measure .501 for the New Englander.

.506 for the Optima.

.501 for the Hawken.

I checked my caliper accuracy and it is within 1/2 of a thousand, unless the 30 caliber .308 dia Nosler Ballistic Tip bullet is off 1/2 thousands.

 

[WP79Vet]

I suppose this can vary with specific rifle, but what is the average diameter for a .50 caliber? I am referring to the riflings.

When measuring the barrel on my New Englander my measurements with a dial caliper I'm seeing is .491 on average.

The Optima I have here is measuring .499

Hawken measures .494

Measured a PowerBelt as a reference and its showing .498

Just cast some Maxi Balls out of pure lead and they are 5.05

Does this sound right for the New Englander. Considering a .491 rifling and a .505 bullet that seems like a big difference.

My understanding is that the caliber of a muzzleloader is specified as the interior diameter of the lands. ("Lands" are the inward-protruding ridges created by the rifling, while "grooves" are the valleys between lands). .491 sounds awfully tight for a .50 caliber New Englander, which I would expect to have the same, or nearly the same, dimensions as my .50 Renegade. A .495 round ball free-falls down the barrel of my Renegade, the .495 diameters of the bases of Hornady GP and PA conicals fit into that bore with fingers, and those bullets don't get too tight to push in by hand until the .504 driving band touches the rifling. So... the ID of the lands on my Renegade is .500 or perhaps just a bit larger.

From experience in precision machining, measuring the inside diameter of any cylinder with a dial caliper is tricky because all misalignments of the caliper and all placements of the jaws on any chord of the circle which does not pass through the axis of the bore result in erroneous readings that are too small - and it's very difficult to ensure perfect alignment and placement of the jaws. Measuring the ID of a rifled bore is especially tricky because, in addition to the difficulty of measuring the ID of a smooth tube, you also have the rifling to deal with.

For these reasons, the standard way to measure the inside diameters of bores is to "slug" the bore by pushing a piece of soft lead - usually a soft lead bullet of slightly larger diameter than the bore - all the way into the bore, pushing or pulling out the bullet, and then measuring the deformed bullet. The outside diameters engraved on the bullet will be the same as the inside diameters of the bore, and they are much easier to measure. It's a little trickier with a sidelock ML because you don't have an open breech to push a slugged bullet back out after it's been conformed to the ID of your bore.

If you have a bullet puller, you could push a Hornady GP bullet a couple inches into the bore of your New Englander, screw your bullet puller into the bullet, and then pull it back out. No need to screw the bullet puller in very far, as the Hornady bullets are soft lead and are pushed down the bore very easily once they're started, so they will pull out easily, and the hollow point will help the screw of the bullet puller get started. Once you pull the bullet back out, you can measure the diameters of the lands and grooves which have been engraved into the bullet, which is much easier to do than measuring their interior diameters in the bore.

 

[ETipp]

My understanding is that the caliber of a muzzleloader is specified as the interior diameter of the lands. ("Lands" are the inward-protruding ridges created by the rifling, while "grooves" are the valleys between lands). .491 sounds awfully tight for a .50 caliber New Englander, which I would expect to have the same, or nearly the same, dimensions as my .50 Renegade. A .495 round ball free-falls down the barrel of my Renegade, the .495 diameters of the bases of Hornady GP and PA conicals fit into that bore with fingers, and those bullets don't get too tight to push in by hand until the .504 driving band touches the rifling. So... the ID of the lands on my Renegade is .500 or perhaps just a bit larger.

From experience in precision machining, measuring the inside diameter of any cylinder with a dial caliper is tricky because all misalignments of the caliper and all placements of the jaws on any chord of the circle which does not pass through the axis of the bore result in erroneous readings that are too small - and it's very difficult to ensure perfect alignment and placement of the jaws. Measuring the ID of a rifled bore is especially tricky because, in addition to the difficulty of measuring the ID of a smooth tube, you also have the rifling to deal with.

For these reasons, the standard way to measure the inside diameters of bores is to "slug" the bore by pushing a piece of soft lead - usually a soft lead bullet of slightly larger diameter than the bore - all the way into the bore, pushing or pulling out the bullet, and then measuring the deformed bullet. The outside diameters engraved on the bullet will be the same as the inside diameters of the bore, and they are much easier to measure. It's a little trickier with a sidelock ML because you don't have an open breech to push a slugged bullet back out after it's been conformed to the ID of your bore.

If you have a bullet puller, you could push a Hornady GP bullet a couple inches into the bore of your New Englander, screw your bullet puller into the bullet, and then pull it back out. No need to screw the bullet puller in very far, as the Hornady bullets are soft lead and are pushed down the bore very easily once they're started, so they will pull out easily, and the hollow point will help the screw of the bullet puller get started. Once you pull the bullet back out, you can measure the diameters of the lands and grooves which have been engraved into the bullet, which is much easier to do than measuring their interior diameters in the bore.

EDIT:

Thank you for the information. Yes, I was getting caught up in terminology. I knew this before but always fell back to the old term "rifling". My mistake when describing this.

Indeed, it is a bit tricky to measure the inside of a barrel with a dial caliper, but that's all I have. Thus I measured two other ML in the house because I was not liking what I was seeing.

However, I just did some remeasuring using a slightly different way. The new average I am coming up with is .498, so that's much better. If those measurements are close, and there is still room for error, that would leave a .007 difference between the Maxi Balls I just cast and the lands. I do not know what is considered a ball park fit for a .50 ML.

Do you happen to have an idea on what the average difference between the lands and a projectile is, or should be, in a .50?

Considering these Maxi Balls are cast from pure lead instead of hard cast, I am hoping the fit will work.

Also, I just measure a .495 round ball I found in my ML toy box. It easily rolls all the way down the barrel. So, that proves the bore is larger than what I had originally measured or thought.

Sadly, I do not have any HGP bullets left. Actually, I melted down what few I had to cast the Maxi Balls yesterday. So at least for now, slugging the barrel will have to wait.

What I do know for a fact is, every bullet I have tried to push down the barrel of this New Englander, with the exception of the PowerBelt and a patched RB, has been a very tight fit. So tight that I actually broke a ball starter trying get a HGP bullet started.

 

[WP79Vet]

EDIT:

Thank you for the information. Yes, I was getting caught up in terminology. I knew this before but always fell back to the old term "rifling". My mistake when describing this.

Indeed, it is a bit tricky to measure the inside of a barrel with a dial caliper, but that's all I have. Thus I measured two other ML in the house because I was not liking what I was seeing.

However, I just did some remeasuring using a slightly different way. The new average I am coming up with is .498, so that's much better. If those measurements are close, and there is still room for error, that would leave a .007 difference between the Maxi Balls I just cast and the lands. I do not know what is considered a ball park fit for a .50 ML.

Do you happen to have an idea on what the average difference between the lands and a projectile is, or should be, in a .50?

Considering these Maxi Balls are cast from pure lead instead of hard cast, I am hoping the fit will work.

Also, I just measure a .495 round ball I found in my ML toy box. It easily rolls all the way down the barrel. So, that proves the bore is larger than what I had originally measured or thought.

Sadly, I do not have any HGP bullets left. Actually, I melted down what few I had to cast the Maxi Balls yesterday. So at least for now, slugging the barrel will have to wait.

What I do know for a fact is, every bullet I have tried to push down the barrel of this New Englander, with the exception of the PowerBelt and a patched RB, has been a very tight fit. So tight that I actually broke a ball starter trying get a HGP bullet started.

.498 sounds much closer.

I think the difference between the ID of the lands and the projectile OD is going to depend on the projectile design, how hard the lead is, and so forth. Most of the readily available commercial full bore conicals that I'm aware of use the tapered HGP system - a base diameter of .495 - .499 to facilitate getting the bullet started, tapering up to a top driving band diameter somewhat larger than the land ID to provide initial engagement of the rifling. Thus they will work, in some fashion, with most bores, but you have to really pound on them to get the top driving band started. The No Excuses bullets are an exception - they seem to be the same diameter from base to ogive, and thus the need for "sizer packs" and offering a range of bullet diameters. Some molds also use the HGP system - notably the Lee R.E.A.L. bullet molds and the Lyman Great Plains molds.

The other approach is to use a cylindrical bullet like the No Excuses which is cast or cast and sized down to a diameter which loads acceptably in your rifle - perhaps with a paper patch to customize the fit. The most accurate bullets seem to be those which are just slightly larger than the land diameter, but will still push down the barrel with finger pressure. The acceleration of firing compresses the bullet enough to expand the diameter and engage the rifling. Most of the guys who are getting exceptional accuracy - like the Idaho guys (Ron and Lewis) - seem to use this approach. In one of his videos, Lewis demonstrates starting one of his bullets with finger pressure.

So... to shoot full-bore, all-lead conicals well, it seems that you either have to choose a tapered design like the HGP, perhaps sized down a bit so that it loads easily in your rifle, or figure out a cylindrical diameter which loads acceptably and then expands acceptably to engage the rifling well.
My next step will be to buy a sizer and try it on commercially available tapered bullets like the HGPs and HG PAs - and maybe TC Maxi Hunters too - to see if I can get them to load easier and still perform well. Then I will try sizing custom cylindricals like some that The Bullshop offers. If I feel the need for adding yet another hobby, I may try casting my own and then sizing them.... I really like some of the Accurate Molds designs for 50 cal bullets in the 350 grain range.

 

[ETipp]

.498 sounds much closer.

I think the difference between the ID of the lands and the projectile OD is going to depend on the projectile design, how hard the lead is, and so forth. Most of the readily available commercial full bore conicals that I'm aware of use the tapered HGP system - a base diameter of .495 - .499 to facilitate getting the bullet started, tapering up to a top driving band diameter somewhat larger than the land ID to provide initial engagement of the rifling. Thus they will work, in some fashion, with most bores, but you have to really pound on them to get the top driving band started. The No Excuses bullets are an exception - they seem to be the same diameter from base to ogive, and thus the need for "sizer packs" and offering a range of bullet diameters. Some molds also use the HGP system - notably the Lee R.E.A.L. bullet molds and the Lyman Great Plains molds.

The other approach is to use a cylindrical bullet like the No Excuses which is cast or cast and sized down to a diameter which loads acceptably in your rifle - perhaps with a paper patch to customize the fit. The most accurate bullets seem to be those which are just slightly larger than the land diameter, but will still push down the barrel with finger pressure. The acceleration of firing compresses the bullet enough to expand the diameter and engage the rifling. Most of the guys who are getting exceptional accuracy - like the Idaho guys (Ron and Lewis) - seem to use this approach. In one of his videos, Lewis demonstrates starting one of his bullets with finger pressure.

So... to shoot full-bore, all-lead conicals well, it seems that you either have to choose a tapered design like the HGP, perhaps sized down a bit so that it loads easily in your rifle, or figure out a cylindrical diameter which loads acceptably and then expands acceptably to engage the rifling well.
My next step will be to buy a sizer and try it on commercially available tapered bullets like the HGPs and HG PAs - and maybe TC Maxi Hunters too - to see if I can get them to load easier and still perform well. Then I will try sizing custom cylindricals like some that The Bullshop offers. If I feel the need for adding yet another hobby, I may try casting my own and then sizing them.... I really like some of the Accurate Molds designs for 50 cal bullets in the 350 grain range.

Indeed, that all makes sense. The Maxi Balls top band is the largest for sure. Measuring .510 on the pure lead Maxis I cast yesterday. The aft bands seem to want to fit easily into the muzzle as a basic test. I won't know more until tomorrow when I go to the range as to how well the forward band behaves. Being pure lead, as well as more consistent, I would think it should load easier than the hard cast I had been using.

So yeah, not sure how far I will take this one, considering its only for deer hunting. The No Excuse sounds like a good option should I find the need to pursue this further.

 

[WP79Vet]

Just pulled the trigger on a new adjustable sizer die from Hankins. I have about 75 H PA conicals, 40 H GPs, and 40 TC Maxi Hunters to size down and try. Although they aren't legal for MT's Heritage ML season, I also have 30 H FPBs that can be sized down and tried, and I may use them during the MT general (any weapon) season if I haven't filled my elk or deer tags during the preceding archery season.

The FPB is a 300 grain copper jacketed cylindrical with a hollow base (and a ballistic tip). I bought the FPBs several years ago because I thought the 300 grain weight would stabilize in the 1-48 twist of my TC Northwest Explorer (basically a TC Omega with the exposed cap ignition required in WA, and maybe Idaho and OR too), but I never shot them because I couldn't load them without a hammer. In one of his videos Hankins demonstrates his adjustable sizer on a bullet that's either an FPB or identical to the FPB, and says that the ideal size for best accuracy can be pushed down the barrel with a pinky. If that works out, an appropriately sized FPB might be a great option for hunting any-weapon seasons with my Renegade.

 

[bronko220002]

Reading WP's post and his idea of sluggung the bore for a more accurate measurement is good.
The method i use to slug my sidelocks is to take a pure lead bullet and drill a hole in the center maybe about a 7/64" and then tap the bullet a bit on either end to "fatten" it. Once you get where it will be slightly larger than the bore put a 3" or 3 1/2" screw into the drilled hole far enough so its secure and tap the bullet into the bore just flush with the muzzle. Grab the screw loosely with a pair of pliers and gently tap it out allowing it to follow the rifling.

 

[coupe]

Try this use an 8 to 10" brass rod that slips into the bore, put it in and then press in the flattened soft lead slug next tip the bbl down and make back and forth motions to slide the rod into the slug knocking it out of the bore. All done no pain, now measure the slug.

 

[bronko220002]

Try this use an 8 to 10" brass rod that slips into the bore, put it in and then press in the flattened soft lead slug next tip the bbl down and make back and forth motions to slide the rod into the slug knocking it out of the bore. All done no pain, now measure the slug. The brass rod may not be able to knock it out!

The bullet needs to be tight in the bore to get an accurate measurement. This may not work if the slug fits tight enough to completely fill the rifling.
A method I used to use to slug my sidelock barrel was to put a couple heavily lubed patches about 3- 4" down the bore. The a brand new brass brush of appropriate caliber (leave threads sticking out of the muzzle). Pour enough molten lead down the muzzle to fill at least 1/2 of the brush and allow to cool. Screw the brush onto a cleaning rod loosely so the brush/slug will follow the rifling. Presto - a perfect slug for THAT bore.

 

[Hausser1]

, has been a very tight fit. So tight that I actually broke a ball starter trying get a HGP bullet started.

ow. ow, ow, ow, OW! Thathaddahurt!

 

[CatamountRob]

Why can’t you just drill a hole in a maxi ball, put a small threaded rod through it with a nut on either side and then push it into the bore a few inches, take it out and measure it? If the bullet needs to be able to turn, use a jam nut and don’t tighten them against the bullet.