Bore diameter

[sdkidaho]

How do you measure your bore diameter? I've been talking to the guy at Bullshop about bullets and the ones I'm looking at come in several diameters from .500" to .504". I'm guessing every barrel is different and so asking the manufacturer probably won't get me an answer.

I've never had to measure this before and I'm not even sure if I have the right tool(s) to do it.

 

[sdkidaho]

Would using a micrometer in the end of the bore work? Or is that not going to be accurate enough for the whole length of the barrel?

 

[SteveH]

I have never done it, but I am told one of the more accurate ways to measure bore diameter is to push a piece of pure lead, with a slightly larger diameter than your bore, through your rifle. Then you measure the lead itself. Apparently egg sinkers (for fishing) work well. Again, make sure it is pure lead as some of the newer sinkers are an alloy.

 

[GM54-120]

Bore is usually groove diameter in centerfires BUT in a ML its a little different. A 500S&W for instance is a .491 or .492x.500

Common 50cal ML barrels .500-.502 Land to Land by .510 groove. I shoot BH209 so i like my conical to be about .002 over Land to Land. You can go a bit more but they will be harder to load after a little fouling.

If that is not confusing enough a 45cal ML barrel is basically the same as a .458 CF barrel such as a 45/70. Roughly .450x.458

 

[Widude]

What gun do you have? So are you trying to shoot the 'bullshop bullets'? It's it's a common gun there should at least be some generalities about bore size.

 

[ShawnT]

If it is a 50 caliber, one way to measure it is to take a slug of the bore. I do that by taking a round ball, put it on a bench and flatten a little with a hammer then put it on the muzzle and hammer it in with a mallet. IF you use a mallet and soft lead ball you will not hurt the bore or crown. Once in the bore, I put a dowel down from the other end and drive it back out. It is not that hard to do. it is easier to measure then.

 

[sdkidaho]

Thank you for the replies - I'll see what I can find from the manufacturer (sent an email a few days ago), and see about trying what ShawnT suggested.

It's a Knight Ultra Lite, and yes, I'm looking at some bullets from the Bullshop, but they range in diameter from .500" to .504", so I want to be able to order the right one so I don't hose myself from the get go.

 

[sdkidaho]

Found a post here that's similar to what ShawnT said to do:

Here's what I do for a .50 caliber in-line.

First, take out the breech plug and make sure the bore is squeaky clean and well oiled, and take the barrel off of the stock.

Get yourself a 7/16" by 36" hardwood dowel from your local hardware store and cut in into two pieces, one 12" and one 24".

Lay a piece of heavy cloth down on a solid surface like a concrete patio or carport.

Put the barrel of the gun muzzle down in a vertical position on the cloth.

Drop the 12" dowel section down the bore from the breech end.

Drop a soft lead .490 or .495 ball down on top of the dowel.

Drop the 24" dowel on top of the ball and pound it with a hammer so as to flatten and expand the ball between the two dowel sections and into the grooves of the rifling.

Remove the dowels and push the ball out with your ramrod.

The only thing I think I'd change are the wooden dowels as I've read about a few guys having them break in the barrel and cause a heck of a jam. Others suggested aluminum rods or fiberglass.

 

[JStanley]

I've slugged barrels by simply taking a pure lead conical that you know is pretty tight, .504 might work for your Knight, turn it around backwards and load it in the bore nose first. You might need to give it a few taps with a plastic hammer to get it started. Then smack it further with a short starter and push it out the breech with your ramrod. Kinda the same as what others have posted but you get a nice long slug for measuring and even if the bullet is real tight, pure lead won't hurt your gun.

 

[muzzle-loader]

Thank you for the replies - I'll see what I can find from the manufacturer (sent an email a few days ago), and see about trying what ShawnT suggested.

It's a Knight Ultra Lite, and yes, I'm looking at some bullets from the Bullshop, but they range in diameter from .500" to .504", so I want to be able to order the right one so I don't hose myself from the get go.

It sounds like these bullets are very similar to Thor bullets. Thor has a sizing pack that includes a .500, .501, .502, and .503. You may just want to pick up one of those sizing packs to make life easier on yourself.

 

[sdkidaho]

Thanks again for all of your help and suggestions.

I think I got it done, but I have a couple more questions. I couldn't find an aluminum rod that was 7/16" so I found a steel rod and used it instead. It worked pretty well I think. The first plug I made I used a wooden mallet to tap the rod to flatten the round ball, and it didn't flatten much, though it was enough that I couldn't see light passing the ball while it was in the barrel. It seemed hard to measure so I thought I would do it again, but this time I tapped the rod with a regular hammer. The plug this time came out much better as far as surface area to measure, and is the one in the pictures. I pretty much followed the instructions that I had found and quoted above.

Here's the rod cut in the two pieces:

And here is the round ball and the finished plug that came out:

You can see about where the round ball started, size wise:

Now here is my question. There are a couple different measurements on the plug that I made. The largest is .510, and the most common smallest is .503, so what I'm wondering is, does this mean the bullet size that I would need to order would be the .503?

I did also see some .502 and a half, and .503 and a half, but the most common was the .503, which of course that could be the digital calipers I'm using, but... I'm not 100% sure. More thoughts and or advice?

Thanks again for your time.



Here's the three together. Regular ball, first try at making a plug and second try at making a plug:

 

[rangerod]

I would contact Bullshop and see what they advise. It looks like a .504 full bore should be about right. If using bullet/ sabot .505-.506 should be good.

 

[sdkidaho]

I checked with the Bullshop and this was his response:

Sounds like you will need .503" or .504" diameter. .504" is the most commonly asked for diameter. Engraving .001" should be very easy with these pure lead bullets in a clean bore. The slight engraving will also help hold the bullet on the powder when handling the gun in normal hunting situations It may seat with more resistance in a fouled bore so you have to be the one to decide what you prefer.

Looks like the .504" it is. I'll get some coming and then finally get to shoot this muzzleloader.

Thanks again for all the help.

 

[GM54-120]

I would be surprised if the Ulite lands are .503. I dont think you are getting the caliper all the way into the slug you made.

If it was that large a SST red 3 petal sabot with bullet would pretty much fall down the bore with just the weight of the ramrod. A Harvester smooth black would load with 1 to 2 finger pressure.

For about $13 you can get 3 pin gauges. Get a .501, .502 and a .503
http://www.mscdirect.com/product/details/78376993

http://www.amazon.com/Vermont-Gage-Stee ... s=gage+pin

 

[sdkidaho]

I'm not sure how I would measure differently. I measured just like you see in the pictures above - was that not correct?