Measuring Bore

FISMA

Has anyone a relatively simple way of measuring bores: lands-lands or grooves -grooves?

I have a firearm that I am concerned may be approaching its barrel life and would like to see how much is left.

More importantly, I am looking at a used firearm that is supposed to be as new as the day it left the factory, but would like a way to measure the bore.

Finally, if I have to buy a special tool, so be it. Has anyone any bore gauges they would recommend?

Thanks

stick shooter

FISMA wrote: »

Has anyone a relatively simple way of measuring bores: lands-lands or grooves -grooves?

I have a firearm that I am concerned may be approaching its barrel life and would like to see how much is left.

More importantly, I am looking at a used firearm that is supposed to be as new as the day it left the factory, but would like a way to measure the bore.

Finally, if I have to buy a special tool, so be it. Has anyone any bore gauges they would recommend?

Thanks

Bore scope is your best bet

Sparks

Bore scopes examine the inside of the bore visually, I've not heard of any that'd measure it.

A cheap set of vernier calipers should do the job, at least at the ends of the barrel, just be careful not to scrape the bore while measuring it. A quick way to ensure the bore's consistent would be to clean the rifle and then pass through a brush or patch afterwards and check that the resistance to the rod doesn't increase or decrease as you push the brush all the way through, but bore scoping would pick that up faster (you'd see increased wear and damage).

FISMA

Sparks wrote: »

Bore scopes examine the inside of the bore visually, I've not heard of any that'd measure it.

A cheap set of vernier calipers should do the job, at least at the ends of the barrel, just be careful not to scrape the bore while measuring it. A quick way to ensure the bore's consistent would be to clean the rifle and then pass through a brush or patch afterwards and check that the resistance to the rod doesn't increase or decrease as you push the brush all the way through, but bore scoping would pick that up faster (you'd see increased wear and damage).

True, it would be nice to know the thickness throughout. However, I am willing to settle for the end.

I have several machinists and am well capable of making accurate measurements of bullets and cases. However, I was concerned to use the caliper to take the inner diameter measurement.

The main concern is that my caliper has straight edges and the bore is round. Is this enough to cause variance?

Does anyone know how much metal a barrel has to lose before replacement is recommended?

Slan

Sparks

FISMA wrote: »

The main concern is that my caliper has straight edges and the bore is round. Is this enough to cause variance?

Most calipers I've seen have bevels on the edges so that you're measuring from single points of contact rather than over several millimetres. It'd depend on the model of calipers of course.

stick shooter

What you are looking for is a bore gauge but to find one that small will take a bit of looking .I have used a lot larger ones to check engine cylinder bores after being honed .

Half-cocked

You might find an engineering works with a suitable set of pin guages. I used to use a set that went from 1.0mm to 6.0mm in steps of .001mm - yes, that's 500 pins! Unfortunately I don't work there anymore. What calibre are you wanting to measure?

tomcat220t

The main ware on a barrel is around the throat so if its any way shot out it should show up there .If you slug the full barrel and measure the lead it with give you a reffernce to your tightest diameter of your barrel .Im sure you could slug the first 1" of your barrel and compaire to your full slug for ware .Best of luck either way .

gunhappy_ie

OP... could you tell us what firearm and caliber it is and what you plan on using it for.


Unfortunatly calipers arent going to show you anything but a different reading every time if you arent ultra carefull in there exact placement every time. I wouldnt reccomend this method and measuring the muzzle isnt where you need to gauge

Your first stop would be to get headspace gauges. Manson reamers or Pacific tool and gauge will be able to sort you out with a go and no go.

http://www.mansonreamers.com/

Pacific tool and gauge also sell some throat erosion gauges...

http://www.pacifictoolandgauge.com/products/gaugesnbushings/t_e_gauges.htm

Depending on the caliber of the firearm that you have I may already have headspace gauges if you want to borrow them Im sure we could arrange something.

GH

FISMA

I am looking at a 338 Win Mag Sako Finnbear.

It is an old gun and I would like to know if it is as new or has a few rounds put downrange.

I would also like to know for my 30-06 and in general how to check the wear.

I like the idea of the pins. I am surprised that someone does not make a set of cylinders, incremented similarly, that could be pushed down the barrel to check wear.

GunHappy,
Thanks for the links and the offer. Unfortunately, I am out of the country and this firearm will not be home for a while.

I am kind of surprised that all of the usual suspects like Cabelas haven't a tool like this for sale.

gunhappy_ie

FISMA wrote: »

I am looking at a 338 Win Mag Sako Finnbear.

Nice Just had to google it ... looks like a peach but the rifles Sako commenced production in 1961, it would be a good idea to check head space at a minimun.

It is an old gun and I would like to know if it is as new or has a few rounds put downrange.

Unfortunatly I havent seen a throat erosion gauge big enough for a .338 WM but if you are interested in parting with your money im sure manson reamers or pacific tool and gauge will grind you one

I would also like to know for my 30-06 and in general how to check the wear.

The M1 Grand gauge will suffice for the task, also while I think its a bit of a gimmic.... http://www.scott-duff.com/ShooterAcc.htm the muzzle wear gauge there is reasionable money.

I like the idea of the pins. I am surprised that someone does not make a set of cylinders, incremented similarly, that could be pushed down the barrel to check wear.

500 precision ground pins..... €€€€€€€ LMFAO most Gunstealers that I know dont even know what a headspace gauge is so they obviously dont check the guns that they get on trade in.

GunHappy,
Thanks for the links and the offer. Unfortunately, I am out of the country and this firearm will not be home for a while.

Sorry, I cant help you with a 30-06 or 338 as I only have 9mm .223/.308

I am kind of surprised that all of the usual suspects like Cabelas haven't a tool like this for sale.

What your looking for are gunsmithing/armourers tools, Cabelas is more for shooters not gunsmiths. If i need tools/parts id first look to brownells, who do have 30.06 throat erosion gauges in stock (should you want I can add it to my next order to save you on postage)

To be honest, a throat erosion gauge will be a waste of money because not only will it be really hard (if even possible) to read the gauge as the barrel sits in the reciever but if your barrel is shot out, youll know as you wont hit the back end of a bus.

The same can be said for the muzzle erosion gauge, sure it will show you that its wearing at a slower rate than the throat, but unless your at the top of the league in F Class shooting it generally doesnt matter.

Headspacing on the other hand is very important to check as if excessive can lead to shooter with bolt embedded in face syndrone

GH

rowa

The only way i have ever seen a barrel measured by a non-gunsmith is slugging it , pushing a soft lead slug down the barrel and measuring it with a mic.
I did see a kit of some sort of hard silicone that you put in the chamber and throat and let it set , measuring it afterwards. You could try the same thing with hard wax maybe ?