Things I’ve decided Gunsmiths should offer 🧐

[D̷e̷v̷i̷l̷D̷o̷c̷A̷Z̷]

I think I caught a cold so with all my free time I’ve decided to tackle some serious issues.

First off, let’s discuss something I’ve always found a little odd.


Why can I reach out to my gunsmith, order a chamber cut for whatever the heck I want? I can go as far as ask for a chamber cut to a specific projo, awesome. When the rifle arrives it comes with all kinds of awesome data. Twist rate, contour, rail screw dimensions, you know all this detailed stuff.


Here’s the rub…..why doesn’t the gunsmith tell me the distance from the bolt face to the lands? Wouldn’t this be useful?

Wouldn’t this be ideal for handloading? For checking barrel wear?

Or did I have too much cough syrup?

 

[Bradu]

I think I caught a cold so with all my free time I’ve decided to tackle some serious issues.

First off, let’s discuss something I’ve always found a little odd.


Why can I reach out to my gunsmith, order a chamber cut for whatever the heck I want? I can go as far as ask for a chamber cut to a specific projo, awesome. When the rifle arrives it comes with all kinds of awesome data. Twist rate, contour, rail screw dimensions, you know all this detailed stuff.


Here’s the rub…..why doesn’t the gunsmith tell me the distance from the bolt face to the lands? Wouldn’t this be useful?

Wouldn’t this be ideal for handloading? For checking barrel wear?

Or did I have too much cough syrup?

I'll have to try to dig up a receipt, I'm pretty sure I got that information on a build from a few years ago when I had 3 barrels chambered for my defiance. But you can do this yourself. Measure to the lands using a bullet, keep that bullet and the information together, then you can check it anytime you want. If you use a bullet from a different lot, it will change some but it's still pretty good information.

 

[NoDopes]

Won't that be different for every ogive?

 

[Supersubes]

Won't that be different for every ogive?

Yep, that would be aaaaalmost completely useless info. Every respectable handloader should have a tool to measure that.

If the gunsmith throats to have a certain amount of jump from a dummy sent by the customer, then you’d know the answer.

 

[338 Mollett]

Done a barrel or two, this is not a standard unit of measure. They are unique to the chamber any tool that catches the ogive can be used but it is specific and only for your reference .

 

[D̷e̷v̷i̷l̷D̷o̷c̷A̷Z̷]

I'll have to try to dig up a receipt, I'm pretty sure I got that information on a build from a few years ago when I had 3 barrels chambered for my defiance. But you can do this yourself. Measure to the lands using a bullet, keep that bullet and the information together, then you can check it anytime you want. If you use a bullet from a different lot, it will change some but it's still pretty good information.

Damn. I was hoping I was on to something.

Won't that be different for every ogive?

I have no clue.

Yep, that would be aaaaalmost completely useless info. Every respectable handloader should have a tool to measure that.

If the gunsmith throats to have a certain amount of jump from a dummy sent by the customer, then you’d know the answer.

I’m kinda trashy. I still shoot 243Win


So a dummy round is best practice. Thank you.

Done a barrel or two, this is not a standard unit of measure. They are unique to the chamber any tool that catches the ogive can be used but it is specific and only for your reference .

I was wondering that very thing. Does an Ogive tool have a real standard or am I just measuring from some random, yet repeatable, distance. And hoping copper jacket doesn’t vary too much round to round?


I thought the lands is where the ogive met? Or is that the bearing surface?

 

[Thumper580]

Hornady tool. Specific ogive for each bullet, once measured keep the bullet as a reference with the measurement. Use it later to see if the throat has any erosion.

 

[6.5SH]

Damn. I was hoping I was on to something.

I have no clue.


I’m kinda trashy. I still shoot 243Win


So a dummy round is best practice. Thank you.



I was wondering that very thing. Does an Ogive tool have a real standard or am I just measuring from some random, yet repeatable, distance. And hoping copper jacket doesn’t vary too much round to round?


I thought the lands is where the ogive met? Or is that the bearing surface?

It's called a "comparator", the measurements gained from it are only "true" for you and your technique/repeatability using it.

There is enough variance in the parts and especially the technique that providing your measurement as a standard to someone else likely will not match, unlike COAL.

Calipers are cheap enough that I dedicate one so the adapter stays in the same place and I can have some historical consistency on my measurements.

 

[Downzero]

The answer to your question is that information is basically useless. I used to be all worried about getting my bullets jammed into the lands or at least not too far away from them. It turns out that there's bullets that will shoot really well even jumped nearly 1/4 inch (not a typo). Once I realized that, I stopped worrying about where the lands were and so should you.

 

[Supersubes]

Damn. I was hoping I was on to something.

I have no clue.


I’m kinda trashy. I still shoot 243Win


So a dummy round is best practice. Thank you.



I was wondering that very thing. Does an Ogive tool have a real standard or am I just measuring from some random, yet repeatable, distance. And hoping copper jacket doesn’t vary too much round to round?


I thought the lands is where the ogive met? Or is that the bearing surface?

Nothing wrong with a .243. Are you hand loading? Not all gunsmiths custom throat chambers, either because the like to chamber with the reamers they have with their included freebore dimensions(easy but less flexible), or the dont have/dont like throat reamers(variety of reasons). Mostly the data is out there for the popular chambers. If you know the bullets you want to shoot, its pretty easy to match.

 

[Llatikcuf]

 

[iceng]

If the customer requests, i often chamber a spare piece of barrel with thr reamer im using. I only chamber it as far as the shoulder or 2mm past shoulder onto the body. This gives the end user a nice easy way to measure lands.

 

[Bradu]

Damn. I was hoping I was on to something.

I have no clue.


I’m kinda trashy. I still shoot 243Win


So a dummy round is best practice. Thank you.



I was wondering that very thing. Does an Ogive tool have a real standard or am I just measuring from some random, yet repeatable, distance. And hoping copper jacket doesn’t vary too much round to round?


I thought the lands is where the ogive met? Or is that the bearing surface?

There is no standard on the comparator tools which is why people still use overall length when discussing reloading.

 

[M4orturnate]

The answer to your question is that information is basically useless. I used to be all worried about getting my bullets jammed into the lands or at least not too far away from them. It turns out that there's bullets that will shoot really well even jumped nearly 1/4 inch (not a typo). Once I realized that, I stopped worrying about where the lands were and so should you.

Exactly. Only check where they are so i know im not seating anywhere near them. My br shoots great .120 off

 

[338 Mollett]

My br shoots great .120 off

You have a particular bullet that shoots well .120 off others might not shoot as well jumping that far .

 

[ggmanning]

I order my barrels based on a a dummy round that I seat to get the most case capacity. Seat bullet of choice in case of choice as long as possible based on the bullet dimensions. Measure case base to ogive, send smith dummy round so he can measure with his comperator also......tell smith I want the chamber this length. Barrel comes with a chamber to my specefied length which represents dummy round just kissing lands. Then I work up my load seating from .120" deeper to .005" deeper for best accuracy node. I end up with a barrel custom chambered to the the bullet I am shooting at the longest base to ogive length possible. COAL is variable, length to ogive is very reproduceable.....opposite of that stated above.

 

[338 Mollett]

^ Throating out a barrel for a certain bullet is done by feel inserting the dummy round ,the throating reamer cuts so subtly you can't tell by the feedback on the tailstock .

 

[M4orturnate]

You have a particular bullet that shoots well .120 off others might not shoot as well jumping that far .

I guess it depends on your standards for accuracy. I dont shoot benchrest but pretty much every rifle and bullet ive loaded can shoot well with big jumps. Like sub .3. Im ok with cloverleafs at 100y, one hole slightly bigger than the bullet is usually achievable minus 1 i pull lol

 

[338 Mollett]

No benchrest here ,my Buds and I shoot LR but still that is a new one on me.

 

[Threadcutter308]

Cautionary note to everyone........

Every manufacturer's comparator insert ID's are different. Don't make the mistake of thinking that a measurement using Manufacturer's Comparator/Insert "A" is equivalent to Manufacturer "B". They are not, and they are no where close to each other. Because of that, COAL/O-H is a relative measurement, not absolute.

A small ID change/difference on the insert makes a huge difference in actual measured COAL/O-H.

Oh, and FWIW, I am a big fan of the SAC comparator/inserts. They come the closest to providing inserts that are very close to a given bullet diameter.

 

[rjacobs]

i shoot semi auto's only... if a bullet cant jump im pretty well fucked...

So far so good though...

 

[M4orturnate]

No benchrest here ,my Buds and I shoot LR but still that is a new one on me.

Yep prs is my game. If youre shooti g bergers try jumping them... A lot. Youll be suprised. Hornadys so far seem to like being in the first .030 or after .060 ime

 

[iceng]

Hornady 108eld, jump 55-60+ thou as a reference to start testing. Berger.. those things are weird. I know people doing 2 thou jam, 12-20thou jump, but most people do 100+ thou.

 

[Rthur]

Do you need to know what these numbers all mean or just find the lands and decide on jump?

R

 

[338 Mollett]

Find the lands and decide on jump.

 

[338 Mollett]

The numbers I pay attention to the most are the neck O.D. and the free bore.