Decrease throat erosion with longer barrels?

[Lefty7mmstw]

There are a few things I look at as I try to get good service life from my rifles. I've knocked out a few barrels (one 24 cal and two 7mm's) so far but not nearly as many as some of the guys here.

The things I see affecting bore life the most are

1. the weight ratio of the powder and bullet ( ie. a 120 grain bullet and 60 grains is a 2 to 1; a 120 grain bullet and 90 grains powder is a 1.5 to 1 ratio. I don't like to get less than 1.5 to 1 ... I'd rather stay to 2 to 1 or more)
2. The pressure generated by said load- I don't run many top loads- many are near top but I leave a few Kpsi headroom
3. The (barrel and ambient) temperatures encountered while shooting- I like to shoot my more overbore rifles only when it's dang cold
4. the bore diameter- larger bores have more surface area to take on the affects of the powder blast and bullet friction
5. the composition of the load- ie. molly bullets, what primer ( certain brands have more abrasives in the mix than others), double base/ single base powder, etc.
6. the case design- a longer neck may help with throat erosion- my personal jury is out on that but others have given me plenty of reasons to at least think of it
7. the throating/ chambering- a freebore will shorten bore life but may drop pressures if actually utilized by the handloader- many people are to enthralled by seating bullets out there to chase the lands
8. steel composition itself- some steels are said to wear quicker than others
9. barrel treatments -- I don't use them myself but they can help

 

[BountyHunter]

I did a small amount of research concerning melonite on barrels. I thought I read something about using this process on stainless steel that might be a problem.
I know for fact when you begin mixing carbon with stainless steel it takes away the qualities of stainless steel. In the past, I've had a few lengthy conversation with metallurgists at Carpenter Steel. Carbon always induces magnetic qualities in stainless steel. Not to say it becomes magnet, but a magnet will be attracted to it. Carbon also can begin to reduce it's resistance to rust.
The description I read indicated the melonite process infuses nitrogen & carbon into the metal.
As a machine shop supervisor in a research facility at the University of Illinois, I learned there aren't very many surface treatments that don't add at least some thickness to a surface. I didn't look into this process long enough to know it that's true or not. I saved a couple of bookmarks to remind me to look into it more.

Melonited three SS barrels with zero issues. No problems with the chambers once you clean them. They leave a gunk type coating that is fun to get out but that is the only drawback.

 

[TracySes23]

Something else to consider and this is pretty self evident is that the bigger the charge and the smaller the caliber (internal diameter) of the barrel, the faster you'll have throat erosion. With a cartridge like the 22-250 you're pushing a lot of hot burning powder down a relatively small hole and that also increases throat erosion.

Using pressure as a guage is a good rule of thumb but there are many more factors.

How about the fact that a 30 caliber bullet needs less powder to get it up to speed and has a larger "hole" for that all that burning powder to crowd through than a 243 shooting the same weight bullet needs. In this case it's about the efficiency of larger base of the 30 caliber bullet being acted on by the pressure of the burning powder vs the relative inefficiency of the 243 caliber bullet with the smaller diameter for the powder to push against.

I've had 308's fire virtually thousands of medium pressure loads show almost NO barrel throat erosion while a 243 at the same pressure shows a lot more and faster.

There are so many factors to consider and all of this is why my high volume shooting is done with cartridges like 223's and 308's. It's not just about the cost of rebarreling but also the time the gunsmith takes to get around to rebarreling for you. LOL

This is a very interesting topic and I'm glad the OP brought it up.

The only two barrels I ever cooked to the point that accuracy was seriously affected was a 22-250 barrel that got really hot shooting in a target rich environment (prairie dogs) and a 30-378 Weatherby that simply showed accuracy degradation after a mere 200 rounds and was never fired hotter than two shots and a complete cooling and I bought that rifle new so I was sure of the round count.

Interestingly enough I shot a few thousand rounds out of a 300 Win Mag Sendero a few years ago and it seemed to get more and more accurate as I shot it more and more. The throat showed a fair amount of erosion but accuracy seemed to be affected only posltively as time went on... Maybe I just got really comfortable shooting it and will never know but rifle would flat out shoot... I guess I sold it... I don't see it around here... LOL

Bob

LDHunter,

I don't know what "the OP" is, but I was the person who originated this thread.

I especially enjoy reading & pay close attention to input from a more experienced shooter such as yourself.
I chose the 22-250 mostly for 2 reasons. First because I like the lighter recoil & second because I have over 30 boxes of 22 caliber bullets to shoot up. Left over from my days of being an FFL holder. I also have over 20 boxes of new 22-250 brass. I have incentive to shoot this caliber. Im also a titewad.
The new found range I'll be shooting at has only 500 yards available. The 22-250 will suit my needs fine for this. I have a 788 Remington I purchased the first year they were manufactured with a pristine barrel. The barrel was always allowed to cool to where it was comfortable to touch between shots. I'm never in a hurry when punching paper from the bench. After a couple of years I lost a place to shoot beyond 50 yards until recently. The 70 gr Speer shot between 3/4 & 15/16 inches. Everything else was between 5/16 & 1/2 inch. All 5-shot groups. It has maybe 1000 rounds through the barrel.
I have no desire to shoot competition, but I do pay close attention to everything I do for every shot I take.

I chose a new Model 12 Savage as my next rifle for a number of reasons. Relative ease of changing calibers was only one of them.
The added weight of the new Savage I haven't received yet was a custom order. It will have the Savage BR stock and the special order dual-port action. At nearly twice the weight of my old 788, I should be able to consider a 6mm or 6.5 mm in the future with recoil I'm comfortable with.

It's quite apparent you're a 1000 yard plus shooter. I admire anyone who has not only learned how to shoot at extremely long range, but has also learned why he does every little thing involved from way the rifle is built the way it is, up until the moment the trigger is gently pulled for each & every shot. People like you always know if you've done what's necessary for very shot.

Thank you very much for your input!

Spencer

 

[TracySes23]

Melonited three SS barrels with zero issues. No problems with the chambers once you clean them. They leave a gunk type coating that is fun to get out but that is the only drawback.

BountyHunter,

Would I be correct if I assume this is a one-time thing when you first get it back after it has been Melonited?

Since my new Savage hasn't arrived yet, I don't want to send it off to be treated while in the middle of decent shooting weather. Would waiting until November cause any problems with a barrel that has been already used some. I don't want to do without this new rifle the remainder of good weather.

 

[shortgrass]

The barrel needs to be treated when it is new.

 

[TracySes23]

The barrel needs to be treated when it is new.

I know Savage shoots a new rifle and sends the target with the the rifle to show what it's capable of. They may even shoot several groups to insure it grouped consistently.

Then should I assume factory test rounds shot by Savage would also cause a problem?

Another thought crosses my mind. If a new barrel needs to be broke in to smooth out minute areas roughness, then the Melonite process actually wouldn't remove this, I would think the break-in process should be done first In fact, since the Melonite process increases the surface hardness significantly, I would think it would hinder the break-in process??

 

[LDHunter]

LDHunter,

I don't know what "the OP" is, but I was the person who originated this thread.

OP = Original Poster

In this case it would be you...

bob

 

[TracySes23]

OP = Original Poster

In this case it would be you...

bob

Thanks! lightbulb

Now I think I recall a list acronyms listed some where on this site. But I ain't sure.

Spencer

 

[shortgrass]

The barrel needs to be "broken in" and perfectly clean before it is sent out. The barrels I've had treated were made by Brux, Krieger, and Hart. I do the chambering and crowning. I fire 2-3 rounds and measure the case heads, examine the bore with a HawkEye Bore Scope, looking for problems (copper build up, which I have not found in any of them!), throughly clean the inside (and out), bore scope again, and ship 'um out. I do all caliber and shop name before shipping.

 

[TracySes23]

The barrel needs to be "broken in" and perfectly clean before it is sent out. The barrels I've had treated were made by Brux, Krieger, and Hart. I do the chambering and crowning. I fire 2-3 rounds and measure the case heads, examine the bore with a HawkEye Bore Scope, looking for problems (copper build up, which I have not found in any of them!), throughly clean the inside (and out), bore scope again, and ship 'um out. I do all caliber and shop name before shipping.

Do any of the barrel makers sell barrels melonited as an option that you're aware of?

 

[azsugarbear]

It's hard to work on barrels (threading, chambering, etc.) once they have been melonited. It is up to the owner to get it done. Many smiths will handle the request, but not until ordered by he owner.

The other question regarding barrel break-in and meloniting: yes, the barrel needs to be broken in prior to meloniting. For some, that may mean just a few rounds. For others, it may mean 40-50 rounds.

 

[TracySes23]

It's hard to work on barrels (threading, chambering, etc.) once they have been melonited. It is up to the owner to get it done. Many smiths will handle the request, but not until ordered by he owner.

The other question regarding barrel break-in and meloniting: yes, the barrel needs to be broken in prior to meloniting. For some, that may mean just a few rounds. For others, it may mean 40-50 rounds.

I considered you might be able to order a barrel chambered & threaded, but I wasn't sure.

The Model 12 Savage headspace can be adjusted, although I don't know how much adjustment is available, but it appears to be substantial.

Check it out. http://www.savagearms.com/accuracy/

 

[shortgrass]

I think if you buy a Benchmark blank and have them fit it to your action they will get it treated for you. Most barrel makers don't want you messin' with their 'work', 'cept to thread, chamber & crown. Barrels that have enough rounds down them, that show some cracking, are not good candidates for treating. I have set several back, that showed minor cracking or rounded/eroded edges, a turn or two and re-cut the chamber to head space, then fired a couple of rounds just for the heck of it and to measure brass (because I'd had a reamer in there, again). I know very little about Savages and don't want to know anymore than I know now.

 

[TracySes23]

I think if you buy a Benchmark blank and have them fit it to your action they will get it treated for you. Most barrel makers don't want you messin' with their 'work', 'cept to thread, chamber & crown. Barrels that have enough rounds down them, that show some cracking, are not good candidates for treating. I have set several back, that showed minor cracking or rounded/eroded edges, a turn or two and re-cut the chamber to head space, then fired a couple of rounds just for the heck of it and to measure brass (because I'd had a reamer in there, again). I know very little about Savages and don't want to know anymore than I know now.

Thanks for the info.