Barrel Life?

[mikecr]

I've posted it before & this version allows for future adjustments (due to nitriding):
There is 6ppc loaded in to begin

 

[Quinc]

Has anyone tried meloniting their barrel in something like the 6.5x284 or other "burner" calibers?

 

[mikecr]

Donovan, with your numbers, I get 209 @ 3sec/sht, and 697 @ 10sec/sht
How many shots at 3sec/shot do you actually shoot within peak accuracy?
Do you get more than a 6PPC?

I'll certainly listen & consider more anecdotal research w/regard to shot timing.

 

[mysticplayer]

Trying to understand that chart and how it can help bore wear....

Each powder has a rating of the energy per unit mass.

so does a powder with a "low" number need MORE powder to perform the same work? ie a powder with a rating 10% lower then another need 10% MORE powder to get the same performance?

6CM with H1000 take 10% more powder to reach the same speed in the same barrel effective length as a 6XC OR does the 6CM reach the same performance using 10% LESS energy?

can a powder of lower value provide equal performance more effeciently thus "need" less energy?

I understand there is no free lunch but can one source of fuel deliver work more effeciently thus providing the same result but using less energy to do it.

If that is possible, then this powder would wear a bore less.

If it is not possible, then bore wear of similar systems will be the same cause they are experiencing the same amount of energy input

Then better or worse bore rate has more to do with other ingredients and/or the actual life experience of the barrel.
Jerry

 

[savagedasher]

I have a 34'' MC Gowen barrel I used for testing.Round count is near 3000 .Started as 6/47 never shot good.Cut 2'' off chambered to a 6 dasher sub 1/4'' with most powders.Just re chambered it
from27.02 to 27.005 my gun smith said it had very little fire cracking.When i told him 3000 rounds he was shocked.2500of the 3000 was shot with H4350 . I have a theory H4350 uses 19.6''to get 95% of max speed. Varget uses 11.4''to get 95% max speed .I'm spreading 95% heat over 8.2''more area. My other dasher has 7.5 Kreiger it has 700 round with no throat wear.
Quickload has the information on it. Good Shooting Larry

 

[BoydAllen]

Often discussions such as this one become one fellow's assumptions vs. another's, with no real hard data. Obtaining meaningful data would cost more than any of us want to spend, but discussion and argument are harmless and free. Personally, I don't know, and I am not sure that anyone else does either. If someone claims to, I would like to hear how he arrived at his conclusion. "Where's the beef?"

 

[JRS]

You could try McMillan for one Boyd. They probably have the documentation from the vast amount of testing compiled during their barrel making/testing days. Another, is our US Army. Sniper rifles (in 30 cal) are re-barreled at roughly 1400 +/- rounds due to throat and barrel wear.

 

[mikecr]

There are a couple factors to consider for sure:
#1 there are incredibly bogus claims out there for barrel life
#2 By far most shooters never gain awareness of 'peak' accuracy from a barrel. It's coming or going.

With this, someone claiming <1/2moa, but truly shooting worse, could 'think' their barrel life goes on forever.
But they never had, nor likely will have seen peak accuracy fall off.
And if others are consistent at 1/4moa, while not actually seeing peak accuracy from the gun(it could shoot better), then a loss of peak to the point of awareness represents higher numbers than reality.
Only competitors, and only those with their own eyes open, can sense it.

And yes someone can reset a barrel & most life for it. But ultimately carbon restrictions will kill it. Typically by the third setback.

 

[mysticplayer]

Bummer, that is pretty much what I had suspected but hoped there was new research that could shine some light on this.

I do like the premise on time/distance of burn of various powders. We know this does happen as we can see it on a pressure trace.

My experience with long F class barrels mimics this that the slower burning powders use more barrel length to combust so damage per inch per shot is extended. The barrel might maintain accuracy longer but when it goes, it has cooked far more barrel length.

Setting back would have less benefit as the barrel may not have enough shank to thread.

Anyone have experience using Nitride Bath hardening?

Jerry

 

[Steve Blair]

Anyone have experience using Nitride Bath hardening?

Jerry

[br]
I have a .22-250 with only 496 rounds down the tube. It was nitrided when new. My borescope show no wear and machining marks are still visible in the freebore and leade. The loads are about factory pressure, so I would expect to see a little wear but there is none.

 

[mysticplayer]

did you test accuracy before and after?

Concern is that it might change the conditions of the bore... ????

Like to get more info if possible - who to do? costs? turnaround?

if you would prefer to discuss offline... info@mysticprecision.com

Thanks

Jerry

 

[Steve Blair]

No, it was nitrided as new. Other folks have noted no accuracy change.

 

[bozo699]

No, it was nitrided as new. Other folks have noted no accuracy change.

I shot with a fellow two years ago that had some Kroil left in the throat just before the Nitride bath and in about 400 rounds it started to peal and flake loose in the throat area you could see it with the bore scope but it did not degrade accuracy one bit.
Wayne.

 

[mikecr]

Nitriding really does seem like a free lunch. Well, practically free.

 

[mysticplayer]

With more and more shooters using bore cooking set ups in F open, adding a step that can prolong bore life is not a bad thing.

More to do with less time fussing with brass then saving $$. I moved to FTR in part to get longer barrel life and less fireforming - it was a huge part of my shooting time.

But no one in Canada has any experience from a competition stand point. If the cost is the same as a barrel, then you save 1 install cost but extend the time you need to reset all your cases. For some that may not be worth the fuss... and risk,

If the treatment allows for the equivalent of more then 2 times the bore life (say 3 to 4 times), then there becomes some real savings in mucking about.

Love to hear some thoughts and experiences.

Jerry

 

[tunered]

Here is a good read on bullet dwell time in the bore,

http://www.accurateshooter.com/technical-articles/facts-about-barrel-life/

 

[Martin52]

Nomad47,

As for barrel life ...under very controlled laboratory conditions... it normally took me about three-four weeks to wear out a barrel, from freashly threaded and chambered, to shot out and in need of replacement.

Kevin - can you indicate the approximate round count for a barrel tested under these conditions to go from new to being shot out ? I am particularly interested if you performed this test using a 308 barrel/155gr combo. This is what I use. I am currently trying to figure out why I need an increasing number of fouling shots after cleaning before the barrel settles back in - suspect this is due to either powder forming just ahead of the chamber or the barrel wearing out (30 inch Krieger 1700 rounds now, typical load 155gr Sierra 2156 with 46gr Varget)

Thanks
Martin