New Posts New Posts RSS Feed - erosion
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

Check GunBroker.com for SWFA's No Reserve and No Minimum bid firearm auctions.

erosion

 Post Reply Post Reply   Topic Search Topic Search  Topic Options Topic Options Page  1 2>
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: May/03/2007 at 07:54
Dale Clifford View Drop Down
Optics Jedi Knight
Optics Jedi Knight


Joined: July/04/2004
Location: United States
Status: Offline
Points: 5087

What exactly causes erosion-all theories welcome

97 yds ,71 deg, 3 declination start of 200 rds.  Five round fouling shots.

 

 

My portable "bench rest"

 

 

Using stoney-point to measure erosion as more rds shoot

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: May/03/2007 at 09:03
RifleDude View Drop Down
MODERATOR
MODERATOR
Avatar

Joined: October/13/2006
Location: Texas
Status: Offline
Points: 14310
Intense heat and repeated thermal cycling.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: May/03/2007 at 09:23
silver View Drop Down
Optics Master
Optics Master


Joined: November/04/2005
Location: United States
Status: Offline
Points: 2291

 

 

Go down to the local welding shop and watch the plasma cutter...  When you hit the primer its like turning on the cutting torch.

 

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/03/2007 at 11:52
Dale Clifford View Drop Down
Optics Jedi Knight
Optics Jedi Knight


Joined: July/04/2004
Location: United States
Status: Offline
Points: 5087

usually my shooting style from prone strings shots horizontally due to grip pressure, very seldom vertically, so when this group came up -- immediately suspected problems with ES and started web checks. sure enough late lots of R22 have been giving problems see www.6mmbr.com if interested. will be switching to H4350. no significant change in land readings.

 

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/03/2007 at 13:06
pyro6999 View Drop Down
Optics Retard
Optics Retard
Avatar
OT TITAN

Joined: December/22/2006
Location: North Dakota
Status: Offline
Points: 22024
thats a big difference between r-22 and h4350
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/03/2007 at 15:55
Dale Clifford View Drop Down
Optics Jedi Knight
Optics Jedi Knight


Joined: July/04/2004
Location: United States
Status: Offline
Points: 5087
about 4-5 grs/ faster index
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/03/2007 at 16:00
pyro6999 View Drop Down
Optics Retard
Optics Retard
Avatar
OT TITAN

Joined: December/22/2006
Location: North Dakota
Status: Offline
Points: 22024
isnt that going to throw the test off a little since your changing powders? i mean it would be big deal if your burn rates were more comparable but this kinda stains the results with that much difference. reloader 19 or 4831 would be closer than h4350.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/03/2007 at 18:06
Dale Clifford View Drop Down
Optics Jedi Knight
Optics Jedi Knight


Joined: July/04/2004
Location: United States
Status: Offline
Points: 5087

the question was more of what erosion did to and at what point, not if one powder caused faster erosion that another. even then if 2 lots of the same powder showed (and they are) extreme ranges it would be like substituting another powder. another reason I'm hesitant is while working with 22 (and 4831) I was always getting the feeling it would have worked better with mag primers. moving to 4350 which I've shot a ton of and standard primers gives me more confidence in the loads results.  

 



Edited by Dale Clifford
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/03/2007 at 18:27
Dale Clifford View Drop Down
Optics Jedi Knight
Optics Jedi Knight


Joined: July/04/2004
Location: United States
Status: Offline
Points: 5087

also the load has been worked up to coincide with the night force np1-rr reticle thed first dot is 4 moa up with 100 yd zero and dead on at 300 yds the second 8 moa and dead at 450 yds the 3rd is 650 and the 4th 20 moa dead at 800 with 8 moa dial in for 1000 yds. recenter to 200 yd poi is 1.8 moa and shift, to 350,500,750,900 that easy

 

 

 

 

 

 

 

 

 

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/03/2007 at 20:25
pyro6999 View Drop Down
Optics Retard
Optics Retard
Avatar
OT TITAN

Joined: December/22/2006
Location: North Dakota
Status: Offline
Points: 22024
wouldnt the faster powder accelerate the erosion process??
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/03/2007 at 20:45
Dale Clifford View Drop Down
Optics Jedi Knight
Optics Jedi Knight


Joined: July/04/2004
Location: United States
Status: Offline
Points: 5087
this is one of the reasons I ask the question at the start of the post. If the total number of particles, assuming the same flame temperature, is a determinate in the erosion process, the slow burning powders because the are used in greater weight charges would cause more erosion all things being equal. If the erosion process is more dependant on thermal cracking, excess heat then a seperation of local metal surface resulting in cracking, then heat generated by the hottest powder would be relevant, which in any case could be offset by more cooling time. faster powders don't increase erosion per se. a good deal of the process involves the bore capacity relationship. in reducing the charge weight of 4350 about 5grs to reach the same ballastic performance means the thermodynamic relationship and the amount of work done is the same. If a higher temp is present, it offset by less number of particles causing abrasion as in silvers plasma example.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/04/2007 at 06:28
pyro6999 View Drop Down
Optics Retard
Optics Retard
Avatar
OT TITAN

Joined: December/22/2006
Location: North Dakota
Status: Offline
Points: 22024
ok so in other words buy switching to 4350 your decreasing the charge weights to equal out the performance. so your going to get r-22 like performance with a faster burning powder.which would mean your still being consistant with your ballistics but with another brand of powder.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/04/2007 at 10:01
silver View Drop Down
Optics Master
Optics Master


Joined: November/04/2005
Location: United States
Status: Offline
Points: 2291

Originally posted by Dale Clifford Dale Clifford wrote:

this is one of the reasons I ask the question at the start of the post. If the total number of particles, assuming the same flame temperature, is a determinate in the erosion process, the slow burning powders because the are used in greater weight charges would cause more erosion all things being equal. If the erosion process is more dependant on thermal cracking, excess heat then a seperation of local metal surface resulting in cracking, then heat generated by the hottest powder would be relevant, which in any case could be offset by more cooling time. faster powders don't increase erosion per se. a good deal of the process involves the bore capacity relationship. in reducing the charge weight of 4350 about 5grs to reach the same ballastic performance means the thermodynamic relationship and the amount of work done is the same. If a higher temp is present, it offset by less number of particles causing abrasion as in silvers plasma example.

 

I guess that it would work out to a tempature and duration problem.  Somebody from Aberden or Crane problely has a file the size of the Chicago phone book from where they have worked out that problem.  Here is the thing as the tempature goes up then things flow better.  So then it becomes does hotter faster out way hot longer.  It is a guess on my part that the more intense cycle would make things more brittle and at the end of the cycle the erosion would pick up a bit. 

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/04/2007 at 10:37
Dale Clifford View Drop Down
Optics Jedi Knight
Optics Jedi Knight


Joined: July/04/2004
Location: United States
Status: Offline
Points: 5087
its not the heating that causes the problem its the cooling and the uneven contraction of the metal (not talking machinge guns here) which results in the "dried creek bed" appearance under the microscope. I don't think the problem has been solved, just as silver suggests a lot of raw data on the phenomena, nobody "owns" the event. The event has to fit within the gas laws and thermodynmic heat transfer regardless of whos pumping the data. As  a more simple observation, the same pressure loads of 296 in a 357 mag wear out a forcing cone on a revolver faster that the same pressure loads of 231 regardless of when the peak pressure occurs in the barrrel, because of more material from lthe 296 load. The localized effects of each type of powder may have a materials engineering effect on that metal, however a faster index doesn't mean a higher temperature.

Edited by Dale Clifford
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/18/2007 at 11:46
Dale Clifford View Drop Down
Optics Jedi Knight
Optics Jedi Knight


Joined: July/04/2004
Location: United States
Status: Offline
Points: 5087

change to 142 gr. SMK 45 grs. H4350 erosion measure 3.160 (must have worn a corner off) 6 shot group no wait for barrel cool down group .8 1st 3 almost same hole --- right 1st shot fouling

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/20/2007 at 12:11
Dale Clifford View Drop Down
Optics Jedi Knight
Optics Jedi Knight


Joined: July/04/2004
Location: United States
Status: Offline
Points: 5087
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/23/2007 at 19:08
tahqua View Drop Down
MODERATOR
MODERATOR
Avatar
Have You Driven A Ford Lately?

Joined: March/27/2006
Location: Michigan, USA
Status: Offline
Points: 8043

I am glad you have taken the time to look at this issue for us Dale.

Barrel erosion is caused by thermal, chemical and mechanical mechanisms. I think you are right about the thermal aspect being a bigger influence, at least in the throat area. Thermal cycling affects all metals and the more you shoot the more erosion.

Certainly mechanical forces wear down the barrel but this is away from the throat.

There seems to be debate on powder burning rates affecting erosion. One thing there is no doubt about, there is far more heat generated from large cases with small diameter bullets. The stories we have all heard about barrel burners are true, though there has been a lot of spice added to them.

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/24/2007 at 10:13
Dale Clifford View Drop Down
Optics Jedi Knight
Optics Jedi Knight


Joined: July/04/2004
Location: United States
Status: Offline
Points: 5087
Currently running into the dreaded doughnut of carbon build up just ahead of the neck, for which some calibers are notorious. Having some pressure differences that may be part of the problem of vertical stringing along with inconsistent lots of R22. will post the JB paste clean up swabs as time permits.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/30/2007 at 19:08
Dale Clifford View Drop Down
Optics Jedi Knight
Optics Jedi Knight


Joined: July/04/2004
Location: United States
Status: Offline
Points: 5087

 

gun does not like 4350, 4831, with v-max. found some old lots of R22  with last group at 2900 fps. erosion .015 going into 800 rds estimated, life.  looks like it could easily go to 1200

 

 

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: August/14/2007 at 21:22
hot30 View Drop Down
Optics Journeyman
Optics Journeyman
Avatar

Joined: December/27/2006
Status: Offline
Points: 378

Dale, Id like to take a wack at this if none of you object.  Now granted I dont think like the normal person, so here goes.

  Lets leave the heat index and barrel material out of the equation till later.  Lets look at the "throat " only for now.  Can we look at the throat as a combustion chamber.?  With this picture, lets look at 2 types. The typical or SAAMI throat or the longer type that will accomidate longer bullets.  As ignition occurrs, the bullet leaves the case and jumps to the lands.For another  split second the bullet  stops.  During this part of a second, the throat or chamber is filling with the hot gasses until enough heat and pressure sends the bullet down the bore. Now in the short throat, also smaller and more restricting, would this lend to the dredid

dognut that forms right at the necks end.?  Also in the short throat, would there be insaficiant volume of combustion to cause severe erosion.?  Now, in the long throat, with more volume, heat and pressure, would this lend to more erosion with less deposit due to more efficiant combustion.?

 

    Lets plug in the powder factor.  In the short throat, would a fast burn cause the same problems as a slow burn.? Which powder is going to move the bullet first.?  Now in the long throat, fast or slow burn, which is going to move the bullet first.?

 Is the period of time that the bullet spends plugging the bore have anything to do with erosion.? Would the time and volume

of the heat contained in this throat or combustion chamber be the direct cause of erosion.? 

 

   The last factor, the sandblasting effect caused by unburned powder.  Say the lands are vulnerable to erosion after being super heated due to the earlier processes. Unburned powder will travel some distance down the bore pitting and burning as it is being

ignited . Well thats the long and the short of it for me.  If this isnt part of the problem, barrel material enters into it. I like chrome moly for rapid fire high heat duty, stainless for life span. Is moly less affected by heat, does it change it properties more or less with heat, or does stainless temper abnormally with high heat and erode less or does it all go back to the time spent in the throat. To me it seems that "time" spent, that is the time spent in the throat, that would decide what takes place.

 

,

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: August/15/2007 at 11:39
Dale Clifford View Drop Down
Optics Jedi Knight
Optics Jedi Knight


Joined: July/04/2004
Location: United States
Status: Offline
Points: 5087

If you've ever had a squibb 44 mag load using 296, you know that the primer will blow the bullet and powder into the forcing cone along with a lot powder (to say nothing of shotguns loads) . The same thing happens in rifles, the primer has enough poop to start the movement, and the rest depends on the powder burn index, and the physical constraints you describe. The typical looong standard remington throat no doubt has different wear characteristics as to say a custom "tight" bench gun. Actually it amazes me how accurate the out of the box remy is with a little tweeking. The doughnet is more of a collar, but I think its is formed upon condensation, when the pressure suddenly drops as the bullet leaves and the carbon residues precipitate out of the atmosphere of the chamber and throat area. Then when the hot gases of the next round come in contact, it "bakes" the varnishes and carbonyl cmpds onto the metal. I'm sure all the factors you have stated are at play, the question is quantitative, how much is contributed by each, and if at certain times one has more importance than another.

To some all that matters is the final result -- the change in accuracy-- which is indeed important also, and hopefully to get others to input with their thoughts and experience also.



Edited by Dale Clifford
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: August/15/2007 at 13:12
hot30 View Drop Down
Optics Journeyman
Optics Journeyman
Avatar

Joined: December/27/2006
Status: Offline
Points: 378
If the element of "time" has any influence at all, would changing the forcing cone angle determine the outcome of "any" event that takes place.? I dont know offhand if there is a "standard" angle, but I would think that any angle that was less abrupt in this area would create less of a "time" factor. Condensation will form reguardless during the process, but if it were sped up would it be less.? The mechanical process that unburned powder creates would be less distructive in the forcing cone if the angle was taylord to allow a more "gentle" exit to the bore.? I dont know...  If less time was spent while this "damage" was occurring, would there be less damage.?? Then maybe the heat index would be the real factor.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: August/15/2007 at 14:12
Dale Clifford View Drop Down
Optics Jedi Knight
Optics Jedi Knight


Joined: July/04/2004
Location: United States
Status: Offline
Points: 5087
changing the forcing cone angle on handguns affects accuracy a lot, I use an 11 deg. cutter from brownells on all handguns. Rifles have to be "straight" cut for reliability. it doesn't really effect the life of the forcing cone, which is a wear problem. If the same event has to occur (same amount of powder, same temp, and mass) in a shorter time the wear will be more.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: August/15/2007 at 22:58
hot30 View Drop Down
Optics Journeyman
Optics Journeyman
Avatar

Joined: December/27/2006
Status: Offline
Points: 378
Maybe the characteristics of the 3 land and grooves would retard the process.? Way more material to erode. My "cut" rifled barrels seem to go pretty quick compared to a button job. Im thinking the cut type has some very "sharp" area that would easily be eroded.?  Well, lets see what some others think.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: August/30/2007 at 20:02
Dale Clifford View Drop Down
Optics Jedi Knight
Optics Jedi Knight


Joined: July/04/2004
Location: United States
Status: Offline
Points: 5087

gun is outstanding plains rifle, installed Leo 4.5x14 varmit reticle and zeroed for 300 yd. has 3 moa for each consective 100 yd interval.to 900 yds.

erosion to 3.176 and appears to be linear

group after carbon sleeve cleaned out with carburator cleaner

was so excited pulled 5 th shot.

 Post Reply Post Reply Page  1 2>
  Share Topic   

Forum Jump Forum Permissions View Drop Down

Similar Threads: "erosion"
Subject Author Forum Replies Last Post
There are no similar posts.


This page was generated in 0.359 seconds.