MolyCoated Projectiles

[Old Trev-39]

Hi All,
Was browsing through some old Precision Shooting Magazines and came across this paragraph.
When molybdenum disulphide is exposed to high temperature and pressure, breaks down and causes a sulphuric acid by product which is very difficult to remove. This can significantly reduce accuracy and harm your barrel.
This is probably why it lost favour with the short range B/Rest shooters years ago.
Thought I would post this for present and those pondering using moly to think about it.
Cheers,
Trevor.

[mike H]

Hi All,
Was browsing through some old Precision Shooting Magazines and came across this paragraph.
When molybdenum disulphide is exposed to high temperature and pressure, breaks down and causes a sulphuric acid by product which is very difficult to remove. This can significantly reduce accuracy and harm your barrel.
This is probably why it lost favour with the short range B/Rest shooters years ago.
Thought I would post this for present and those pondering using moly to think about it.
Cheers,
Trevor.

Have used moly for more than ten years,no problems in about eight barrels,one of my gunsmiths uses it,he would know.
Mike.

[Cliff Austen]

Mike H is on the money. I too have been using Moly coated projectiles for 15years without any problems.
Moly does not start to metl until 1185degC. It take an awful lot of energy (that is, temperature and pressure, a pressure far in excess of what we experience in a chamber) to get the Sulphur atom to break away from the Molybdenum atom and for sulphuric acid to form.
Iron melts at about 1500deg C and stainless ranges from 850 to 1050deg C so your barrel is likely to start melting long before moly will decompose.
Hence, moly is not detramental to the barrel.
if we have any metallurgists out there then they may be able to clarify the issue more precisely.
Cheers. Cliff.

[Cliff Austen]

Mike H is on the money. I too have been using Moly coated projectiles for 15years without any problems.
Moly does not start to metl until 1185degC. It take an awful lot of energy (that is, temperature and pressure, a pressure far in excess of what we experience in a chamber) to get the Sulphur atom to break away from the Molybdenum atom and for sulphuric acid to form.
Iron melts at about 1500deg C and stainless ranges from 850 to 1050deg C so your barrel is likely to start melting long before moly will decompose.
Hence, moly is not detramental to the barrel.
if we have any metallurgists out there then they may be able to clarify the issue more precisely.
Cheers. Cliff.

[johnk]

Then again, the original Hoppes & GM upper engine cleaner are carcenogenic & we all lust for access to those again.

[KHGS]

Hi All,
Was browsing through some old Precision Shooting Magazines and came across this paragraph.
When molybdenum disulphide is exposed to high temperature and pressure, breaks down and causes a sulphuric acid by product which is very difficult to remove. This can significantly reduce accuracy and harm your barrel.
This is probably why it lost favour with the short range B/Rest shooters years ago.
Thought I would post this for present and those pondering using moly to think about it.
Cheers,
Trevor.

This was a "scare tactic" initiated by the "arm chair expert" brigade some years ago as a move to discredit the use of moly, they pretty much succeeded too.
I have personally used it for over 20 years in all my barrels & I have examined many other barrels from moly using customers. I have not seen any problems except from those who thought that by using moly they did not need to clean at all!! That does not work!!!!
Keith H.

[ShaneG]

As an aside Keith, what process do you use to clean when using moly as opposed to "naked"?
Shane

[KHGS]

As an aside Keith, what process do you use to clean when using moly as opposed to "naked"?
Shane

Shane, pretty simple really, bronze brush, carby cleaner & either ProShot or Boretech Eliminator solvent. The solvent is your choice & many work, but these are my favoured solvents. I do not use ammoniated solvents. I bronze brush with the carby cleaner (my choice at the moment is Nulon Throttle Body cleaner), patch out & repeat. After this I use a nylon brush to apply the solvent & leave overnight (optional) then patch out & oil with Sweets oil, I use only Sweets as I have found that using this oil ensures my first sighter will be at the bottom of my group in all the barrels I have used it in. The whole process takes no more than 20 minutes.
Bronze brushing does not harm barrels which is at odds with popular belief, also a furphy started by the "armchair brigade".
I do subscribe to the theory that it is best not to use ammoniated solvents in stainless steel barrels. I am led to believe Nasa do not allow such solvents to be used in the precision stainless steel tubing of their space shuttles, if this is so, I am not going to use it in my barrels when there are very good alternatives. By this I am not claiming that such solvents cause damage, just that I prefer not to risk the possibility.
Keith H.

[ShaneG]

Thanks Keith
I have some exposure to moly in a .222AI I used on rabbits or years.
It was a very light L46 Sako limited to OAL by the detachable magazine.

I found that in that barrel it shot very well for about 80 rounds then the groups opened up to 3 times the size.
A look down the barrel and it was if I may have been shooting black powder!
Maybe I had too thick a coating?
Anyway I ended up with a carby cleaner as well to shift it and it always came clean fairly quickly with that.
This was in the days before Eliminator unfortunately.
Shane

[Josh Cox]

Hello Keith,

Thanks for taking the time to help.

I also use moly on my 155 hybrids, after receiving the same advice from you and Mr Mastin, I use boiling water down the barrel then hoppes and bronze brush, which has been doing a spectacular job. Krieger barrel shows absolutely no copper and only ever removing carbon.

It has been noticeable every 7-800 rounds that the rag feels a little rough when pushing through the clean barrel,at which time ,my vertical becomes over Moa. A hot barrel (usually after hot water ) and the grey jb's in the throat and I'm good to go for another 7-800 rounds.

Any other suggestions ?, 2000 rounds through this barrel and it is performing wonderfully.

[KHGS]

Hello Keith,

Thanks for taking the time to help.

I also use moly on my 155 hybrids, after receiving the same advice from you and Mr Mastin, I use boiling water down the barrel then hoppes and bronze brush, which has been doing a spectacular job. Krieger barrel shows absolutely no copper and only ever removing carbon.

It has been noticeable every 7-800 rounds that the rag feels a little rough when pushing through the clean barrel,at which time ,my vertical becomes over Moa. A hot barrel (usually after hot water ) and the grey jb's in the throat and I'm good to go for another 7-800 rounds.

Any other suggestions ?, 2000 rounds through this barrel and it is performing wonderfully.

How often do you clean?
Keith H.

[KHGS]

Thanks Keith
I have some exposure to moly in a .222AI I used on rabbits or years.
It was a very light L46 Sako limited to OAL by the detachable magazine.

I found that in that barrel it shot very well for about 80 rounds then the groups opened up to 3 times the size.
A look down the barrel and it was if I may have been shooting black powder!
Maybe I had too thick a coating?
Anyway I ended up with a carby cleaner as well to shift it and it always came clean fairly quickly with that.
This was in the days before Eliminator unfortunately.
Shane

What powder were you using?
Keith H.

[ShaneG]

Hi Keith
Long time ago and still have some loaded rounds at work but away at moment ?
May have been 2206H , BM1 or BM2?
Cheers
Shane

[Josh Cox]

Usually after each weekend, or at the end of each day.

[KHGS]

Hi Keith
Long time ago and still have some loaded rounds at work but away at moment ?
May have been 2206H , BM1 or BM2?
Cheers
Shane

I would suggest that you were experiencing powder fouling not moly fouling.
Keith H.