What results with HBN or Moly coated bullets?

[dok7mm]

Whoops, 7 years old!

 

[Mikecr]

OMG
DAGNABBIT

 

[Capt RB]

I know nothing about HBN, but it's important to understand that moly does not lower MV due to friction change.
Instead, with moly, there is a cooling of the charge as moly vaporizes.
This does reduce land erosion, but unless moly is managed perfectly, accurate barrel life itself goes down.

For sure HBN would not have the exact same affect.
WS2 has a far lower friction coeff than moly, and it does not affect MV at all.

Norma testing would disagree with your findings

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I have been using WS2/Danzac for about 5years now. I used moly off and on for the previous 20. Mostly in the 243 and 300wby. I have found that the above article is quite accurate. In my rifles that are on a WS2 diet. Dirty, they will shoot into a group and cold bore is always 1/4moa low right. Or about as good as I can shoot so meaningless. If I clean the 6.5 Creedmoor spotless like to put up for a period of time first 2-5 shots will be 1.75moa high and 1/2moa left and if I have a way to measure speed they are 50-75fps faster than my book notes. Sometimes I will get an ejector mark sometimes not. I have only shot naked bullets from factory ammo in either 6.5cm I've owned and I cannot give you enough data to be relevant for comparison.
With moly, I would see unobtainable speeds in the 243 with like components but in practice, I could shoot at the same speeds with less recoil and longer shot strings. I tested the recoil theory with the rifle on frisbees on a countertop not highly scientific but effective nonetheless.
This is a good debate and I welcome any information that counters mine because I feel I have a pretty solid background and proven examples. If I can find a better answer without coated bullets I'd switch tomorrow. Today though I will continue with my methods and expected results

 

[RidgeTop]

I used molybdenum disulfide and did not check velocity, I was more interested in group size. Not impressed and very dirty to work with so I quit using it.

 

[Mikecr]

WS2 does not change MV. If Norma thinks otherwise, they are wrong.
I can go back & forth from clean to coated and back with zero affect to MV.
Been using WS2 since before it was briefly merchandized as Danzac, which I'm sure is longer than Norma.

It's normal for cold bore POI to be different from hot bore, regardless of coating.

 

[gohring3006]

Things I observe when people can't get good results when using hbn.
Failure to give it enough time. Some barrels take longer than others to season.
Not being consistent in the application of hbn.
Not tumbling the bullets long enough.


If you start with clean bullets, always clean your bullets. I tumble for 5 hours.
I use a clean bore snake after every range session and apply two strokes of slurry before putting in the safe. The key is to do it every time. (Consistency).
If you're having trouble with hard seating afterwards, either wipe your bullets more or adjust neck tension. Always clean the area where the seating stem contacts the bullets because you get build up from hbn and before you know it, your seating deeper. I learned that the hard way.
Velocity does change with hbn and if you have enough room in the case you can add more powder, I don't unless I have to, if I can get the precision I like with the lower pressure/velocity I stay there and enjoy long brass and barrel life.
It's not always a tumble and play process, adjustments have to be made. Wether it's neck tension or powder charge or both.