Loading moly coats

24 November 2002, 19:50

Pete

Loading moly coats

Having a box or two of moly coated VMax 55 grainers, I thought I'd give them a try on the range next week.

The first piece of received wisdom is that compared to non-moly coated, a larger powder load is required to compensate for the reduced back pressure as the bullet "slips" up the barrel. Generally, is the result worth the effort?

Secondly, I've just been reading in The Varmint Hunter that seating by conventional methods scrapes off the moly coating, nullifying the potential benefits and, presumably, causing an excess of pressure as the increased powder load acts on a bullet which, by now, is only partly moly coated. (Am I making sense?) I will pull one today to see how much coating has been scraped off in the seating process.

Comments from pundits who've actually tried loading moly coated bullets, especially VMax in .22/250, warmly welcomed.

25 November 2002, 02:42

Hot Core

quote:
Originally posted by Pete:
The first piece of received wisdom is that compared to non-moly coated, a larger powder load is required to compensate for the reduced back pressure as the bullet "slips" up the barrel. Generally, is the result worth the effort?

Secondly, I've just been reading in The Varmint Hunter that seating by conventional methods scrapes off the moly coating, nullifying the potential benefits and, presumably, causing an excess of pressure as the increased powder load acts on a bullet which, by now, is only partly moly coated. (Am I making sense?) ...

Hey Pete, I use Moly Coated bullets in all my rifles now and will continue to use it util something better comes along. Good stuff, but can be a bit aggravating to get the process started correctly.

Your best bet is to get a small amount of MOS2 powder to pre-coat the bore. One nice source is any Gun Shop which carries Beeman Air Rifles. Since you are using factory coated bullets, get the small 1/2oz squeeze bottle of Beeman B100 Powder, part# 9190.

After cleaning the bore so it has "ZERO" copper in it, lightly oil a patch, squeeze some of the powder all around the patch and give the bore a few strokes. Shoot, clean the bore with something like Hoppe's BenchRest, re-Moly the bore and re-shoot.

Do this a few times and you will notice as you look down the barrel after cleaning that it begins to take on more of a "flat darker gray" appearance compared to the "hall of mirrors" look prior to using Moly. Once it gets to the flat gray, your bore is ready to go to multiple shots.

I still clean the bore more than most folks that use Moly, but that is just me.

1. Yes, you can often use a bit more powder. The amount depends on the particular cartridge and bore condition. So, just don't get the impression you can take an existing load and toss in x.xgr more powder and take off shooting. You still have to work-up the loads as always.

2. After Chamfering and Deburring, if you "Polish" the case mouth, the Moly will stay on the bullet "IF" it has been peened into the jacket. (The Spray on Moly powders don't work well at all for staying on during Seating.)

Make the Case Mouth Polisher(CMP) by wrapping an old 0.224 Bore Brush with "0000Steel Wool" and put the brush into a handle. Push the CMP into each case mouth so the 0000Steel Wool overlaps the mouth and give the brush a few twists.

No need to do this with an electric screwdriver or drill. It just isn't necessary to be that aggressive.

Once the case mouths are "polished", the peened on Moly will stay on the bullets. And you can verify this by pulling one to see for yourself.

Always clean your rifle after using Moly coated bullets just like you do with non-coated bullets. Not cleaning can still draw moisture to the bore and result in pits whether Moly is used or not.

Good luck to you.

25 November 2002, 04:02

<Varmint Hunter>

If your case mouths are clean & lightly chamfered, and the bullets are molycoated correctly, the seating operation should not remove the moly. I have molycoated by the impact methon (NECO) and the spray and back method (MS Moly). The spray and back method actually leaves an unbelievably hard moly finish on the bullet and is nearly impossible to scrape off. These bullets also have more moly remaining on the bullets after firing, as can be determined by retrieving bullets from the sand banks.
I shoot mostly impacted plated moly bullets because its easy and I'm all set up for them. Besides, the wife isn't partial to me putting a tray of moly bullets into the oven right next to the turkey [Wink]

When originally switching to moly bullets don't bother increasing loads. Just get the barrel seasoned and work towards accuracy. The small reduction in velocity varies with each cartridge and rifle combination, and will require a chronograph to determine the reduction and the tiny increase in powder to bring it back. Not worth the trouble. Plus the slight reduction in pressure makes life easier on the brass.
Just my 2 cents