WHY won't my beloved H&N .218 23 gr slugs shoot anymore?

[Khornet]

For months I could do no wrong, average 0.4" 5 shots at 70 yd, averaging .95 MOA at 101 yds. Then the slugs changed. Most noticeable was that they no longer had the slimy mottled lube that so many found off-putting. Newer batches seem to have either a dark gray glossy coat or a lighter gray sticky coat, and they don't shoot worth a crap in my .22 Impact 700 mm despite trying various tunes.

This is a Davidson seating depth comparator. In the PB world we use these to set cartridge OAL. There are holes around the rim for different calibers; in the .22 hole is an NSA .217 23 gr slug. The tool measures where the diameter reaches nominal, where the ogive begins if you will, so that you can seat bullets to touch the lands of be off them by a given amount. With your calipers you measure from the base of the bullet to the opposite face. It's a .224 hole, of course, but .217 and .218 slugs won't drop through.

For the NSA slugs the measurement is 1.108". For the old slimy good-shooting H&N .218 23 gr it's 1.085-1.088. For the newer batches of the same .218 23 gr slug it's 1.094-1.098.

So maybe the seating depth is different. Maybe I should try the pin probe.

 

[qball]

Maybe try lube them? 

 

[uhfradarwill]

The slugs changed? I think you answered your own question...

 

[mercado]

I know when my moment comes to have more time to shoot I enjoy slugs so I keep labeled by caliber n size what slugs my guns like...so I could eventually order a Corbin press n dies..so this don have to deal with slugs changes..it really sucks.

 

[Khornet]

I have tried straight-from-the-tin, sorted by weight within 0.2 gr, washed and unlubed, washed and lubed with Napier oil, washed and lubed with Lemon Pledge, washed and lubed with Brownells Mag-Slick, all of the above after sorting by weight, and sorting by weight then examining the bases under magnification and culling out any with deformed bases. None of it helped, except weight sorting of the old slimy slugs.

So yes, it appears that the shape of the slugs changed, and the newer ones have harder contact with the rifling and they don't like it. I will now try decreasing the seating depth with the newer slugs, as long as I still have a bunch. If that doesn't help, time to find a new slug.

 

[Stone02]

I've given up on slugs. Just too frustrating. Working fine one day, then rubbish. Same slug.

Couple of things you may want to try: Size to .217 and bronze brushing the barrel.

 

[Khornet]

Thanks, Bluestone. I've bronze brushed plenty. gonna try more .217 slugs before I give up.

 

[Khornet]

Two different lots of the newer, non-slimy slugs mike out at 1.098" average with the comparator. The old slimy stuff averages 1.088". As best I can measure with my calipers, the dish is....0.01" deep. I put in the pin probe but not the rest of the slug power kit. With the pin as far forward as it can go without blocking the mag, the newer slugs are beginning to group like the old. I was getting 1" or 1.5" groups at 70 yd where I used to average 0.4". Now I'm getting 0.7-0.6", and very hopeful. More tuning and pin adjustment to come. I bet if I back the pin off another 0.01" the NSAs will begin to shine too.