Ending the MrodAir M-10 saga:

[Ribbonstone]

Final up-date to the M-10 posts over the last months.

Likely to P.O. "slug shooters"....but it is just the way I see it.

50 yard test (as measured by steel tape).


5 shots at 50 yrds.

M-10 .22 PCP



Cast 34.2gr. vs 30gr. swaged.



LIMITED number of slugs for testing (the last of the 30gr. swaged).


#1. can only guess at the BC by drop numbers/ guesstimates of the BC.  Do know the muzzlevelocity. Do know the scope height (.1.38") over bore line. Can't be sure of the 25 yard zero by more than 1/10th an inch.

 BC is not bad, but not quite a "mega-change" for best heavy pellets.  Might be as much as a BC of .06 or as little as .048 for the cast slugs.

#2. Accuracy seems about equal to the best heavy wegiht .22 pellet so far (the JSB 25.4).

#3. Energy at the muzzle is higher than the JSB's, and the energy at 50 yards is likly considerable higher.

#4. Drop favores the JSB's/ windage favores the higher BC "slugs".

Sorry slug shooters...am going to call this one in favore of the  .22 25.4gr. JSB (with the heavier Eun Jins as a 2nd choice)...it's just so much easier to just oder the pellets than to hand-cast the slugs.

SO...HOWMUCH TROUBLE TO HAND CAST THE SLUGS?

You'd eed (which I hsppern to have becasue I do shoot big-bore BP cartridge rifles):

1. Bottom pour electric casting pot.
2. Mold (and one spepcific to airgun use would be a way big plus).
3. Stock pile of realitively uniform lead alloy (better to be on the soft side of things for airgun use).
4. Somthing to size the cast slugts (unless you really get an airgun specific mold that's made for a known alloy of lead).


In my case, I do have the above already paid for.

So why the PIA in making slugs for airguns.

1. Basically, becasue we tend to shoot a "ship load" of them. I'm not likely to shoot a 50-70 or 45-90 every day.  I'm not likely to shoot them ever WEEK for that matter.  I'm not likely to shoot them for 50-100 shots at a sitting. And I'm CERTAINLY not going to shoot ehem in my back yard.

2, I am likely to shoot the snot out of an airgun, even a "slug gun". Can empty one of those little containers (125-200 pellets) the heavy weights come in in what seems to be no-time-flat.

3. Basic rule of casting: the smaller the bullet, the MORE attention to getting every thing as close to perfect as you can.


Lets look at a typical castins session:

Typical quick casting session, will go as follows (and I hate casting these skinny little slugs).

Becasue they are so small and skinny, really need some hardness to the lead (it's not really for hardness, but harder allowys have less surface tension and fill out an ity-bity mold cleaner). I'd like softer leasd, but softer lead leads to even more rejects than slightly harder lead.

Last session, 2 cavity mold,  like this:

Made 78 "good"  casts.  So with a double cavity mold, if all 78 mold-fills had been good, that would have beeen 156 slugs.

Easch of those attempts has to pass an "it looks good" test when you first srike the sprue plate and look at the base.   Only 56 out of 78 casts (112 bullets of 156) passed that.  YEAH..some of the doubles likely could have salvaged a single good single bullet and a bad 2nd cavity, but it's just quicker/easuer to dump them both back into the melting pot.

Of those 112 bullets, 37 were reejcted for some visual defect that didn't show on the base (bubble, poorly formed band,  rounded edges, etc.). With itty-bitty bullets, really have to be ruthless in inspection.

Of the 75 passing visual inspection, 67 of them pasted the lathe shortening to the picutred length.  OFten, it was some little internal centeral void (a little hoolow foollowing mid line f the buellet...kind of a radial void).

Of that 67, 5 failed the weight test (wich detects some not-on the surface defect that missed the visual exams).

Of the 62 that passed the lathe shortening, 3 got lost in knurl sizing.  I don't even own that kurling tool, I have to borrow it, convert it to this use, and adjust it.  To add to the problem, much-much prefer to borrow it when the owner's wife is away for the day ot out of town.

So there were 59 out of the original  as closr to "right" as I could make them.

That's real close to a 50% reject rate when you're trying for the best-of-the-best.

(BTW: the Corbin knurling tool I have my eye on that would very likely work as if, or with slight modification, but might end up costing nearly the cost of the rifle.)

DUDE...that's a "ship-load" of work and moneyfor a minor advantage.

[Ribbonstone]

LEt me add this before I shut up about the M-10 forever.

Using the 25.4gr., JSB's (which this barrel seems to really like) at the same steel-tape measured 50 yards.



LEts face facts: with me at the trigger, a 3-9X scope at 50 yards, oudoor variable conditions, anything less than a 10% difference "ain't ship".

1. SHort test, but the accurace is at least as good if not better.  Not more than 10%, so am going to call accuracy pretty much even.
2. 1 DOT more hold over (and I have to say, whatever 1 dot equlas in this cheap sope is not real likely to be a true-mil-dot). Cannot tell what the real dop at 50yards is as I never zeroed it at 25 yards.
3. Maybe a 12% decrease in energy  at 50yards...whoopie.. it is more than 10% so counts as a "significant" number.


So basical, for 50yard shooting, all I have to do is buy standard JSB 25.4gr. pellets.

[Rich_B]

So, you would recommend the M-10 and JSB 25 gr pellets, right?

[Ribbonstone]

YES...if there were availiable...haven't a clue about the repeater version that may replace the single shot version now that it is old out.