NOE .25 cal Pellet Moulds

[rintafile]

Also You can heat pins on blowtorch between pours...I think that is critical issue to get those pins hot as possible

[Wayne52]

I think that on the next batch that I'm going to use a hotplate for the mold like Travis did, I don't think it's staying quite hot enough just laying it across the top of the pot to warm up.  I've get a hot plate that I never use for anything, now I have a use for it . . . . cool

If there was a secondary swage die made for these pellets it might make a considerable difference in the way they perform too.

[Mark Davis]

I think that on the next batch that I'm going to use a hotplate for the mold like Travis did, I don't think it's staying quite hot enough just laying it across the top of the pot to warm up.  I've get a hot plate that I never use for anything, now I have a use for it . . . . cool

If there was a secondary swage die made for these pellets it might make a considerable difference in the way they perform too.

The swage die, do you mean for forming the skirt, or bringing the diameter up?

[Wayne52]

Mark I'm thinking maybe a swage die for rounding off the nose of the pellet to a dome rather than flat like it is from where the sprue is sheered off.  My skirts seem to be forming good.

[rsterne]

A while back I wanted to try shooting pellets from a .308 barrel, and when I pushed through a JSB 44.8 gr. it had barely any rifling marks on it (.30 cal airgun barrels are 0.300" bore, not 0.308").... I made a tapered anvil for the skirt that I could put a pellet on and slide the other die half over and tap it with a hammer.... The flat on the inside of the die creasted a Meplat and forced the skirt, and head, to expand a bit....



Once I found the correct spacing between the tapered anvil and the front punch (the die was adjustable), the pellets came out extremely consistent on diameter, with a nicely formed Meplat on the front.... as in the photo below.... There is a formed pellet sitting on the mandrel....



The two pellets on the right show a stock JSB (R) and one of the ones bumped up to .308 cal, that were pushed through the .308 barrel.... You will notice the difference in length.... and you can clearly see the much better rifling engagement on the shorter, enlarged one.... The reason I bring this up, is that I have experimented with pellets with a Meplat on them, and found the Meplat had no affect on the accuracy.... The Meplat did, however, make a big difference to the performance when fired into a block of soap.... The pellet with the Meplat produced a larger diameter wound channel, and penetrated less.... ie it dumped its energy quicker.... not as fast as a hollowpoint, but significantly better than a round nose.... That is reason I designed the pellets with a Meplat, although it is also, of course necessary for a nose-pour mold, which is required to make the hollow skirt cavity.... I don't think the Meplat is creating an accuracy issue, if there is a problem (and we won't know until the heavier weights are tested), IMO it must be something else....

Bob

[Mark Davis]

I would like to read any speculation on why this design does not shoot well.

Is it diameter?
 
Because it is difficult to cast?

Shape?

Length, and could be better with a faster rifling twist?

Because the front bearing area is to close to the center?

[dyotat100]

I haven't seen the drawing but just looking at the pellets in the pic they look nose heavy. I was shooting some 33 gr jsb thru chrony yesterday and the skirt is not as hollow.

Hard to say. I'm sure it's a front to back weight thing though.

[Wayne52]

I'm kind of thinking along the same lines as being nose heavy too.  I'll try making the heaviest ones today instead
of the middle weight to fill the tail of the pellet, hopefully it will balance it out some

Here is a comparison between the molded ones and the JSB 33.95 MKII

[dyotat100]

Yeah that would be the problem. I think pellets are more fussy then bullets on the weight distribution.

How different is the depth of the skirt?

[Norm_m]

Well I've been on the fence about getting into casting once again and when I saw this topic I was ready to jump in. Many many years ago I did a lot of casting of bullets and round balls for myself and friends who also had muzzle loaders. I enjoyed it very much but when all the new muzzle loader ammo came out I phased myself out of casting.

So after seeing Noe's new mold for 25 gr pellets I began looking at the items I would need to get back into it and had my shopping cart already to press purchase when I began reading about the poor accuracy with these pellets.

I am now on hold to see what happens!

Norm

[rsterne]

Doug, there are three different pins supplied for the hollow base.... That allows you to vary the weight and the CG, without changing the outside shape.... The drawing below is for the .30 cal, with the dimensions shown for the other calibers.... It is simply scaled up or down....



Guys had been asking for heavier pellets with a Meplat to have increased impact on game.... so that is what I tried to provide.... I am still hopeful that the heavier ones will have better accuracy, with the CG further back.... If that doesn't work, then my guess would be that the nose is too long, ahead of the front contact point with the barrel....

Bob

[dyotat100]

I measured the back of a 33 gr .25 and the skirt is only .058" deep. On a 44 gr it's is .150" deep.

Anyway to figure out the CG of the JSB'S and keep it close to what they are?  Shallower skirts to bring the weight back.

[rsterne]

The three skirt lengths are shown on that .30 cal drawing.... The shallowest is 0.050" and the deepest is 0.150", on the .25 cal pellets.... similar to the range of the JSBs.... which makes perfect sense, as I used JSBs as a reference for my design where applicable (skirt and angles).... The only real difference is the nose, which is longer and heavier....

Bob

[Mark Davis]

Thanks for posting your thoughts.
This design is very similar to what I would have gotten cutting a mold with the cutter I have been working on.
The angles are different, but the length and location of front bearing surface are very close.
I my mind's eye, this design is a thing of beauty.
But if it won't  shoot well, it must be time to start on a new cutter.
I was not going to use pins in the mold to form a hollow base, but scheming on making a clamshell swage die to form the base.

[K.O.]

well I wish for more $ just so I could try my idea... if Al would be able to mod this mold after it is already cut... I think the long wide meplat nose wants to be more H&N Sniper Med/MAG like..?

... I think a shallow waist will help...

So modded the drawings for a .200 waist and a .210 waist drawings bellow..? watcha think..?

Maybe even slightly easier to pour good  skirts... 

[Wayne52]

I molded and tried both of the heavier ones today, they both grouped a little tighter than the light ones but then I put some H&N's on a dot next to the heaviest dots for mold pellets, it was just a ragged hole at 20 yards, both of the heavier ones grouped at about and inch and a half.  I recovered some of the pellets and they're catching the rifling really good but that isn't making them very accurate.

[rsterne]

Wayne, could you post a closeup photo of some fired pellets, please.... along with info on what barrel you used....

Kirby, I looked at designs with a cylindrical waist like that, and of course the weight increases significantly, unless you shorten the pellet.... JSB seem to be going away from the cylindrical middle in their latest designs, eg. the .22 cal 34 gr. Beast.... The .22 cal 25.4 gr. cylindrical Monsters were not as accurate as the 18.2 gr. Heavies in most guns, and the 50.2 gr. cylindrical .30 cals tend not to group quite as well as the 44.8 gr. Exacts in the .30 cals.... Tat is why I was trying to stay away from the cylindrical waist design, unless required to get the weight desired.... Probably two of the most consistently accurate pellets out there are the 25.4 gr. King .25 cal and 44.8 gr. Exact .30 cal.... and they are very "conventional" looking with a narrow waist, only 71-72% of caliber.... The waist diameter on JSBs runs from as low as 66% to as high as 85%, with heavier pellets having a larger waist, of course.... The waist on the 34 gr. Exact .25 cal is 79% of caliber.... All the JSBs I have looked at have a "tuck-in" angle behind the head of about 30 deg., which is what I used.... Some have a sharp edge at the back of the head radius, while other have a narrow band at the back of the head.... I didn't bother with one, because the 1R Ogive I used tapers so slowly at the back of the head, it provides a fairly wide area to grip the rifling without one.... That is why I am interested in Wayne's photos, to examine what that area looks like....

Bob

[Wayne52]

Murphy's law said to keep those other recovered ones but I put them back in the pot, I had plenty molded up so I put some more in the target with denim inside.
I had some better examples but these will probably do for ya Bob !

These were all really close to 36.5 grains

Also I added to the pot before I molded these, I took a chunk of an ingot I found in a cornfield with my metal detector at a spot where the use to be a farmhouse, there might even be a little tin in these, next batch I run I'll use the old sewer pipe cause it seem to work better.

[rsterne]

Thanks, Wayne, that is just about perfect rifling engagement, IMO.... It shows the width which engages the lands is not just a fine edge at the back of the head, but about 1mm wide or more, which is what I expected to see.... It looks like my idea on that was spot on, at least....

Bob

[Nomadic Pirate]

Wayne, could you send me 100 or so of the heavies to test in my Storm ? of course I would pay for them.