Do You Cast .22 or .25 bullets or pellets?

[rsterne]

Carl, I don't know the reason for any lube grooves in a airgun bullet.... I think the best solution is a midbody that just clears the rifling lands.... and only two support areas, as far forward and back as possible, while still leaving length for a decent nose.... For the basics, you want a flat base, tangent ogive nose, and a meplat that can be made into a hollowpoint?.... Diameter 0.250", length about 0.340" if possible, and a weight of about 35 gr.?.... The problem is that is such a short bullet in .25 cal you have to make some compromises.... Nick uses a dished base to reduce the weight, you can't have that and a HP in a cast bullet.... His 35 gr. bullet also has a very short bearing section because he is trying to make the nose as long as possible.... Just look at the proportions of that bullet, and then try and figure out how to make the base flat so you can cast it.... Perhaps that is the reason for your lube grooves, to reduce the weight?....

35 gr. is really pushing the lower limit in a .25 cal bullet, IMO....

Bob

[Kinetic45^]

Yes, besides the reduced friction in the bore and easier engraving into the rifling on chambering I was considering the tiny weight reduction or slight elongation of the bullet due to displaced volume from the grooves.
That short a slug is going to have problems with only two contact points. A pellet only has two but effectively it is longer due to the waspwaist and hollow base.
I've shot a lot of RatSniper, AirgunsofNebraska and NSA .25 slugs in the lighter weights of 34 to 39gr and done BETTER than pellets at longer ranges past 60 yards into the 100 to 150 distance.  I think a cast .25 is a viable option for medium powered guns that can shoot the 33gr pellets well.

Using the corrugated/ripple tumble groove on the sides still casts easily in the smaller caliburs and helps stretch the bullet to give it more stability and centering in the bore, which is always a problem with short stubby bullets.

On the nose, it would have to be less pointed than the swaged but not a round nose.  A hollow point for some expansion but mainly to move the center of gravity rearward.

Down through the years, casting for center-fire .224 and .257 the conventional lube grooves frequently were the cause of culling due to poor fill out. My experience with the shallow 'micro-groove' was less culling and just as good of accuracy.  That has stood up in shooting (and casting) big bore air rifle too.
In this case, I believe a smooth sided bullet is just too short, but even a single conventional lube groove would cause the slug to be too long to fit the twist of most air rifles.
Yes/No?

[Aldea6]

Did anybody try the Corbin swaging system ? they sale swaging dies for airgun pellets using a current reloading press .

http://www.bulletswage.com

[Kinetic45^]

Did anybody try the Corbin swaging system ? they sale swaging dies for airgun pellets using a current reloading press .

http://www.bulletswage.com

That's what the NSA bullets are made on: Corbin equipment.

It costs $$$$

I tried the manual swaging and it was less than satisfactory, sold it to someone else.

[Aldea6]

Yes , the equipment seems expensive ,even if I already get the reloading press; and I don't fully understand their explanations to order a given set of dies for a given pellet.

[KnifeMaker]

I don't get why the short bullet being made longer  would be an issue in the .25 ag barrels. I am shooting a cut down 257420 from Arsenal molds that is longer in the nose than a normal Lyman 257420, and at 57 grains, it is .439" in length.


The Rainstorm I am shooting it in has a 21" Walther/Lothar barrel with the choke removed and lapped barrel, and it is shooting apx. 1/2" at my 80 yard home range. Seems to work just vine.


The bullet you are describing, would be substantially shorter. No?


I also have a cut down NOE Ranchdog FP in hollow point at 50 grains and it too is very accurate, and has the thin driving bands, (lube groves), and a huge gaping hollow point for vermin. It's length is .397".


The most accurate of all is a NOE 110 gr. spire point that I decked the mold to .5255" and it is a laser.


the second most accurate is from an 8 cavity mold owned and cast in from D-Rig. It is the MP molds .25 mold and has very-very thin lube grouves. Almost microscopic. LOL! Its OAL is .4335" and comes in at .2545" before sizing.


some of these bullets are .257 bullets. Noe's are .260 as cast, the Arsenal is in the .258 range, and the bullets all size to .2495 easily in the NOE sizing system using an upside down press. 


Not one of these bullets shoot well in a faster 1-14 twist such as fund in the factory RS barrel, or the TJ's .257 barrels which are available in 1-10 and 1-14 twist. They do however shoot the much longer non modded bullets with extreme accuracy. The barrel I have in the gun now shows right at 1-18". W/L list it at 1-17.8 twist.


they also show the W/L barrel to be .254 in the grouves, it however measures the same .2495 I am sizing to.


This gave the best accuracy and fps of several sizes I tried in it. 


I have it currently tuned to push the 57 grain spitzer to 899 to 918 fps  for 102 to 107.70  fpe.


Speaking of the MP mold, a buddy of mine, Gregor from Slovenia or Slovakia, Never can remember which,  designed the bullet for the Hubben. He is or has just joined the GTA at my invitation.


If  he chimes in here, or other parts fo bullet shooting, and or casting, please welcome him to our family!   



Knife

[Kinetic45^]

I think the length limitation is more based on weight so it is light enough to work in the more common lower powered airguns like unmodified Marauders, etc.       34 or 35 gr
Plus, the shorter bullet does better in their twist rates.  Just trying to duplicate the swaged slugs. The heavier bullets shoot so slow they have bad trajectories in guns like that.
Seems like the .257 barrel guns have more power right from the go, so there's not much out there for the .250  guns JMHO

So design with a weight of 34gr and use grooves and HP to give a long enough bearing surface length to properly align the bullet in the bore.  Too short a bearing length and the bullet cocks and accuracy is gone.  Subsonic does not need the spitzer nose, mostly people like it because it looks pretty so design for the important factors first

Note that most of my molds are either boattail or gas check but for this one I think a flat base would be better for most people's purposes overall

[rsterne]

Such short bullets will not be an issue in any conventional airgun twist rates.... It seems strange to put a bunch of grooves in a bullet just to make it longer, grooves which will increase the drag.... JMO....

Yes, a flat base will increase the bearing length, the only way to go for such a short bullet.... If you don't mind a large Meplat, then it gets much easier.... How about a 60-70% Meplat, and a large HP?....

Bob

[Kinetic45^]

The grooves would benefit the internal ballistics of a good launch with a small penalty in the external aerodynamics drag.

...a 60-70% Meplat, and a large HP?.... 

Something like that seemed to be necessary to get the parameters needed.

Plus, I believe the bands feed through the choke better than a solid slug does which has more swaging to get through

A short Ranch Dog style?

[rsterne]

I started from one of my BBTs, removed the BT and then stretched out the nose.... This is the result.... The dotted line on the nose is where the Ogive first touches the lands if they are 0.244".... ie the start of the bearing length...




That has a 60% Meplat and a huge HP.... I could not get the weight of the HP less than 37 gr. without shortening it further.... That could actually be done, because the bearing length is 0.200" (80% of caliber, and over 1/2 the bullet length)…. At 1.3 calibers long (0.325") the weight would be 35 gr. for the HP and 39 gr. for the FN.... That would make the midbody (which just clears the lands) 0.015" shorter, and the bearing length would still be acceptable, IMO....

Bob

[Hobbyman2007]

I’m starting to think the CG has a lot to do with how the bullets perform . Is there anyway to calculate the CG from bullets that are proven performers such as the 257420 and work your way from there? Knife has been decking molds for some time now and is getting some really good results . Or how about a comparison from CG to twist rate instead of basing the twist rate on bullet length. This could very well be already done , I just missed it in the details .

[tracker1955]

I would love to try some of the 22cal NOE cast pellets in my air rifles, would consider casting but don't have money to waste on a mold for ammo the rifles didn't like. Almost as bad as buying tins of pellets to find that magic pellet.

[Ribbonstone]

I borrowed a friend's old CH bullet Knurling tool...made to put crimp groves in bullets.With a bigger knruming wheel,it can cover the whole length of the bullet...and with the adjustable stop,can manage to reduce them to various dimeters.

Can't make too much of a change in diameter, but can certainly cover .006" of diameter well (so anything from .218"to .224").


 

So I had to make a new much taller knurming wheel,be really careful of the coarse thread adjustable stop, but it worked for me.

Fiar warning...willneed a lathe to make the thicker knurming wheel out of kind of soft steel,a knurling bit on the lathe, and harden the new wheel to adapt one of these.

Slugs look kind of odd with that waffle pattern impressed on them,and if you want to try a lube it seems to hold it quite well. MAin advanatge was using it an adjustable sizer.



Recovered pellets:



Corbin does make a bullet knurling tool that would work (Although not cheap). More geared to big bore lead slugs,but can see where it would work with small bore slugs and end up with that same waffle pattern....may have to set up your own "stop"to adjust for diameter.

[Kinetic45^]

I started from one of my BBTs, removed the BT and then stretched out the nose.... This is the result.... The dotted line on the nose is where the Ogive first touches the lands if they are 0.244".... ie the start of the bearing length...




That has a 60% Meplat and a huge HP.... I could not get the weight of the HP less than 37 gr. without shortening it further.... That could actually be done, because the bearing length is 0.200" (80% of caliber, and over 1/2 the bullet length)…. At 1.3 calibers long (0.325") the weight would be 35 gr. for the HP and 39 gr. for the FN.... That would make the midbody (which just clears the lands) 0.015" shorter, and the bearing length would still be acceptable, IMO....

Bob

As drawn it would work in my rifles but I would like some feedback from other guys here if they thought it should be lightened from the 37 to the 35gr instead so it's closer to a 33.95 JSB pellet?
Keeps it close to the same FPS, FPE and trajectory a shooter is used to.
Sure would be cool to have a four cavity mold and bang out a bunch of these   

[KnifeMaker]

Tidbits;


I knurl a few bullets from time to time. I use two mill files and with medium pressure I roll the bullets between them. Some take 1 pass, some take a return pass. Works well.



The trajectory won't be the same with a pellet and bullet of the same weight. The bullet will hit at a much higher poi at any range longer than 40 yards. Even then it is slightly higher. Only not much. At 60-80 yards, Woah, a huge difference. So not an issue using a slightly heavier bullet to replace a pellet.  I will help with poi issues.


No advantage in using a spitzer in an ag bullet. Well, on paper, No. However, the two most accurate bullets I have tested are spitzers. In a lengthy test, Cedric and Dyotat found the same. In the .257, Nothing, and I mean nothing beats the old .257388 Ideal. It is Pin point. Unreal accuracy.  Additionally, even though conventional wisdom says a spitzer does not help at sub sonic, it says the same for a BT. Both however will show less wind drift, and a higher poi at longer distances. So much for theory. Actual testing shows differently.   
For hunting however, it needs to be HP'd as it pokes tiny holes in game.  Yep, tried that too. 


A flat base will not be normally as accurate as a gc bullet. The reasons have been proven, and shown here repeatedly. There are two that come to mind at the moment.
 One, the base leaving the muzzle is cleaner on a boat tail or GC bullet. It will be able to leave cleaner. And the base (Push a slug thru the bore to see this effect), will have a number of trailers on the base with the number being the number of lands in your barrel. This will show both the effects of the escaping gas upon leaving the bore, and down range as the tiny paddles of lead in the rear cause drag and are churning the air, and I would just about  bet that they increase spin drift.
These are things not seen in a jacketed PB bullet, but are very noticeable in a Lead AG bullet.


When I deck a mold, I leave the last lube groove on the base to act in the same manner as a GC in the shooting of the bullet.(many times only half of the lube groove) I have tested the same bullets left as such, and bullet with the semi GC removed. The differences are dramatic. Two such bullets, both decked NOE RD, the flat base will print 1 1/2 at 80 yards, with fliers, and the semi GC's are in the 1/2" to 3/4" range. Huge improvements!
The same differences have shown up in the decked Arsenal 257420 bullets and the Lyman 257-420's as well.


This was a costly test, as it required the use of two identical molds to do the test properly. Both exactly the same in all respects except the decking of the molds for GC and Without GC.  This was repeated in 4 different mold designs with the same results each and every time. Regardless of whether .257 .250, or speed at which the bullets were being tested. I shot from 780 fps to 960's and many different fps in between. Same-same every time. The test included hundreds of bullets being shot down range starting at 30 yards and carried out to 80+ yards.
Once the fps goes over 1000 to 1050 fps the differences are even more dramatic. 

And finally, it is NOT the weight, nor the weight difference of a longer bullet in the rifling that makes the difference in the accuracy. The length had a huge bearing on the stability of the bullet in flight in direct relation of the length to twist ratio.  Otherwise, and generous HP would at times require a different twist rate. It doesn't! 


Knife 

[Kinetic45^]

OK, good thoughts n points KnifeMaker.

Agreed on the gas check shank, see my Accurate 155gr being tested by TriggerTreat and ShakySarge. Plus the NOE TL.358 128gr too

What would you set out to someone like Bob as the design parameters for a .25 slug for the standard powered air rifle most shooters own ( not guys like you and me who have modified guns or high dollar guns). That's what this is, working out the details and trying to get a mold where there is none to fill that gap.

For example, my .25 WARP shoots both slugs and pellets very well, but not anything heavier than 40 gr.  My Gen2 unmodified Mrod is about the same...
My higher FPE Hill valved and .187 TP/barrel .25 Synrod likes the heavier weights, 30 to 45.

The TJ barreled FLEX .25 with the openned up Cothran valve (it's actually a .357 rifle that also has a .25 barrel too) and elongated bore size port needs 50 gr to 60gr to preform and lighter pellets n slugs don't do very good at all.
FYI- I have both the NOE 50gr and 60gr BBT just for this rifle

There's enough heavy bullets out there but not enough light so I want everyone's input on what they want.
Tell Bob the way you would do it, please.... for .25, not a .257
How would you have enough bearing length but still keep it a lighter bullet AND have a GC shank base?

[Hobbyman2007]

So what your saying Mike is that the length of bullet vs .twist rate have a bigger impact on the accuracy then the Centre of Gravity based on your testing ? If only there was a magic formula for what works and what doesn’t .

[KnifeMaker]

Sure seems so Denis. I do know that adding a HP to a bullet will often times help by moving the COG back more.

[KnifeMaker]

Carl, I suggested a long time ago to AL t try making a shorter version of the noe .257 RD FP. No reason it can't be made in .250. Exactly what I am doing, but it has more friction, as it started at a .260 as cast.


I have them down to 36 grains. But shoots better at 44 grains in my gun. A lower powered gun could benefit from the 36 grain bullet no doubt. A HP would lower it further. 

Mike

[Kinetic45^]

Sure seems so Denis. I do know that adding a HP to a bullet will often times help by moving the COG back more.

+1