Like some of you know, I have sam yang big bore 909S. I bought it last winter… and waited a good deal of time to get it in FIN. Well in the time when I waited I studied about airguns, their working mechanism, principles, what they could do or are capable to do. I learned that airguns are much more powerful than people usually believe they are, I learned that they (PCP´s) are very interesting in their mechanism of action. I was surprised about several facts about airguns (note Girandoni and such), and in particular, I noticed that those Korean PCP airguns (one of which I was waiting) are somehow strange in relation to other airguns, to all PCP airguns, custom airguns, I mean. namely, small bore Korean airguns are very powerful in relation to other airguns… But big bore Korean airguns are not so powerful in relation to other big bore airguns (now mostly custom airguns…). Maybe it is because the comparison to custom airguns is too tough. But, I thought that there must be something that I can do to make my Korean big bore slightly better in that respect.

Well, I must tell you that I, of course, hope that I could have airgun enough good so that there is no need to tune it or try to make it work better. But as long as things are like they are, I could and must say, that I have had some serious fun of -- or from -- the current situation, although I still don’t have exactly the gun I want.

Now about half year after I got the sam yang in my hands, I could say that I’m somehow succeeded in that tuning operation; but, there are still things to do, of course. Those things are now mostly centered on the search of appropriate slug and slug mold.

Well, since I got interested in airguns again, in somewhat more mature age than when I first got interested in airguns or guns, I have had a drive to build or have a good, well performing, powerful big bore airgun. When I was kid and was interested in guns, I was just interested in guns in general, like most of the boys are, with no intention to build one or get involved to these in somehow deeper sense. Well I guess that deeper involvement came along the years or started when I got interested in engines, systems and tuning engines to work slightly better.

Now… To make a long story little shorter.

I’m not after ultimate power if accuracy is somehow lost. Accuracy is something more principal to all guns, than power.


So, because of those modifications and the accuracy thing, I have started to cast my own bullets or slugs to tuned or modified, now smoothbore sam yang. I have made several molds for slugs because I chose to have one oddball caliber barrel and I don’t want to shoot plain shots or round ball.

One friend of mine has castes slugs for me before and he made them according to shotgun slug models (Foster type). I have shot those foster slugs and while I’m quite satisfied to those, I’m not fully satisfied to their accuracy: some of them fly well, but some don’t. It is pretty impossible to predict which slugs fly well and which don’t. All slugs are very good looking thare are no external signs to determine which will fly well, which don’t. I think that instability is in their shape, stabilization factor is missing. Although they are stabilized by weight (there are more weight in front of the slug than in base), that is not enough. They should have fins or something…

I was thinking about those foster slugs and diabolo pellets, I talked to Gary about slug making and those problems, and I asked about were I on right track… Well, I had no intention to seek ready made models… I’m interested in principles which command those slugs in their flight. I was trying to find out HOW I could make a particular type of slug which I could fly well and straight. Gary told me to use certain structure to get some pull to the slug “Try a "spool" shape”, he adviced. Bore diameter on each end, with an undersized shaft…. That was good advice, of course. Now when I have some molds which instantiate that spool shape, my slugs have gained some accuracy.

They are not ready yet… those molds are quite crude still and I have several problems to overcome, but certain progression there is. Accuracy was almost enough this weekend with home made slugs.

I think those slugs are little too long for the diameter, because slugs have slight tendency to tumble (slugs are one inch long and the diameter is .469). That tumbling is nothing serious and I could say those slugs are starting to group in 50+ yards, and that is a GOOD thing!

This all sounds great! Thanks for sharing the progress so far. You're going to have to post some pictures for us now! What mods have you done besides the barrel swap?

sepeteus,

Thank you for a fine report. It's interesting to see you developing and enjoying your craft.

I could tell, from your mail, that you were seeking to understand those things that you were already applying your time and effort to. I can tell that you have not avoided either the shop work, or the field testing. This is a whole different level of enjoying the hobby. You have a bunch of real time and effort to prove each time you go to the field. Each bit of knowledge you learn, you can apply ... because you took the time to understand it.

Well done.

You'll get your slug to work. You must be close ... so don't overcompensate. It will be the smallest of details that will dial in your work now. When it's right ... you'll have a very well deserved smile on your face.

Best,
Gary

Thanks!

Jerry, I made quite alot to that 909 and almost everything, every changed thing -- other than longer smoothbore barrel -- is internal modification. I opened up transfer port all the way (to as large in diameter as it is possible to make). I drilled even the valvebody, or the hole in there, larger. I ground smoother the whole way where air goes, started from that valve body and from there to its way up to the barrel... I drilled and ground the port larger and made curves smoother, lathed new tubes for the barrel (which goes in barrel) and the receiver; those are sealed by step-in-tubes (or whatever those are). And for the hammer, I tested lots of different springs and finally made one from a longer special spring... It was quite a hassle at one point: had to open and reshape the spring about ten times, opening and closing the hammer system and receiver of the gun.

It was quite a job, at some points ofcourse little frustrating, but all in all and in the end, very satisfying and fun project. I at least know the gun now pretty well.

Now that 909 pushes 355 grain slugs better than it pushed 140 grain round balls in the beginning. I will test it with gronoraph soon, with those heavy slugs of course, so that we'll get the exact fpe numbers for that gun.... And of course, that gun eats air quite alot now. I could get two consistent good shots and third not so good one with one fill. That's just enough... BTW, I will post some pictures of that gun, when I have digicamera... It is similar to all single tube 909s, except there is longer 32 " barrel there (it is shiny stainless steel one).

Gary, you said it exactly like it is (of course)... Namely today I made some minor changes to the mold, and casted few slugs for a test. I went to the range and shot. BIG SURPRISE: those newly casted slugs didn't tumble at all! Didn't have enough slugs or time to make thoroughgoing test, but that was more than enough to know!

One goal is fulfilled as I wanted to get round holes to the paper, wood or whatever I shoot... Very nice indeed.

Glad to hear that you made just the right adjustment. Often, it doesn't take much, once you are close.

Have fun - stay safe.

Hey - we need pics of the gun and groups. Also - pics of stuff you're blowing up! haha. You have to decide if you want to give away your development work on the slugs. I've shared some - most I don't. I figure people with an interest can take the time and effort to do what I've done - rather than just have it handed over.

Glad you've had a good project.

Gary

So with the longer barrel how long is it overall, about 55"? Dory

Hey Dory,

it is nearly 55" long, maybe 53 " exactly. I'd try to rememeber to check it... Planned to go hiking today, and will take the gun with me.

Thanks Gary!

Smoothbore is interesting just because its great versatily! One could shoot shots, slugs, darts, and what ever through a smoothbore. Rifled bore is just for spinning one size bullets (though these are many of course ). But with smoothbore I could shoot a big bore airgun at almost everywhere, just because I could limit its shooting range to very short distances with tiny tiny shot projectiles when needed, or I could stretch that range to 100 yards and over with heavy slugs when I could and choose to do so.

Well, it is pretty hard to find much data regarding good shapes of smoothbore projectile, because --as you guys know -- there aren't too many smoothbore projectiles except shotgun slug projectiles, and even those often turn out to be for rifled barrels today. There are those kinetic energy penetrators, armor piercing saboted smoothbore projectiles and all, but these are saboted and not too near airgun projectiles... Well, of course it is so that one could find, if one really wants. But that requires extra work of digging piles of information, some irrelevant, some relevant, without previous knowledge of relevance.

I started testing with foster type of slug because it seemed naturaldirection. Foster type of cup or cap slug is shotgun slug as you know... it is like shuttlecock in the sense that most of its mass is in front of the slug and it has skirt like end. Foster slug when correctly made tends to fly corectly nose first without much of tumbling. Our slugs tend to tumble little, and they don't go exactly straigh, they wander. Tumbling wasn't so much the difficulty than a wandering was; especially shorter slugs didn't tumble, but the didn't group either. I have seen quite good groups shot with foster slugs though... they weree shot with one .410 shotgun (firearm)... but my own test weren't proving.

Then I took a look at usual diabolo type of slug again, and asked from Gary.


I'll edit this message and put one picture of the winner slug this far; it isn't the best quality picture, but show the slug shape. I was shooting these slugs yesterday (slugs weight is now just about 300 grains), and I was satisfied to the results. It seems that these go quite fast and straight... I'll try to get the shape of slugs still smoother. By the way, these slugs are full lead, quite hard lead though, and molds are made with elementary tools; slugs look better in person than in this picture though.







Edited 2 time(s). Last edit at 05/22/2009 07:54AM by sepeteus.

Good show. Glad they are working for you. Try putting just a very little bit of pure tin into your lead mix. It makes the molds fill out better when casting. You can get tin from "Midway USA". Try about a inch long pc. of their sticks of tin to 15-20 pounds of lead.

Best,
Gary

I have refined the mold (of the slug in picture) a bit and have one other mold (for heavier slug). That smaller slug weights quite exactly 300 grains and heavier one is 400 grains.

I'm thinking new modifications and new possibilities all the time. I just don't have too sophisticated tools, but I'm trying to compensate the lack of fine machinery with interest and desire.

My goal is, in the first place, to find and make well flying, enough accurate slug for hunting... not to develop any bench rest level of slug... well I guess I have almost found enough accurate slug for hunting, but of course I still want little bit more

By the way, I was shooting those slugs last the weekend, with my son... but as you know, because my son is seven years old, the experiment couldn't last too long... We had fun though, and got few quite nice hits from 65 - 70 yards. We were hiking and I was shooting couple of brief sessions when I had opportunity. We were near the quarry where I usually shoot; there is one lake near that which has appeared to one of those old trenches...lots of sand there everywhere and really nice atmosphere.

I have had some problems in my car's motor recently and that limits my teststing, because I haven't dared to go too far from home with that car. And I could not shoot big bore anywhere too near my home; I have to drive at least fifteen minutes away, and it would be a slight catastrophe if the car would break down somewhere out there... Tow trucks are heck of expensive, scuba bottle is bit too heavy to carry home... though one could not leave anything in a broken car because of thieves... and it would be bit difficult to repair car somewhere in the middle of nowhere, miles from home, without proper tools... OK, enough rationale now .

But it's nice to think and try to develop molds when I could not go testing ones I already have... and I still got shooting twice in the previous weekend.




These are my heavier slugs (about 400 gr)



Edited 1 time(s). Last edit at 05/25/2009 08:22PM by sepeteus.

Was testing slugs today. The problem is lack of exactness in production phase. There are differences between slugs, and that is the current problem.

Now from this moment I'd put all effort to improve the exactness of molds and the process of casting slugs... The basic shape of slugs is enough good now, or satisfying regarding purposes.

I was testing those smaller slugs today very briefly. After I came home from work, I took my gun, some slugs and bottle and drove to the range near the place where I live (not the best place to test but a place to test). I shot only one group, but it was quite pleasing.

Best individual slugs behaved very well. Five shot group was something like four inches total (I was shooting from 60 yards). But like I said all of slugs weren't identical in shape, in fact, far from it and I believe that this thing makes the greatest faults now. If I could get the slugs more similar (as exactly as possible) between each other, then I could see the real "potential".

In the next week and near future I'd try to get the general shape of all slugs I make the same, so that the difference between each slug will be minimal... Then we'll see, how well they could group and how similarly they could behave when the sameness of slugs is the greatest I could produce.

The progress now: slugs don't tumble anymore, and the best of them drill exact round holes and the go where they are aimed.



Edited 1 time(s). Last edit at 05/26/2009 07:29PM by sepeteus.

Hello Sepeteus,

Thanks for your post. I appreciate it. You are doing some good work. That's how to proceed.

When you discuss makihng all the slugs the same, I must assume that you are talking about "grading" the slugs for quality. I'm sure you are casting them in a mold you've made ... correct?

If you are having trouble with casting, maybe you could ask specific questions here. If you have made a mold, remember that you have to "vent" the mold by cutting little lines from the bullet shape to the edges of the mold. That allows the gases to escape as the lead is coming in. This is important to getting the mold to fill well. They only need to be shallow lines, but there must be many of them.

Make sure your mold is hot enough. A relatively cold mold will not fill out well. You can use a small torch to pre-heat the mold. You'll want to cast with the lead around 800 degrees F.

After casting, make sure you grade the slugs. Put similar ones together - and shoot them together. Use the lesser quality slugs for sighting in, and then same your best for shooting your groups, or hunting.

I'm glad to see someone enjoying their hobby, and developing their craft. Well done.

Gary

Hey all!

Many thanks for those advices, Gary!

I got small amount of tin and it seems to make great difference, although the percentage of tin is very low (probably less than 1%).

Hehe, I'm relatively green/newbie in that bullet-making thing... or better: not relatively but completely (newbie)

I don't know much about grading or other gratifying things... trying to group/put all similar slugs together and recast those which are not similar (to which I'm not satisfied with). I haven't casted lots of slugs yet because I'm still thinking about making new draft of the mold (new mold with slightly different slug shape, pointed nose, longer front part etc etc).

My buddy made me already one sizing die to cal .25 airgun, but that .469 is not yet ready. BTW; I will drive to see that shooting and casting buddy this weekend, probably the Sunday (he's one grown up airgunner, namely over 65 years old now) . I'll try to get him taking some photos of us and guns etc... We planned to do some chronographing too. He's old hunter and mainly interested in seeing energy levels of slugs after those have traveled 50 yards from muzzle (the energy what hits the game) and I'm interested to see the muzzle energy and the energy what the game meets.

My molds have small air escaping holes in them because they are made out of components and there are those tiny holes in every corner I put there. And I have preheated those on lid. But I bough one torch to...

And because of the heading I want to make clear some points...

These Korean airguns and Barnes Airguns are something which shouldn't even ever be compared (because they are so different), and from different worlds... In my opinion, Korean ones (with possibly some exeptions) are not even made ready before they are hastily shipped.

Korean guns like samyang 909 are in best something which could be termed as unripe, rough, not yet ready gun. And Barnes guns are all unique, well designed marvelously working pieces of art, made for the person who gets them. When Korean guns are made for tuning, or made to be tuned, slightly refined; I could say that only fool tries to touch to Barnes guns and try to tune them...

I have two Korean guns... mostly because I wasn't able get other Big Bore guns to Finland in that period... Well, I like those guns, but I have worked with them and had to repaired them from the very beginning. Both of those guns, for example, have been leaky, plus there have been several other problems which I had to fix in both of them.

That is one thing which most people should know... If they want a gun with which they could work with, and most surely with which they have to work with (and sometimes even hate the gun). And if people want gun which they must most surely need to rebuilt in some sense, then Korean guns are fine. If people need a gun with which they could learn by doing and tuning, then Korean guns could be worth buying. But these guns are very roughly made drafts rather than ready-made and finished guns.... And many people could disappoint, if they want good, reliable gun and they buy Korean gun...

I have had good time when I have worked with that sam yang and I bought it mostly for tuning (but also because I couldn't get other one).

I want better gun too, a gun which is well made and well behaving gun from the beginning. I have learned to even respect more well made guns when I have worked with that Samyang (while knowing that it could not be made or tuned to the point that it satisfies me wholly). And the same goes with that bullet thing... I could not make absolutely good bullets or slugs unless I could do it for living, putting my whole person and all efforts to making those things...

Building my gun and making slugs are "only" my hobby, and I know that there will be quite a difference between doing it for a hobby and doing it for living (and living for doing it).

Knowing about airguns and knowing what making these involves, makes me respect more the work of Gary. I mean, I respect Gary's work even more than before because now I understand the work better and that what it all involves.

Hey all,

I'll put the news to this thread because the idea topic is just the same.

My friend made mold to new slug which we have planned and designed together... and he did cast few slugs for test.

Today's test weren't as promising as those slugs look, but I'll get back to these and we'll see how will it be tomorrow or in near future...

That's neat. Looks like a challanging mold. How hard is it to remove the cast slugs after casting?

I see somebody has a flair for history too. I see the title of the slug pic.

GAry

barnespneumatic Wrote:
-------------------------------------------------------

> I see somebody has a flair for history too. I see
> the title of the slug pic.
>

So the next design would have to be called the "Fat man"?

Airgunning ahs entered the atomic at finally? Can the Soviets be far behind? Gary, you dont have any friends named Rosenberg do you?

ok, I'll stop......

Thanks for your kind words. You know ... I think I somehow missed a couple of these posts. I caught the picture of the little finned slugs ... but missed these earlier. Thanks for reporting these stories. I'm glad you are enjoying your hobby well.

Gary

Nice looking slugs Seppo, look like they could fly true in a smoothbore.

Regardless of how they end up working, they look very interesting. I'd bet you could sell them based on their looks alone.