Hi all,went for a hunt a while back up in the hills where we live. My partner had been in the same area a few weeks earlier and shot a nice red deer in good condition.At this point I hadn't yet shot a deer using an air rifle so was keen to give it a go.Well I got the .60 cal out earlier in the day to give it a sight in intending to use it on the hunt but found was not grouping at 100 yards which is my usual zero for such an air rifle.So I pulled out the .30 cal instead.I allways considered the .30 to be a bit light for deer although I have shot a fair few goats with the same.My partner was with me and had her 7mm 08 as back up incase the .30 didn't do the job and produce a clean kill.Any way we drove up to the forestry where we were to hunt and started walking.Now a friend and I were up there some months earlier and had seen 17 deer in half an hour so I was sure to get on to one.After having walked for about an hour and a half we hadn't seen anything except some wild sheep(we have sheep in NZ you know)so decided to head back to the car along the opposite side of the forest on the of chance the there may be a deer or two feeding on the neighbouring farm land.By this time my partner is lagging behind and I'm keeping a close eye on the paddocks as well as the clearings occure here and there in the forest.I came over a rise and here is this young spiker feeding about 40 yards off.The .30 has about a 7inch hold under at 50 yards(which I clean forgot about in the excitement)'I cocked the gun placed the cross hairs on the animals shoulder and squeezed off the shot,pink(thats the sound the .30 makes)and the slug passed over the deers shoulder.Being a young animal he just trotted off in no great hurry so I jumped the fence reloading as I went and there he was again about 70 -80 yards off quartering away looking back over his shoulder at me.This time I allowed for the hold under and placed the shot(pink) high in the ribs just forward of the diaphram.The slug passed diagonally through the lungs and exited behind the opposite side shuolder.He ran about 15 feet and dropped,kicked a wee bit for a few moments and it was all over.So I didn't need the .60 cal or the7mm08 after all.The .30 proved to do the job efficiantly and is a nice light weight unit.We hunt alot myself always with an air rifle so will no doubt have some more story's and picks.Cheers Danny.

Thanks for posting a great hunt story Danny. I really enjoyed reading it. With a complete pass through, the .30 had plenty of power for the job!

Very interesting Danny. Thanks.

Just looking at your pic. Can't see a shroud or moderator. Looking for one because of the "pink" sound. Tell us more about your rig.

Thanks for the post!



Gary

Excellent. Loved the story and Congrats on the hunt.

I too wanna know more about your .30. Velocity, Name Brand of gun, velocity....etc....etc..etc.

Hi guys,well the availability of good quality nice performing big bore air guns in nz is just about zelch.There are a few people making custom guns but I haven't seen anything yet that grabed me,and of course there are the Korean guns that are ok out to say 60 yards.A few years ago I was doing a bit of rifle and pistol smithing(I have a trade in fitting and turning)and I thought it would be realy neet to build my own air rifle,now at this stage I had no Idea that big bore air rifles even existed.So anyway i had a loan of a mates .22 pcp and got the gist of how it works but wasn't so taken by the light construction.So I set to and built a .22 with a 9 shot revolving mag.It worked pretty good first off with a 2500 psi fill and about 30 shots at 1080 fps but didn't group so good.I had used an old chineese barrel that obviously wasn't quite right.So I made a muzzle break type silencer for it and that tightened the groups up to about .500'' at 40 yards(close enough for rabbits).I had the pcp sitting on the bench one day wondering if I could ever get it to perform good enaugh to take goats ,it also happens that i had an old 308 barrel sitting on the bench(left over from a rifle project)and I looked at the pcp and looked at the 308 Barrel and thought I wonder.I rebarreled the.22 pcp with the .308 changing the bolt probe to suit poped a 115gr lead slug in the chamber aiming this contraption at a piece of wood squeezed the trigar(pop) and the slug made a dent in the piece of wood.After some opening up of valves,ports and increasing hammer energy I got the gun to put out a 80gr hallow base slug out at 760fps.The first time up on the goats I had know Idea how it was going to go,so I crept up to within about 20 ft of a goat lined up the shot and pop.The slug passed through one shoulder blade,took out a rib,passed through the aorta,passed through the off side shoulder blade and hung under the skin(nice my first larger game animal taken with an air rife and my first hanger in one).To cut a potentialy long story a bit shorter Iv'e built a number of different calibres and configerations although I have yet to build a rear hammer rifle(I love rear hammers)All just as a hobby and learnt a number of new things with each project.The .30 I used to take the deer with puts out a 104gr round nose slug at just over 800 fps,It is what I would consider a medium power .30 cal.Its based on an old parker hail barrel with an11'' pitch which is way to short for the small slugs I'm putting through and they tend to be a bit over stablized.As a result if there is a change in valosity(like falling reseviuor presure)it not only effects elevation but also windage.Because of this I have had to work realy hard to get the string of shots as close in valosity as posible.This .30 call will give 3 full power shots with a 4fps spread or 4 shots with a 10fps spread which gives me 1.5'' group at 100 yards every time(conditions permitting).On top of this by the time you cut the chamber off a rifle barrel you're left with a barrel that is about 19' long which adds more challeges,How to get reasonable performence from such a short barrel without loosing a hole lot of air out the end of the muzzel in the process.After doing some tests I've come to the conclusion that a larger valve with a shorter duration would suit a short barrel as opposed to a medium sized valve with a longer duration that runs the risk of still being open when the slug leaves the barrel therein waisting air.I achieve this buy having a fairly large valve(I don't use a piece of delrin placed on the end off a small piece of rod,nor do I use convex valve seats)coupled with a light hammer in this case about 4.75 oz and a long strong spring that has about one half of remaining compression on contact but not so hard that the gun can't be easily cocked.Also of course I minimize the free port as much as possible,although i haven't found this to make a huge difference to air consumption or valosity.Now flatness of trajectory is more importent to me than fpe as in most cases the slug passes through the animal anyway so I tend to use lighter weight slugs which the above mentioned valve hammer configeration tends to favour.Although the very light slugs use more air as it can flow more freely with less residual pressure,this little .30 carbine will putt out an 87 gr hallow point at 936 fps but at that it'll only get 2 full powered shots and a third about 30fps slower.I hope this helps you to understand why the .30 performs and sounds as it does.Its would probably help to know that this unit has a fill of 3800psi whch is down to 3300 psi after three shots on a 200cc tank(bout 12cu in)Regards to all Danny

Thats excellent danny. Wish i had some machinery to make my own project gun. Thats something i would love to give a go at.

Great story with lots of detail.

Danny,

You've got some tantalizing comments there about your valve. The performance seems spectacular, can you share any details?

Hi Jerry,Well it aint rocket science but then there is'nt a book or books you can go to that will till you exactly how its done.There are existing formulae and tables etc that can get you close'ish but the rest of it is tri'al and error.I'dealy if you want a gun to give ex amount of shots off one fill with as flatter power curve as possible it would be tuned for a particular slug(weight design etc)and or build in some items of the set up that can be adjusted like main spring compression,air flow restrictor,regulator.The first air rifle I built ended up with an externaly adjustable regulator,was capable of 18 viable shots off one fill at about 100 fpe.With the regulator of course the power curve was more or less flat.However it is yet another complexity which is fine for a bench rifle but I prefer to keep my hunting rifles simple. The consideration then is how to ballance out the shots,Do we set the sweet spot high so we have descending power where the first shot is powerfull,or do we set the sweet spot at the middle of the string.One thing is for sure just because you have two shots(one either side of the sweet spot) that are of the same muzzle velosity doesn't mean that you will necessarily have the same poi. With the first of the two shots the reserviour pressure is higher,the valve has a shorter duration(isn't open for so long)so the slug achieves more velocity in a shorter length of barrel whilst the valve is open.Shot number two of course is asked two do the same velocity off a lower preasure(no prob).Number two reach's the gole velosity slower but over a greater length of barrel as the valve is open for a longer duration.Now as we have come to realise with relatively low velocity rifles like pcp's the recoil is happening wilst the slug is still well with'n the barrel therein effecting the poi.Now shot number one reach's its gole velosity quicker than shot number two,although both shots have the same muzzel velosity shot number one exits the barrel quicker than shot number two,the muzzle hasn't had as much time to lift therein causing shot one to have lower poi.Now to help counter this effect I set my valves up to have as shorter duration as is practiable and use shorter barrels than would be usual.The trade off(theres always trade offs)is that I cant fire heavy slugs at any great velosity as the set up prefers light to medium weight slugs but as I've previuosly said flatness of trajectory and accuracey are of more interest to me.If I were to increase the barrel lenght on the .30 cal by 6'' it would increase the muzzel vellosity by about 50fps(I've found that about 10fps per inchof barrel with this set up) and flatten the trajectory over 100 yards by 2.5'' but would open the group up slightly which would probably still be manageable on goat and deer size game.Down to the valve/hammer etc.I can appreciate that some people have worked hard to come to variouse conclusions that help them to produce a better product and like to keep there interlectual property under wraps.As such I will only devolge so much here,however the .30 cal is very simple as are most of the refinements which have no doubt been done by others many times over.The majority of the gun is 6261 aircraft grade alluminium with the ecception of valve stem,hammer triggar bolt,barrel screws etc.I've found alluminium to be far more consistant in differing temperatures than cromo or stainless.The 6261 has a yeild strenght of 275 mpa(40000 psi)which is higher than stainless and about two thirds of cromo but at one quarter the weight.The rockwell is lower so you have to allow extra thickness for thread depth.The net result for reserviours is half the weight,less distortion and less prone to dent.I used quarter inch 1065 rod for the valve stem turned down to three sixtenths at one end and threaded two take a disc of a material called peak(or peek) 1000 of the appropriat diameter with a thin steel spacer under to spread the load and a nut two hold the whole lot together.I recessed the under side of the plastic disc two take an o ring but this probably isn't needed just screw the whole lot down with an appropriate sealent.The valve block is also 6261 but the valve seat is inserted with aluminium bronz,again this probably isn't needed as 6261 work hardens two a quite high rockwell.(I've put thuosands of shots through my first airgun on a 6261 valve seat and it shows no sign of ware on inspection).The outer diameter of the peek 1000 is about .500'' with a 35 degree face turned on it.The valve seat has an ID of .430'' and also has a 35 degree face of .025''(no interference angles here)The valve stem protrudes at the back of the valve block about .750'' with slight groove turned near the end to take a star washer which retains the return spring(yes the return spring is on the out side).This way there is no interference around the valve and I can easily swap out the return spring when tunning.With this valve set up the return spring does make difference to how flat the power curve is.I know the return spring only represents a small portion of the residule pressure but testing has showen than in this case the stronger the return spring(within raeson) the flatter the power curve.The face of the hammer is recessed two take the retainer and spring and makes contact with the valve block without scrunching the return spring.It is about 1'' in diameter and2'' long with the back bored out to a depth of about 1.250'' to accept a five eighth of an inch sping by 8'' that has a section of .075''.On full cock( the bolt has two cocking positions) the bolt travels just short of two inchs.I've incorperated a main spring adjuster which is tuned to be fully in on full power,that way if I choose two use the first cocking position for close range shooting(104gr at about 760fps) I can wind the main spring adjuster out part way through the string and then back for the last few shots which flattens out the power curve some and gives me about 12 shots that are viable at about 40-50 yards.Then I can simply wind the main spring adjuster back home without haven to note where I had it set.My next project is going to be rear hammer gun with a bolt that cocks the hammer when pulled back.I know I wont be the first,I was at an antique arms auction about 9 years ago and saw a rifle there that opperated on the same set up and thought cool.I shot target pistol for a number of years so love rear hammers,also a like the simplisity and strenght of bolt action so it is a natural progression for me.I'l set it up with a cocking lug on the back of the bolt that pulls the hammer back some when lifted so as the gun cant be fired with the bolt open and maybe incorperate a safety position at this point.I 'm sure I can take advantage of pin placement and cam over two inprove the hammers effect on the valve and reduce sear preasure .Well Jerry I hope this helps you and others,buy the way you'd be surprised how much you can do with simple hand tools and a lot of improvising.Regards to all Danny.

Wow, thanks for the description of the design Danny. That's a lot more than I expected. It's neat to follow along and note the design tradeoffs that guys make as they build their ultimate airguns. Thanks.

Hello Danny,

One factor which may cause a gun to shoot somewhat differently, while producing essentially the same velocity during a string of shots ....

The diminishing pressure in the reservoir, over several shots, will be offering less and less resistance to the hammer when it opens the valve. The hammer striking the firing pin, creates a shock thru the gun. As it becomes easier for the hammer to open the valve (psi diminishing) ... that shock will be less/different. May cause a difference in recoil.



Good to see another builder working. Happy hunting ...

Gary

Thats right Garry,I've found another advantage of having a fairly light hammer reduces this effect considerably.Generaly speaking as long as the valve hammer etc are ballanced,the lighter the hammer the tighter the group.

Gidday Danny

Here is my NZ made .50 cal with external hammer


Made in Auckland, I'm just out of Christchurch, where are you?
Your gun sounds great
Cheers
Neil

Looks very nice Neil. Thanks for posting.



Gary

Hi Neil,Nice looking gun.I'm down in the teviot valley just below alexandra.I think a mutual contact of ours passed on some 80 gr hallow base .30 cal slugs to you that I had cast. I have other moulds that I have spun out including a .50 cal. If you'd like to try some give me a bore size or slug your barrel and send it to me so I can size some accordingly.wbblaze@slingsot.co.nz.mind you by the look of the groups you're getting you may allready have the ultimate slug.Cheers Danny

Hey Danny, that must be Don you are talking about (without whom I would be in the airgunning wilderness)...yes he gave me some .308 hollowbums to try and I must admit that with the overwhelming choice of slugs I have had available I may not have done them justice!
My .50 cal shoots slugs sized to .501 very nicely... I'll drop you an email.
Funny we should meet up on the maestro's site, so far away......
Cheers
Neil

Well it is the Airgun Rendezvous!

Danny,

Thanks for all the information. That seems like a great gun. Great story

Great post from down under! I like the gun design you've created.

I can't follow all the tech details of the build but am intrigued by the different reasoning about POI changes in the shot string. I wonder if both are factors or if we need to call Mythbusters for some high speed camera work?

The hunt story was great! I like to see good shot placement do what no amount of power miss-applied (pun always intended) ever can, a clean kill. Current powder burning "wisdom" has the minimum killing energy of medium game at 1000 ft/lbs. Thanks for proving them wrong.

Kent

Thanks Kent,prior to getting into air rifles I was a big fan of silenced sub sonic .30cal powder burners for shooting goats.Now heres an interesting thing that I have found,the air rifles are more effective at bringing down game quickly than there powder burning equivelents.I've come to a conclusion(that may indeed be wrong)that the slug from a powder burner is sizling hot when it hits the animal,even at sub sonic loads were as on the other hand as expanding gas's cool(which is how refrigerators work)the slug from a pcp is cold.Now on investergating the bullet path on verious animals I've shot the equivelent wound from an air rifle seems to bleed a lot more than that caused by the powder burner.It is possible that the hotter slug of the powder burner is cauterizeing the wound some as it penitrates therein slowing the bleeding.It would be interesting to test the theory by shooting slugs from both past some kind of heat sensor.Perhaps we should put it to the boys and gals at myth busters.Danny