GTA
All Springer/NP/PCP Air Gun Discussion General => Air Gun Gate => Topic started by: Taso1000 on October 11, 2016, 02:08:45 AM
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Hi All,
These pellets have intrigued me for a long time with their .082 ballistic coefficient. H&N's next closest ballistic coefficient pellets are the Sniper Magnum with .035 and the Rabbit Magnum II with .049.
I have looked online and found a lot of information about the Piledrivers, but no one except for Ribbonstone has gotten decent accuracy out of them.
So that is what I would like to explore with this post with your help. If an air rifle can be made to shoot .177 Piledrivers accurately to 100 yards and beyond.
Why am I stuck on .177 caliber when other calibers can easily be more accurate than .177?
The reason is I live in Illinois. In Illinois any air rifle that is .177 caliber is an air rifle. In Illinois, all air rifles over .177 caliber and shooting over 700 feet per second are considered firearms. Most local ordinances ban shooting firearms within city limits. Can you guess what an ldc turns into when mounted on a firearm? That's right. The NFA word we cannot type out. And those are illegal in Illinois.
So if it were physically possible and you could build an air rifle that could shoot Piledrivers at 4000 feet per second it would still be considered an air rifle and a .22 Marauder shooting at 701 feet per second is a firearm that includes a shroud that could be interpreted as having an illegal NFA part.
So a firearm can only be shot at a designated range. I don't have any ranges close except for 25 yard pistol ranges. I don't think it's safe to shoot a 40 fpe air rifle in a residential area so I will have to make some friends very soon that have a farm or long property to shoot at lol.
So that is why I'd like to flesh out the .177 Piledrivers.
So I got my caliper out and made some measurements and input them into the barrel twist calculator Bob (Rsterne) likes, http://www.geoffrey-kolbe.com/barrel_twist.htm (http://www.geoffrey-kolbe.com/barrel_twist.htm) and got that at a stability factor of 1.5 shooting at approximately 950 feet per second the Piledriver needs a barrel with a 1:10 twist rate. As long as my measurements are correct and I used the program correctly.
So I also sent an email to H&N Sport technical support asking what barrel twist they recommend to stabilize the pellet for best accuracy at 100 meters. Their response was:
We do not experiment with different twists as we have to observe that our pellets/bullets should work in most common rifles.
For precision tests we use one Weihrauch HW 100 4,5 mm in FAC-Version (30 Joule). It has a 1:16 twist which is common here in Germany.
I had hoped for more information.
So then I looked at Lothar Walther's barrel website to see what they offer in .177 twist rate. They only offer 1:17.7 twist rate for .177 air rifle. There are some chrome moly .17 barrels but the bores are too tight at .168 land .172 groove versus their airgun dimensions of .176 land and .182 groove.
I don't know who else would offer faster twist rate .177 barrels so I'm kinda stuck.
So here is where I am asking for your help and experience. I'd like to put the barrel on one of my BAM B51's as they have the power to push the Piledriver easily.
I want to stay subsonic for the quietness. I know pellets do some weird stuff around the speed of sound so I'm eagerly awaiting Bob's (RSterne) findings using LabRadar.
If someone has already tried to optimize a rifle to shoot the Piledrivers accurately, could you point me to their findings? If I missed something or made an error somewhere could you point that out too?
Thanks in advance for all Your help!
Taso
EDIT: I forgot to attach my pictures! Sorry
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I don't think any springer will push that pellet fast enough for it to shoot well.
You'd need something along the line of an Evanix Rainstorm II.
But before you get all crazy, what do you need that kind of power for? My .177 Marauder shooting CPH at 18 FPE punches right through squirrels, with enough energy left to blow up a big puff of bird seed on the far side of them.
Assuming you COULD launch it fast enough for it to be accurate, and you had a target that needed that kind of penetration, it'd blast right through, without even transferring all the energy. You're talking about 25+ FPE in a dense little .177 caliber package.
Here's one way you can predict it, from your BAM51.
Start shooting at maybe 7.9 gr. pellets. UP to 8.4, Up to 8.6. Up to 9.2. Up to 10.5. Up to 10.65. AT this point, accuracy is probably peaking. Now, you're getting into the exotic, heavy pellets: Rabbit Magnum II, Sniper Magnum. I just BET it doesn't shoot them as well as the 10.5s. From that, you know that going up to a heavier pellet is going to be counter-productive.
I gave away my tin of Rabbit Magnums after trying maybe 10-20 shots with them. They grouped like the cheap Crosman wadcutter pellets from Walmart. Which is to say not at all. Even from my Marauder and Diana 56TH. (20 FPE)
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Jeremy,
Thanks for your response. The BAM B51 is a Chinese copy of a Daystate Huntsman MKII pcp.
Here is a link to my first B51 project:
http://www.gatewaytoairguns.org/GTA/index.php?topic=99648.0 (http://www.gatewaytoairguns.org/GTA/index.php?topic=99648.0)
I want to use it for 100 yard target shooting hopefully moa or better.
The higher ballistic coefficient will help with wind drift and thus help accuracy.
Taso
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Ah, sorry. I thought BAM only made springers. (learn something new every day)
I think you'll need to tune it up to at least 25 FPE for it to shoot the Piledrivers well. Let's see how it goes.
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I have no experience with these. No experience with PCP's.
That said, I am blessed to be from a family of engineers and have a mind geared for physics and mechanical things.
My take= you need to get the RPM up. There are only 2 ways to do that, more FPS, or faster twist.
Order a custom barrel, or disregard your desire to stay subsonic.
A sonic crack is ONLY relative to the frontal area of object. Therefore, the crack from a .177 projectile will be quieter than from a .22.
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I have never shot the slug but looking at I don't think it looks like it is balanced correctly with the nose way too heavy for that type of a design. I have a hard time believing many, if any, guns will shoot that accurately and especially at long range.
Increasing the rpm's will most likely make it shoot worse if it is imbalanced because over stabilized bullets tend to show bullets imperfections more than well stabilized ones.
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Ah, sorry. I thought BAM only made springers. (learn something new every day)
I think you'll need to tune it up to at least 25 FPE for it to shoot the Piledrivers well. Let's see how it goes.
Jeremy,
Don't worry about it. I didn't know either 2 years ago. I would see them on the Flying Dragon website and think those are cool but crazy expensive and I didn't know anything about high pressure air lol. Now I have 5 of them! lol They are all steel and built like tanks. A great foundation to play with but there really isn't an aftermarket for them. So everything is pretty much diy or have a friend that's an airgunsmith. :) So it's a good thing they are a simple design.
I don't remember which B51 rifle it was but it was shooting the Piledrivers at 960'ish feet per second. It must of been one of the new ones out of the box. They were shipped with air so I was just messing around. They have heavy hammers and high rate springs throughout. Not efficient and they beat themselves up.
I have no experience with these. No experience with PCP's.
That said, I am blessed to be from a family of engineers and have a mind geared for physics and mechanical things.
My take= you need to get the RPM up. There are only 2 ways to do that, more FPS, or faster twist.
Order a custom barrel, or disregard your desire to stay subsonic.
A sonic crack is ONLY relative to the frontal area of object. Therefore, the crack from a .177 projectile will be quieter than from a .22.
Sam,
Thanks for your response. I thought about going high when I saw the twist rate graph. So then I looked up how fast lead can be pushed without smearing in the barrel and messing up the pellet. I read no more than 2000 fps and that is with lots of lube. I'd like to keep the rifle quiet so I'm stuck with subsonic. I've shot some 7.4 grain Crosman milk carton pellets that go supersonic and crack and echo quite impressively.
I have never shot the slug but looking at I don't think it looks like it is balanced correctly with the nose way too heavy for that type of a design. I have a hard time believing many, if any, guns will shoot that accurately and especially at long range.
Increasing the rpm's will most likely make it shoot worse if it is imbalanced because over stabilized bullets tend to show bullets imperfections more than well stabilized ones.
Nick,
Thanks for chiming in. I don't have any first hand experience in this. I found the twist rate calculator on GTA and figured I could input the numbers to see what comes out. I do agree with everything you said though. Over stabilized pellets may disintegrate. Under stabilized we already have millions of barrels to try lol. Or maybe I get lucky like Ribbonstone where a barrel theoretically shouldn't shoot the pellet well and it does.
It seems every time we try to apply what we've figured out it doesn't work as expected.
So I figured if it was economically feasible and the physics can be figured out why not try? If it doesn't work someone could reference this post and maybe think of something we didn't and get them to work.
Maybe it can or can't be done but you won't know unless you try. That's why I also asked if anyone has tried before.
Thank you All for submitting your thoughts and keep them coming!
Taso
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The new range at Willow slough in Morocco In. is airgun friendly and has 100 yard ranges..
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I would suggest you try the 10" twist rate as per your stability graph.... As to diameter, measure the Piledriver, and make the groove diameter the same.... The lands about 0.004" smaller should be fine....
Bob
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I have never shot the slug but looking at I don't think it looks like it is balanced correctly with the nose way too heavy for that type of a design. I have a hard time believing many, if any, guns will shoot that accurately and especially at long range.
Increasing the rpm's will most likely make it shoot worse if it is imbalanced because over stabilized bullets tend to show bullets imperfections more than well stabilized ones.
Hornady PA conicals shoot pretty accurate driven to 1600 fps. Is a nose heavy design bad for acuracy? Does the spinning put a 90° force on the projectile that causes it to try changing direction?
Are imperfections in projectiles somewhat swaged out by the lead/forcing cone in PB's or the choke in AG's.
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I have never shot the slug but looking at I don't think it looks like it is balanced correctly with the nose way too heavy for that type of a design. I have a hard time believing many, if any, guns will shoot that accurately and especially at long range.
Increasing the rpm's will most likely make it shoot worse if it is imbalanced because over stabilized bullets tend to show bullets imperfections more than well stabilized ones.
Hornady PA conicals shoot pretty accurate driven to 1600 fps. Is a nose heavy design bad for acuracy? Does the spinning put a 90° force on the projectile that causes it to try changing direction?
Are imperfections in projectiles somewhat swaged out by the lead/forcing cone in PB's or the choke in AG's.
I see recommendations about spinning this faster which I disagree with. You mentioned the PA Conical bullet and how it is accurate. I found this bullet on Midway and I notice a few things about it and for arguments sake I will assume it is accurate which I tend to believe it is looking at it.
1. Look how short the bullet is, very similar to an EPP bullet. I put a link below to one of my EPP slugs for reference. EPP in my Dragon Claw is very accurate, I have tested out 135 yards with impressive results.
2. In the Midway description it says this round if recommended for a 1:66 twist rate. That is extremely slow. One revolution of the bullet for every 66 inches it travels. Your pellet gun is most likely in the range of 1:16 which is way too fast for this style of slug to have a chance.
3. It is a cup base, like a hollow base just not as deep. This is similar to a diabolo pellet where the hollow base creates a negative draft to help stabilize.
The Pelletdriver does not share these similarities. It is way too nose heavy with out a hollow base to help stabilize and is way too long which I think will make it's tail wag when it slows down and the rpms are still spinning too fast.
http://www.midwayusa.com/product/730932/hornady-pennsylvania-conical-muzzleloading-bullets-50-caliber-512-diameter-240-grain-box-of-50 (http://www.midwayusa.com/product/730932/hornady-pennsylvania-conical-muzzleloading-bullets-50-caliber-512-diameter-240-grain-box-of-50)
EPP:
https://nielsenspecialtyammo.com/collections/50-cal/products/50-caliber-epp-slug-sized-495-498-as-cast-209-grain-epp-slug (https://nielsenspecialtyammo.com/collections/50-cal/products/50-caliber-epp-slug-sized-495-498-as-cast-209-grain-epp-slug)
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Hi All,
I've been going back and forth with the H&N engineer for his thoughts. I will report back with what we come up with. :)
Thank you,
Taso
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Use a smooth twist barrel and send it down-range at ~ 930 FPS and see what happens. Maybe magic, maybe shotgun patterns, or maybe nothing special either way.
IIRC, there's been some info somewhere here about the FX barrels having a very slow twist rate- which I would expect since most of the barrel is smoothbore. If I had an FX gun, I'd buy some of these pellets and give it a go.
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FX barrel may work with this pellet, I have no idea, not tried and don't own one to try. FX smooth twist barrels only have rifling in the last few inches of the barrel. I have not seen an FX shoot a slug on the forums, maybe this will be the first.
In my opinion, the bullet is out of balance and will not matter what twist rate it fires from. I have swaged and cast many, many different shapes, sizes, weights and out of many types of barrels and guns to have an idea of what works and what does not. My swage machine allows me to make many shapes and make them any length or weight I want them and I have experimented with hundreds of bullet designs.
Does not mean I know everything and I am not trying to come off like that, but after a while you get a feel of works. Hopefully an FX owner will try them...
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Peter,
I'm going to start setting up one of my B51's as a dedicated Piledriver shooter. I have 3 other .177 barreled receivers to swap in between to see if any one of them shoots better than the others. Maybe I'll get lucky.
By necessity I will have to start at 10 meters in my basement and see how it goes. I won't have a problem in the speed department but I don't have access to long ranges.
I also have a spare regulator I could use. My only issue is that I have to drill a vent hole in the air tube to use it. Once it's drilled the air tube is stuck as a regulated rifle and at that plenum size.
I hate making irreversible modifications so I have to be absolutely sure. It's not the end of the world as too big a plenum is better than too small.
I also have 2 .22 barreled receivers I could use if I have to.
Thanks,
Taso
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Nick, do you think when sectional density gets deep enough, it is good to have CofG at CofP, or are there to many variables?
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The center of pressure is almost always going to be in front of the center of gravity. A hollow base bullet would be the exception. There is controversy over whether or not to get the center of pressure and center of gravity at the same point. The most accurate slugs I have shot have the center of pressure forward of the center of gravity. CG is normally around 40-48% from the base of the bullet on most bullet designs we use.
There is more to a bullet's stability than just the CP and CG. The twist rate matching the bullet, the sizing matching the bore are two way over looked factors and with no standards in the AG industry all guns may be different.
I have not fired this slug before so I am only basing this on similar designs I have tried that totally failed. I have a $300 point forming die to make a .25 caliber round nose bullet which would look very similar to this slug. Do you know why you don't see it for sale on my site - yep, totally sucked eggs. Way too front heavy, looks great and shoots terrible. I am only sharing based on my testing. However, I have spent thousands of dollars on molds, guns, lead, punches and dies. Ask anyone who has been in my bullet room how many bullets, molds, dies, etc I have in there - would blow you away.
My suggestion if you want to come up with a good bullet is to start with a design that works and not try to get a bullet that nobody gets good results with and try to make it work in a magic gun. Draw up your bullet, send to a mold maker and have them make it for you. If it don't work, try a different design. Sound expensive? Don't tell my wife this, but, IT IS! LOL
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Got it. Sorry, not looking to get a custom mold (well one day). Just thinking out loud. Supposedly HBWC are accurate, and they look nose heavy. But a football is accurate, and it is perfectly balanced, etc.
Also, the PA conical out of a 1:48 gun is MoBambi at 100. I realize you have higher standards than that.
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Got it. Sorry, not looking to get a custom mold (well one day). Just thinking out loud. Supposedly HBWC are accurate, and they look nose heavy. But a football is accurate, and it is perfectly balanced, etc.
Also, the PA conical out of a 1:48 gun is MoBambi at 100. I realize you have higher standards than that.
I don't doubt that bullet at all. If you shot that bullet in a twist rate like you have in a pellet rifle (1:16 or so) I bet you can not hit a 6 inch target at 100 yards with it 3 times in a row. Good groups at 100 yards is the standard I use for slugs. 50 yards most slugs will do OK, it is past that, say 70 yards, where they fall apart so if I can get good results at 100 I feel the bullet is stable.
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Peter,
I'm going to start setting up one of my B51's as a dedicated Piledriver shooter. I have 3 other .177 barreled receivers to swap in between to see if any one of them shoots better than the others. Maybe I'll get lucky.
By necessity I will have to start at 10 meters in my basement and see how it goes. I won't have a problem in the speed department but I don't have access to long ranges.
I also have a spare regulator I could use. My only issue is that I have to drill a vent hole in the air tube to use it. Once it's drilled the air tube is stuck as a regulated rifle and at that plenum size.
I hate making irreversible modifications so I have to be absolutely sure. It's not the end of the world as too big a plenum is better than too small.
I also have 2 .22 barreled receivers I could use if I have to.
Thanks,
Taso
I'm definitely looking forward to what you find out. Hopefully it will turn out to be a bumblebee :) They're not supposed to fly but do a pretty darn good job and do it with grace.
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Nick,
Do you like the Rabbit Magnum II design any better? I think the Nomad pellet making kit is a similar shape. I've attached a picture of the Nomad pellets.
I see that the Piledriver longitudinal splines are to reduce the contact with the lands and make it easier to push or load in the breech where as the nomad has full contact. Plus the Piledriver had the boat tail.
As always I defer to your expertise as I am not a bullet designer or tester of what works. I don't comprehend the other projectile factors you guys are mentioning i.e. center of gravity etc. So I'm trying to learn. ;D
Taso
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Nick,
Do you like the Rabbit Magnum II design any better? I think the Nomad pellet making kit is a similar shape. I've attached a picture of the Nomad pellets.
I see that the Piledriver longitudinal splines are to reduce the contact with the lands and make it easier to push or load in the breech where as the nomad has full contact. Plus the Piledriver had the boat tail.
As always I defer to your expertise as I am not a bullet designer or tester of what works. I don't comprehend the other projectile factors you guys are mentioning i.e. center of gravity etc. So I'm trying to learn. ;D
Taso
That bullet is almost identical to one I tried with point forming die I mentioned earlier that "sucked eggs". I tried with a hollow base, flat base and cup base. That looks like a cup base.
I have seen non favorable reviews from the accuracy of those homemade pellets. Based on my personal experience and reviews my guess is most guns, or none, will shoot well at 100 yards with that slug. Again, short range, probably work just fine but slugs shine at long range where their superior BC makes them favorable. Here is a review from one guy but there are others out there (also, please note I am only giving my opinion and theory, real facts require testing):
http://www.airgunnation.com/topic/nomad-pellet-making-kit/ (http://www.airgunnation.com/topic/nomad-pellet-making-kit/)
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Hello All,
Just a small update. I sent and email to Lothar Walther inquiring if they would make a 1:10 twist rate air rifle barrel in .177. I will let you all know what they respond.
Thanks,
Taso
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Hi All,
I received a response from Lothar Walther Sales on my second attempt. They want $175 a barrel and a minimum order of 5 barrels and need a 2 month lead time. I have asked for the spec's and diagram to approve.
I think I'm going to want to get my ankle all healled up from my car accident first before I proceed. Or I may just go ahead and order them. We'll see what mood I'm in lol. I'm really curious if the faster twist will work.
Thank you,
Taso
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I'm subscribing because this thread has been a cool read so far. I have no useful input for the barrel or projectile, but I have to throw something out here regarding location. Would it not be cheaper and faster to move to Indiana or Wisconsin and shoot what you want? ;) :D :-X
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Jentry,
That would be "toooooo" easy. ;) But I like a challenge and at least we'll know whether a faster twist rate barrel will work. Maybe then we can get some true bullets or "slugs" in .177.
Maybe going through TJ's barrel liners may bring the cost of the barrels down after the initial purchase of the new 1:10 twist mandrel? I think it's called.
Taso
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Taso, I just took another look at the Kolbe Twist graph you posted in your first post.... You forgot to put in the boattail length, so it may be out of whack....
Bob
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Taso, I just took another look at the Kolbe Twist graph you posted in your first post.... You forgot to put in the boattail length, so it may be out of whack....
Bob
Mr. Sterne,
Good catch! Thank you. I must have confused my and's and or's in the boat tail section. I entered the missing information but it doesn't seem to have changed the graph much.
What do you think Mr. Sterne?
Thank you,
Taso
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Have any shoot .22 Piledriver pellets out of Marmot Militia barrel?
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Another small update:
Today I shipped two barrel blanks and an HW100 and Daystate MK4 barrel to copy to Matt at JSAR. I think he said it should take around a month or so to complete.
I apologize for the delay. I got swamped with work and had to focus on many projects.
I still have to find property to setup a 100 yard range.
I thought about putting an add in a local paper or maybe Craigslist. Has anyone done this before? Any tips?
Thank you,
Taso
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When were the pile drivers first released to the public? Reason I'm asking is because I'm trying to figure out what pellet I was given back around 03 or 04.
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I don't know when but before H&N acquired or licenced making them them they were labeled Prometheus Piledriver.
I don't know more about their history.
Taso
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Thanks. I've done some looking under Prometheus and haven't found what I'm looking for. All the dates lead to being released around 2010 but I know I was shooting them and 2003-2004. It's quite possible I was given some during a testing phase when these were developed. Used to have a buddy of mine that was an engineer that did a lot of traveling... showed me a lot of neat stuff Unfortunately I don't have any contact with that person anymore
I was only shooting those piledriver slugs around 600 ft per second, just a guess because I didn't have a chronograph back then but they were very very accurate from my air arms Pro Target Field Target Mark II
Was also given some pellets that looked like a small V2 rocket. Those shot like &^^& at all ranges.
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There are quite a few videos on youtube about the Prometheus pellets. Maybe the upload dates will give you a clue or they give a little history about them in the clip?
Thanks,
Taso
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UPDATE!!!
I just got off the phone with Matt at JSAR. My barrels are done! :D
I paid for the machining and they will be shipping back to me today.
That I am excited is an understatement!
Taso