American Air Arms

predator-pellets

Neil Clague Air Strippers, Shrouds and LDCs

windmeister-ad

Wicked Air Rifles - Flex

Marmot Militia Machine Works

Author Topic: Hybrid pellet/bullets possible???  (Read 754 times)

oldpro

  • Hero Member
  • *****
  • Posts: 1131
    • View Profile
Hybrid pellet/bullets possible???
« on: September 18, 2017, 05:14:46 PM »
 Is there a way to design a hybrid bullet that could expand to bore and shoot as well as the JSB pellets do?


  • Mount Shasta Ca.

rsterne

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 1208
  • Mozey-On-Inn and see what Coalmont has to offer!
    • View Profile
    • Mozey-On-Inn
Re: Hybrid pellet/bullets possible???
« Reply #1 on: September 18, 2017, 05:49:28 PM »
We could make a nose-pour bullet where the sprue cutter worked on the Meplat, and then use a pin to create the hollow base, the way it is done on the NOE pellets.... It would have a forward CG, which Nick thinks is the wrong way to go.... Since the rear section of the bullet would be parallel to the bore, it wouldn't expand as much as the skirt on a waisted pellet, but with a relatively thin edge around the base cavity, it should still expand and seal properly.... What weight and caliber are you thinking of?.... I can have a go and see if you like the drawings.... and we can have Al at NOE cut a set of custom molds.... Alternately, you might ask Nick if he already has something like that which he can swage for you?....

Bob
  • Coalmont, BC

oldpro

  • Hero Member
  • *****
  • Posts: 1131
    • View Profile
Re: Hybrid pellet/bullets possible???
« Reply #2 on: September 19, 2017, 12:09:34 AM »
Rough idea of weight range?....

Bob
« Last Edit: September 19, 2017, 07:10:15 AM by rsterne »
  • Mount Shasta Ca.

Motorhead

  • Sr. Member
  • ****
  • Posts: 358
  • Older & Slower ... Field Target Shooter
    • View Profile
Re: Hybrid pellet/bullets possible???
« Reply #3 on: September 19, 2017, 08:17:54 AM »
Rough idea of weight range?....

Bob
Pending caliber ... duh  ;D
  • Old Hangtown ... California
"Home of Motorheads Air Gun Tuning Service"
    ***** Airguns need love too !! *****
http://airgunguild.com/index.php/topic,38.0.html    
Scott

rsterne

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 1208
  • Mozey-On-Inn and see what Coalmont has to offer!
    • View Profile
    • Mozey-On-Inn
Re: Hybrid pellet/bullets possible???
« Reply #4 on: September 19, 2017, 01:16:19 PM »
Sorry, I "Modified" Travis' post instead of Replying....  ::)

He said to start with .25 cal, and I intended to ask him what weight range....  ;)

Bob
  • Coalmont, BC

rsterne

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 1208
  • Mozey-On-Inn and see what Coalmont has to offer!
    • View Profile
    • Mozey-On-Inn
Re: Hybrid pellet/bullets possible???
« Reply #5 on: September 19, 2017, 02:39:49 PM »
OK, so here is the first idea I came up with.... The nose is 0.250", the same as most .25 cal pellets, but the skirt is a bit smaller, it is designed to be the groove size of the MRod (GM) and LW barrels.... The lip of the skirt at the back is only 0.027" thick, which I would expect to expand nicely at our pressures.... It should be possible to size it to work in the 22" twist TJ's airgun barrel, which is 0.250" groove and 0.243" lands.... that is the slowest twist I would recommend....



It is basically the forward portion of a conventional Tangent Ogive bullet, with the smallest Meplat (60%) I think will work with a Nose Pour.... and made the correct length to function in a Hatsan magazine, which means it will also fit in the .25 cal MRod and Flex mags.... The center portion is small enough to not drag on the lands.... As a Flat Base bullet it would weigh 50 gr.... The two different hollow base configurations, as drawn, are 42.2 gr. for the deep one, and 44.8 gr. for the shallow one.... Basically, any weight between 41 to 46 gr. is possible by changing the base pin, and should not really affect the way the skirt expands and obturates (seals) to the bore.... The shallower hollow base would have the CG further aft, and the heavier pellet would not require as long a bolt probe to seat it ahead of the barrel port, of course....

Bob
« Last Edit: September 19, 2017, 07:51:52 PM by rsterne »
  • Coalmont, BC

int3man

  • Sr. Member
  • ****
  • Posts: 412
    • View Profile
Re: Hybrid pellet/bullets possible???
« Reply #6 on: September 19, 2017, 07:51:49 PM »

I like the ..25 start point as those are the most of what I own.  So the only question is will it work with a Chocked barrel?  If it works with Green mountain barrel, LW Barrel...   I'm down with that!!!

Thanks!
Michael :- )
  • Central California
WAR .22 PRod
WAR .25 Marauder
Broadening my Horizions
.22 Brocock Super 6 XL
.25 BSA Scorpion Huma Reg.
.25 Air Arms Extra FAC

WAR .22 Marauder, Huma, LW Hammer,  Rapid 70 Bull  Stolen
Flex .30  Stolen

Yes I still have an ICQ Number.  Raise your hand if you do.

rsterne

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 1208
  • Mozey-On-Inn and see what Coalmont has to offer!
    • View Profile
    • Mozey-On-Inn
Re: Hybrid pellet/bullets possible???
« Reply #7 on: September 19, 2017, 08:03:25 PM »
I see no reason it would not work just like a pellet in a choked barrel.... The head is the same diameter as, for example a JSB, and the skirt is free to expand with the air pressure to seal, and be contracted by the choke.... The key will be how the balance works out, and the relationship between the CG and CP positions and the twist rate.... Only making a mold and trying them will prove it one way or the other....

If a lighter overall pellet is needed, then it would have to be shortened.... To make a heavier one, it would have to be lengthened.... If the change is made in the center portion, it takes roughly a 0.040" (1 mm) change in length for each 5 gr.... I would not want to go much shorter in the middle section, as the length supported by the barrel gets shorter.... For shorter, lighter pellets I think we would have to reduce the Ogive Radius to shorten the nose instead.... We could get to about 50 gr. and still fit it inside an MRod magazine.... Of course any length change requires new tooling and a new mold.... so the only practical way, initially, is to make sure we pick the right length and weight to start with....  ::)

Bob
  • Coalmont, BC

oldpro

  • Hero Member
  • *****
  • Posts: 1131
    • View Profile
Re: Hybrid pellet/bullets possible???
« Reply #8 on: September 19, 2017, 09:17:33 PM »
 Im a novice for sure in bullet design but what I do know is they have a better BC therefore they can retain more energy further out(distance from muzzle) what I also know is its very hard to find a bullet that shoots well from a PCP air rifle believe me Ive tried them all. So if we can make a hybrid that shoots like a pellet but has almost the same BC as a bullet we will have the Golden Ticket.  Id gladly pay for a mold if we can agree it will have a good chance at working. I would like some others to chime in on thoughts here.
  • Mount Shasta Ca.

rsterne

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 1208
  • Mozey-On-Inn and see what Coalmont has to offer!
    • View Profile
    • Mozey-On-Inn
Re: Hybrid pellet/bullets possible???
« Reply #9 on: September 20, 2017, 06:41:47 AM »
In addition to discussions here, please choose the weight you would like to see in the poll I started here....

http://airgunguild.com/airgun-ammo/hybrid-bullet-pellet-poll/

I only allowed you one choice so that we find out what you REALLY want....  ::)

Bob
  • Coalmont, BC

oldpro

  • Hero Member
  • *****
  • Posts: 1131
    • View Profile
Re: Hybrid pellet/bullets possible???
« Reply #10 on: September 20, 2017, 11:36:00 AM »
 Bob why is it I have a PCP that will shoot most any pellet sub MOA but havent yet shot any air rifle sub MOA with a bullet? Will this hybrid make the bullet shoot closer to the pellets?
  • Mount Shasta Ca.

rsterne

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 1208
  • Mozey-On-Inn and see what Coalmont has to offer!
    • View Profile
    • Mozey-On-Inn
Re: Hybrid pellet/bullets possible???
« Reply #11 on: September 20, 2017, 12:23:29 PM »
Travis, I really have no idea.... The only slugs I have seen shoot sub MOA at 100 yards from a PELLET CALIBER barrel are Nick's swaged designs.... He spends a huge amount of time trying different designs and weights in different guns, and for most PCPs he knows what to recommend.... There are quite a few guys who can get dime sized groups at 50 yards, but very few of them can repeat that at 100 yards.... mind you, the same thing applies to pellets.... There are very few guys who have qualified as "Master" in the NUAH Club, which requires a 5-shot group under 1"....

There are a few "specialists" like Doug Noble and Carl who seem to be able to get MOA groups at 100 yards frequently.... but they are using PB barrels and calibers, and generally FPE levels well beyond what we are....  I have never managed it with any airgun.... Sub MOA groups at 100 yards remain uncommon in airguns, and quite elusive, IMO....

Bob
  • Coalmont, BC

Shorty

  • Newbie
  • *
  • Posts: 40
    • View Profile
Re: Hybrid pellet/bullets possible???
« Reply #12 on: September 20, 2017, 02:01:38 PM »
Of course this will sound dumb but I tried it.

When I was running the .357" barrel on the 22 synrod, the only thing that shot straight was the JSB's. I wanted to use a heavier projectile so I bought some 95 grain air venturi's. They shot like crap at 15 yards and 25 yards was all over.

When i got the 25 synrod, I wanted to shoot heavier as well even though the 43.2 eujins shot darn good so I bout some of those 50 grain hunter supply RN's. They shot like crap too.

When I was playing with the 357 I took some of those air venturi's and drilled into the base ever so slightly (making a pocket). Instead of chucking the pellets into the lathe I made something like a teflon chuck to fit into the lathe to hold the projectile without damage.

I kind of thought after 10 or 20 that the groups were better and smaller but never really did anything precision. Although, there was a difference. I tried the same thing with the 25 and got similar results but never really got into it because it's a PITA.

So,
I am no bullet expert either but something was definitely different going on with an expansion at the base.

Maybe you can try chucking a few bullets into your lathe and see if there really is something to it before going into the molding as it takes some time to get the mold made. Might not be perfect but should get a good idea if the concept will work for a hybrid.
  • Palm Coast Florida

oldpro

  • Hero Member
  • *****
  • Posts: 1131
    • View Profile
Re: Hybrid pellet/bullets possible???
« Reply #13 on: September 20, 2017, 02:52:01 PM »
That's a great idea Tim!!!
  • Mount Shasta Ca.

rsterne

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 1208
  • Mozey-On-Inn and see what Coalmont has to offer!
    • View Profile
    • Mozey-On-Inn
Re: Hybrid pellet/bullets possible???
« Reply #14 on: September 21, 2017, 02:46:30 PM »
I have been doing some playing around with this idea at different calibers, and I think it might be an idea to shorten the design slightly as it would then scale better.... If we shorten it to 1.50 cal. long, it reduces the weight about 4 gr. and gives this design in .25 cal.... SD = 0.091 for the 40 gr. version.... BC should be about 0.08....



This bullet can then be scaled up exactly to .30 cal and still fit in the MRod and Flex mags.... SD = 0.111 for the 70 gr. version.... BC should be about 0.10....



I haven't drawn it yet, but if scaled up to .357 cal the weight would be 110-118 gr.... and if scaled down to .22 cal it would be about 25-27 gr.... Half the length of the bullet is supported by the barrel, which would increase the stability in the bore a bit.... and I think the weights are more realistic for high powered PCPs without having to get silly about the required FPE.... To reach 950 fps, this design would require 50-54 FPE in .22 cal.... 75-80 FPE in .25 cal.... 130-140 FPE in .30 cal.... and 220-235 FPE in .357 cal.... I think that is a good balance between the desire for a heavy bullet and the ability of the more powerful PCPs available today.... At 850 fps, the required FPE drops by 20%....

On the other hand, there is an advantage to using longer, more slender designs in the smaller calibers, to take advantage of the reduction in SD they give for the same shape.... This would mean making the .22 cal longer, and the .357 cal shorter to keep the SD constant....

Bob
  • Coalmont, BC