Slug diameter difference??

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woogie_man

woogie_man

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May 3, 2021
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North Dakota, United States
Ok guys I am working on getting my HM1000x set up for NRL22 shooting. And with that I am needing to find a slug that will perform not only at short ranges but at distances out to 150 yards at least. Yesterday I was at the indoor range getting some basic testing done with some 218 slugs, made from a Corbin press, as well as some NSA 217 slugs. Tested from 24 - 28 grain slugs, and while some showed promise there was nothing that really stood out. I did have some ZAN 217 25.5 grain slugs that were right at 1" at 100 yards, but being as these are no longer produced...... I need to find something different. So today it was very light wind, around 5-8mph at most, and decided to make the most of it and head to the range. While there I made sure to grab some JSB KnockOut slugs in 216 and 217 both in the 25.45 grain as well as some H&N slugs in 25 grain. The JSB 216's didn't shoot to bad but nothing good, while the 217's were stable at 50 all the way out to 100 yards. The H&N didn't shoot well at 50 so I didn't even try them further.

So being as the 218 slugs didn't shoot very well past 50 yards, and the 217 slugs shot in the 1" range out to 100 yards....... would there be much of a difference between a 217 and a 2175? I do have some NSA 217 and 2175 slugs coming to test so I can see if there is a difference or not. But being as I am planning on getting a Corbin press as well I need to make sure that my diameter is correct before dropping the coin on an entire set up.

I did shoot a few different Javelin V2 slugs as well, and while at 50 yards they all shot very nice tight groups......at 100 yards they were all like a shot gun pattern. These are a sample of the groupings at 50 yards.

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Huge difference with my RAW .22 between .2175 and .217's, .2175 have the same accuracy as JSB 18gr pellets at shorter distances and better at longer distances FYI 👍. My RAW's groups with .217 are hit or miss while the .2175 are so darn consistent.

IMG_7275.jpeg


Here are 4 shots @ 20yds my max back yard range with NSA 20.2gr .2175.
 
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Are you guys talking non choked barrels? In my testings barrel groove dia plus 5 microns show a difference.
5 microns is 0.00019685039 inches.
You talking 217-2175, that is 12.7 micron difference. ;)
If your barrel is choked - you chasing a wrong magic.

A good practice - measure and resize (if needed) at the barrel operating Temp. You cannot measure in a AC running basement and go POI testing @ 30C noon time.
 
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I have been talking with Corbin about getting a presskit, but got to thinking about the price of everything. For $1900 for a starting kit that is a hell of a lot of slugs! Say $18 or so for 200 slugs, and a 10lb spool of lead would make around 2,700 26 grain chunk to press. That would be 14 tins of slug for a cost of $252. So that would be cheaper that the spools of lead...BUT....... to cover the cost of the press it would cost the same as 106 tins of slug, or 21,200 slugs! And that is just for a single 217 slug, now I could make any weight I wanted so there is that.

So trying to decide if that would be worth it..... or just buy the slugs and not have to worry about it. As much as making my own slugs would be fun that is a ton of money and work. Though the ability to control the quality is a plus as well...... .I hate decisions.
 
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That was what I was thinking as well.

I wish the dies were not so damn expensive. I understand that quality parts and precision machining is expensive but I can get a high quality die set for my powder burners that is cheaper than the $550 for a set of Corbins! That and the press isn't really anything special. Really wish they would make something that would work in a standard reloading press.
 
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woogie_man,

Do not shoot slugs larger in diameter than the barrel groove diameter. You increase the risk of distorting them on loading due to the extra loading force. The amount of blow-by is less than one might think, even with the projectile diameter 0.001" smaller than the barrel groove diameter. Certainly, the reduction in friction with undersized slugs is greater than the effect of blowby, for such small radial gaps. Obviously one can take that too far, but unlike PB, airguns can shoot "undersized projectiles" that are well over land diameter, well.

Probe type and slug base shape can also interact poorly to potentially cause base distortion. On the other end of the spectrum, if some of your projectiles are "short" for the chamber, they may not properly align with the bore; or may have a variable "start" on firing. So, probe type and length interact with slug shape and length; and with chamber diameter and depth, that may favor some slugs over others.

In terms of displaced lead the shape of the polygon bore may operate best with a projectile diameter larger or smaller than one with conventional spline rifling. Certainly, the effective bearing length of the projectile is also important for in-bore stability, and effective bearing length changes depending on how tight the projectile is in the barrel. Nose shape has a lot to do with the latter.

If you shoot slugs into a deep container of water and then look at the rifling marks that might offer some insight. Else, push slugs through the barrel with a cleaning rod from the chamber end. While this requires removing the barrel, it will let you feel if some slugs go loose partway down the barrel. That would suggest greater potential for yawing of the slug as it travels down the barrel, and may correlate with poor performance on target. Ideally, you would want an even drag on the slug all the way down the barrel when pushed through. Yes, there may be more force at the start with the force trailing off a little as it goes down the barrel, but abruptly going loose, or tight (other than at a deliberate choke) is a sign of trouble with the barrel. Some slugs may be more forgiving of such barrel trouble, but many would not shoot as well as advertised.

Slug diameter is important, as is diameter consistency; but it is not the only thing that is important. The shape of the projectile and the location of the center of mass, front to rear, are also important. So, my suggestion is to try to copy the ZAN projectile shape with custom Corbin dies, if possible. Or any other slugs that shoots well to over 150 yards.

The quality of the slugs matters, not only in terms of the diameter and its consistency, but that the "nose" and shank are concentric, along with the base (flat or dish or boat tail), and hollow point; if any.

This all assumes that your barrel's twist rate is high enough that all of the slugs you are shooting don't run into trouble there. If you are shooting bullets around 30 grains in .22 caliber, then 1:20 twist should be OK. Even 1:24. If you are going up to 40 grains, you probably want to be near 1:16.

It seems that many .22 slugs want to be driven fast to shoot well. while 950 FPS may be fast enough with some, others may perform better at 1000+ FPS. On the other hand, if you are shooting them closer to the speed of sound, you will need a higher twist rate barrel; as the twist rate requirements are the highest right at the speed of sound. So, trying some of the best and wort performing slugs at 100 FPS faster and slower than you are shooting them now, might provide useful info.

What is the twist rate on your barrel?

What velocity are you shooting each of those slugs at?
 
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What is the difference in feel; when you load these slugs with the probe, open the breech and push the unfired slugs back out with a cleaning rod from the muzzle? How do the rifling witness marks compare?

I state not to shoot slugs with a diameter over barrel groove diameter, but if the chamber is generous and deep, that advice may not hold. Then alignment with the bore on loading has to take precedence. Besides, loading into a generous chamber would take no effort, as there would be no close contact with the slug.

How many "fouling shots" did you allow between shooting groups with each change in projectile? Probably not a factor if you are shooting various JSB slug types, but possibly a factor when shooting other slugs, with other alloys and lube or graphite coatings.

There may be several velocity nodes where groups open and close, so a little faster may shoot worse; while a lot faster may shoot better. If you are shooting too close to max power for the platform, you may seem excessive vibration with a lot of potential for bad harmonics.

If I am looking at the correct airgun, 950 FPS with a 25.4 grain projectile is max. If so, you may already be pushing hard enough where grouping could suffer if you push harder.

Is this your 1000X?:

www.pyramydair.com

RAW HM1000x Chassis | Hunting Rifle | Pyramyd AIR

We've got a great price on the RAW HM1000x Chassis Rifle. Get a great price and expert advice at Pyramyd for your next outdoor adventure!
www.pyramydair.com


Does it have a moderator like shown at the PA link? Either way, you would need good air stripping to shoot well at full power. So, that would depend on what the moderator looks like inside - something we are not allowed to discuss on this forum.

How does this airgun shoot with pellets?



 
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No moderator but I have a muzzle break on it. I do have a tunable break as well I can put on and give a try. Have a match next sunday and will give the rifle a go to see a base line. Then will do more tuning and try and make things better.

20240424_170613.jpg



Have had the rifle out only a few times, hoping to shoot more this week after work. Have a few things to try for sure to make sure things are good.

Haven't shot pellets through the rifle. Honestly I enjoy this type of stuff. I did the same testing with my AAA Paradigm as well. Need to really sit down and do velocity testing now and see what each slug likes. Same thing I do with my powder reloading....fun fun stuff

Here is the barrel that the rifle has...
www.lothar-walther.com

Airgun Blank NO CHOKE - Twist:17.7" | .22 air polygon | OD:.63" | L:24.21" | precision rifle steel t

www.lothar-walther.com www.lothar-walther.com
 
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woogie_man,

Based on that twist spec, you could go heavier on your slugs, providing you can shoot them at useful velocities. Of course, it is actually length and the relationship between center of mass and center of air pressure that matters. There is also the matter of magazine depth that might limit what can be loaded - unless you single load, but that would slow things down.

What I notice is the .215 bore and .221 groove spec for your barrel. That suggests your slugs are not too large, but may be "too small". Anyway, there is no arguing with what shoots consistently well. If that is a .218 spec slug, then I would measure it to see if it is actually .218". Other than that, slugging you barrel to see what it actually measures - I think you have already done that.

LW airgun barrels are known to be "loose" in .22. Closer to rimfire specs than Weihrauch or FX barrels, for example. So, LW barrels probably need larger diameter slugs, while still working with skirted pellets.
 
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sonnysan said:
What is the groove diameter of your barrel after slugging it?

How to Slug an Airgun Barrel

This process is designed to educate the user to minimize wasting money on slugs where the probability of randomly purchasing slugs that shoot inaccura...
airgunwarriors.com airgunwarriors.com
Click to expand...
Super helpful to a newcomer who was planning on going with the 'just keep buying and trying' plan on slugs. Thank you!
 
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