Old "Favored" .22 Caliber JSB 25.39 Monster Design - Which One?

[KodiakJac]

I've only been shooting PCP airguns for about 2 years, so I'm catching up on the various .22 caliber JSB 25.39 pellet designs. And I recently saw a post about the various .22 JSB 25.39 pellet designs and redesigns that I can't find now, so here is my question in a new thread...

From what I understand, there is the current 25.39 MRD in .22 that started production in 2022. They are currently called the "redesign." And then there is the older 25.39 that ran from 2019 to 2022. And then there was the 25.39 design that were in production prior to 2019. So, there are 3 versions that I think are being referenced...

2022
2019
pre-2019

And then there is the post from someone representing JSB (or a JSB distributor) that said JSB has been listening, and that they are going back to the 25.39 design favored by benchrest shooters. But which favored design are they talking about? The 2019 design or the pre-2019 design (which I've never seen). I guess this old, favored design should reach the U.S. market in about 90 to 100 days according to the post I saw?

Thanks!

 

[KodiakJac]

Cross post from Hard Air Magazine Forum...

@JSB/Predator Official / @Predator Int.
Hello gentlemen,

I'm happy to report JSB will be ready to ship the old style MRD in about 2 weeks, which means we'll have them in stock in the USA in about 100 days. They will have a new unique label and have extra packaging protection, as it was the thinner skirts that were damaged too often that made them go to the thicker skirts several years ago. Anyway, stay tuned and keep on the lookout in about 3 months at your favorite retailer.

But still not sure which "old style MRD" they are talking about.

 

[Franklink]

The earliest couple years of Monster RD production is what we want back. The ones that shot well, ie went where they should.

Production for the last couple years has been rough, flyers galore. Broken many hearts in competition and elsewhere.

I'm personally not so sure it is as simple as skirt thickness or depth. I've inspected and attempted to sort here and there, with mixed results. JSB has always changed the pattern slightly, with just a bout all their pellets. Sure various design tweaks would shoot slightly different, but not absolutely horrible versus exceptional. The .22 MRD is the only pellet I've ever tried to sort, and only because theyre the only JSB I've ever gotten frustrated enough with accuracy from TO resort to sorting.

I'm currently involved in a huge personal vendetta against these pellets. This involves extensive and methodical testing from a couple different barrels, changing one factor at a time (barrel and pellet), to try to unravel what about the the later batches causes the flyers.

I'm kinda leaning to the opinion that they're not concentric, like the two halves are ever so slightly misaligned, causing an imbalance and therefore junky flight characteristics. (They certainly not round, but pellets typically aren't and it doesn't usually cause a huge problem. So it's not a round versus oval issue, but rather one half is heavier or not symmetric to the other half).

 

[KodiakJac]

Thanks for the explanation, @Franklink !

 

[bigHUN]

Since 2020 up to 2023 I have seen several revisions in MRD's but never could remember the batch numbers which one I liked the best.
The difference in Dictionary for ordinary people is in skirt thickness. But if you start digging deeper in your brain, the skirt thickness affects the center of gravity, because a 25gn is a 25gn, the material from skirt thickness will need to be moved somewhere...right? Move the material from the skirt into neck or into head?
So from this standpoint, all those 3-4 versions of MRD's have their own personalities.
Currently I have probably at least one tin of each version probably ten tins like that in total.
Last time I was comparing earlier in a Spring, and I can remember only if I compare them from a same liner they will group different. Shoot from other liner will group different, shoot from next liner again ...
So that center of gravity thingy in each version will behave different every time with different twist rates.
Like 1:16 or 1:17.7 or 1:19 or 1:24 or 1:27 or whatever.
And then you figure which twist rate would need what speed.
And this how the game goes on for couple of weeks I promise you.

Pretty much up to 50 meters rings I could get a MOA in a good day, but in a good day I can do that with 15gn AAFFT or 16gn Baracuda or 18gn Baracuda as well, or the 21gn Baracuda for example.
but at 70 my MRD's started opening up and the lighter pellets started drifting, and 100 is mostly just ripping your hair off.
Some people claim to push the MRD's same as the slugs speeds 960 fps and higher...1000...1050 fps. I have no comment for that.
You gotta try
Welcome

A

 

[MartyMcFly]

I’m not a metallurgist so this might be off the mark but I don’t think anyone has mentioned lead alloy porosity. If the wire that is used to swag pellets has bubbles then simple weighing or deformation culling will still miss bad pellets.

So maybe part of the problem isn’t the shape but JSB’s lead supplier or whatever process that is used to turn it into wire/swag balls?
-Marty

 

[mackeral5]

But when they are good, often times 3 go into a single ragged hole, only for shots 4 and or 5 to make the group open up to 2moa....

I have only shot them in 950-1010fps out of 1:16 to 1:18 barrels
I have not tried them in slower twists, perhaps that is a missing link.

Right now my best performer is a 700mm CZ .22 that had the OEM burrs cleaned up at each end as well as a tapered lapping. I believe it measures between 1:17 and 1:18


I know this isn't necessarily logical, but MRD's seem to me to be much more sensitive to the entire process, even hold sensitivity and follow through. That may just be my imagination though as these pellets keep me guessing. Very sensitive to wind, but of course this could be my shooting at higher velocities coupled with a relatively fast twist.

In calm wind conditions swapping to 18gr without any changes results in just under 1100fps and is as accurate as MRD's, sonic crack and all......sometimes the 18gr running faster than they should run are even more accurate than MRD's.

 

[RangerPete]

I’m not a metallurgist so this might be off the mark but I don’t think anyone has mentioned lead alloy porosity. If the wire that is used to swag pellets has bubbles then simple weighing or deformation culling will still miss bad pellets.

So maybe part of the problem isn’t the shape but JSB’s lead supplier or whatever process that is used to turn it into wire/swag balls?
-Marty

25gr of lead is still 25gr of lead, with or with out bubbles.
And the way the 25gr lead “lumps” (balls) are “smashed” into a pellet shape lead lump in those huge presses, I personally think any “bubbles” in the lead are going to be compressed into a non issue

 

[Spinach]

Last year I purchased 20 tins of .22 redesigned. What a disappointment.

Tried them in cz barrel, 1:16 twist RTI and a RTI 1:32 long range barrel. No consistency with these latest pellets.
My head was hurting, so much so I found more satisfaction using slugs.

Let's hope the latest redesigned redeem themselves, I'm certainly looking forward to testing them.

 

[Franklink]

A couple mentions of bubbles and porosity......

This is from a while ago, and not a .22 Monster RD, but makes a guy raise an eyebrow for sure.

A JSB (FX) .177/10.34, in all its glory...

Interesting JSB/FX 10.34

Pulled this out of a tin of FX branded 10.34s a bit ago, while shooting. Got back in the gunroom and decided to weigh that little misfit. 10.2grains. hmmmmm. Thought to myself that the only way for a bulged out pellet to weigh less than it should is if there's a void in there. Razored that...

www.airgunnation.com

 

[MartyMcFly]

A couple mentions of bubbles and porosity......

This is from a while ago, and not a .22 Monster RD, but makes a guy raise an eyebrow for sure.

A JSB (FX) .177/10.34, in all its glory...
View attachment 401616
View attachment 401617

Interesting JSB/FX 10.34

Pulled this out of a tin of FX branded 10.34s a bit ago, while shooting. Got back in the gunroom and decided to weigh that little misfit. 10.2grains. hmmmmm. Thought to myself that the only way for a bulged out pellet to weigh less than it should is if there's a void in there. Razored that...

www.airgunnation.com

I knew I had read about it before! Thanks for the refresher. I recall some online source indicated that if the smelter had high humidity the result was hydrogen separating from the water/steam and causing bubbles in metal. The one you cut open is an extreme case but surely it’s not as uncommon as we may think.

-Marty

 

[Gear_Junkie]

The first batches of the Monster RD were the best. Current production (and for the past year +) has been very poor quality and consistency. 1 out of 5 - 10 pellets is a flyer, which is unacceptable. I've gone back to AA 18gr.

 

[Airlead]

Good day
I'm new to the 0.22 caliber. Currently for my 0.177 caliber 12ft/lb, I weigh and size my palettes also JSB 8.44 gr. I bought some JSB redesigns and JSB Exact Jumbo Monster, same weight. Playing around I decided to weigh them too and found quite a difference. From 25.21 lowest weight to 25.84 highest weight. My question in all of this is does everybody have to do the same thing or do we in SA just get the bad batches? Also will this really have an impact on HP guns? Recently bought a Red wolf safari HP. My focus will be 50m and 100m Benchrest. Any advice will be appreciated.

 

[wimpanzee]

i bought a bunch of tins of the .22 MRDs in early 2021 and they are all crap in my k1. Like others said, a few good shots then fliers. They are all the thick skirt variety.

 

[Reg Creep]

Good day
I'm new to the 0.22 caliber. Currently for my 0.177 caliber 12ft/lb, I weigh and size my palettes also JSB 8.44 gr. I bought some JSB redesigns and JSB Exact Jumbo Monster, same weight. Playing around I decided to weigh them too and found quite a difference. From 25.21 lowest weight to 25.84 highest weight. My question in all of this is does everybody have to do the same thing or do we in SA just get the bad batches? Also will this really have an impact on HP guns? Recently bought a Red wolf safari HP. My focus will be 50m and 100m Benchrest. Any advice will be appreciated.

You're experience is average. I've weighed many a tin, and seen spreads of over a full grain between high and low. Also true with the FX of the same design.

 

[RangerPete]

A couple mentions of bubbles and porosity......

This is from a while ago, and not a .22 Monster RD, but makes a guy raise an eyebrow for sure.

A JSB (FX) .177/10.34, in all its glory...
View attachment 401616
View attachment 401617

Interesting JSB/FX 10.34

Pulled this out of a tin of FX branded 10.34s a bit ago, while shooting. Got back in the gunroom and decided to weigh that little misfit. 10.2grains. hmmmmm. Thought to myself that the only way for a bulged out pellet to weigh less than it should is if there's a void in there. Razored that...

www.airgunnation.com

Wow! That is very interesting indeed.
Almost impossible to explain!

My understanding of the pellet production process is that the lead is melted and extruded into long continuous wire.
You wouldn’t expect there to be bubbles in it, but I guess it is possible.
The diameter of the extruded wire will contribute towards determining the pellet weight.
The wire is then stamped into a ribbbon which has balls in it. Each ball of lead will become one pellet and thus the weight of the ball will determine the weight of the pellet. If they stamp bigger balls from thicker wire, heavier pellets, thinner wire equals smaller balls and lighter pellets. The ball, with their pre determined weight are then “smashed” or pounded or compressed into the dies. Because lead is so soft it will conform under pressure to the shape of the die with out needing to be heated, softened or melted.
Well that’s my understanding of the process anyway.

So how the heck can you account for a cavity inside a pellet…? Well there must have been a bubble in the ball/wire…? Ok.
That’s plausible.

But there is no way to account for the bubble expanding AFTER the ball of lead has been cold pressed/compressed into the die and mounded into the shape of a pellet…???

I’m at a total loss…???

Someone enlighten me

 

[BSJ]

Air is a compressible fluid. Once the pressure is released it expands back to its previous volume.

You know, like how airguns work.

 

[MartyMcFly]

Air is a compressible fluid. Once the pressure is released it expands back to its previous volume.

You know, like how airguns work.

Most likely! My guess is that the wire had a compressed air bubble, which expanded when the lead surrounding it became thinner in certain point as the pellet was shaped. Thin enough for the air to finally bulge out.

-Marty

 

[Spinach]

Myself, like many others have had a bit of a rollercoaster lately with the redesigned.
I went from loving the MRD to hating them after I purchased my last 20 tins.

It's been mentioned before, JSB have redesigned the MRD. Latest version.

I've tested a few variations out to 50m, 55yds. So far I'm impressed. Just need the weather to improve . So far I'm optimistic.

Posting this is probably going to raise a few questions, that's not my intention. Let the testing continue.

My intention is simply, JSB are working on it. So far I'm optimistic.

Gary

 

[EPG]

I have some amazing targets with MRDs… and some flyer ruined targets.

I had more consistent results shooting the 18.13g in .22 cal - with a wide velocity range. (18.13s have shot great at 800fps up to 1,025 fps).

Its a big jump from 18 to 25g. I’d love to see JSB offer a 21g - similar to the H&N Baracuda at that weight. For 25g, I prefer the .25 cal JSBs - really nice, consistent pellet.