Slug weight. Which to choose? .25 cal

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What velocity are you getting? What are “good groups” at 50 and 75? Also, do you know where your reg. is set or how fast you can shoot the JSB 33.95? Trying to get a baseline for your settings. 

The 33.5gr shoots pretty well out of the RAW but if I was you I’d buy some of Nielsen’s new 29gr. They are cheap and super accurate out of my RAW, probably the best yet out of any I’ve tested. Really, they’re that good. 

Stoti
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Stoti I have wondered if the dish based slugs as a general rule shoot better from a raw style pellet probe. Because these guns are designed for pellets with a recessed skirt. If there’s no recess and a flat base the slug gets pushed into the barrel to far. 

Im RedWolf with smooth x slug liner shoots cup based pellets well. It has the centre style probe. 
 
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In my FX Impact .22 cal. the NSA .23 grain flat base with .217 diameter. were not accurate but the .218 diameter were. I then bought some Griffin 23 grain .217 diameter with what they call 'dimple back' and they were just as accurate as my .218 NSA's. I was thinking maybe those dimple back bases were expanding some to grip the lands like my larger diameter .218 Nielsen's. Im hoping when I get my Crown Continumm in .25 caliber that the Nielsen's 29 grain .249 dia dish base will work as well as the flat base .250 diameter. Bill
 
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Air Supply, I've tried to figure out what makes some slugs shoot well and others terrible, in the case of the flat base vs. the dished base, there are many theories but I don't know. The bearing surface is the same, the dish base just a tad lighter. The skirt area on the dish base could expand a bit but there isn't much material there. The depth the probe pushes the slug into the barrel could be but part of it but I really have no way to know for sure. The new series of dish base slugs we've been testing all shoot very well in the LW barrel, all of them! Pretty impressive. Most of these new slugs will be offered with a flat base or a dish base. Some of the dish base slugs shoot really well out of the FX liners, it's just that the flat base usually shoot better. Could be the probe, just don't know.

AirgunBill, I can't speak to the .22 slugs accuracy, but I know when people first started shooting the .22 caliber slugs out of the FX liners there was a huge difference in accuracy depending on which diameter slug you were shooting... .217" VS .218". I Have a bunch of the Griffin slugs but unfortunately, I've never heard of a "dimple back". I really don't have any idea what that is, I can only guess. All of my Griffin slugs are either flat base, dish base or boat tail. Sorry, I just don't know anything about them. I should get my Impact back in about a week at which time I will thoroughly test the 29gr and all of the other new Nielsen slugs that I haven't tested well enough with it. I did test the 29gr a little bit out of my Impact before it took a dump...Again!! They shoot so well out of my RAW and from what little shooting I did with them in my Impact that they're the first ones I want to test when I get my Impact back. Get a hold of me in a couple weeks and I'll let you know how they shoot. Keep in mind what I said above, all of Nielsen's new lighter slugs are going to be offered in dished or flat bases. So, if the dished 29gr doesn't work well in the Impact, I'm sure the flat base 29gr will. It might be a while down the road, Nick is super busy right now with all of the different stuff he's rolling out but he did tell me all of the new lighter slugs will all be offered with flat or dished bases. Have a good one.

Stoti
 
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What velocity are you getting? What are “good groups” at 50 and 75? Also, do you know where your reg. is set or how fast you can shoot the JSB 33.95? Trying to get a baseline for your settings. 

The 33.5gr shoots pretty well out of the RAW but if I was you I’d buy some of Nielsen’s new 29gr. They are cheap and super accurate out of my RAW, probably the best yet out of any I’ve tested. Really, they’re that good. 

Stoti
Click to expand...

Stoti I have wondered if the dish based slugs as a general rule shoot better from a raw style pellet probe. Because these guns are designed for pellets with a recessed skirt. If there’s no recess and a flat base the slug gets pushed into the barrel to far. 

Im RedWolf with smooth x slug liner shoots cup based pellets well. It has the centre style probe.
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I've mentioned several times here on AGN that the "lead-in" is more important than most of us think. 

I had a .25 cal. slug I was going to shoot, that was used to cut the lead-in into my barrel to sit exactly where my bolt would seat it. 

No big surprise that anything shorter or longer just won't work in that barrel. Too short might shoot 4 - in one hole @ 40 yards and the 5th and 7th shot could be .5" - .75" outside. 

Too long (hard to close the bolt) and about 1" groups @ 40 yards. 

I got the same results with my stock .25 Cricket. 

In .25 cal. I would start light 30gr. - 32gr. unless you have serious FPE ......Just my thought. 
 
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I just purchased the Nielsen 36.2gr. slugs to run through my ImpactX. The chrony is telling me my avg. FPS is 740. I am thinking these may be a little too heavy for the gun. I have the reg. set at 140 bar and the hammer dialed out to 4 lines. I haven't adjusted the hammer tension yet but I am not sure what FPS to target.
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For a .25 caliber I would think your regulator pressure would have to be higher and hammer adjuster at or near the maximum. I just got my FX Crown Continumm .25 cal. and the reg. was set at 155 bar and the hammer adjuster set at .558" with the hammer wheel still able to use all settings of max through minimum. I was getting 890 fps with the 34 grain JSB's for 58 plus fpe. A good purchase to make for those with FX Impacts and Crowns and others that adjust spacings and clearances is a cheap digital vernier caliper like Harbor Freight sells or that you can get off Amazon for $20 bucks. It will aid in more precise and repeatable adjustments. Bill
 
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I have always had better results on average with heavier ammo in real world conditions (when shooting at long ranges). I have gravitated towards shooting projectiles with the greatest sectional density with PCPs (pellets included). The lighter stuff is fun to challenge yourself with, but the bigger projectiles hold together more consistently overall.

My advice:

  • Forget about BCs. They're pretty useless if the projectile does not shoot well out of a given barrel. Greater BC doesn't equal greater accuracy.
  • Learn how to break in, care for, and inspect your barrel. Hardly anyone ever stresses this point online.
  • Avoid "slugs" unless you're shooting long range or in brutal weather.


If you want to get nerdy with finding a bullet's optimal twist rate, see http://www.geoffrey-kolbe.com/barrel_twist.htm


 
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What’s driving me nuts is the inconsistency. I’ll have a good group going and then one will blow out of the group by an inch. Or I’ll have two in the same hole and the two more in a hole high and right.

This makes me think there is something “off” with the slugs but they appear to be beautifully made 

some one mentioned sizing. Can you elaborate on that. What you do and how
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What I've found is the liners are .245 thats way to tight for the size of available slugs.
 
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What’s driving me nuts is the inconsistency. I’ll have a good group going and then one will blow out of the group by an inch. Or I’ll have two in the same hole and the two more in a hole high and right.

This makes me think there is something “off” with the slugs but they appear to be beautifully made 

some one mentioned sizing. Can you elaborate on that. What you do and how
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Less than a .001 inches can make all the difference so sizing the slugs works. I’ve only just worked this out sizing some .218 slugs down and really tightening up th groups. In my case there was not much resistance pushing the slugs through the die but it really worked well. 

http://noebulletmolds.com/NV/index.php?cPath=564_104_412

In .25 I have 5 dies starting at -251 going down in size. Use the push rod at the bottom of the page to push the slug through the die. I clean them again after doing it. There is more info and more experienced on the forum if you search. 

Michael
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Are you using these dies, pusher through a Lyman sizing press ? 
 
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I have a impact mk2 700mm that shoots the 36.2 nsa slugs @900fps with the new tune on max and on power level 5 shoots the jsb mk2 at the same poi from 50-100yds with the groups that are so identical that I have one clip for slugs and the other for the mk2 JSBs. I go back and forth with Moa groups from both this is convenient for me when I run out of one or the other, I just adjust power wheel and need not touch my scope but I have not shot over 100yds yet. When I do I know I will reach a point with longer distance where the pellets fail and slugs will be the clear choice!
 
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