Preparation for Slugs in FX Crown 22

[Bob_O]

Thought I'd do some chronograph work today while I wait for my Slug-X liner to be shipped.

I was curious if my Crown could push the 21gr NSA slugs to 930fps out of the 500mm barrel. The short answer is no. Not at 150bar anyway. 

I did not do any testing at higher reg pressure as I didn't want to push the limits of the gun. That and the gains were minimal going from 140 to 145 then 150bar....only 10fps faster.

The best I got out of it was 905fps shooting 21gr H&N Barracuda Match pellets. This was done at 150bar, TP-25/30, PW-Max (adjusted for max pre-tension).

Compare that to 895fps with the same power settings but at the lower reg pressures of 140 and 145bar. This is why I said the gains were minimal.

Using the TP setting of 177/22 lowered the velocity anywhere between 10 and 30fps depending upon PW setting.

I already had a good idea that the 21gr weight would not reach that velocity in the short barrel, as Roelf from Air Hunters advised me he didn't think 930fps was possible out of the 500mm barrel. He recommended the 19gr slugs.

I ran a shot string with the 21gr pellets just to check what the performance was like....it's impressive as you can see.

So to sum it up.....if someone was wanting to shoot the 21gr slugs at 930fps, a 600mm or longer barrel would most likely be needed. 500mm just isn't enough length for the 21gr to accelerate any faster than about 905fps.

Just thought I'd share my observations with those who are waiting or wanting to go the slug route with the FX guns.

 

[cahil_2]

What velocity do they need to be stable and accurate?

 

[Bob_O]

Roelf advised me to aim for 930 to 950fps. I can get 970 fps from 18gr pellets so the 19gr slugs should fall into that range easily.

 

[HD2010]

Nice homework Bob.

 

[Bob_O]

Thank you Sir!! 

 

[Spray1Mark]

On a slightly different not here I was also thinking earlier that the 500mm .22 barrel is the limiting factor on the Crown. I wanted to shoot the 25g monsters rather than buying the Daystate RW HP just to get the extra velocity.

Anyone know if FX will make a .22 600mm STX normal barrel?

 

[AirSupply]

On a slightly different not here I was also thinking earlier that the 500mm .22 barrel is the limiting factor on the Crown. I wanted to shoot the 25g monsters rather than buying the Daystate RW HP just to get the extra velocity.

Anyone know if FX will make a .22 600mm STX normal barrel?

Hi Mark. They already do make the 600mm barrel in.22 and I’m pretty sure a 700mm .22 barrel is in the pipeline as that is what Matt Dubber is now using on one of his Impacts. The Impact and Crown barrels are interchangeable. I have the .22 600mm on my Crown. 

Michael

As a side not the redesigned monsters don’t shoot at all well from the A liner. Thayne Simmons used the B line in .22 at EBR and did well but there not available yet. 

 

[AR]

"Bob.... you don't think the 19gr will be accurate in a 600mm slug liner? 

 

[Bob_O]

I hope the 19gr is accurate in the 500mm barrel that I have. 

The 600mm barrel does me no good as I don't have a sleeve and shroud that length. If I did, I'd shoot the 21gr slugs.

FX states that the lighter slugs will shoot better out of the 500mm barrel, but they list 21gr as the lowest in the range. No mention of the 19gr. If they don't do well, I'll try the 21gr slugs at 900fps.

 

[jking]

Bob, have you thought about trying to add some hammer weight while going with a higher regulator pressure like Ernest has done here?

Jking

https://www.airgunnation.com/topic/earnests-crown-hammer-mod/ 

 

[Bob_O]

I have but it would just amount to more wasted air with the short barrel. When I got 895fps at 140bar, it sounded good. Same velocity at 145bar but more air out the barrel. Only 10fps more at 150bar with more air out the barrel and a lot more recoil.....probably not accurate despite the tight ES.

 

[Bob_O]

On second thought, only a longer sleeve is needed....the shorter shroud would work regardless of sleeve length. You'd just have 100mm of sleeve showing when fully retracted.

 

[socaloldman]

Bob, Not trying to hijack your post but you posed an interesting note about the 21gr H&N's.

What kind of accuracy did you get out of the HN 21gr Match? I was just testing some today out of a Cricket and very surprised at the performance. Shot higher and maybe faster than the JSB 18's. Did not have chrono with me but the gun was sighted with JSB18 and these 21 shot 1.5 inches higher at 46 yards. Shot very tight. just a first time test so no extra details. Thanks Enjoy your stuff always. Nick

 

[Bob_O]

I didn't get to shoot them at the range, just in the basement over the Chrono yesterday.

I did shoot them at a 50ft indoor shoot a few weeks ago though, and they didn't group well at the close distance where I can usually get most of the AA or JSB pellets in a 3 or 5-shot group to touch or make a ragged hole.

 

[ChuckHunter]

Now that I know the real difference in these X barrel's I wonder if the unchoked slug liners will perform with harder alloy pellets like the H&Ns are? That would open up a whole new world for FX that is based solely around JSBs....

James from Michigan, 

 

[Bob_O]

Someone posted somewhere that pellets shoot well in the slug liner. I don't remember which pellets though.

 

[Centercut]

Ernest was shooting .22 cal 18.1 JSB at 1020 to 1030 FPS in the slug liner at 95 yards and getting good groups. Don’t think they were MOA but they were close. 

 

[Bob_O]

Thanks Cc.......that's the information I remember.