A little more FX, 600mm, slug liner testing info...

So, for those of you that have seen my posts testing the various slugs I have in the FX, 600mm, .25 caliber slug liner, I have a little more info for you guys. After I last posted all of the results I had up until that point, I wasn't really thrilled with the results I had been getting. After polishing the barrel a second time, results got a little better but still were not that great. Over the last couple weeks, I've been testing all of the same slugs at lower velocities and the results weren't very good. Kind of what I expected. The slugs seem to shoot better out of the FX 600mm liner at higher velocities, to a point anyway. Slower didn't improve my results so I decided to try faster!

So, lately I've been testing the slugs at higher velocities and the results are getting better. I turned my regulator from 154BAR to 160BAR and tightened the hammer spring one more half revolution. This increased my velocities on average about 20-25FPS. I've already stated that I've had best results with the flat based slugs and that has held true at higher velocities as well. So, to the point. Today I shot some really good groups with the Varmint Knocker slugs in 30gr and 30.4gr. The best group I've shot in all of my testing came today with the 30.4gr FB slug at between 925-928FPS. I shot a bunch of groups today and the picture below is the best yet, a 13 shot group at 50yds. All of the other groups were pretty similar to this one, pretty impressive. If you aren't aware, slugs are not as accurate as the JSB's at closer distances, that really can't be expected. Pellets(Diablo) have a self stabilizing design which makes them great at shorter distances. They also have horrible BC's which again makes them best suited for shorter distances. Slugs on the other hand are stabilized by the twist rate and velocity. They have terrific BC's, some upwards of .099, which make them best suited to longer distances. Luckily, with my gun sighted for the 33.95 MKII's, the 30.4gr slugs shoot about 3/8" high with the same zero. Works out almost perfect... I can shoot the MKII's out to about 50 yds. and use the 30.4gr. slugs at longer distances with the same zero. That is very, very lucky because all of the other slugs tested with the exception of one or two, had POI that were no where near the zero I use with the JSB MKII's. Some are 3" right, 2" low left, 3.5" high, you get the picture. They group well but the POI could be anywhere.

I'm still going to continue my testing but for those of you that have asked where to start, first and foremost, stick with the flat based slugs. In all of my testing, over 900 slugs shot so far, they have shot better than anything else. Second, shoot them as fast as you can. The only problem I had with too much speed was with the 25.4gr. AONCO at over 1000FPS and the 26gr. and 28gr. Varmint Knockers at between 980-995FPS. That was a bit too hot and the results showed it. They didn't shoot well at slower speeds either! For most of us shooting a Crown or Impact, anything from about 30gr and heavier should do fine as fast as you can push it unless you have a really hot or souped up gun. Third, if I had to do it all over and knew what I know now, I'd start with the 30gr., 30.4gr and 31gr. from Dale at Varmint Knocker. All of these slugs had the flat base and the large hollow point, I don't know why the large hollow points shoot so much better than the 2-S hollow point, but they do. I tried to test and shoot Rat Sniper but only had one tin, ran out and couldn't get anymore. I called numerous times, told the owner what I was doing and couldn't get anymore slugs. I was also told that the slug that was shooting the best, the 31.3gr Rat Sniper has been discontinued. He is making a light slug made especially for the FX liner, but I couldn't get any of those either because of the long wait. Hopefully when he gets caught up on production I can get some to test. I also bought a bunch of Nielsen's slugs to test, the 34.7gr. the 36gr. and 39gr but unfortunately my gun couldn't get them going fast enough to shoot accurately. I really like the Nielsen slugs, but the heavier weights didn't shoot well in my testing. I just wish he made a slug in .25 cal. that was a bit lighter. I think a 30.5gr. would be about perfect! His slugs have a large hollow point and slightly dished base and the weights are very consistent, I'm sure if I had a lighter slug it would shoot great!

So, in summary... shoot the flat base slugs, faster is better for the most part, shoot the slugs with the large hollow point, and start your testing in the 30gr-31gr range. I am no expert! However, I have tested over 30 slugs with different weights and designs and have taken detailed notes on every single shot. I'm doing my best to methodically test every variable I can to figure out what and why some slugs shoot better than others in these FX slug liners. Those are the things I've shared with you here. Liners may vary, but I think these results are a very good indicator of what will and will not work in a .25 caliber, 600mm FX slug liner. Keep in mind that these results are for the 600mm slug liner only! I've heard and been told that the 700mm liner shoots completely differently. Not sure if that is true or not though. Hope this helps at least somebody!

For the record... my fingernail is 5/8" across. This 13 shot group at 50yds is about 1" and 10 of the slugs are about 3/8". The other groups I shot today were similar but a tad larger overall. Certainly tight enough groups that I'd feel confident taking shots and smoking ground squirrels at 150+ yards! I'll give it a shot, or lots anyway!

One last thing, this 1:21" twist slug liner absolutely loves the JSB 33.95gr. MKII's. It will shoot 3/8"-5/8", 10 shot groups at 50yds regularly. If not, I screwed up, not the gun! 

SORRY, I'M SO LONG WINDED, JUST TRYING TO BE THOROUGH!

Stoti

1554349357_4587616075ca57d2de8bde7.83332377_IMG-1421 30.4gr. slug super group!!!.JPG


Anyway
 
You the man!

Really. Thanks for the summary

I was at the range on Wednesday and shot the Nielsen 34.7 gr. concave-based(?) slugs through my Impact at 970+ fps. They would not even group at 50 yards. At 100 yards, 10 shots looked awful. This was with the FX 700mm slug liner.

Ahhh, but then I went to my Taipan Veteran Long .25 cal. with the 21.5 inch LW barrel and things vastly improved with the 34.7gr. slugs. My 10-shot group at 50 yards was 0.624 inches. The holes on my "shoot n see" targets looked as though they were made with a hole puncher -- very clean and symmetrical. 

Groups with the Veteran at 100 yards looked very promising through 8 shots. The last 2 shots, number 9 and number 10, ruined the group. More testing and less wind is in order at 100 yards for the Veteran before any conclusion can be made. 

When I got home from the range I found a package had arrived from D-Rig containing Varmint-Knockers slugs:

*.22 cal., 22.1gr. slugs

and:

*.25 cal. 30.1gr slugs for my Impact with the 700mm slug liner.

I will update you as I get results on the Varmint-Knockers.

Again, thanks for your summary, it really does provide me useful info.
 
I'm sure the Varmint Knockers will shoot great for you out of the LW barrel. They usually do! If you've been shooting the 34.7 grain slugs at 970 FPS, you'll be able to push the 30.1 grainers at like 1015 FPS. Woohoo, smokin'.

Dale at VK has been a huge help making me exactly whatever I ask for to test. It's really helped me narrow down what works best and what doesn't. We've also talked many times and bounced ideas off of each other's heads to dial in this slug liner. His slugs really are awesome and the weights are crazy consistent! Thanks Dale!

I too have had a lot of great 10 shot groups that are plagued by one or two fliers. Not really bad fliers, just enough to ruin my good grouping. Really doesn't bother me anymore with slugs. It just seems to happen. After Dale told me to start shooting 2 - 10 shot groups instead of 1 or 2, five shot groups, so the gun could settle in to the slugs being tested, I really started being able to see what slugs were actually most consistent and showed the most promise. 

I'm perplexed by two things... first, why Lothar Walther barrels shoot slugs and pellets so well and why FX's liners, made specially for slugs from the ground up, are so hard to get to shoot properly? It shouldn't be this difficult to get one of 30 different slugs to shoot properly without having to polish my barrel twice, the second time aggressively. I don't want to talk negatively about FX because I've been absolutely thrilled with every product I've owned up until this liner and it is finally coming around. However, every single person I've talked with... store workers, slug makers, friends, video makers, testers, peers, etc... without exception has told me that they've had problems getting the .25 cal. slug liner to shoot accurately, consistently without much trial and error. It's really too bad. I wish it wasn't this difficult but at least I'm getting mine figured out.

The second thing that I can absolutely not figure out is why the large hollow point slugs shoot so much better than the 2-S tip hollow points? In almost every instance, the large hollow points shoot better. I really wouldn't care but the large hollow points don't shoot with the velocity of the 2-S hollow points. Sometimes the same slug with the large hollow point can be 25FPS slower other times similar slugs only 10FPS difference. Why? I guess as long as they're accurate it shouldn't matter but those are the types of things I've really been thinking about throughout this whole testing process. Just bothers me not to know why.

Have a good one. Kevin
 
Nice review Stoti, 1:21 twist rate?! I am lost with twist rates now! for slugs it suppose to be faster like 1:16 and you are shooting with a slug liner @ 1:21, me on the other hand with a pellet 0.22 liner shooting slugs good (moa accurate) with a twist rate of 1:19 it is weird!!

Today I will get a new batch of slugs in my hands to test.
 
The 600mm 25 caliber slug liner is indeed 1:21 twist rate. The original STX liner that came with the Crown is 1:27 or 28 twist rate I believe. I've talked with Bob O quite a bit about the twist rates. It sounds like they made the .22 cal liner faster but chose to go with 1:21 for some reason with the .25. It really depends on what slugs you choose to shoot and explains why the lighter slugs are shooting better than the heavier slugs in the .25. Don't know why or what the thinking behind it was? In any case, they got the .22 slug liner right, they seem to shoot great. Maybe they just need to dial in the .25 caliber liner like they did with the .22 and the .217 vs .218 issue in the beginning. Who knows?

Stoti
 
stoti - You test things out the way I like to do things... Big!

Great info. your're sharing with us. I know this is a FX barrel liner you're testing here. 

But, I believe some of these things your doing, do pertain to other barrels too. 

I find it interesting that in .25 cal. your best weight is 30.5 gr. give or take.

Because I have found my Cricket .25 cal. likes that weigh best. I swag my own slugs with 4 different bases. 

I've found that a heavy cone base in that 30.5 gr. weight to be the best, so far in my barrel. 1-18 twist I think. 

Obviously there's a lot more than weight alone involved in achieving the kind of accuracy we all want. 

I just found it to be interesting that a similar weight 30-31gr. in .25 cal. worked well for you with the FX also.....


 
Great thread. I've been thinking back to the days I first started watching Cedrics aka 'tofazfou' videos and his . 257

Fx must be going with a slower twist rate because the slugs we are shooting are really quite small, at 30-40gr they are hardly much longer than they are wide.

I recon once we are able to push these weights 'too fast' and are looking to heavier slugs then we will see faster twist rates needed as the longer the slug the faster you will need to spin it to get them stabilised.