My .22 Impact slug shooting journey begins!

I'd like to thank Heavy-Impact for posting some info on modifying the Impact barrel port and probe for more velocity. I did a mild porting job last night with the Dremel and a carbide rotary burr. With the same settings the velocity of the JSB 18.1g increased 59 fps (1021 fps to 1080 fps) and the velocity of the NSA 27g slugs increased 48 fps (892 fps to 940 fps). Neither pellet nor slug loading seemed any different. Thanks! 

Today is a perfect day: clear, sunny, warm and calm. I tested seven of the slugs at 100 yards. Here's what all the groups looked like. I wrote the average group velocity and the group measurement in Sharpie next to the group. Click on the image once to pull it up on Imgur, click on it again and it "should" zoom in more (it does on my computer).

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One slug really stands out: the Griffin 24g 0.218" dish base. It shoots well under 1" at 100 yards at multiple velocities. I'll pick up a 100 pack of these and do some more testing but it looks like this is the one I'll go with.

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Just for fun I tested the 24g Varmint Knockers. At max settings it was averaging 975fps and shot a 5-shot group of under an inch with 4 of the shots at 0.50". I'll play around with this a little more. I bought a 100 pack so I may zero it at 50 yards and try it on pigeons today. 

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I plan to try some of the new design NSA 23g slugs out soon. 

I zero'd my Impact with 24g Varmint Knockers doimg 945fps at 50 yards and checked holdovers for both 40 and 60 yards. I then went to the local pigeon hangout near the RR bridge and tested them out. Just a handful if pigeons today. The first was at 58 yards but there was a stiff cross wind. I hit it less than ideal but it fell out of the sky within 50 yards of flying. The second one was the same range but the wind was less and it went Straight Down. Whop! No movement.

I just picked up 100 more of the 24g 0.218" to test more extensively. These are the ones that shot the great groups so I feel confident I call fall back on these if nothing else is more accurate. I also bought 100 of the 25g 0.218" version. Mike included a handful (20?) of some 23g 0.218" that his son's Impact shoots well as well as some 30g 0.217" BTHP and 30g 0.218" BTHP to test out. I'm trading another AGN member for some of the new NSA 23g HP slugs to test out. That's five more types to try out!!!! I'll post results when I get a chance. 

Today I tested out four new-to-me types of slugs. Griffin 23g 0.218" dish base, 25g 0.218 dish base, 30g 0.217 BTHP, 30g 0.218" BTHP and the new NSA 23g 0.217".

The Griffin 23g & 25g 0.218" dish based slugs show some promise. I only have enough of the 23g for one 100y group but have a bunch of the 25g. That makes Griffin the three most accurate (at least at 30 yard testing) slugs in my 600mm Impact. The 23g & 25g 0.218" dished based slugs are all worth trying at 100 yards in the 920-940fps range. I already know the 24g shoot 2/3" groups at 100 yards.

The NSA 23g weren't anything to write home about. Average slug accuracy for me.

The 30g BTHP look BEAUTIFUL but had some major issues. They wouldn't load. Out of the nine I shot from the 0.217" sample batch about 1/2 wouldn't load and I had to use a cleaning rod to push them backwards. Some wouldn't chamber and would stick 1/2 way into the loading port and jam the magazine. One double load because of this issue. When they did load they shot OK with velocity not down as much as I'd expect from the 23-25g stuff I'd been shooting. I was so frustrated I didn't even try the 0.218 BTHP batch. I think the problem was I modified the pellet probe for higher velocity. The tip of it now looks like a "C" shape. I think the probe wasn't pushing the rebated tail evenly, causing the pellet to tip and the nose tipping down into the transfer port.

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Tomorrow I hope to really wring out the 24g & 25g Griffins at 100 yards, then then order more of the best shooting ones. I'd like to go on a full day pigeon hunt on Veteran's Day and see how many I can bag.

The target is 1" diameter. I had a stamp making company make it for cheap, under $20. It's made thousands of targets on cheap typing paper. I'd highly recommend it.

Today was a beautiful day, calm and sunny. I got home from work, set up the bench, put out targets, set up the chronograph and started in. I wanted to test four types of slugs at 100 yards. Here are the results. My chronograph worked perfect yesterday under the same lighting conditions but didn't even register one shot today. Piece of junk! The four I tried were: Griffin 23g 0.218" dish base, Griffin 24g 0.218" dish base, Griffin 25g 0.218" dish base and Varmint Knocker 24g. I only had three of the 23g and I think I've got an indication they aren't the best for my Impact, same with the Varmint Knockers. I didn't feel like I was shooting well today (eye issues, shadows on the targets, etc). I'll try to test the 24g & 25g again tomorrow after work and order more of the best ones for a Veteran's Day pigeon hunt on Monday.

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My target stamp looks like this. It's a "2000 plus" model sold by "thestampmaker.com" (888) 451-7300. I contacted their sales department and e-mailed them an image of the target shape with directions to make it 1" diameter and red in color. Less than $20 delivered. I bought two and gave my best friend one for his birthday. I ink mine up every couple years and it's gone strong for nearly a decade.

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I always aim at the bullseye but I do adjust the scope turrets between groups if the previous group was a ways off.

I shot five 5-shot 100 yard groups with both the 24g & 25g after dark last night. The 24g shot better average groups by about 1/8 inch. I ordered a bunch of the 24g 0.218" dish based slugs to fine tune and hunt with into the future.

Thanks to Mike @ Griffin for a great product, reasonable prices and very quick shipping!

After 2 months of no daylight after work and windy weather on the weekends, it was calm yesterday afternoon so I took off from work and shot the Impact again. I tested the Griffin 24g 0.218" dish bases slugs a 6th or 7th day? The first few days were with 3 shot groups. The last 5 sessions were either 5 shot groups or 10 shot groups. I feel that 3 shot groups only shot an indication of potential accuracy and are statistically much easier to shoot small groups. 10 shots really shows what it will do. Anyway, after 36 groups over those 5 days I made a chart to see what velocity I'll tune it for. Sometimes lighting was getting dim and eye strain was an issue so some of the not-so-good groups were my fault. I shot well over 400 slugs doing this. The 7 best groups are in the 930-940fps range so it looks like 935fps is where I'll set it at. I'd like to get the 935fps by tuning the regulator pressure with the hammer spring tension on MAX. That way I can turn it down to MIN and possibly shoot pellets at the 900fps range and get more shots before it falls off the reg.

I'll zero my Impact for 40 yards and set the zero stop there. I'll use the dial for further ranges (60+ yards) and if I have time to range/dial the scope. For closer shots (-40y) or quick shots I'll have a holdover chart and use the reticle. I'll be getting an Athlon Midas TAC 4-16 pretty soon and I can't wait to try it out.

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