I started some magazines soaking late yesterday and shot into them this morning. This paragraph will all be things I've posted before so if you've heard it before feel free to skip ahead. I shoot wet paper based upon writings by Finn Aagard who was a professional hunter in Africa and later a writer. Finn said penetration in wet paper (he used newspaper as I used to) better simulated penetration in animal muscles than things like ballistic gel. I also use wet magazines because they cost me nothing. I just save them up and shoot them. My minimum standard for penetration is my Prod. With it's original tune I lost a couple squirrels and hung one I did kill on a tree to see how far various pellets would penetrate. None made it through. My Prod was tuned to 12-13 fpe. I did a retune to it's current level of about 18 fpe. With domed pellets it will shoot through a squirrel at 25 yards but only if I do not hit the shoulder or other heavy bone. I've only lost one squirrel since the retune and it was a brain shot that flopped itself into a rotted out area of a large oak. I always shoot a few pellets from the Prod into the test block of paper. I get fairly consistent results but this lets me calibrate one test to the previous tests. Normally the Prod penetrates about 9-10 magazines.
I used mostly American Rifleman magazines but there were a couple old Car and Driver and one or two AARP magazines in the stack. They average about 80 pages. Glossier magazines like the BMW magazine I also get seem to resist penetration more. They might also have more pages. So I try not to use those. As long as the magazines have about the same number of glossy printed pages and about the same number of pages I don't think it matters what they are.
I fired at least 3 projectiles of each type into the block but I couldn't find a couple. That is not unusual for me, that's why I shoot several. There will be pictures so you might want to know the Prod is at the bottom left, next to it is the P35-177, then my Caiman X, then my P35-22, then the P35-25. I thought this bottom portion of the pile might be more consistent but when I took it apart I don't think it was. I got more penetration in a couple shots that hit low and might have skipped a magazine or part of it. On the top right there are several shots from my 25 caliber Avenger and then to the left of that several from the P35-22 shooting metal mags and further left 4 H&N 34 grain slugs from my P35-25.
The Prod was shooting H&N copper plated FTTs at about 750 fps. The two pellets I found went through 9 magazines.
The P35-177 was shooting H&N Baracuda FTs at about 880 fps. I found 1 in the 9th magazine and three in the 10th. One fell out of the 10th.
The Caiman X was shooting H&N Baracuda 18s at about 920 fps. I found 2 pellets in the 17th magazine, one in the 18th, one low in the 19th and one low in the 20th.
The P35-22 shoots H&N Baracuda Match at about 820 fps. I found three in the 17th magazine and one in the 19th but it hit low.
The P35-25 was shooting JSB MKII heavies at about 750 fps. I found them in the 18th, 19th, and after the 20th magazine.
The 25 Avenger was shooting FX 25.4s at about 900 fps. I found them two in the 15th magazine and one in the 17th.
I found 2 of the three metal mags I shot in the 6th magazine. I don't know their velocity but I was using the P35-22 so it was probably close to 900 fps.
I found the 4 H&N slugs from the P35-25 in the 10th, two in the 11th, and one in the 13th magazine. Velocity was probably only about 700 fps.
I shot the metal mags and the slugs just to illustrate the difference expansion makes. The P35-22 shooting the domed pellets it likes went through 11 more magazines than the metal mags. I would not use a metal mag from this gun on a squirrel because in my opinion the penetration is insufficient. This sort of result is why I test. On the other hand, the 34 grain slugs penetrated sufficiently even if it was 7 magazines or so less than the pellets. Using them instead of pellets could limit over penetration.
This was a new pellet for the P35-177 since my last test with it and the Caiman X is a new gun for me and a new pellet. I used to use slightly heavier H&N Baracuda Match in the 177 but the penetration of the under 11 grain FTs was fine. The Caiman X is similar in fpe to the P35-22 shooting 18 grain pellets faster than the P35s 21 grain. Penetration was about the same with the Caiman possibly going a bit deeper. This type of penetration turns into a high percentage of exit wounds in squirrels in my experience. My 25s are modestly power in the world of 25 caliber airguns but with domed pellets they have plenty pf penetration. With the right expanding pellet or slug they should still be fine for small game.
The first picture shows the magazines in the drywall bucket I soaked them in. The twine was very loose before they soaked in the water. The next picture shows the pellets I dug out of the paper. The metal mags are on the bottom and the slugs in the middle right. The expansion is pretty obvious. The domed pellets show rifling marks but otherwise look about like what they did before I shot them. I had a picture of the front of the paper file but it seems to be too big. It doesn't show a lot but the holes of the paper do not look bigger, at least at the front and to my eye inside the stack, for the expanding projectiles. They probably are bigger holes but the difference is not remarkable enough for me to notice it.