Beeman SS1000H Dual-caliber rifle combo - Part 6
.22 barrel retest
by B.B. Pelletier
It's been quite a while since I tested the Beeman SS1000H Dual-Caliber rifle combo, and if a reader hadn't recently pried me out of a stupor, it would have been even longer. Someone asked if the rifle was back from Beeman yet, and I discovered that I hadn't sent it. Don Walker at Beeman had asked me two weeks ago to send the rifle with both barrels and a report of what velocities I was getting. So, in preparation for that, I installed the .177 barrel to see how much velocity had been lost since I first tested it in November 2007. Very little, it seems.
Velocity with .177 Hobby pellets
A string of eight RWS Hobbys ranged from a low of 963 to a high of 993. That's not as tight as I would like to see, but it's acceptable. I hadn't tested the rifle with Hobbys the first time around, so there was nothing to compare to, but clearly this rifle was performing to spec. I needed to shoot something I could compare to.
Velocity with .177 Kodiak pellets
Beeman Kodiaks were tested the first time around, so I shot five through the Chrony, just to see where things stood. The first test gave an average of 806 f.p.s. and this time the average was 787. That's lower, but close enough that the rifle is still performing within spec. And there were no shots at significantly lower velocity this time.
Had the rifle somehow healed itself? Had I been mistaken in my measurements the first time around? I would have to install the .22 barrel to find out.
Installing the .22 caliber barrel
When I installed the barrel, I looked closely for any problems that might cause a velocity loss with this barrel. Things like nicks at the breech or looseness in the barrel mount were what I looked for, but I also just looked to see if anything seemed out of place. Barrel looseness has been a complaint from more than one owner, but both barrels on my test rifle fit tight. Walker had suggested that I check the breech seal because he had experiences with them falling out. The one in the test rifle never fell out, but there was a small ragged piece of rubber coming off the inside of the O-ring, so I removed it and flipped the O-ring around. That's an old spring gun trick that usually restores performance, if the breech seal is the problem.
Velocity with .22 Hobby pellets
On the first test of this rifle with .22-caliber RWS Hobbys, it averaged 748 f.p.s., but two shots in the string of 10 that were not considered in the average went 517 f.p.s. and 500 f.p.s. This time the string averaged 760, but three shots that were not considered went 491, 501 and 590, respectively. This was the kind of performance I experienced on the first test of the .22 barrel, but now I had some new data. The rifle wasn't slowly losing velocity - otherwise the test with the .177 pellets would not have come out so high. And, this time, the .177 barrel had not a single low-velocity shot, where in the first test it had several. Instead of losing velocity, it seemed as if the rifle was trying to hold its velocity, with occasional drops of several hundred f.p.s. That's not normal, but it's also not indicative of a failed mainspring.
I no longer think the rifle has a broken mainspring, like I originally thought. Instead, it seems like something mechanical is getting in the way of the pellet sometimes. Whatever it is, it isn't happening with the .177 barrel any longer. I examined the muzzlebrake on the .22-caliber barrel very closely for signs of pellet impact, but there are none. I also felt for air escaping at the breech and there is none.
Velocity with .22 Kodiak pellets
On the first test, the rifle averaged 544 f.p.s. with Beeman Kodiaks, and there were no lower-velocity shots. This time, the gun averaged 566 f.p.s., and again, there were no slower shots! That's 14.94 foot-pounds of energy at the muzzle.
It seems I panicked when I pulled the plug on the test before. The rifle is, in fact, shooting well, but it does seem to have a strange quirk that I will associate with break-in. I've never seen this kind of performance before, because, during break-in, rifles are normally dieseling and shooting much faster - not much slower. I still don't know what's going on, but things seem to be sorting themselves out - and it looks like each barrel had the same problem that had to be worked through. That would make it a barrel problem, and not a permanent one.
Do you notice that the average velocities for specific pellets from earlier tests and these tests are close to each other? For some strange reason, the .177 seems to be getting slightly slower while the .22 is getting faster. And, the rifle is slightly more powerful in .177 than in .22, which we've also seen in other modern spring rifles, like the Gamo CFX. So, what's next?
I won't send this rifle back to Beeman, because I don't think there's anything wrong with it. I think the break-in it has received so far, which has been under 300 total shots, hasn't been sufficient to sort things out. I'll continue to shoot it and test it for you. The next test will be accuracy with the .22 caliber barrel. If we see some vertical stringing, it may be due to abrupt velocity changes.