Multi-Pump Conversion of MP 46 M by Innova USA

Multi-Pump Conversion of MP 46 M by Innova USA

Joined: September 13th, 2009, 4:26 am

August 7th, 2012, 1:42 am #1

Arrived this PM. Very quick turn-around! Ran six five shot strings over the chronograph at 10 feet. Used JSB Exact Express 7.87 gr. pellets. A very quick look, but seems very promising. Still has tack driving accuracy at all velocity levels.

1 Pump--343.5 fps, sd 0
2 Pumps--465.3 fps, sd 3.6
3 Pumps--532 fps, sd 0
4 pumps--592 fps, sd 1.5
5 pumps--611 fps, sd 2.0
6 pumps--629 fps sd 2.5

One or two pumps work just fine at paper targets at 33 feet. For shooting roof rats off the bird feeder, 5 pumps would be more than sufficient out to about 60 feet. For extended shooting, 5-6 pumps are about right as I don't find 7-8 pumps much fun.

Only issue is that the breech no longer opens and cocks at the first forward stroke of the pump handle. It must be unlatched and cocked by hand. I have written to Mike to ask if this is a characteristic of the conversion or if there is a part still on the bench (Grin!).

Overall, I'm very happy with what is now both an excellent target pistol and a sufficiently powerful small vermin buster.

Leon Umsted
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Joined: May 12th, 2001, 1:29 pm

August 7th, 2012, 2:40 am #2

...from the production conversions that the South Gate guys are cranking out. All I can say is Hank must be doin' 'em right, because your pistol's numbers (e.g., 629fps = 6.9fpe at 6 pumps) are significantly hotter than my prototype's figures.

Meanwhile, the requirement that the Izzy VIP be manually cocked before pumping is normal and by design. That arrangement seemed to make more sense for an MSP than the alternative - repeatedly beating on the bolt mechanism with every stroke.

Anyway - I'm delighted you like it, anyway!

Steve
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Joined: February 27th, 2002, 5:58 am

August 7th, 2012, 2:57 am #3

Arrived this PM. Very quick turn-around! Ran six five shot strings over the chronograph at 10 feet. Used JSB Exact Express 7.87 gr. pellets. A very quick look, but seems very promising. Still has tack driving accuracy at all velocity levels.

1 Pump--343.5 fps, sd 0
2 Pumps--465.3 fps, sd 3.6
3 Pumps--532 fps, sd 0
4 pumps--592 fps, sd 1.5
5 pumps--611 fps, sd 2.0
6 pumps--629 fps sd 2.5

One or two pumps work just fine at paper targets at 33 feet. For shooting roof rats off the bird feeder, 5 pumps would be more than sufficient out to about 60 feet. For extended shooting, 5-6 pumps are about right as I don't find 7-8 pumps much fun.

Only issue is that the breech no longer opens and cocks at the first forward stroke of the pump handle. It must be unlatched and cocked by hand. I have written to Mike to ask if this is a characteristic of the conversion or if there is a part still on the bench (Grin!).

Overall, I'm very happy with what is now both an excellent target pistol and a sufficiently powerful small vermin buster.

Leon Umsted
Looks like after after 4 pumps, you're not gaining much velocity. I would probably just leave it at 4 pumps.

Does it feel noticeably harder after each pump?

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Joined: September 13th, 2009, 4:26 am

August 7th, 2012, 3:33 am #4

Arrived this PM. Very quick turn-around! Ran six five shot strings over the chronograph at 10 feet. Used JSB Exact Express 7.87 gr. pellets. A very quick look, but seems very promising. Still has tack driving accuracy at all velocity levels.

1 Pump--343.5 fps, sd 0
2 Pumps--465.3 fps, sd 3.6
3 Pumps--532 fps, sd 0
4 pumps--592 fps, sd 1.5
5 pumps--611 fps, sd 2.0
6 pumps--629 fps sd 2.5

One or two pumps work just fine at paper targets at 33 feet. For shooting roof rats off the bird feeder, 5 pumps would be more than sufficient out to about 60 feet. For extended shooting, 5-6 pumps are about right as I don't find 7-8 pumps much fun.

Only issue is that the breech no longer opens and cocks at the first forward stroke of the pump handle. It must be unlatched and cocked by hand. I have written to Mike to ask if this is a characteristic of the conversion or if there is a part still on the bench (Grin!).

Overall, I'm very happy with what is now both an excellent target pistol and a sufficiently powerful small vermin buster.

Leon Umsted
Mike from Innova called me after dinner--really nice gentleman! The loss of the automatic unlock/cock function is a necessary part of the conversion. Air tube must be turned out a few turns for the conversion to work properly which means that the arm that opens and cocks the breech will no longer work. It was included with the pistol, but I had overlooked it in my excitement to get at it!!! If the pistol is ever converted back, it will go back in place. Meanwhile, manually unlocking and cocking is not a problem and after a few shots I don't even think about it.

First few pumps are easy. Pumps four and five take a bit of effort but no big deal. Pump six starts to firm up and pumps 7 & 8 are rather stiff. Actually, the increase in velocity per pump drops with the number of pumps, so going past 5 or 6 really doesn't gain enough to be worth the effort.

My MP 46 M is actually a carbine, with an LDC, Bushnell Red Dot, and shoulder stock. For the use to which I put it (plinking and small vermin bashing) the conversion is going to be well worth the investment.

Leon Umsted
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Joined: May 12th, 2001, 1:29 pm

August 7th, 2012, 3:55 am #5


Your carbine setup sounds cool. Any chance of a picture or two?

Steve
Last edited by pneuguy on August 8th, 2012, 3:06 pm, edited 1 time in total.
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Joined: September 13th, 2009, 4:26 am

August 7th, 2012, 4:42 am #6

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Joined: March 26th, 2008, 2:38 am

August 7th, 2012, 1:23 pm #7

Arrived this PM. Very quick turn-around! Ran six five shot strings over the chronograph at 10 feet. Used JSB Exact Express 7.87 gr. pellets. A very quick look, but seems very promising. Still has tack driving accuracy at all velocity levels.

1 Pump--343.5 fps, sd 0
2 Pumps--465.3 fps, sd 3.6
3 Pumps--532 fps, sd 0
4 pumps--592 fps, sd 1.5
5 pumps--611 fps, sd 2.0
6 pumps--629 fps sd 2.5

One or two pumps work just fine at paper targets at 33 feet. For shooting roof rats off the bird feeder, 5 pumps would be more than sufficient out to about 60 feet. For extended shooting, 5-6 pumps are about right as I don't find 7-8 pumps much fun.

Only issue is that the breech no longer opens and cocks at the first forward stroke of the pump handle. It must be unlatched and cocked by hand. I have written to Mike to ask if this is a characteristic of the conversion or if there is a part still on the bench (Grin!).

Overall, I'm very happy with what is now both an excellent target pistol and a sufficiently powerful small vermin buster.

Leon Umsted
lemmie say that from the start....in fact, I am saving money up for one of these

Hence my questions....

Accuracy.....it is tossed around here alot that match type guns have match barrels and that thier twist rates are matched to a velocity range that seems to usually run in the 450-550 fps range.
Have you noticed that velocity is affected either postitively or negatively at 7-8 pumps?
If it has been affected adversely, have you tried to counter that with heavier pellets?

It stand to reason, if pumping effort is increased/gets harder...then the stress on the pump arm and pivots is greater.

Have any measures been taken to reinforce this? My Steroid comes to mind...I bought one with the billet arm, so that the wear-n-tear will be miniminzed/controlled.
Also, will the rest of the gun hold up to this? I am guessing the grip is where you hold the gun to pump....is the material/fastening hardware up to enduring 8xtimes the friction, and most likely 2-3 times the stress per shot?

Again, not seeking to tear this down....in fact quite the opposite. Pondering spending what I consider a large amount of money, and just want to weigh pros and cons....
IF it is built like any other typical Rusky arm, probably wont make a difference.

Do your instructions include a "revised/beefed-up" maintenance regieme?

Thanks for your patient replies, and God's blessings,

Farmer
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Joined: May 12th, 2001, 1:29 pm

August 7th, 2012, 2:41 pm #8

The reason is, the way the Innova conversion works is to massively increase the volume of the air charge (by about 400%, in fact) - not its pressure. In fact, operating PSI - even when you input the max suggested number of pump strokes - is actually reduced from the stock SSP.

Note that this is very different from the way the usual MSP power tunes work, which (just as you say) always do involve a pressure increase and therefore added stress to the pump components, shortening their life if not reinforced.

The Innova VIP kit doesn't work that way, but instead takes advantage of the fact that the power of an airgun can be increased by either of two routes: Increasing pressure or increasing volume. I chose the second route when I designed the VIP, and thus avoided adding any stress on the arm of the pump - or the arm of the pumper.



Steve
Last edited by pneuguy on August 7th, 2012, 2:45 pm, edited 1 time in total.
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