Benelli MP90S "Blank test spacer"

dixon · Post by **dixon** » Wed Aug 20, 2008 3:21 am

What is the intended use for the "Blank test spacer" part code 064P for the Benelli MP90S/MP95E. It looks like it might be a dry-fire adapter but there is no mention of use in the user's manual.

Thanks

dixon

pgfaini · Post by **pgfaini** » Thu Aug 21, 2008 12:41 pm

If you're referring to the red plastic piece, that's exactly what it's used for.
Paul

dixon · Post by **dixon** » Thu Aug 21, 2008 2:20 pm

It is not a chamber plug/snap cap but is pictured in the picture below from the manual if it's red plastic then yes that is what I mean.

pgfaini · Post by **pgfaini** » Fri Aug 22, 2008 1:53 am

That's exactly the piece I mean. When it's inserted, it keeps the slide out of battery, and when the trigger is pulled, the hammer moves forward a very short distance, doesn't reach the firing pin, instead, striking the body of the slide. That's why you only have to bring the slide back about 1/4" to re-cock it.
Paul

dixon · Post by **dixon** » Fri Aug 22, 2008 7:50 am

Thanks

I didn't receive one with my pistol and I was hopeing that is what it did.

Seems to be a nice solution for dry fire practice.

pgfaini wrote:That's exactly the piece I mean. When it's inserted, it keeps the slide out of battery, and when the trigger is pulled, the hammer moves forward a very short distance, doesn't reach the firing pin, instead, striking the body of the slide. That's why you only have to bring the slide back about 1/4" to re-cock it.
Paul

Fred Mannis · Post by **Fred Mannis** » Fri Aug 22, 2008 8:40 am

I use this ECI for dry firing my Pardini and I think it will work in your Benelli

https://www.brownells.com/aspx/NS/store ... AF-T-ROUND

pgfaini · Post by **pgfaini** » Fri Aug 22, 2008 8:58 am

Yes, I use mine for dry firing all the time. If it's not available from Benelli, it should be easy enough to make. It doesn't need to be tunnel shaped, unless you want to leave your magazine in, just able to fit down between the slide rails, with a clearance notch for the extractor. The length, front to back, is .550". This may be important because it determines where the hammer contacts the bottom of the slide.
Paul

pgfaini · Post by **pgfaini** » Fri Aug 22, 2008 9:41 am

Fred, That ECI won't work with the Benelli, because the ejection port is vertical, and the tab would have to be removed so's not to interfere with sighting. The rim of the brass "case" would have to be removed in the extractor area to be able to cock the pistol without it being ejected. The shape of the ejection port/cocking bosses on the Benelli is such that any 1/2" cube could be used, such as a die(half a pair of dice).

Paul

Gwhite · Post by **Gwhite** » Fri Aug 22, 2008 8:01 pm

Folks should be aware that somewhere along the way (15 years ago?), Benelli changed the trigger/disconnector design in the MP90S. One of the reasons I bought one was so that I could use the red plastic widget to dry fire. By the time my dealer got one, it was the new design. It comes with a chamber plug, but it doesn't work as a dry fire device. I contacted Benelli, and they said the new version couldn't be dry fired the way the old one could.

It's still a nice pistol, but I've always been disappointed that they eliminated the easy dry fire feature. I can use aluminum snap caps, but they aren't cheap & get chewed up pretty quickly.

adouglas · Post by **adouglas** » Sat Oct 11, 2008 1:26 pm

I just use spent brass. Free, plentiful, and no different than using a snap cap, right? Insert the case, make sure the existing divot in it isn't in line with the firing pin, and you're good to go. You can use each case four or five times before the base is too dented to use any longer.

Is there any reason on earth NOT to do this?

David Levene · Post by **David Levene** » Sat Oct 11, 2008 1:52 pm

adouglas wrote:Is there any reason on earth NOT to do this?

On many guns, holding the slide opened slightly prevents the hammer from hitting the firing pin at all.

Using the correct dry firing adaptors not only protect the breech face, they also reduce stress on the firing pin. They are therefore much more efficient than just using an old case.

adouglas · Post by **adouglas** » Sat Oct 11, 2008 2:24 pm

Using spent brass allows the gun to fire in battery, right?

Please explain why spent brass does not protect the breech face or reduce stress on the firing pin.

Positioning the rim where the firing pin strikes is exactly like firing a live round, is it not?

Also, per the above posting the MP90 has no "correct dry firing adapter."

I repeat my question...is there any reason why using spent brass is not a good idea?

David Levene · Post by **David Levene** » Sat Oct 11, 2008 2:45 pm

adouglas wrote:Please explain why spent brass does not protect the breech face or reduce stress on the firing pin.

Using a brass case might reduce the stress on the firing pin, but nowhere near as much as not putting any stress on it at all during dry firing. That's what the proper "hold-open" adaptors do in suitable guns; the firing pin is never even hit.

pgfaini · Post by **pgfaini** » Sat Oct 11, 2008 2:49 pm

Each rimfire firearm is different in its ability to be dry fired. Years ago, most rimfire firearms were made so that the firing pin impacted the edge of the chamber, if fired without a cartridge. This cause the edge of the chamber to peen over, interfering with cartridge insertion and extraction, requiring a reamer be run into the chamber.
Most modern firearms, are made so that the pin won't quite reach the chamber edge. While this solves the chamber peening problem, another one arises: The ability of the firing pin to absorb the stress caused by reaching the end of its travel, without being cushioned by the cartridge. This, of course differs with the design of the gun. Double barreled shotguns are notorious for breaking firing pins if snap caps are not used to uncock an empty gun.
An empty rimfire cartridge, will only give a cushioning effect for a few "shots" without being rotated to a new spot.
The Benelli dry fire block is designed so the hammer impacts the frame and not the firing pin. I have no idea how well it's firing pin could take the shock of either impacting the chamber rim, if it does, or impacting the portion of the firearm which would limit its forward travel if not cushioned by the cartridge.
Paul

pgfaini · Post by **pgfaini** » Sat Oct 11, 2008 2:52 pm

Sorrry, David, Was typing my tome, while you posted your pithy answer.
Paul

adouglas · Post by **adouglas** » Sat Oct 11, 2008 6:19 pm

Okay, then, so IF your gun can be dry fired without the firing pin being struck by use of an appropriate spacer, then obviously this is the best thing to do.

But for the MP90 (or an MP95 with an MP90 trigger group, which is what I've got), which as noted cannot be fired without being in battery, then the only option to prevent the firing pin from being jarred as it reaches the end of its travel is to have it impact something relatively soft.

Like a snap cap, or the undented part of the rim of an empty cartridge case.

Correct?

Aside from being able to use the empty for only a few shots (I note here that rimfire snap caps aren't known for longevity either), I still see no reason NOT to use an empty case. Logically, it's exactly like firing a live round.

David Levene · Post by **David Levene** » Sun Oct 12, 2008 3:02 am

adouglas wrote:Like a snap cap, or the undented part of the rim of an empty cartridge case.

If that's the only option available to you then it's better than nothing.