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Post by davem on Jan 29, 2007 13:52:02 GMT -5
I havent measure the rate of fire on my AGM MP-40. For those of you that have it, which battery (with the stock spring) do you think gets the gun closest to the correct (approx 500rpm) rate of fire?
8.4V or 9.6V?
Thanks,
Dave
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Ungar
Private
Blut und Ehre
Posts: 227
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Post by Ungar on Jan 29, 2007 18:41:49 GMT -5
Lower voltage=lower rate of fire
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biged
Master sergeant 
Posts: 468
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Post by biged on Jan 29, 2007 19:39:05 GMT -5
A quick and dirty way to measure the ROF:
Record the gun firing for 3-seconds via your computers microphone and save it as a .WAV file.
Count the peaks in a 1-second region of the wav and you have rounds(bb's)-per-second, multiply by 60 and you have the cyclic ROF.
///ed///
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Post by stukaace on Jan 30, 2007 21:53:51 GMT -5
I took a recording on the MP40 on stock battery. I think my battery was a little low, but I managed to get a reading of about 9-10 rounds per second, or 600 Rounds Per Minute.  |
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Post by davem on Jan 30, 2007 22:25:25 GMT -5
Thanks Stuka ace. That's actually what I wanted to know. I was thinking about putitng a 9.6v in it but I now think I wont. It would be way off scale. It should sound like this: wilk.wpk.p.lodz.pl/~whatfor/mp40.htmThanks. Dave |
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Post by stukaace on Jan 31, 2007 7:07:23 GMT -5
I think ROF on an actual MP40 is somewhere around 500 RPM, or so says wikipedia.
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Post by stukaace on Feb 1, 2007 15:59:30 GMT -5
Sorry for the double post:
With a fresh battery, rate of fire is more like 720 RPM, 12 per second.
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Post by davem on Feb 1, 2007 17:16:47 GMT -5
Yikes...Thanks... I wonder if my M120 spring will get the ROF down closer to 500 with the 8v battery... I guess I will know next week.
I dont do WW2 impressions, but do you guys (who do) worry about unrealistic ROFs? Or is it immaterial..
Dave
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Post by mauser98k on Feb 2, 2007 0:37:59 GMT -5
Not much of a concern, but the closer the better. No hurt in going that extra mile-and-a-half.  |
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Post by CharleyNovember on Feb 2, 2007 13:56:30 GMT -5
Doesn't cpncern me but some people like to have a realistic ROF.
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Post by Ripper on Feb 12, 2007 13:45:19 GMT -5
I ran a 9.6V, 1200 mah battery in my MP40 this saturday. It was about 20 degrees and I noticed that the mags had difficulty feeding BB's fast enough to keep the gun fed. I had a hand warmer on the side of the gearbox and the battery to keep them limber. But the mag springs seemed very stiff and slugish. Semi worked just fine, but only two of the six mags could feed reliably on auto. I opened them all up and lubed them, so hopefully the problem is solved.
With that battery, the gun is a little unrealistic in ROF, but I fire it in 5-6 round bursts so it isn't that bigga deal.
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2nd Bat
Master sergeant
Posts: 11,813
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Post by 2nd Bat on Feb 12, 2007 14:25:27 GMT -5
Unless you have an upgraded spring I wouldn't recommend going with more then a 8.4 battery as the added juice will be hard on your gearbox. The BB feeding issue is a sign that your motor is running faster then design tolerances. A jam at that speed can cause your gearbox to eat it's young prematurely.
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Post by Ripper on Feb 12, 2007 14:26:54 GMT -5
OUCH. I'll grab a high amperage 8.4 and go with that.
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