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Discussion Starter · #1 · (Edited)
I just picked up a new MK25 and a new MK25-10. They are both new, never fired with a light coat of oil. The MK25 was manufactured in late 2013 and the MK25-10 was manufactured in late 2014. Both came with the cert. that they are the genuine MK25 used by military. Both have the UID sticker. The MK25-10 is shipped with 10 round mags. I promptly sold those to someone in CA and replaced them with 15s.

The strange thing is the MK25 seemed some how different, some how better than the MK-10. I thought maybe that was in my head. But without looking at the UID sticker - I could repeatedly tell which one I liked better when picking them up. I inspected them closely inside and out for any differences. There seemed to be none. So I took the slides off and weighed all four pieces to look for weight differences on a decent scale. This scale is always in agreement with the Post Office scale. The total difference between the two is 0.04 oz or 1.3 grams - with the MK25 being the heavier. The difference between frames and slides were both 0.02 oz. I weighed them 3 times in oz and grams in different orders. The total weight was 32.27 oz and 32.23 oz (914.9 and 913.6 grams) with mag. I used the same mag. when weighing each pistol. Makes me wonder why the Sig website and others say 34.4 oz with mag. But more importantly, I can't figure out why the significant weight difference. I put enough oil on the scale to amount to 0.04 oz. No way it's oil. There was a sizable puddle on the scale. I googled 1.3 grams of gold (which would be denser and thus smaller than aluminum, any alloy or steel). Every 1.3 gram nugget of gold I found for sale was just too big to be some sort of difference in machining. It's not like Sig has sloppy tolerances or sloppy machining. Does anyone know if Sig changed their design in the last year that would account for the weight differences? Does anyone know if there is some difference between a MK25 and an MK25-10 that is escaping me. Neither one of these is the CA or MA compliant versions with the ugly chamber indicator on top or the unwise mag. release safety. It can't just be a change in the alloy formula as that wouldn't account for the slide weight difference. ..and no, the difference is not a round in the pipe of the heavier one - lol. Any thoughts, any help is greatly appreciated.

Four .177 BBs weigh about 1.3 grams. If it's extra metal, then there is about 2 BBs worth of extra metal - either added by extra density or extra volume - in the slide and in the frame. That's just too much to make sense to me.
 

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I just picked up a new MK25 and a new MK25-10. They are both new, never fired with a light coat of oil. The MK25 was manufactured in late 2013 and the MK25-10 was manufactured in late 2014. Both came with the cert. that they are the genuine MK25 used by military. Both have the UID sticker. The MK25-10 is shipped with 10 round mags. I promptly sold those to someone in CA and replaced them with 15s.

The strange thing is the MK25 seemed some how different, some how better than the MK-10. I thought maybe that was in my head. But without looking at the UID sticker - I could repeatedly tell which one I liked better when picking them up. I inspected them closely inside and out for any differences. There seemed to be none. So I took the slides off and weighed all four pieces to look for weight differences on a decent scale. This scale is always in agreement with the Post Office scale. The total difference between the two is 0.04 oz or 1.3 grams - with the MK25 being the heavier. The difference between frames and slides were both 0.02 oz. I weighed them 3 times in oz and grams in different orders. The total weight was 32.27 oz and 32.23 oz (914.9 and 913.6 grams) with mag. I used the same mag. when weighing each pistol. Makes me wonder why the Sig website and others say 34.4 oz with mag. But more importantly, I can't figure out why the significant weight difference. I put enough oil on the scale to amount to 0.04 oz. No way it's oil. There was a sizable puddle on the scale. I googled 1.3 grams of gold (which would be denser and thus smaller than aluminum, any alloy or steel). Every 1.3 gram nugget of gold I found for sale was just too big to be some sort of difference in machining. It's not like Sig has sloppy tolerances or sloppy machining. Does anyone know if Sig changed their design in the last year that would account for the weight differences? Does anyone know if there is some difference between a MK25 and an MK25-10 that is escaping me. It can't just be a change in the alloy formula as that wouldn't account for the slide weight difference. ..and no, the difference is not a round in the pipe of the heavier one - lol. Any thoughts, any help is greatly appreciated.

Four .177 BBs weigh about 1.3 grams. If it's extra metal, then there its about 2 BBs worth of extra metal - either added by extra density or extra volume - in the slide and in the frame. That's just too much to make sense to me.
I bet you are an engineer huh?
 

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:confused:What's the tolerance on the scale?........thats somewhere around 2% difference, I bet you'd have to weigh at least ten of them before you found two under 1%.;)
 

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My brother bought a MK25 here in Commiefornia dated Apr 2014, and I bought one dated Oct 2013. Both purchased in July of this year, His S/N starts 47A and mind starts UU7. Will have to verify ours next time we take the 'boys' out using the same digital scale and will report back. Should be in the next week or two. Very curious though.
M
 

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As a fellow member of the OCD club I can tell you that you need to adjust your meds and not worry about the differences. Could be production tolerances causing the issues. I can do the same thing with my Son's Shield and mine. It's just the way things are. No real explanation for it other than tolerances. As MC says relax and "Shoot it like you stole it"

FYI the Meds line was from my son. He is used to me being "way to picky" according to him. Family joke.

Michael
 

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What you have there is a very dangerous situation. The lighter one is made from sub par alloys that could fly apart upon rapid fire shooting. You need to ship it to me ASAP for proper termination of this extremely unsafe weapon. I promise to treat it with total animosity.
 

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Honestly, I thought this was going to be a post highlighting some form of even-slightly significant difference.

LOL.
 

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Discussion Starter · #9 ·
a 1.3 grams is significant for a precision piece of equipment that barely weighs over 800 without the clip. That's the point. It's something like a 1.6% difference in the product. I could in no way get away with that where I work. But it that's the norm. that's fine - as long as it shoots.
 

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a 1.3 grams is significant for a precision piece of equipment that barely weighs over 800 without the clip. That's the point. It's something like a 1.6% difference in the product. I could in no way get away with that where I work. But it that's the norm. that's fine - as long as it shoots.
i don't think the difference is a big deal. but for some people it is and i can understand.

did you do a full strip down and of all parts and clean? could the factory grease make the difference in the weight? maybe one of them has more grease (not oil) on the internals for the 1.3 grams. could also be overall coating thickness causing the weight difference. and also consider the barrels have to be fitted. perhaps one of them needed a tad bit more adjustement to fit properly with the slide. all things to consider and all possible reasons for the difference. i am sure Sig uses an estimated average weight for their spec. if they both shoot well, i am sure there is nothing to be concerned about.

have fun with them.
 

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Discussion Starter · #13 ·
Ok. I looked up the formula and plug this variation and it's a IT Grade 7 which is in the middle of ITG scale and is in the meaty part of the curve of the "fits" section. Just surprised it wasn't higher. Case closed - I think.
 

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Ok. I looked up the formula and plug this variation and it's a IT Grade 7 which is in the middle of ITG scale and is in the meaty part of the curve of the "fits" section. Just surprised it wasn't higher. Case closed - I think.
The gun is dangerous to shoot... Pm me for my address and you can send it to me so you will be safe...
 

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For measurements, there is accuracy and repeatability.
For measurements such as you are conducting, one needs to know, what scale you are using and it's accuracy. I assume the scale is not calibrated and I don't know how you did the comparison with the PO scale.
I use a digital Ohaus 5000 and have a 2kg cal weight.
1.3 grams is very little but until you use the proper equipment and techniques, I don't know if your measurements are correct.
And in the Grand Scheme of things, so what?
I am an engineer.-Dick
 

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I'm not an engineer. I'm not a scientist. I'm not really even that smart. But I learned young in life, there are no two things, either man made or in nature that are exactly, precisely, 100 percent completely alike.
Things can come close but not truly exactly the same.
 

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Scales and balances are one of the most accurate and reproducible devices we USS everyday, some easily to 1 part in 10,000,000... So what's the standard deviation of 6 weighings of the same part? ;-)
 
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