9mm to 10mm conversion

[Eargesplitten]

Sorry if this is a dumb question, but I'm having a hard time getting a clear idea from Google because of the small vs large frame thing. Assuming a large frame, what's needed to convert from 9mm to 10mm? Do you need a full slide or is it just barrel and magazines? Maybe recoil spring too? I know EAA sells 10mm conversion kits, but it seems like if you buy those new you're looking at nearly as much as a whole new gun. Is the extractor going to pose a problem? I've never worked on a Tanfo before and I don't have my CZ anymore to look, I can't remember if the extractor is in the sear cage, I assume the difference in rim size could pose an issue there. Is it easier to convert a 10mm into a 9mm? I know there are some models of gun that just need mags and a drop-in barrel for .40 to 9mm but vice versa is more difficult.

 

I'm looking at getting a large frame Stock of some type or Limpro for a practice and eventual competition gun, currently looking between those and a Shadow 2 since Grand Power's optic ready model isn't in the US and it's going to be a like kind and quality insurance claim so getting a cheaper model is just leaving money on the table. I've wanted a 10mm Witness since I was a teenager, so if it's possible to do a conversion relatively cheaply that would be a point in favor of the Tanfo. The bigger grips of the Tanfo seem like they could be nice because it still feels like it fits my hand well (my current 9mm's safety recoils into my thumb knuckle if I do a high grip which means my accuracy goes downhill after about 100 rounds), but there's no reason I can't buy/3d print bigger grips for the Shadow.

 

Second-ish question, is it true that you can't do .40 in a 10mm Witness like you can with a Glock due to the longer firing pin? My understanding is the Glock 10mms can fire .40 safely because the firing pin is short enough that if it slips under the extractor the FP won't hit the primer, but with an EAA the FP is long enough that it will still hit the primer while the round is sitting loose in the barrel, which is bad for some reason I don't understand but accept is bad because I accept the concept that explosions going off in the wrong way in your hands is generally a bad thing. Cost of practice 10mm is significantly higher than practice .40, and cost of full power 10mm is even higher, which is a consideration since I don't currently have any space for a reloading setup.

[DesertTortoise]

You need the slide because the bolt face is bigger on the 10mm

[Eargesplitten]

Thanks, I had a feeling there might be something like that. I wasn't sure how important bolt faces are with a pistol vs an AR or similar.

[Yondering]

9 hours ago, Eargesplitten said:

 

Second-ish question, is it true that you can't do .40 in a 10mm Witness like you can with a Glock due to the longer firing pin? My understanding is the Glock 10mms can fire .40 safely because the firing pin is short enough that if it slips under the extractor the FP won't hit the primer, but with an EAA the FP is long enough that it will still hit the primer while the round is sitting loose in the barrel, which is bad for some reason I don't understand but accept is bad because I accept the concept that explosions going off in the wrong way in your hands is generally a bad thing. Cost of practice 10mm is significantly higher than practice .40, and cost of full power 10mm is even higher, which is a consideration since I don't currently have any space for a reloading setup.

 

This is correct. I believe I was one of the first to figure this out and posted about it on the Glock forum about 10 years ago, so you may have seen the pic below that illustrates what you're talking about. The slide on the left in the pic is a 1911, but Tanfo/Witness firing pin protrusion is usually similar. (Use a thin punch to push your firing pin as far as it goes, and compare to the pic below.)

The danger is in allowing a .40 S&W round to fire in front of the extractor (really excessive headspace) - this causes the round to slam back into the breech face, and it's possible to rupture the case when that happens. You'll hear from people that say "It's fine I do it all the time", but if you examine the fired brass from doing this (and don't have a case rupture), you'll likely find a few cases that fired in front of the extractor and show severe case head damage & expansion.

 

 

 

As to your question about conversions - to convert a 9mm large frame Tanfo to 10mm, at minimum you'd need a complete new top end (full slide, barrel, recoil spring/rod, etc). It's really not worth it. 

I've been shooting both calibers for a bunch of years in a bunch of different guns, and honestly in my opinion - if you want a great 10mm setup for full power loads, get a Glock 40; it's just better equipped to handle heavy 10mm than the Tanfos. 

Edited August 5, 2019 by Yondering

[Eargesplitten]

Thanks. I shot a friend's G29 and it was surprisingly not bad even with the full-power loads he put in for the second magazine. I guess it helps that despite being the "subcompact" 10mm, it's really about the size of a G19. Due to being a horrible gun hipster I'd probably be tempted to go for the Grand Power P40L though. Especially with the rotating barrel to help with the extra power.

[Yondering]

Here's an example what happens to a .40 case fired in a 10mm Witness chamber:

 

 

Edited August 5, 2019 by Yondering

[Yondering]

7 minutes ago, Eargesplitten said:

Thanks. I shot a friend's G29 and it was surprisingly not bad even with the full-power loads he put in for the second magazine. I guess it helps that despite being the "subcompact" 10mm, it's really about the size of a G19. Due to being a horrible gun hipster I'd probably be tempted to go for the Grand Power P40L though. Especially with the rotating barrel to help with the extra power.

 

I will say that as a fan of the 10mm, I have zero interest in a G29. Full power 10mm is at it's best in a longer barrel with a heavier slide (one strike against Tanfos with their lighter slides). A full size G20 or 5" 1911 is where I'd start considering the 10, and the long slides are better. 

 

For reference - I shoot a 200gr hard cast at 1,350 fps from my 6.5" Glock 20 long slide (built before the G40 existed) as the primary load for that gun. It's powerful but relatively easy to shoot, however, the same load in a G29 loses quite a bit of power and is significantly harder to control for multiple accurate quick shots. 

[Eargesplitten]

Fair enough, I really wasn't shooting for speed. And to be frank I'm not exactly a great shot. My groupings are decent for a newbie, but my rapid fire is hopeless. I need to get out and do some competitions, but I need to gear up first. Belt, holster, mag holders, etc. And new gun, currently I only have a Bersa Thunder 9 UC that, while much better than the reputation would suggest, bangs up my thumb knuckle with the safety with the stock grips. I only got through a few magazines before my thumb started hurting enough that my groupings doubled, and it's still sore when I put pressure on that part of my thumb a week later.

 

He bought the G29 living in Florida spending a lot of time in the swamps, he was looking for the most carriable hog gun he could find since they can get aggressive and you're likely to be in bad breath distance by the time you and the hog realize each other are there. He doesn't carry it anymore up in Colorado. He's not worried about bear and mountain lions will be on top of you before you know they are there.

[ATLDave]

13 hours ago, Yondering said:

 

 Full power 10mm is at it's best in a longer barrel with a heavier slide (one strike against Tanfos with their lighter slides).

 

Man, I just totally disagree with the notion that the Tanfo' is a less-good gun for 10mm than the Glock.  I just do not agree with that at all.  At all.  

 

And of the Elite-series Tanfo's (Match and up) make "real" 10mm very manageable.  

[FALAR]

6 hours ago, ATLDave said:

 

Man, I just totally disagree with the notion that the Tanfo' is a less-good gun for 10mm than the Glock.  I just do not agree with that at all.  At all.  

 

And of the Elite-series Tanfo's (Match and up) make "real" 10mm very manageable.  

 

Especially the Hunter.  I can only imagine what that slide weighs, I've weighed the "Limited" in at 13.3oz.  With an extra 1" I'm sure it is more than stout enough for any 10mm load.

[Yondering]

7 hours ago, ATLDave said:

 

Man, I just totally disagree with the notion that the Tanfo' is a less-good gun for 10mm than the Glock.  I just do not agree with that at all.  At all.  

 

And of the Elite-series Tanfo's (Match and up) make "real" 10mm very manageable.  

 

I have no problem with your disagreement, but do wonder about your basis for comparison. Have you spent much time with heavy loads in both and tuning the pistols to work with those loads? Or are you just a Tanfo fan? 

 

My Witness 10mm pistols were the older flat side (~2000-2001 era, essentially the modern Match slides) before they changed the standard slides to the round top. They could be made to work, but even with heavy springs and careful load development, full power 10mm was always pushing the limits of what they could handle reliably and without beating themselves up. I'm not talking about how the recoil feels. 

 

Slide speed was always pretty high with top loads, and even with the extra power Wolff mag springs the slides would often outrun the magazine, just enough to cause occasional feed issues. There was not very much difference in LF Tanfos I measured between 9mm and 10mm models, particularly slide weight and barrel lockup geometry, and different springs are not enough to make up the difference between minor 9mm and full power 10mm and be really good for both. In comparison, the 5" 1911 responds better to heavy load tweaks like a FBFPS and heavy main spring, and the Glock 20 and 40 10mm guns have heavy slides designed for 10mm from the start. 

 

The long slide Tanfos are probably much better of course, and the 6" Hunter model may do very well with it's heavier slide, but my comments above are about the standard size slides and are based on personal experience. 

[FALAR]

And I thought 1911s couldn't handle the full power loads....I know I've seen a bunch of "my Delta Elite is bulging cases" and/or frame cracking, but not from more specialty 6" models.  At least 1911s have I believe up to 24lb recoil springs available from Wolff.

 

If I ever jump into a 10mm it will be a Hunter.  I like the guide rod extension they designed that makes contact with  more of the frame too.

[Yondering]

You are right about the Delta Elite, but it's not what I'd consider a well set up 10mm 1911. I don't care much for the DE to be honest, and Colt's in general for that matter. 

Also - something like a 24lb recoil spring is NOT the right way to set up a 1911 for heavy 10mm or 45 Super. That beats up the locking lugs and doesn't do much to delay unlocking and slow down the slide speed. A moderate recoil spring (16-18 lb) and extra power mainspring combined with a flat bottom firing pin stop is a much better 1911 setup for heavy loads. 

 

Full power 10mm is a whole different thing than the standard 9/40/45 service calibers, and most pistols chambered for it are not really designed to handle it. Of course the manufacturers expect a lot of people to shoot primarily the weak "FBI lite" 10mm factory ammo that is essentially 40 S&W in a long case, so that's what guns like the DE and the "round top" Tanfos are really intended for. 

[shabodah]

Modern tanfos are not round tops anymore, haven't been for almost 5 years. Not that there isn't still old stock out there. The lightest for the slide length 10mm modelsI am aware of are the poly match models.

[Yondering]

3 hours ago, shabodah said:

Modern tanfos are not round tops anymore, haven't been for almost 5 years. Not that there isn't still old stock out there. The lightest for the slide length 10mm modelsI am aware of are the poly match models.

 

That would be news to me; EAA still lists them as current production on their site for the standard model steel frame: http://eaacorp.com/guns/witness-steel-full-size-tanfoglio-52

Maybe they just haven't updated their website? What are you basing your statement on?

 

The models I had were before they went to that round slide though; essentially the same slide style as the current Elite Match: http://eaacorp.com/guns/handguns/witness-elite-match-93

Edited August 6, 2019 by Yondering

[Yondering]

7 hours ago, FALAR said:

 

Especially the Hunter.  I can only imagine what that slide weighs, I've weighed the "Limited" in at 13.3oz.  With an extra 1" I'm sure it is more than stout enough for any 10mm load.

 

Correct me if I'm wrong, but I'm pretty sure the Tanfos use the same slide (other than breech face size), meaning about the same weight, for all of the service pistol calibers. In other words, my understanding is the 10mm Tanfo slides are not heavier than the other calibers. Glock on the other hand uses much heavier slides in 10mm than in 9mm or 40. 

 

Here's some info from my postal scale this evening:

 

Tanfo Stock II 9mm slide - 12.2 oz (that ~1oz difference from your Limited is probably due to the bull barrel; note that you can buy a 10mm Stock II)

Glock 19 - 12.1 oz - almost identical to the Stock II

My Glock 10mm long slide (aftermarket, but within 0.5 oz of the G40 slide) - 21 oz - that's 72% heavier than the Stock II, and 58% heavier than your Limited. 

 

Obviously the different lockup geometry and other things matter as well, but the difference in those slide weights is huge for heavy 10mm loads. In my experience, that difference shows up in slide speed, which directly relates to the level of recoil the gun will tolerate reliably and overall durability over a lot of rounds. Those heavy slides are the opposite of what we want in a target gun, but exactly what's needed in a woods/hunting pistol for heavy loads. 

[shabodah]

If they let this link post, it contains pictures of current models.

https://www.gunbroker.com/item/820845296

Yes, the website pic, and most listing pics are far out of date.

[ATLDave]

20 hours ago, Yondering said:

 

I have no problem with your disagreement, but do wonder about your basis for comparison. Have you spent much time with heavy loads in both and tuning the pistols to work with those loads? Or are you just a Tanfo fan? 

 Yes, I have substantial experience with 10mm Tanfo's and my own handloaded ammo (typically max or near-max loads of AA#9).  

 

I have both a Match and an Limited in 10mm.  I know several other people who have shot a lot of 10mm out of other Match'es as well. 

 

I have no experience with the base-model guns in older vintages.  But the design in the Elite series is quite well suited to 10mm.  

Edited August 6, 2019 by ATLDave

[Yondering]

1 hour ago, ATLDave said:

 Yes, I have substantial experience with 10mm Tanfo's and my own handloaded ammo (typically max or near-max loads of AA#9).  

 

I have both a Match and an Limited in 10mm.  I know several other people who have shot a lot of 10mm out of other Match'es as well. 

 

I have no experience with the base-model guns in older vintages.  But the design in the Elite series is quite well suited to 10mm.  

My question was whether you have experience in the other guns mentioned for comparison, or just the Tanfos. You claim the Tanfo is just as good, but how do you know? 

[FALAR]

21 hours ago, Yondering said:

 

Correct me if I'm wrong, but I'm pretty sure the Tanfos use the same slide (other than breech face size), meaning about the same weight, for all of the service pistol calibers. In other words, my understanding is the 10mm Tanfo slides are not heavier than the other calibers. Glock on the other hand uses much heavier slides in 10mm than in 9mm or 40. 

 

Here's some info from my postal scale this evening:

 

Tanfo Stock II 9mm slide - 12.2 oz (that ~1oz difference from your Limited is probably due to the bull barrel; note that you can buy a 10mm Stock II)

Glock 19 - 12.1 oz - almost identical to the Stock II

My Glock 10mm long slide (aftermarket, but within 0.5 oz of the G40 slide) - 21 oz - that's 72% heavier than the Stock II, and 58% heavier than your Limited. 

 

Obviously the different lockup geometry and other things matter as well, but the difference in those slide weights is huge for heavy 10mm loads. In my experience, that difference shows up in slide speed, which directly relates to the level of recoil the gun will tolerate reliably and overall durability over a lot of rounds. Those heavy slides are the opposite of what we want in a target gun, but exactly what's needed in a woods/hunting pistol for heavy loads. 

 

The slides would be nearly identical.  I didn't include the barrel in my measuring because that would be retarded.

 

Again, I would only use full-house 10mm loads in the 6" Hunter.

[ATLDave]

15 hours ago, Yondering said:

My question was whether you have experience in the other guns mentioned for comparison, or just the Tanfos. You claim the Tanfo is just as good, but how do you know? 

I have shot a number of other 10mm launchers.  Including a few generations of Glocks (20's, 29's, and one 40).  And several 1911 platforms.  

 

I'm pretty familiar with the cartridge.  It is not some nuclear device.  In terms of recoil force, it does not generate a great deal more than stout 45ACP +P.   

 

You seem to attach a great deal of weight (ha!) to the mass of the slide.  We're talking about Browning-type locked-breech tilting barrel actions.  The slide's mass is not the primary control on the timing of unlocking; nor, for that matter, is the recoil spring.  These are not Hi-Point guns where the mass of the slide is the thing keeping the chamber from opening early and allow the case to blow out.  

Edited August 7, 2019 by ATLDave

[Yondering]

11 hours ago, FALAR said:

 

The slides would be nearly identical.  I didn't include the barrel in my measuring because that would be retarded.

 

Again, I would only use full-house 10mm loads in the 6" Hunter.

 

The barrel mass actually does count as part of the reciprocating weight for initial unlocking delay, which is what really matters for heavy 10mm loads. However, I didn't include the barrel in any of the weights I listed above either, those are just the slides with no barrel or recoil spring assembly, to compare fairly to your Limited slide weight. The Glock 10mm long slide really is that much more massive than the others. 

[ATLDave]

Yondering, 

1 hour ago, Yondering said:

The Glock 10mm long slide really is that much more massive than the others... 

Including other 10mm non-long-slide Glocks.  Even the little Glock 29 works very reliably.  Are you contending that G 20's and G 29's are not well suited to handling 10mm safely or reliably?  

 

I do not believe you are thinking about this correctly.  I think you're attaching WAY too much importance to slide mass in terms of how/when the action unlocks.

 

I also think you are mistaken about the effect of slide mass on recoil/battering.  Momentum is mass times velocity.  If a slide is lightened, it will move faster... but it will have less mass.  The momentum will be the same when it hits home at the end of the slide's rearward traverse.  

Edited August 7, 2019 by ATLDave

[Yondering]

What you think is incorrect then; I'm not voicing an opinion of what I imagine might happen, I'm talking about the proven mechanics of the tilt barrel locking system. This is not new information, but most shooters don't really understand it.

The mass/inertia of the slide has a huge impact on unlocking timing, which can be demonstrated rather than just "I think so". The recoil spring has a relatively small affect in most guns, which is why just using a heavier recoil spring for 10mm in a slide that's the same weight as a 9mm isn't enough to compensate. 

 

The ramp angle and free travel in the barrel locking lug geometry plays a big part too, but have you actually compared that in a 9mm and 10mm Tanfo barrel? You might be surprised in what you see...

 

In hammer fired guns the hammer cocking effort has an affect as well, but that is less pronounced in the Tanfo/CZ design than in a 1911, because of the location of the hammer pivot relative to the bottom of the firing pin stop. This is why a flat bottom firing pin stop helps in a 1911 as well; it lowers the slide contact point against the hammer down closer to the pivot, increasing cocking force and delaying unlocking.

[Yondering]

1 hour ago, ATLDave said:

Yondering, 

Including other 10mm non-long-slide Glocks.  Even the little Glock 29 works very reliably.  Are you contending that G 20's and G 29's are not well suited to handling 10mm safely or reliably?  

 

 

No... Where did I say that? 

It seems that you're really just looking to argue about something instead of responding to what I actually said. Did I hurt your feelings when I said the Tanfos are not as good for full power 10mm? I'm happy to logically discuss what works best for the 10mm, but I'm not interested in debating brand preferences; I really couldn't care less about Chevy vs Ford arguments.