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Discussion Starter · #1 · (Edited)
Hi guys,

This came up in the General Glocking section, so thought I would ask here. Is the Underwood 10mm ammo loaded within SAAMI specs? In particular for me, the 180 XTP and FMJ (both show the same velocities). I'm new to 10mm and recently bought a Gen 4 Glock 20 and 29. I went with Underwood for full power 10mm for black bear defense but wasn't trying to find nuclear loads that would damage my guns.

What's the word on Underwood. Some are saying they are having problems running their Glock 20's with it. Mine are running fine so far, but have only shot a couple hundred rounds in each gun so far.

Thanks!
 

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I don't know if it's within saami specs, but it also shoots just fine out of my glock. it's not showing over pressure signs for me, and i haven't really heard of anyone having issues with it.
I keep a couple different types loaded in different mags and no issues so far.

I know that doesn't actually answer the question, but i still figured i'd say something positive for it. as soon as i get some money for another ammo order need to pick up more of it.
 

· Micheal D Dokes
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Yes Underwood ammunition exceeds saami maximum recommended pressure for the 10mm by a lot. Be careful with it, don't shoot it right away if it's been sitting in a hot car. Underwood also recommends this ammunition only be shot in a firearm with a ramped feed barrel for case support and I'd definitely invest in at least a 21# recoil spring. Honestly I don't think this ammo is very useful because they're using bullets designed for 40 S&W velocity. Check out some of tnoutdoors9 10mm Underwood videos for gel tests that show what happens when 40 cal bullets are driven too hard.
 

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Discussion Starter · #5 · (Edited)
Yes Underwood ammunition exceeds saami maximum recommended pressure for the 10mm by a lot.
That's disappointing. I didn't think about SAAMI when I bought it.

Honestly I don't think this ammo is very useful because they're using bullets designed for 40 S&W velocity. Check out some of tnoutdoors9 10mm Underwood videos for gel tests that show what happens when 40 cal bullets are driven too hard.
I had seen some of these videos and that's why I went with the Hornady 180 gr XTP. Its the only bullet I found that Underwood was using where they were not exceeding the bullet's velocity range. They've got it running at 1300 fps from a Glock 20 (they say, haven't chrono'd it yet). Hornady has the bullet's velocity range rated at 750 to 1450 fps: http://www.hornady.com/store/10mm-.400-180-gr-HP-XTP/
But if its not within SAAMI I won't be buying any more.

Thank you.
 

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Yes Underwood ammunition exceeds saami maximum recommended pressure for the 10mm by a lot.
How do you know that? What is 'a lot'.

I've seen information that suggests you're right, and Underwood isn't the only one. But 'suggests' and 'does' are two different things. Where are you getting facts from, and are those facts pressure measurements?

SAAMI doesn't publish 'specs', by the way. They publish 'recommendations'. I very much doubt if any of the boutique handloaders has the wherewithal or resources to test their products to determine if they meet recommended statistics or not...even some who are SAAMI members.

And by the way, just because a manufacturer lists itself as a SAAMI member doesn't mean you should conclude they load and test their products to ensure they are within SAAMI recommendations. I've specifically asked SAAMI if doing so is a requirement of membership, and got no response. I take that to mean 'No'.
 

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But if its not within SAAMI I won't be buying any more.
Also understand (or read) SAAMI recommendations, and that they cover peak pressure in the context of ammunition samples, as they should. What I mean is this: you can't just say "ammo average peak pressure will not exceed..." because that has no meaning. 'Average' pertains to an average of something, and that something can't be 'everything you produce, have ever produced, or intend to produce'. SAAMI is quite careful to put their recommendations in terms that relate to 'quality'...in the sense that you have to be within recommended values x percent of the time, etc.

So, even if someone grabbed 20 rds of product, measured the peak chamber pressure of those 20 rds (good luck with that), and said hey, they're all within the max...you still don't know if the ammo meets recommendations.

Really, I think the only question that needs to be asked is: "Do you have your ammo pressure tested?". Pretty sure the response will be a doe in the headlights, but I could be wrong.

If a representative of an ammo manufacturer says something that includes the phrase "pressure signs" (e.g., "we look for..", "we don't see evidence of...", etc), then you can conclude they have no earthly idea what their ammo is doing.
 

· Micheal D Dokes
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How do you know that? What is 'a lot'.

I've seen information that suggests you're right, and Underwood isn't the only one. But 'suggests' and 'does' are two different things. Where are you getting facts from, and are those facts pressure measurements?

SAAMI doesn't publish 'specs', by the way. They publish 'recommendations'. I very much doubt if any of the boutique handloaders has the wherewithal or resources to test their products to determine if they meet recommended statistics or not...even some who are SAAMI members.

And by the way, just because a manufacturer lists itself as a SAAMI member doesn't mean you should conclude they load and test their products to ensure they are within SAAMI recommendations. I've specifically asked SAAMI if doing so is a requirement of membership, and got no response. I take that to mean 'No'.
Go over to 10mm-firearms and take a look at their pull downs. They're using off the shelf components, you don't have to be Archimedes to understand they're using way more powder than what's recommended anywhere and they're not changing the laws of physics too achieve those velocities either.
 

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Go over to 10mm-firearms and take a look at their pull downs. They're using off the shelf components, you don't have to be Archimedes to understand they're using way more powder than what's recommended anywhere and they're not changing the laws of physics too achieve those velocities either.
I agree with Bongo Boy. If you go over to the 10mm reloading forum, and look under Hodgdon data, Mike McNett posted data that is well over Hodgdon's recommendations. He claimed to have them tested and they were all under 37.5 kpsi. Now, where he had them tested, and how they tested them, and what their calibration certifications were, he didn't say. Now, I'm not advocating blowing off book recommended maximums (unless you're OK with blowing off your fingers), but book data is usually conservative, and for very good reasons. While manufacturers strive to make every lot of powder, primers, and bullets as consistent as possible, there are lots of factors that they can't control. Not all barrels have the same bore and chamber size, some are fouled more than others, bullets have different diameters, brass varies, etc.

The point is that there is usually some safety margin built into those loads to keep reloaders safe. And I'm not saying it's safe to exceed those loads, but many (including myself) have done so safely. The risk isn't zero, but there are safe ways to work beyond published loads for a given set of components and in a particular barrel. Temperatures play a factor, too, so even if you have a load that is safe at one temperature, you need to recognize that may change at hotter or colder temperatures.

I reload, so I don't shoot Underwood ammo. I have seen a few rare reports of what I would agree were excessive pressure rounds. But I suspect that was due to some variations in components and not necessarily a load formula. The thing is, when you push velocities, you have less margin for variations like that. But I would bet that typical Underwood ammo is within SAAMI recommendations.

It would be interesting to know if Underwood has had their ammo pressure tested. I would be very suprised that anyone would sell ammo without having each load pressure tested for liability reasons, but you never know (unless you ask).
 

· F.S.F.O.S.
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I agree with Bongo and TDC.... The short answer is - I wouldn't go assuming that a load is beyond SAAMI recommendations just because it's a hard and fast shooting load. In addition, there is a good chance that loads already out on the market by other commercial manufacturers that very well could be skirting the line between safe and unsafe simply because of the fact that they're using, for example, a fast powder and heavy bullet combination that may only reach 900 or 950 ft./s but yet is grossly over pressure.

Many of us here on the 10 ring have been discussing every nuance of high pressure 10mm handloading even before McNett @ DoubleTap started his business. Not to say at all that we know more then those guys but I would definitely say that we know more than 95% of the general shooting population at least here in the USA. For that matter, McNett probably got a lot of good information from this forum alone and also *shared* quite a bit of information here and I know for myself I've been on this forum for well over 10 years. Many of us have.

I think you'll find that most of us long-term 10-ringers will agree - the best way to find out whether whether they ammunition is within SAAMI specs is to call the manufacturer and ask otherwise you will never know for sure.

Bottom line: hard and fast loads can be made safely and I presume Kevin at Underwood is doing exactly that… 37,500 psi is a very high number and most manufacturers who load even the hot stuff probably have a margin of error below that number even. Call Underwood and find out for sure
 

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I don't know if Underwood's ammo is SAAMI spec, but keep in mind that SAAMI and Norma spec ammunition are different beasts. The SAAMI spec is 37.5k CUP, while the original Norma spec is 44k CUP. Also keep in mind that pressure is going to be dictated by bullet seat depth and powder used; given that Underwood has recently changed their powder so that unsupported chambers (such as in the Delta Elite) are no longer an issue, I would think that it is in fact to SAAMI spec.
 

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Yes Underwood ammunition exceeds saami maximum recommended pressure for the 10mm by a lot. Be careful with it, don't shoot it right away if it's been sitting in a hot car. Underwood also recommends this ammunition only be shot in a firearm with a ramped feed barrel for case support and I'd definitely invest in at least a 21# recoil spring. Honestly I don't think this ammo is very useful because they're using bullets designed for 40 S&W velocity. Check out some of tnoutdoors9 10mm Underwood videos for gel tests that show what happens when 40 cal bullets are driven too hard.
The 180 grain XTP is rated 700fps-1450fps. This is from Hornady. So it is designed for ten velocities.
 

· F.S.F.O.S.
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Let's
The 180 grain XTP is rated 700fps-1450fps. This is from Hornady. So it is designed for ten velocities.
Let's also remember that 37.5 CUP is very different from 37.5 PSI....
 

· Some Dude
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Here is Underwood Ammo, 180gr, XTP at 20 yards out of a Glock 20 G4 with a 6" KKM barrel from last week.

Red
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· Some Dude
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Here is the doe....notice the bulge in the rib cage? Thats the XTP.

When I started shooting Underwood a couple of years ago in my Glock 9mm and 357sig, I contacted Underwood and they stated the ammo was within the SAAMI specs.
 
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