this may help...

BBTI - Ballistics by the Inch :: 10mm Results

(statement of intent)

www.ballisticsbytheinch.com

 

Is there a particular purpose that requires that additional 53 FPS?
Since Underwood's website doesn't list a barrel length and neither does the box, maybe Underwood isn't all it's that much better than the competitor's products? SIG 180 gr @1179 FPS is nothing special either- that's where the Underwood 200's should be, right?
If you are truly looking for top-end 10mm ammo, your choice is reloading or buying Buffalo Bore.
Buffalo Bore is expensive, but they have the integrity to list actual muzzle velocity and specific firearm and barrel length used to derive their specs.

 

Is there a particular purpose that requires that additional 53 FPS?

The mathematical equation on penetration in gel and stopping power would be inaccurate, as well as the angle of the dangle.

 

I get around 1175-1200 fps from my G29SF. About 50-60 fps less than the G20.

 

With what ammo? The underwood or just 10mm 200gr FMJ?

 

Never works out exactly like the book says it will. That extra speed is probably through a Delta Elite barrel. Cold day?

 

Nothing specific or special about the extra 53fps or 103fps or whatever. I want to shoot full power 10mm to become used to the recoil, anything less then it might as well be .40S&W. So just inquiring as to others experiences.

My hand loads using a coated lead bullet with Accurate #7 are at 1140fps with a 180gr bullet. But again with an interest in shooting full power 10mm I have some experimenting with other powders to do.

Buffalo Bore publishes their velocity specific to a few different gun models, Glock 20 being one of them so somehow they are able to get some pretty impressive velocity out this platform. I will not be attempting to go that far with hand loads but 1200-1250fps with a 180gr bullet is my goal.

 

Most ammo manf will test in a pistol & conditions that gives highest vel, then post that. So its not misleading but everyone knows or should know that vel varies from gun to gun, even with the same bbl lengths & test conditions vary as well.
The original full power 10 was 200gr at 1200 & 180 @ 1250, from a 5” Bren 10. The original Norma loads gave me those vel in a Bren 10 & my Delta. You wont feel much recoil diff adding 50fps.
For top loads with good accuracy, RC is correct, aa#9 is exceptional, especially with 200-220gr. Longshot is also very good with 180 as is bluedot. For me, never got the accuracy i wanted with 800x, plus meters like crap, so its off my 10mm list.

 

If you are trying to get to the top of the velocity scale, Accurate #7 is not the way. You basically have 3 powders to get there- #9, Blue Dot, and 800x. There are some people who claim that Longshot will achieve that goal but I've never seen it top the other 3 powders I mentioned.
The biggest problem with chasing speed in a 10mm is the accuracy. Just because you get to the top of the velocity scale doesn't mean you have any accuracy at all. Ages ago, I worked with #7, and it just wasn't a winner in the variety of 10mm firearms I own.
I shoot about 5,000 rounds of 10mm in an average month, through 9 different pistols and a carbine. For me, the accuracy goal has to be averaged across multiple firearms. Accurate #9 is the clear winner. 800x had higher scores, but I had to go above book values to do it- the risks were not worth the gains.
As far as your Underwood shortcomings, you will never feel the difference between 1147 fps and 1200 fps. Regardless of what your chrono says, you are shooting a high-end load. Was it accurate?
Absolute speed is a meaningless value if you have no accuracy.
BTW, Buffalo Bore- as well as other manufacturers- use commercial powders that you and I can't get. This is why some commercial ammo is beyond our capabilities.

 

If you are trying to get to the top of the velocity scale, Accurate #7 is not the way. You basically have 3 powders to get there- #9, Blue Dot, and 800x. There are some people who claim that Longshot will achieve that goal but I've never seen it top the other 3 powders I mentioned.
The biggest problem with chasing speed in a 10mm is the accuracy. Just because you get to the top of the velocity scale doesn't mean you have any accuracy at all. Ages ago, I worked with #7, and it just wasn't a winner in the variety of 10mm firearms I own.
I shoot about 5,000 rounds of 10mm in an average month, through 9 different pistols and a carbine. For me, the accuracy goal has to be averaged across multiple firearms. Accurate #9 is the clear winner. 800x had higher scores, but I had to go above book values to do it- the risks were not worth the gains.
As far as your Underwood shortcomings, you will never feel the difference between 1147 fps and 1200 fps. Regardless of what your chrono says, you are shooting a high-end load. Was it accurate?
Absolute speed is a meaningless value if you have no accuracy.
BTW, Buffalo Bore- as well as other manufacturers- use commercial powders that you and I can't get. This is why some commercial ammo is beyond our capabilities.

i agree with you on powders. i got around 1350 out of my glock 40 with 180 XTP with #9. close to that with Blue Dot. don't have 800x.

 

I used Bluedot for years and then started using 800X (availability was an issue at the time) with almost identical results. These two powders have been my 10mm staples and either will get you well into overpressure...be careful and work up. As RCJ mentions, finding the happy place of velocity and accuracy is the whole point of handloading...there is no reason eeking out the last foot per second if your result is 2' groups at 25 meters. When shifting components, I usually work up to max while ignoring accuracy as I want to know where MAX is for my set up and then I work back to the charges that offered the best accuracy. Fine tuning handloads, this is the why.

 

Underwood is generally pretty accurate in their listings. There are variables though, there are fast or slow barrels and cold temps impact ammo pressure and velocity.

 

I've got some of their 200gr XTP but haven't shot it yet, I did run a box of Underwood 180gr XTP and it was extremely accurate from my G40. A lot of things can affect chronograph readings, but it wouldn't get too hung up on it. A 200gr at 1150 fps isn't a bad load, granted I can get that from a G23, but still, it's not a bad performer.

 

That’s the average for a 4.6” barrel G20
Using Underwood Ammo ! Not bad !
Their numbers I think are based off of G40 and 6” barrel.

 

One thing is for sure, Underwood loads some pretty warm stuff regardless of caliber.

 

It’s your 4.6” barrel gets you 1147FPS with 200 XTP add a 6” barrel or G40 and you will get even closer to the advertised vel. I am completely satisfied with 1147 fps out of a 4.6” with 200gr Hardcast for Alaska trails.

 

Surprised I didn't see this thread in January.

I chronoed seven different Underwood 10mm loads. They averaged 76, 26, 56, 89, 104, 59, and 77 fps less than advertised out of my 4.5" barrel. This is pretty standard for most manufacturers as far as I can tell. Sig and Magtech seem to be the exception.

I do not have the 200gr XTP from Underwood to test.

 

Surprised I didn't see this thread in January.

I chronoed seven different Underwood 10mm loads. They averaged 76, 26, 56, 89, 104, 59, and 77 fps less than advertised out of my 4.5" barrel. This is pretty standard for most manufacturers as far as I can tell. Sig and Magtech seem to be the exception.

I do not have the 200gr XTP from Underwood to test.

4.6” 200gr XTP Underwood 1147fps

 

If you want specific perf in your ammo, learn to reload & get a chrono.

 

I believe Underwood vel is with G40 and 6” barrel !