Underwood 200 XTP Brass Blow OUT!

[sqlbullet]

Yep...And I have had some split before too on first firing.  Usually Federal, as you mentioned.

[The_Shadow]

I was looking over the DT ammo that came with my new G-20SF purchase, the primers are concaved slightly.  Not sure what's up with that...   Seater punch must be wrong or worn to a rounded over shape!   

[REDLINE]

I also would like to know what gun they were fired in and what if any mods were done to the gun.

[REDLINE]

Average was 1269 fps has two weird high numbers not sure if I shot way high in the chrono or not.  One was somewhere in the 1300+ range and the other was 1400 something.

WOW!!!  Houston, we have a problem.

Did the ammo really manage it?  Did the Chrono have a brain fart?  Either way, no doubt two nickel plated brass cases ended up in a way they shouldn't have.

[REDLINE]

Yes, I would be interested to see how the rest of the lot chrono's.

I second the motion.  But with the next go around each round should be chronoed and the spent brass casing checked on an individual basis.  BTW, video of said testing would be awesome.  Or at least it could be.

[doverpack12]

Sorry I had a very busy end of the week.  This was a stock G20 SF only modification was a 22 lb ISMI recoil spring was installed on a SS guide rod.  The right side
of the left case is sticking up past where the rest of the neck is.  This was due to the tear in the brass.  I was almost thinking it got caught in the barrel with the
bullet then the pressure started to push the slide back and it tore it until the bullet made it past the brass edge in the barrel.  The brass head stamp is Underwood
and it is nickel.  This is the most recent run of 200 XTP that he had up near the end of the week April 22-26.  I typically kneel about 20 feet back from the chrono
otherwise mine is pretty picky and doesn't even read sometimes.  I do believe those two high velocities the first time were due to either bad shots by me or
chrono errors.  I can chrono some more memorial weekend and inspect each brass piece individually and compare it with its velocity.  I will measure the head of
these brass cases next weekend as well.  These two smiled and there are two more with slightly less severe smiles, this was out of 19 shots.  If I missed replying
to any questions ask again.  Please feel free to suggest anything that you feel may have happened.

[DM1906]

Sorry I had a very busy end of the week.  This was a stock G20 SF only modification was a 22 lb ISMI recoil spring was installed on a SS guide rod.  The right side
of the left case is sticking up past where the rest of the neck is.  This was due to the tear in the brass.  I was almost thinking it got caught in the barrel with the
bullet then the pressure started to push the slide back and it tore it until the bullet made it past the brass edge in the barrel.  The brass head stamp is Underwood
and it is nickel.  This is the most recent run of 200 XTP that he had up near the end of the week April 22-26.  I typically kneel about 20 feet back from the chrono
otherwise mine is pretty picky and doesn't even read sometimes.  I do believe those two high velocities the first time were due to either bad shots by me or
chrono errors.  I can chrono some more memorial weekend and inspect each brass piece individually and compare it with its velocity.  I will measure the head of
these brass cases next weekend as well.  These two smiled and there are two more with slightly less severe smiles, this was out of 19 shots.  If I missed replying
to any questions ask again.  Please feel free to suggest anything that you feel may have happened.

This can't happen, unless there something seriously wrong with your pistol.  The breach doesn't move from the barrel until after the bullet is long gone, from the muzzle.  It's the gas exiting the muzzle, NOT the detonation, that begins the action cycle.  Either something else caused the brass to "stick" to the chamber, or the brass was defective or damaged during assembly.  Even if your chrono velocities were accurate, I don't see anything alarming about it.  I've gone significantly greater than that, and the typical pressure signs were very evident.  Ramp smile, case web expansion and primer extrusion, but nothing catastrophic.  If you were using an OEM Glock barrel, the results you see are at the wrong end of the case to be a pressure issue.  Case smiles aren't uncommon with Underwood 10mm, in any barrel.

As far as the brass source goes, you'll have to confirm that with Underwood.  I suspect it isn't Starline, as they don't stock nickel, and the unique head stamp requires a custom run.  Starline only does nickel brass in drum-lots, with a long lead time.  There's almost no way Underwood got custom Starline nickel brass on short notice because they were out of regular bulk.  They're backlogged for months on custom orders.  A drum quantity is about 8,000 pieces, and 3 drums are required for bulk discount.  The custom head stamp is not significant, as Starline is already tooled for Underwood's (initial expense already paid).  I think he got the brass somewhere else, perhaps Armscor Intl (probably offshore mfg).  If it were a contract fulfillment production, surely it wouldn't have been nickel, as this adds to delivery time and cost.  I dunno.  Ask him.

[REDLINE]

Sorry I had a very busy end of the week.  This was a stock G20 SF only modification was a 22 lb ISMI recoil spring was installed on a SS guide rod.  The right side
of the left case is sticking up past where the rest of the neck is.  This was due to the tear in the brass.  I was almost thinking it got caught in the barrel with the
bullet then the pressure started to push the slide back and it tore it until the bullet made it past the brass edge in the barrel.  The brass head stamp is Underwood
and it is nickel.  This is the most recent run of 200 XTP that he had up near the end of the week April 22-26.  I typically kneel about 20 feet back from the chrono
otherwise mine is pretty picky and doesn't even read sometimes.  I do believe those two high velocities the first time were due to either bad shots by me or
chrono errors.  I can chrono some more memorial weekend and inspect each brass piece individually and compare it with its velocity.  I will measure the head of
these brass cases next weekend as well.  These two smiled and there are two more with slightly less severe smiles, this was out of 19 shots.  If I missed replying
to any questions ask again.  Please feel free to suggest anything that you feel may have happened.

Thanks for the info.  Helps put things into a more definitive perspective.  At the end of the day it's hard for me to come to any other conclusion than Underwood loading those 10mm rounds beyond what Kevin originally intended.  Not good.  Supposedly he's correcting the issue.  My question now is;  When did Kevin adjust his 10mm loads?  Before or after your lot?

[pacapcop]

After.I have the same lot.. However, this ammo insanity is causing issues.

[REDLINE]

Well, at least initiative has actually been taken to correct these issues.  Hopfully nothing catastrophic happens as a result of other older overpowered lots still floating around out there.

[Von]

Another explanation for one of the high readings you got on the chrono is that one or more of the bullets in that box was the wrong weight. I bought some 200 grain xtp's on 4/27 and the first one I pulled out of the box was a 155 grain xtp in the nickel case. Someone must have picked up some from a drum and then droped them in the wrong drum not paying attention to what they were doing? Also are you guys using the date of puchase or date listed as the lot# or is there an actual lot number I'm missing somewhere.

[Intercooler]

Nobody has Gas Ammo beat. I thought I had 180 XTP's and when The Shadow did the tear-down they were all 200 XTP. Sadly, they don't even carry 200 XTP 

[4949shooter]

Well, at least initiative has actually been taken to correct these issues.  Hopfully nothing catastrophic happens as a result of other older overpowered lots still floating around out there.

Amen.

We will have to chrono the new and corrected lots to see what they are doing, quality control, deviation, etc.

[doverpack12]

I was using the numbers on the end flap of the box as the lot number.  They have to be his most recent run because there haven't  been any available since then. 
I put a picture of this number at the top of the first page of the thread.

[The_Shadow]

I was going to mention it earlier, but that number (UA45) refers to the packing box model.  The 45 ammo box works for 10mm.   
The boxes get printed with the label for the company like Underwood.  His info should be on the sticker on the outside of the end flap.  Maybe he is using the Item number to reference his lot.  However that doesn't really provide enough data.
Also a Lot number should be clearly marked, I don't know what he is doing to keep track of different lots!  That could be a potential problem...