[Bub10x]

Doing some load development for a new Glock 20SF. Thought I would list my findings in case they help someone else. Pistol is stock. 45 degress 300ft el

Win 175 Silvertip 1212.6
UMC 180 TMJ 1094
PMC 200 TMJ 1044
From 2005 Alliant Reloaders Guide Max Load 200 TMJ Power Pistol 1058
From 2005 Alliant Reloaders Guide Max Load 200 TMJ Blue Dot 1037
From 2008 Hodgdon Reloaders Manual Max Load 200 TMJ Longshot 1122

FYI Current Alliant guide does not show 200gr loads. Current Hodgdon Manual does not list any 10mm loads

[10mm29]

hogdgon has a bunch of loads listed on thier website.

[Bub10x]

Originally Posted by Bub10x

Doing some load development for a new Glock 20SF. Thought I would list my findings in case they help someone else. Pistol is stock. 45 degress 300ft el

Win 175 Silvertip 1212.6
UMC 180 TMJ 1094
PMC 200 TMJ 1044
From 2005 Alliant Reloaders Guide Max Load 200 TMJ Power Pistol 1058
From 2005 Alliant Reloaders Guide Max Load 200 TMJ Blue Dot 1037
From 2008 Hodgdon Reloaders Manual Max Load 200 TMJ Longshot 1122

FYI Current Alliant guide does not show 200gr loads. Current Hodgdon Manual does not list any 10mm loads

Did some more testing today, temp was only 34 today so that may be affecting readings. Pistol also now has a ISMI guide rod and 20 lb spring.
AVE
Rem UMC 180 TMJ fired as a control from same box as last time 1080
From 2008 Hodgdon Reloaders Manual Max Load 200 TMJ Longshot 1096
Doubletap 200gr FMJ FP lot 006336 1050

Really was a bit of a let down. Have been in search of a heavy woods load, hoping for the magic 200/1200 load and when my handloads were not coming up to speed bought the expensive stuff. Now I know it was cold and that showed from the early groups about a 20 fps drop but the box quotes 1275 a 225 diff. Crono is a PACT MK III with factory screen base mount, first screen is about six feet from muzzle. Not real scentific testing, my crono/ my methods may be off, but a comparison between my results with my pistol. FYI the Doubletap bullet looks like a Montana Gold CMJ, recoil felt sharper with the DT load. Will retest again when the temp comes up.

[Taterhead]

Since you mentioned the 1200/200 ratio, I thought I'd mention one that has been working for me. I've posted this before, but I have a 200 gr load that averages 1205 fps in warm weather. Work this load up slowly because this was not derived from any component manufacturer data. It is certainly a max pressure load and may not be safe in your setup.

Firearm: Gen 3 G20 w/ 22 #lb Wolff non-captured spring and steel guide rod.

Projectile: Double Tap 200 gr WFNGC hardcast
Powder: 13.8 gr A9
Primer: CCI 350 (LPM)
Case: Starline brass
COL: 1.26"

[BusDrvr]

Originally Posted by Bub10x

Really was a bit of a let down... Now I know it was cold and that showed from the early groups about a 20 fps drop but the box quotes 1275 a 225 diff.

One thing to consider regarding the DT loads is the altitude and temperature at which they were tested. We know Cedar City is at 5900 feet and while we don't know the temperature, elsewhere on Glock talk there are references to Doubletap loads being tested at 86 degrees F.

At a standard pressure and dew point this would yield a "density altitude" of about 8900 ft. Since you are at only 300 ft and 30-40 degrees F, I would wager that you would see a significant increase in recorded velocity in your loads if you were testing them at 8900 feet!! Incidentally, the density altitude for your location and temperature is roughly negative 1300 feet.

I have no idea what Doubletap does or doesn't do regarding testing so we can only speculate based on varying environmental conditions, but pressure and temperature are important parts of the equation to consider, and the difference between (-1300 feet) and 8900 feet is quite significant. I believe the difference in velocity is roughly 18%, and 82% of 1275 is equal to 1045.5 fps. You recorded 1050 fps.

I reserve the right to be incorrect as it's well past my geezer bedtime.

[Bub10x]

Thanks for the feed back. Lead generally gives more vel so that is a path to work at. I have run into the changes is vel from summer to winter in the past with hunting loads. Some of the developed in winter loads can make you go whoa when fired in the summer. Since I am going for ma,x will wait to work up more and post the results with the temps up. Right now waiting for starline to get some brass in. Very interesting the percentage results.

[hill billy]

I have a 1200+ load for a jacketed 200 gr or 14+ gr of #9. Work into it slowly.

[Ak.Hiker]

The last box of DT 200 grain FMJ's I ordered are loaded with the MG bullet. Lot number 6044. They did not penetrate as deep in my testing through spruce wood as did the DT load using the 200 grain Hornady FMJ bullet. This was only one test so I do need to try the MG FMJ load out again. I wanted to recover the bullet but was not able to. I want to see if the MG FMJ bullet is as tough as the Hornady. I really like the thick jacket that Hornady uses on their FMJ's. One thing that may have slowed down the penetration is the MG bullet has a wider meplate than the Hornady bullet. If you are only getting 1050 out of the DT that is similar to the 200 grain Blazer TMJ and would explain why I did not get as much penetration. I do have a stash of the DT loads with the Hornady bullet so I think I will save them for woods carry. I can tell you that the Buffalo Bore 200 grain FMJ in my testing seems hotter than the DT. I have seen both loads [DT with Hornady FMJ] cut through 7 inches of spruce wood but the BB seemed a little hotter.

[preventec47]

Busdrvr said:
"225 diff. One thing to consider regarding the DT loads is the altitude and temperature at which they were tested."
------------------------
It is a point of fact that the altitude makes ZERO difference in muzzle velocities. From sea level to 18,000 feet is a difference of only 7 psi on the outside of the barrel. Inside the barrel we are looking at 30 to 37 "thousand" psi.

One or two flakes of gunpowder probably changes the bore pressure by 7 psi. See, velocity results from the difference in pressures on both sides of the bullet and you can see here how 7 psi difference on either side is insignificant. and that is the difference from sea level to 18,000 feet.

Altitude from Atlanta to Utah would be less than 2psi change in pressure !

Remember talking "muzzle" velocities here. NOT down range velocities. THEN altitude makes a measurable difference.

[Ak.Hiker]

I re tested the DT 200 grain 10mm loaded with the Montana Gold FMJ bullet. In some very tough spruce wood they penetrated about the same as the 180 grain hard cast Buffalo Bore 357 Magnum load and went quite a bit deeper than some full power 158 grain Speer Unicore [a tough SP bullet]. The MG FMJ is also very tough as I recovered one. It could have been reloaded. The hard cast bullet in the BB 357 load held up very well as expected but did deform slightly. The Unicore 158 grain mushroomed to about .50.They are a very tough bullet for a soft point. Of course the expansion reduced the penetration compared to the FMJ and HC bullets. Overall I am pleased with the performance of the DT 200 grain FMJ now loaded with the MG FMJ bullet. It looks to me like the MG FMJ's would be a good choice when deep penetration is needed.