Glock 20 feed issues

[sqlbullet]

I would guess the heavier spring is reducing the time the slide spends at full cycle.  This reduces the amount of time for the magazine spring to do it's job.  With the 40 S&W ammo the top round of the shorter ammo rides forward in the magazine, effectively increasing this window of time.  The 20lb spring should help correct this issue for you.

funny, Hornady claims max load is 9.4gr of Blue Dot under their 200gr bullet and Nosler claims 9.3gr of Blue Dot under their 200gr bullet. Alliant must have stricter lawyers Hornady and Nosler.

-matt

This difference is almost certainly due to other factors, like chamber or bore size, condition or reloading components.  These factors aligned so that Alliant reached pressure earlier than Nosler or Hornady.  Alliant even published the MAP as 33,800 PSI. 

There are a number of reasons why they may have stopped at 8.9 grains
    That is heaviest charge of powder they had loaded for test
    9.0 grains exceeded the MAP specs for 10mm (37,500 PSI Transducer)
    9.0 grains exceeded the MLPM (38,700 PSI Transducer)
    9.0 grains exceeded the MPSM (40,500 PSI Transducer)
    9.0 grains had rounds that exceeded the MEV (45,000 PSI Transducer)

This is exactly the point of start low and work up.  You don't know what will happen in your gun.  Alliant, Hornady and Nosler all got different results using lab grade test barrels.

I would also note that reducing any of the published max loads by 10% would give you a starting load a half grain below the lowest published max load.  Reducing tommac919's load by 10% is still .3 grains above the Alliant max.

While I am pretty sure the reloaders here know what they are about and would know to cross reference and work up, this site is publicly visible to non-members who may find this thread by web search.   Those people likely will not see or read the Load Data-Warning thread that is a sticky in the 10mm Reloading area.  For this reason that sticky specifically asks members to document when they have exceeded published load data and site the source data from which they started.  This thread lacked that warning, so I added it using data from Alliant since that data is available online.

I have no issue with sharing over-book data.  I wanna know what people are loading.  At the same time, I wanna make sure everyone that may read the posts knows when they see over-book data.  What works fine for one reloader may be catastrophic for another.

[tommac919]

I have no issue with sharing over-book data.  I wanna know what people are loading.  At the same time, I wanna make sure everyone that may read the posts knows when they see over-book data.  What works fine for one reloader may be catastrophic for another.

Agree.. In the future... will put tag on over book loads mentioned

And while fairly new to loading the 10mm ( couple years ) , I look back to some of the loads my Dad use to run... its amazing to see a s&w revolver frame get bent :O

I do pull from some of the older manual ( 7-10 yrs old  )  and see a big differences in load amounts, I guess then again you can say the powder formulas have been revamped over the years too which may account... , I think its more lawyers .

Will say when running up on the ragged edge +,  I make sure I wear mech gloves too.

[matt85]

I understand the need to be careful (some people don't have common sense). I typically add a "lawyer be gone" warning to my posts when discussing over-book loads.

but if we strictly went by the modern books then the 10mm isn't even able to reach its original weight/speed of 200gr at 1200fps. I have just about every current loading manual in my collection and none of them give you over 1150fps from a 5" barrel using a 200gr bullet. so either powder has gotten worse since the cartridge was invented or the load data is incorrect. another suspicion of mine is that these companies intentionally download their loading data to encourage purchasing of factory ammunition (many factory loads for other cartridges are hotter then the data shows possible).

-matt

[Ridgerunner665]

If the slide is going over the rounds in the mag then the mag spring is too weak and/or the recoil spring is too strong.

Put the factory recoil spring back in and see what happens.

[Benchrst]

I've run stock, 20, 22, & 24# in my G20.4. 20# is what I settled on.

Occasionally with the hottest loads (200 XTP @ 1,275ish) the slide will fail to strip a round out of the mag.

Don't consider it a failure since I know I'm pushing the limits.

[tommac919]

I changed a few months ago out from stock to a 20 lb spring and haven't seen any difference in my middle to warm loads...
I do know it seems better on the hotter rounds, but all works 100% now and I think I'll leave well enough alone

As a side bar,  pushing the 200 to over 1250 has always seem to be a place I'd never reach ...wow

[matt85]

thanks for the replies. ive got a 20lb spring on the way, but will test the stock spring this weekend to see if there is any issue.

-matt

[sqlbullet]

...
I have just about every current loading manual in my collection and none of them give you over 1150fps from a 5" barrel using a 200gr bullet. so either powder has gotten worse since the cartridge was invented or the load data is incorrect. another suspicion of mine is that these companies intentionally download their loading data to encourage purchasing of factory ammunition (many factory loads for other cartridges are hotter then the data shows possible).

-matt

http://www.saami.org/specifications_and_information/specifications/Velocity_Pressure_CfPR.pdf

Page 1 lists the SAAMI nominal mean velocity spec for 10mm auto as 1150 fps measured 15' from the barrel for a 200 gr bullet.  So, this isn't a conspiracy, it is just load data conforming to the spec max velocity suggested for product safety control.

When SAAMI did their testing on the 10mm, they determined the original Norma loadings could not be achieved within SAAMI guidelines for consistency.  If you load to 1200 fps for a 200 grain 10mm, you will have some lots of ammo that exceed the MLPM or MPSM, or some individual rounds that exceed the MEV. This is just due to the inherent variability of primers, case volume, bullet tension, bullet material and, most importantly to a handloader, acceptable variations in mass produced ammo.

Load data has to conform to these guidelines if it to be accepted as SAAMI spec.  Being SAAMI spec provides the publisher some liability protection.  But, as a handloader, we know that we can control that last variable better than a production line running 5K rounds per minute.  As a result, we can with very careful technique achieve velocity gains of 5%-10% over the SAAMI velocity spec.  For 200 grain 10mm this puts our max loads between 1207 and 1265 fps, depending on the gun.

There are some dangers to consider here.  Most serious 10mm handloaders are hardcore enthusiasts.  We have a stable of 10mm handguns and carbines.  Looking in my safes I have six 10mm handguns.  Chamber and bore are a big contributor to max pressure.  So, either I have to work up a load and mark it for a single gun, or I have to build in a safety margin so I know it will be safe in all my guns.  I generally do the latter and end up my 200 grain loads being about 1150 fps.  I have from time to time loaded up experimental batches that were only for my EAA Witness guns that went above that level.

Hopefully that clears up why most manuals don't go over 1150 fps, and why most "major" 10mm producers don't reach 1200 fps in 200 grain.  It is interesting to note that Winchester's 175 grain Silvertip load's advertised velocity actually exceeds the SAAMI mean velocity spec for 175 grain bullets by 15 fps. Actual velocities in production chambers fall a bit short, probably due to testing being done in a minimum dimension chamber and bore, resulting in higher pressure and velocity in testing.

[Benchrst]

As a side bar,  pushing the 200 to over 1250 has always seem to be a place I'd never reach ...wow

Working with the right powder, in the right gun, it can be done safely.

I firmly believe, that with a 200gr XTP, you can not overcharge #9.

That is for my gun, my components, and my conditions.

[matt85]

took my G20SF to the range today, this time with the factory recoil assembly. didn't have much ammunition but it fed threw two 15rnd mags without issue.

did some playing around with a chronograph and managed to get decent velocity (around 1200fps) with the 200gr Rainier RNFP over 13gr of AA#9 (warning: over max load). accuracy was decent but will play around a bit more to see if it can be improved. I found velocities to be quite unstable with heavier loads using the factory recoil assembly where they were much more consistent with the 22lb spring. I can only assume some of the heavier loads to be leaving the chamber a little too soon.

side note: I made a new friend at the range, another guy had an older gen 3 G20 (pre SF). he posted up next to me and we had no shortage of things to talk about. at the end of the range trip he let me keep all his once fired brass (Sig Sauer, Remington, and S&B) and said he didn't hand load yet  . we swapped contact info and I will be directing him to this forum.

-matt