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Glock 34/124gr MG CMJ/Fed SPP/VV 3N37 load confusion


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We recently just bought a new Glock 34. It has had about 500 factory rounds thru it so far and we are wanting to reload ammo for it now.

In years past I reloaded 45ACP, 40 S&W and major loads for 38 super and have no trouble whatsoever. I have never reloaded 9mm, and cannot believe the issues I am having with reloading this common round.

For my Major 38 Super loads in my STI race guns, I am using 7.9 grains of VV 3N37, 124 gr MG CMJ, Winchester SRP at 1.250" COAL. Running at an average of 1340 fps and as expected there is some primer flattening. Years ago, before I could afford a full blown race gun, I used to reload ammo for Glock 24 and my Springfield Armory 45 ACP. I just wanted to put this in here so I can show that I am not a complete newbie to reloading, but I have a lot to learn also.

Now that my son is old enough to shoot with me now, I started him out with my Glock 24 and that was kind of a handful for him so I went out and bought the Glock 34 for him to shoot in matches. He improved majorly just by switching from 40 to 9mm in his accuracy and time. With all of the factory ammo almost gone, and I refuse to pay the prices they want for factory ammo, it is time to reload for the 9 and 40.

We found that the Sierra manual had a load listed for 9mm 124 TMJ, CCI primers, 1.135" OAL using VV 3N37 5.7gr(1063 fps) to 6.4gr(1179 fps) out of a 4" barrel. We loaded up some test rounds using Federal SPP, Federal cases, 124 gr MG CMJ, 1.135" OAL at 5.8, 6.0 & 6.2 grains(all on the low end of the suggested powder charge range) of VV 3N37. Keep in mind that the barrel length in the Glock 34 we are shooting is 5.32", not the 4" barrel that Sierra had listed as their test barrel in their manual.

We took them out and shot 3 of the 5.8 grain loads and the registered 1160 fps average on the chrono, which is way higher than the Sierra manual listed. We were seeing velocities at 5.8 grains that were close to the Sierra's listed maximum load of 6.4 grains, with serious case bulge(I know that all Glocks will naturally have more bulge than other pistols) and serious primer flattening. After really looking at the primers, we did notice that there was some primer material flow back into the firing pin hole. This baffled all of the guys that were shooting with me as they all agreed that they had never seen such a swing in velocities from actual reloads and loads listed in a reloading manual. Not wanting to take a chance on destroying a brand new Glock, and more importantly for our safety we stopped at the 5.8 grains and pulled all of the loads immediately. I did check for crimping rings on the bullets that we pulled and we noticed no signs of over crimping.

Confused with the results, I got onto VV's website and they have loads listed for Lapua 124 RN FMJ bullets at a OAL 1.142". There powder charge for this load ranges from 5.2gr(1102 fps) to a max charge of 6.2gr(1243 fps) out of a 4" barrel. Seeing this coincides with the 1160 fps we seen with the 5.8 gr(minimum charge listed in the Sierra manual) loads we originally tried that seriously bulged the cases and caused primer flow in to the firing pin hole.

We loaded test loads of 5.2, 5.4 & 5.6 grains of 3N37 which was on the low end of the powder charge range listed on VV's website. Took them out and test fired them and they chronoed very close to what the VV data said they would, but once again the primers were flattened and the case bulged pretty bad. The outside of the cases were very dirty and seemed to more discolored from the heat than my 38 super Major loads are.

All in all this makes me pretty nervous about using the 3N37 for 9mm. I have a couple of questions I would like to see if someone could answer. Please feel free to provide any kind of guidance, comments as you see fit. I will probably learn something from it.

How much will a difference of 4" barrel length listed in Sierra reloading manual and VV's reloading data online versus the 5.32" barrel length in our Glock 34 have on velocities, pressure signs and all of that? At this point I am not overly concerned about the difference of accuracy as I am finding a safe load to shoot.

Anyone have any experience loading 9mm using VV N350? I seen that Hornady has listed VV N350(which is right next to 3N37 on the powder burn rate charts) as a powder choice for the 9mm 124 gr FMJ in their reloading manual. I have 8 pounds of this as well as 4 pounds of 3N37 here.

Please feel free to give any advice or comments as you see fit!

Thanks,

Matt

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I'm currently running 124gr MG CMJ's with 3.8gr of Titegroup OAL of 1.150, they have worked flawless in all my 9mm firearms without any signs of high pressure, sorry but I haven't had a chance to chrono this load yet, but my understanding is it should make SSP PF. Getting ready to try VV320 as my TG stash is almost depleted.

~g

Sent from my iPhone

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My data show a 7% increase in velocity going from a 4.1" barrel to a 5.1" barrel.

What does surprise me is the flat primers, are you sure the powder has not been contaminated with faster powder? You should not be seeing pressure signs with those loads...

I would set the 3n37 aside and try the n350 with book loads and see what the primers look like.

Edited by kneelingatlas
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I have 8 pounds of Clays, 8 pounds of VV N350 and 4 pounds of VV 3N37. Plus 4 pounds of VV N105.

All we have loaded with is VV 3N37. The only canister of powder that we have that has a broken seal on the cap is the 3N37.

Atlas, I cant agree more with the worries of the flat primers, it is absolutely baffling to me. This was the first time I have used Federal primers in anything. IN the years past when I loaded 40, 45 ACP & 38 super major loads and now currently with my 38 super major loads I have exclusively used Winchester primers.

I know for a fact that I have on hand if it isn't the proper burn rate for the caliber I am trying to reload, but this is ridiculous. It is listed in Sierra's manual and VV loading data as being an acceptable powder for the 124 FMJ 9mm loads.

What really worries me is why does Sierra list their charge from 5.7 - 6.4 but yet VV lists their range from 5.2 - 6.2? Seems to me that the Sierra data is capable of producing loads that are to hot. I can see a .1 swing in starting and max charges, but the Sierra starting charge is .5 grains different from VV.

I am no expert and do not claim to be and I have to take as they know more than I ever will, but I just would like to know the reason why.

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3 of the 5.8 grain loads registered 1160 fps, which is way higher than the Sierra manual listed. , with serious case bulge and serious primer flattening.

Have you tried 5.0 grains? :cheers:

Any photos of the primer flattening?

I'd triple check the powder weight - going to extreme precautions - just to make SURE you're throwing 5.8 grains,

and do the same with the OAL - not uncommon to mistake 1.135 with 1.035".

I'm sure you haven't made either mistake, but with those readings, I would triple check them one more time.

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I have 8 pounds of Clays, 8 pounds of VV N350 and 4 pounds of VV 3N37. Plus 4 pounds of VV N105.

All we have loaded with is VV 3N37. The only canister of powder that we have that has a broken seal on the cap is the 3N37.

Atlas, I cant agree more with the worries of the flat primers, it is absolutely baffling to me. This was the first time I have used Federal primers in anything. IN the years past when I loaded 40, 45 ACP & 38 super major loads and now currently with my 38 super major loads I have exclusively used Winchester primers.

I know for a fact that I have on hand if it isn't the proper burn rate for the caliber I am trying to reload, but this is ridiculous. It is listed in Sierra's manual and VV loading data as being an acceptable powder for the 124 FMJ 9mm loads.

What really worries me is why does Sierra list their charge from 5.7 - 6.4 but yet VV lists their range from 5.2 - 6.2? Seems to me that the Sierra data is capable of producing loads that are to hot. I can see a .1 swing in starting and max charges, but the Sierra starting charge is .5 grains different from VV.

I am no expert and do not claim to be and I have to take as they know more than I ever will, but I just would like to know the reason why.

1. Your "Sierra" data is actually Speer data, not Sierra - according to my Sierra and Speer manuals.

2. Don't fret over the starting charge weight difference. It's meaningless.

3. No two manuals have exactly the same data. They are almost certainly using different lot numbers of powder, and they certainly are using different bullets shot from different test barrels. If you fired that same load from 5 different guns (with the same barrel length) would would get 5 different velocities. Read the chapter in your Speer manual entitled "Why ballisticians get gray." It's chapter 18 in Manual #14.

4. Different brands of primers react differently to the same load. http://38super.net/Pages/Primers.html

5. Different types of bullets (plated, cast, jacketed, etc.) produce different velocities with the same gunpowder charge weight. Different brands of the same type of bullets can also show different velocities, and some folks on this forum say that MG bullets run slow.

6. The dirtiness and color of your brass probably means nothing.

In my limited experience with Glocks, some of them show evidence of primer flow with a wide range of loads.

How much "bulging" are you seeing in the brass? Can you post some pictures?

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Glock 19

Glock OEM barrel

S&S casting 124grs coated LRN

3N37 5.7

Win cases

COL 1.130

CCISP primers

Avg Vel 1067

SD 7.93

PF 132

15yd accuracy 1.6"

I believe your barrel would be 75fps faster than mine

I have no sign of flattened primers

My velocities are right inline with the Speer # 14 manual

test firearm is a S&W M5906 4" barrel

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