If I shorten

[rooster]

I just got a new Faxon G34 barrel. The chamber  throat is real short, and won’t let me chamber my load of 4.2 grains of N320 @ 1.130. Can I safely shorten to 1.080? It’s a Precision Delta 124 grain JHP. I don’t want to throat barrel as it is salt bath nitrided and the throater die won’t even scratch the coating. If not safe I can always use oem barrel but thought I would ask. Of course I don’t want to pull I have quite a few loaded up. Thanks in advance.

[HesedTech]

40 minutes ago, rooster said:

I just got a new Faxon G34 barrel. The chamber  throat is real short, and won’t let me chamber my load of 4.2 grains of N320 @ 1.130. Can I safely shorten to 1.080? It’s a Precision Delta 124 grain JHP.

I assume you are shooting minor at that load. 4.2 grains is already near max load data from Vih., so I would guess it all depends on your barrel design and strength. Is your PF around 135 with that load?
 

Using Sport Pistol to make 135 with RMR JHP 124 I found 1.08 and 4.1 works in all my pistols, including Glock. I dropped to 3.8 gr for my son’s PCC because that load made about 145 PF and I don’t like using any more powder than necessary.
 

Hope this helps. 

Edited April 4, 2020 by HesedTech

[4n2t0]

Absolutely, shorten away.

 

I'll say it until I'm blue in the face, shortening a published load will never cause a safety issue with regards to pressure. It may create other problems but not a "kaboom".

 

But, but, but the pressure increase......lol.

Edited April 4, 2020 by 4n2t0

[iflyskyhigh]

Absolutely, shorten away.
 
I'll say it until I'm blue in the face, shortening a published load will never cause a safety issue with regards to pressure. It may create other problems but not a "kaboom".
 
But, but, but the pressure increase......lol.

This [emoji1318]

Just covered it in another 9MM thread


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[rooster]

Load is at minor pf, I think it was around 128. I know pressure will increase, it’ll probably be a little stout , but I just want to use until it’s gone. Didn’t want to kaboom gun. I think I’ll crunch a few and check for over pressure signs.

[iflyskyhigh]

Load is at minor pf, I think it was around 128. I know pressure will increase, it’ll probably be a little stout , but I just want to use until it’s gone. Didn’t want to kaboom gun. I think I’ll crunch a few and check for over pressure signs.

You can’t ever say always or never, but I doubt you’ll even notice the difference.

The relationship of COAL to Pressure is not linear. Not even close.

I load 7.8grs silhouette to 1.155” for my Glock 17 major. I needed to shorten some to 1.130” to try out Taylor Tactical’s 170MM mag extension. I had my son do it for me, and the seating die came loose during the process and some of them ended up 1.100” or shorter.

It made almost zero difference. The super short rounds registered 10FPS difference or less.

I’m not alone in this finding. There have been several others on here who have basically found the same to be true with different powders, loads, and guns.

Do a little experiment yourself. I think the results will surprise you.


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[rooster]

Iflyhisky, I read that thread I just wanted to make sure as I’m going to shorten by .050. 

[iflyskyhigh]

Some of rounds were shortened over 0.060”


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[rooster]

This is great, I just shortened 100. Next time I shoot I’ll keep a close eye. If okay I’ll shorten the rest. Thanks for help.

[iflyskyhigh]

This is great, I just shortened 100. Next time I shoot I’ll keep a close eye. If okay I’ll shorten the rest. Thanks for help.

[emoji1303]

Good luck. We’re all counting on you. [emoji23]


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[superdude]

5 hours ago, iflyskyhigh said:

The relationship of COAL to Pressure is not linear. Not even close.
 

 

See the bottom chart on page 3.

 

http://www.castpics.net/LoadData/Freebies/RM/Ramshot/Ramshot_3.pdf

 

 

[rooster]

Thanks superdude, very informative.

[RaylanGivens]

I'd throat the barrel with a carbide reamer...

 

There's a guy here on the forum that makes them...  something with '1911' in his screen name... and also @MemphisMechanic was throating barrels with one for a couple of members on the forum as a favor...  Worth a shot...

[MemphisMechanic]

@1911luvr makes a reamer that will cut it.

 

I do glock barrels sometimes for friends, too.

[superdude]

With respect to shortening a load, pressure will increase if the powder charge is not reduced. If you have to shorten it a lot, pressure will go high. 

 

I plugged your numbers into QuickLOAD for a pressure estimate. I don't have a length for the Precision bullets so I just used a generic 0.570" length which is in the range of several 124 JHP bullets. The pressure estimate with the bullet at 1.130" is 32,547 psi. The pressure estimate with the bullet seated at 1.080" with the same powder charge is 41,414 psi. That's a 8,867 psi increase. 

 

You would need to reduce the charge weight to 3.8 grains to keep about the same pressure = 32,689 psi at 1.080" OAL.

[iflyskyhigh]

 

See the bottom chart on page 3.

 

http://www.castpics.net/LoadData/Freebies/RM/Ramshot/Ramshot_3.pdf

 

 

Stand corrected.

 

Maybe linear wasn’t the right word.

 

So how can you shorten a load 0.060” and only get a 10 FPS increase while increasing pressure that much?

 

What’s the relationship of pressure to fps?

 

 

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[superdude]

23 minutes ago, iflyskyhigh said:

Stand corrected.

 

Maybe linear wasn’t the right word.

 

So how can you shorten a load 0.060” and only get a 10 FPS increase while increasing pressure that much?

 

What’s the relationship of pressure to fps?

 

 

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I can't say in your situation, but one must first ask if all of the possible contributions to pressure/velocity were controlled as in a science experiment. For example, were both OALs loaded at the same time, chronographed at the same time, with the same powder lot #, with same headstamp cases, etc. etc.

 

I tried Ramshot's data with Zip powder and found a 40 fps difference when going from a OAL of 1.155 to 1.082". It's not much. 

 

I did a 9mm OAL test with 115 grain Zero JHP bullets and Silhouette. I loaded everything at the same time and chronographed everything at the same time, same everything. 

 

When using 5.0 grains of Silhouette going from an overall length of 1.075 to 1.135 (0.060") showed a difference of 84 fps. 

 

When using 6.0 grains of Silhouette going from an overall length of 1.075 to 1.135 (0.060") showed a difference of 47 fps.   Maybe, MAYBE Silhouette does not show much change in FPS as the charge weight goes up.  MAYBE! More tests would be required. 

 

Plus, powder doesn't always do what we expect.  ATK/CCI/Speer measured the effect of OAL and pressure in some 357 Sig ammo.  As the bullet was seated deeper, pressure went up - like expected. But only up to a point.  When the powder started to get compressed, pressure flattened (see the attached figure).  They don't indicate what powder was used. 

 

Once we look around at enough data, the thing that becomes clear is that it's not easy to make absolute statements about things only working one way, because surely there will be some data that doesn't fit what we think. 

 

[rooster]

I guess I’m not going to chance it. If superdude is correct that 41k is asking for trouble. I’ll just shoot in my oem barrel until they are gone. I’ve already loaded and shot some at 3.6 at the 1.080 and they were fine. Thanks for the help. I’ll pull the 100 that I shortened.

[superdude]

3 hours ago, rooster said:

I guess I’m not going to chance it. If superdude is correct that 41k is asking for trouble. I’ll just shoot in my oem barrel until they are gone. I’ve already loaded and shot some at 3.6 at the 1.080 and they were fine. Thanks for the help. I’ll pull the 100 that I shortened.

 

The QuickLOAD estimate is just that, an estimate.  I don't always trust what it says the pressure is. Sometimes it's way off from published data. Sometimes not. However, I do put some faith in it's estimate of pressure changes with respect to changing overall length or changing powder charge weight. Right or wrong it's about the only tool we have for that short of asking the manufacturer if they have data.  

 

I can't say what the pressure is in your load, but whatever that pressure is, seating it deeper with the same charge of powder could raise the pressure around 8,867 psi according to QuickLOAD. If your load is already near the upper boundary, adding 8,867 psi (or thereabouts) could be a problem.  That's a big increase. 

 

Your gun might handle it okay if it has good case support. Some of our 9 Major loads are probably at least in the 40,000 psi range or higher. However, N320 is a fast burning powder, and I would be less trustworthy of pushing it very hard like we do with slower powders.  I'm not basing that on any actual data, just my caution with fast burning powders, warranted or not.  There are times when being paranoid is a good thing, and that certainly applies to handloading. 

 

If it was me, I would absolutely pull them.  Better safe. 

Edited April 5, 2020 by superdude

[4n2t0]

And there we have it, full circle, as expected. 

 

Oh well, do what you think is best/safest for you OP. Personally, I will always shorten to the desired OAL without ever fearing a "kaboom" because in real life it just doesn't happen.

Edited April 5, 2020 by 4n2t0

[xrayfk05]

In my experience Quickload can be very inaccurate if you go beyond it's "working" boundaries.

To get some coated 124's chambered I had to shorten the round to 1.04" and loaded with 3.8 grains of Lovex D032 (AA #2) Quickload predicts near 80K PSI. At normal OAL's Quickload is spot on compared to the reloading tables.

Rounds shot fine with no over pressure signs whatsoever, 130 power factor. (normal load would be 4.1 grains to get PF 130) And yes, normal SP primers.

I got there by shooting them at a normal OAL in a gun that would handle them and shortening them step by step shooting over a Chrono.

 

In your case I would start with say 3.5 grains and work up until you get your PF at that OAL, if you are not comfortable with that look for a different bullet.

Edited April 5, 2020 by xrayfk05

[rooster]

Over at natoreloading they had 2 loads that made me think I could do this. Both loads were at 1.095, one at 4.2 for 1045fps at 130pf. The other was 4.8 for 1174, pf 146. They had the usual run at own risk statement. I thought that if they could load at 4.8 that short then I might be ok as I’m going .015 shorter but .6 less powder which would put me a lot less but at this point I don’t think it’s worth the risk. If that 8k is close to the pressure rise i don’t want to be the one behind that gun. vitavouri load data is 4.2 @1.130 for their max, and I’m way shorter than that.

[iflyskyhigh]

And there we have it, full circle, as expected.   

Oh well, do what you think is best/safest for you OP. Personally, I will always shorten to the desired OAL without ever fearing a "kaboom" because in real life it just doesn't happen.

 

I still feel pretty much the same.

 

I probably shouldn’t have made my comment about “always and never”. I know better.

 

Probably too many variables.

 

Whatever you feel safe with. But I’ve had similar experiences with many different powders, bullets, and guns where I shortened a load to fine tune it without changing the load and I haven’t had an issue. And I’ve read about about many others on here with same experience. The example of the 9mm major load was just the most extreme one.

 

And again humans aren’t scientific instruments, but I’m willing to bet most people have had a round go off and though “wow, that was hot”. I’ve never had that moment from a shortened cartridge.

 

And as an aside back to your original post. I run all (except open) JHP from all the major manufactures at 1.110-1.095”. My practices loads are all in the 130-140 FP range with titegroup, HP38, and similarly fast powders. And my practice HD rounds are in the 150+ PF range with everything from TG to Silhouette to HS-6 to Power Pistol.

[4n2t0]

3 hours ago, rooster said:

 vitavouri load data is 4.2 @1.130 for their max, and I’m way shorter than that.

 

The OAL's listed in manuals and data are completely useless unless you're using all the same components and their test jig/barrel as a firearm.

[rooster]

19 minutes ago, 4n2t0 said:

 

The OAL's listed in manuals and data are completely useless unless you're using all the same components and their test jig/barrel as a firearm.

I realize this but we have to rely on some kind of guide. I am using their max recipe but shortening by .050. Being that n320 is a fast powder I want to play it safe. I think I will shoot a few over the chrono and see if there’s any pressure signs. I want to thank everyone’s replies as they are really helpful. Has anyone checked the info over at natoreloading?