The range officer where I shoot asked me an interesting question today and I don't have an answer for him.

 

He was shooting some reloads that he made up and a couple of the people present at the range and he himself all agree that the report from the gun was unusually loud. He has used the same recipe for 9mm before, 6.1 grains of Power Pistol @ 1.12" col with 115 grain FMJ RN bullets.

 

Also, I looked it up online and there are no threads out there on the net with what a louder than normal report signifies. It seems rare that something like this doesn't at least have bad opinions out there.

 

Any ideas?

The sound may be an indication of over pressure. At 6.1gr he is pushing 1100-1200 fps. If his brass is crimped too tight, it will cause a pressure spike and likely velocity spike.

Both conditions will increase the sound pressure of the report. Let him check his scale and his crimp.

Also batches of powder can have different performance envelopes. Some are hotter then others even for the same powder.

 

Also powder measures can get out of whack

 

When you get unexpected, stop, pull the bullets from the cases and re weight the charge

Unusual noise is an indication to stop and check fired cases for loading problems, check firearm for malfunctions, and recheck loaded ammo.  To continue could be a serious safety issue.

Good point on the crimping as earlier in the day he told me he had some issues with his press when he switched from .45cal to 9mm although he did say that he had to weigh all the charges while he was resetting things due some issue with his press. I don't know if he had crimp issues too. I think I'll call him tomorrow. 

I always pull one bullet of each batch to check crimp. Also worth noting the Lee factory crimp dies will cause pressure spikes if u don't properly adjust the charge.

Power Pistol is notorious for being loud and flashy.

Power Pistol is notorious for being loud and flashy.

 

Agreed, I think it's on the slower end of pistol powders

 

A large charge of a slow powder in a short barrel (what kind of gun was it?) = powder burning in the air outside the barrel = fireball and big bang.

I'm not sure on the particulars of the gun, but I did tell him to check out his crimps.  I'll ask about the fireball too.

Contacted my friend and the gun is a Glock 19 with 4" barrel. We plan on taking some of his previous problem free rounds and some of these to the range on Friday and using my new chrony for the first time to see what kind of speeds they are developing, and comparing them to the 1100-1200fps cited above. Will we need to calculate the power factor? I don't think so, right? If the speeds check out properly, does he need to recrimp them all, which is the current plan.

 

Meanwhile it will give me a chance to set up and try the chronograph hopefully without shooting it. Two birds with one bullet!

re-crimping is almost never an answer to any question. If anything he might have too much not too little.

 

Get an impact puller, pull some bullets, double check the charge weight and look for damage to the bullet from the crimp. 

 

If the question is "is my ammo overpressured?" the answer is almost never "lets shoot more of it". Check the charge, check the crimp, THEN chrono and while at it look for signs of pressure on the case and primer. 

>He has used the same recipe for 9mm before, 6.1 grains of Power Pistol @ 1.12" col with 115 grain FMJ RN bullets.

Then, it is a known load for his gun. Noise? Depends on powder and other factors. HE probably did not notice the noise. Others noticed and mentioned it. The load is a Bullseye competition target load for 9x19 and should not be a max load. Max is generally 6.7gn and up.

Of the seven Bullseye shooters who have referenced that load, 6 use a COL of 1.120" and one uses 1.100".

Ask him to try LoudShout, I mean LongShot, if he wants noise.

Just to clarify, we were thinking along the lines of too much crimp, not too little and thought to re flare the cases and then crimp lighter. He will be checking the charges first on a few to ensure they are in range of 6.1 which as stated above is a light target type load.

Has he checked his OAL to see if it's the same as before the loudness was noticed? I would be checking his seating die. If it has been moved somehow and is seating bullets deeper that could cause a pressure increase and problem.

He checked the OAL. We got rained out today, but plan on going on Monday to chrony

So did he ever this out?

Keep in mind, that velocity is rite at the sound barrier, so it could be a very slight change in pressure, charge, temperature, etc. that puts him supersonic.

Couldn't run velocities as I don't have IR setup, but we brought out his original loads ( his first set prior to the questionable ones), two brands of factory rounds, some of the questionable rounds, some new reloads that were redone with the lighter crimps, and some reloads of mine with a different powder for some blind comparisons of loudness, accuracy, and fireball. The guys rating it were 2 other range officers, my friend and myself, and we used an area where there was no other shooters at the time. Mags were loaded with one of each of the above in random order with the order recorded for each mag and then the mags were fired and graded. We all agreed all the bullets were within normal range for any of the factors rated, and only one of us identified a particular round that was a hair louder. It did turn out to be the questionable loads. Accuracy was pretty much identical and fireball was inconsistent.

I don't think I'd dismantle and reload on that basis.