High velocity in 9mm?

[jrayborn]

I'm looking for some ideas as to why I'm seeing higher than expected velocity in my reloads. Before I go into a lot of detail I will say that I am using a Dillon electronic powder scale and have checked the calibration (with the checkweights and with known weight bullets) to make sure it isn't off, and to the standard it is right on.

The other variable I could see is that my chronograph is showing things on the high side, but I have been able to check a very small number of loads against a different chrono and see similar velocity.

I've been at reloading for about 5 years now but still consider myself a novice and ALWAYS take the time to work up a load conservatively.

With .45 I load 5.9 grains Unique with 230 grain fmj's and see about 850 fps which is about right. I have loaded thousands of .45 with no issues at all but it likely has a high safety margin due to the low pressures anyway.

I just started loading 9mm and am aware that the pressures involved are a lot higher, so I'm a little more anxious. Anyway, I'm working on a load for a pistol and have started with 4.8 grains of Unique loaded with 125 grain Bear Creek (coated) LRN bullets at an OAL of 1.150 and a lee crimp. Lee lists 5.3 grains as a start load with 1106 FPS.

So out of a 4" barrel I get an average of 1170!! Not out of the realm of sanity but still a lot faster than I expected. It just seems that at .5 grains under the start load thats pretty fast. Thats the only issue I have with this load, primers look fine, brass looks fine, minor leading after 200+ rounds. Same load out of the 16"AR pushes 1370 FPS with about the same round count and with the exception of the flashhider very very minimal leading. Again operation is fine, brass and primers look good.

So am I missing something or is the published data a little hotter than they are letting on? I have seen some Max loads listed for Unique at 6 grains with only 1150-1250 FPS. If thats the case I must have an issue with either my scale not being accurate at very small weights or my chrono is way off on the high side.

Anyone have any other ideas/experiance?

JR

[daschnoz]

I've often used the published velocity data as a only reference. Rarely do I get the same speeds that are listed in the book.

In your case, the lab's test barrel may be a 3.5" barrel, which would yield slower results than you are seeing from your 4" barrel.

As long as you're not seeing any high pressure signs, you're probably ok.

[Muggzy]

I load 6.0 gr of Unique to push a 115 gr hollow point and the average was around 1250 fps. It shoots excellent groups ( S&W #59)

I have never found the published data accurate and use it for starting
purposes only. They must measure on the side of "safety" for obvious
reasons.

[TerryN]

There could be any number of explanations. Some barrels are just 'faster' than others, for one thing.

[BUFF]

It's not just the guns and barrels, it is often the brass. 9mm brass has more variance in it, from one maker and date of manufacture to another, than any other caliber for which I have loaded. The brass varies tremendously in thickness from one batch to another, and this means internal case capacity varies. Given the 9mm's relatively small powder capacity compared to the .45's, it isn't unrealistic for results to vary wildly.

I used to be partners in a chronograph and me and my shooting buddy were fascinated by the variance between different makers' 9mm loadings. Especially compared to European makers, American-made 9mm seemed pretty mild, both in pressures (guessed at relative to each other) and velocities. Your load still sounds mild-to-average.

If I was you, I would just box up those 9mm pistols, ammo and components and ship them to my FFL for safe disposal after testing. It will avoid all that unpleasant thinking stuff. Who needs a 9 when they have a .45 anyways?

[jrayborn]

:biggrin:

Thanks guys, you have put my mind at ease. I appreciate your help.

JR

[newfalguy101]

My Hornady book shows 1050fps for 4.8 of unique with a max of 5.1 @1125fps


others have given good answers, and I have one more possibility, your bullet being a "coated" lead bullet will run faster than a jacketed bullet.

all things being equal, a lead bullet requires LESS pressure to attain the same velocity..........ergo........ your book data, developed with a jacketed bullet ( most likely anyway ) will be more or less correct with jacketed bullets and lead or coated lead will be faster.

[Indycar]

While I've never had access to a chrono, I too have loaded 6.0 grs Unique under a 115 gr Hornady jhp for years. I've used this load in S&W 39's, P38, AR 9mm, HP's, Beretta 92's and numerous subguns and have gotten excellent accuracy, reliability and feeding.

I found if I seat the bullets long but within spec's the feeding and reliability improved. Seating depth definately changed pressures.

[shootist87122]

What Newfalguy said. Cast bullets take noticeably less powder than jacketed bullets. The base expands for a better gas seal.

Also, some barrels are just faster (or slower) than others. I have a BHP that clocked 100fps faster than two other BHPs with the same (+P+) factory load (Federal's 115 grain BPLE). Primers can make a difference as well and even different lots of powder can vary. Temperature affects velocity - significantly so with some powders. The OD of the bullet used is another.

In short, book loads are just a reference point.

[English Mike]

+1 on what BUFF said about the brass. At least one of my reloading manuals recommends NOT using military spec. brass due to its lower capacity.

[kycrawler]

If your getting pressure signs on (non magnum) pistol primers you need to quit shooting immediately as your probably close to double operating pressure of the gun most primers dont flatten/flow till above 45-50k psi which is way above normal for most pistol rounds

[fire for effect]

what gun are you shooting them out of??? Some manufacturers have been using .357 barrels in their 9mms.

This was an old trick of Super Vel to boost their Velocities. Super Vel would load Bullets .002 thousands smaller than standered to reduce pressure and increase Velocity.

[jrayborn]

The pistol is a new Glock 17. I know about the taboo on lead bullets and glock barrels, and I am very carefully checking. Believe me the very first bullets thru the brand new never fired bore were clocking honest 1170 average.

Anyway so far so good. I guess I can just be happy I'm saving powder:)

JR

[fire for effect]

Id slug the barrel and see if it is .355 or .357. But you are right, If the gun shoots good and you have no pressure signs, then just be thankful fo the God of Guns has blessed you.

[IO_Joe]

Were the loading data based upon jacketed or lead bullets? Lead bullets, along with coated and plated lead bullets, often run faster with the same powder charge than do jacketed bullets. They are generally softer and seal the bore better. I'll bet that if you used 124 FMJs on top of your same load, they'd chrono slower. Also, the polygonal rifling in the Glock can increase velocities a bit too.

BTW, with what are the Bear Creeks coated?

[1MOR]

I have used Barry's 115gr round nose plated and Winny 231. Cleaner than unique, used both. I started at 10% under recommended and worked from there. Loaded to where it would crank the action. No lead to clean and no need to worry about the Glock and lead bullet thing. I have put many thousands down range with this load. I have had some very accurate results, more accurate than commercial.