9mm subsonic ammo question

S

simonrichter

New member
maybe I'm mistaken, but it appears to me that while standard FMJ 9mm ammo is usually round nose, the subsonic variants are more often than not flat nose. Is that just a coincidence or is there any ballistic principle behind that? (again, I'm exclusively referring to FMJ, every other variety like JHP etc. is banned for civilians where I live).
 
I believe that is part of the design of a round intended to used with a suppressor. I always warn people expecting something spectacular with sub-sonic 9mm not to be disappointed, it still is fairly loud even suppressed. It's fun, sure, but ....

I have a lot more fun shooting .45ACP on steel. It suppresses very well and you get to enjoy a loud "DING" or "DONG" depending your steel target.
 
Most of the subsonic ammo is 147 gr vs 124 or 115 gr. To make a bullet that heavy fit in the magazine it has to be flat. A pointed 147 gr bullet would be too long.
 
I see, makes sense, thx...

@WillmannJohn: Never actually tried it, but I've heard that 9mm subsonic suppressed can be quite quiet, depending on the suppressor used...
 
That is complete BS.

https://www.ssusa.org/articles/2018/...-need-to-know/

This is why forums are a source of MISinformation. Forum 'experts' are only experts in their own mind.
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Well that seems a little bit heavy handed. JMR40 never claimed to be an expert, and everything we type is an opinion, and should be treated as such.

JMR's explanation makes sense to me.

The link you provided shows that there are round nose heavy-for-caliber bullets. They exist. However, any heavy bullet has to put that mass somewhere, assuming we are comparing it to a lighter bullet of the same construction and materials. A 124 grain round nose bullet will have a smaller point / meplat than a flat point of the same weight, and be longer/taller. Let's say the factory loading includes a powder that fills up right under the base of a 124 grain bullet. This way the ignition is more consistent and doesn't dependent on position.

Then all the sudden you switch to a 147 or 158 grain projectile like in your link. That projectile is going to be longer. Unless they switch powders or elongate the overall length, you would have a compressed load which may yield inconsistent results. Having a flat nose will shorten the overall length of the projectile, giving the loader a bit more wiggle room to keep things within the maximum allowed overall length. Load a round too long and it definitely won't fit in a magazine or won't chamber. For an individual loader who already has a working load, a flat nose/truncated cone may give the flexibility in overall length needed to keep the same powder.

Makes sense to me. If I am wrong, I think I may need an explanation to figure it out.
 
Unless they switch powders or elongate the overall length,
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You cannot elongate the overall length beyond the spec limit or the rounds will not feed. SO that option is off the table.

What is done is choosing a DIFFERENT powder or charge weight of the regular powder to remain with pressure specs with the heavier bullet.

Using the blunt nose shape for a heavier bullet is done to both save a little "room" and also to increase (to a degree) the effectiveness of the SLOWER, heavier bullet.

The speed of sound is a bit over 1100fps varying with air density, temp, altitude, moisture content, etc. So a subsonic round is essentially below 1100fps. Going to a more blunt nose shape than the usual conical one doesn't hurt anything, and might actually be some benefit.
 
dyl said:
Well that seems a little bit heavy handed. JMR40 never claimed to be an expert, and everything we type is an opinion, and should be treated as such.

JMR's explanation makes sense to me.

The link you provided shows that there are round nose heavy-for-caliber bullets. They exist. However, any heavy bullet has to put that mass somewhere, assuming we are comparing it to a lighter bullet of the same construction and materials. A 124 grain round nose bullet will have a smaller point / meplat than a flat point of the same weight, and be longer/taller. Let's say the factory loading includes a powder that fills up right under the base of a 124 grain bullet. This way the ignition is more consistent and doesn't dependent on position.

Then all the sudden you switch to a 147 or 158 grain projectile like in your link. That projectile is going to be longer. Unless they switch powders or elongate the overall length, you would have a compressed load which may yield inconsistent results. Having a flat nose will shorten the overall length of the projectile, giving the loader a bit more wiggle room to keep things within the maximum allowed overall length. Load a round too long and it definitely won't fit in a magazine or won't chamber. For an individual loader who already has a working load, a flat nose/truncated cone may give the flexibility in overall length needed to keep the same powder.

Makes sense to me. If I am wrong, I think I may need an explanation to figure it out.
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Opinions might not fit with facts, and if something is stated as a fact (declarative sentence) it better have supporting evidence. JMR40 was simply wrong. Heavier bullets, round nose or flat nose, can, and will, fit in the magazine. The bullets are longer so they will sit deeper in the case. That's all. It was clear that JMR40 does not understand ammunition, and his opinion on ammo should be ignored.

dyl, from what you're written it sounds like you're trying to keep the same powder and powder charge for the same regardless of bullet weight. There are plenty of powders in load manuals that will handle all the bullet weights typical of that caliber. But you damn well better change the powder charge - reducing it for heavier bullets - or the gun will kaboom.

OAL is adjusted as needed to fit. Powder charges are adjusted for the bullet weight and length, the OAL and desired speed within safe pressure limits. This is done all the time.

Flat nose bullets can't always be seated to the same length as round nose bullets and still fit in the magazine, so you don't always gain the full advantage of the flat nose bullet being shorter.

dyl, your concern over a compressed charge is unwarranted. Here's what the professionals say about compressed loads. From the Hodgdon website: http://www.hodgdonreloading.com/reloading-education/reloading-beginners/compressed-loads

"Hodgdon notes in its reloading data if the subject charge is a compressed load. A full case, or lightly compressed charge is an ideal condition for creating loads with the most uniform velocities and pressures, and oftentimes, producing top accuracy."
 
44 AMP said:
You cannot elongate the overall length beyond the spec limit or the rounds will not feed. SO that option is off the table.
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This is not necessarily the case. Many folks using 9mm and 40 S&W in 1911/2011 race guns need to load them longer than SAAMI specs or they won't feed reliably.
 
I get all my 147 gr from RMR and they are RN's. For my subsonic load I set the OAL to 1.150 and they run excellent through my full size Uzi , and my Beretta 92FS .
 
This is not necessarily the case. Many folks using 9mm and 40 S&W in 1911/2011 race guns need to load them longer than SAAMI specs or they won't feed reliably.
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So, you're talking about specialty match guns that won't feed regular stock factory ammo??

seems like there's always an exception..
so, ok

Generally, you cannot elongate the overall length beyond the spec limit or the rounds will not feed. SO that option is off the table for factory produced ammo intended to work in all guns.

.
 
I've never shot a 124gr that was supersonic out of my G19, not sure why you would spend the extra money on suppressor loads.
 
My 40 S&W wide body Para Ordnance has this problem, too. It likes longer than normal ammo, and will sometimes choke on ammo loaded to normal 40 S&W specs.
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That is interesting, I had no idea. Usually the problem with length in a semi auto pistol is that rounds have to be shorter than max spec length or feeding issues arise. is your gun one of the "race guns"??

While I can understand it for a specialty piece tuned for a specific game, It seems curious to me why any maker would do so in a service class pistol.
 
44 AMP said:
That is interesting, I had no idea. Usually the problem with length in a semi auto pistol is that rounds have to be shorter than max spec length or feeding issues arise. is your gun one of the "race guns"??
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My Para Ordnance 40 (wide body) is not a race gun, but it does have issues with cartridge OAL.

The problem can arise in some guns like the 1911/2011 in 9mm/40 S&W if there is no spacer in the back of the magazine to keep the rounds forward, because the normal magazine is designed around a 45 auto, which is longer than 9mm / 40 S&W. There are issues with nosedive (often a magazine issue or just using a plain old single column magazine) and three point jams in these guns if the ammo is too short. Bullet nose shape influences this as well. Round nose bullets fare better than flat nose bullets.

Para Ordnance makes 2 magazines for the wide body 9mm and 38 Super guns. They differ in how well the prevent the nosedive gap between the top round and the underlying round. The 9mm magazine has no spacer but starts the transition between the double column to the single column much lower than the 38 Super magazine. It actually works very well for the 9mms by eliminating the nosedive gap. Part of the 9mm's problem is that it is a tapered case, and this raises all kinds of problems in single column magazines by producing more nosedive. But a properly designed double column magazine can eliminate the problem.
 
The problem can arise in some guns like the 1911/2011 in 9mm/40 S&W if there is no spacer in the back of the magazine to keep the rounds forward, because the normal magazine is designed around a 45 auto, which is longer than 9mm / 40 S&W.
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Ok, I get that, and i would consider that a design flaw, not using a magazine properly dimensioned for the rounds.

The 9mm is spec'd 1.169" and the .45acp is 1.275" max loaded length. 0.106" isn't a lot of difference, but it is enough to create issues in certain circumstances.

Loading rounds extra long so they work in a given gun is, to me, a "field fix", something you do so it will work, but not the proper fix for the problem, which is, and should be, something the manufacturer ought to be doing.
 
"...standard FMJ 9mm ammo is usually round nose..." Primarily because that's what the assorted militaries used. A 147 grain bullet isn't military.
"...banned for civilians..." Out of idle curiosity, suppressors are OK, but SP pistol ammo is not? That an Austrian thing or the EU? Really just curious. Nobody tells us anything about real European firearms laws.
 
The problem can arise in some guns like the 1911/2011 in 9mm/40 S&W if there is no spacer in the back of the magazine to keep the rounds forward, because the normal magazine is designed around a 45 auto, which is longer than 9mm / 40 S&W. There are issues with nosedive (often a magazine issue or just using a plain old single column magazine) and three point jams in these guns if the ammo is too short. Bullet nose shape influences this as well. Round nose bullets fare better than flat nose bullets.

Para Ordnance makes 2 magazines for the wide body 9mm and 38 Super guns. They differ in how well the prevent the nosedive gap between the top round and the underlying round. The 9mm magazine has no spacer but starts the transition between the double column to the single column much lower than the 38 Super magazine. It actually works very well for the 9mms by eliminating the nosedive gap. Part of the 9mm's problem is that it is a tapered case, and this raises all kinds of problems in single column magazines by producing more nosedive. But a properly designed double column magazine can eliminate the problem.
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This argument comes from an article of a few years ago from Brad Miller. In that piece Miller took a 1911 chambered in 9mm and decided to test the guns with magazines built for the longer 38 Super round. When the much shorter 9mm nosedived, Miller blamed the 9mm and said that the 9mm had a design flaw which was that the case had a slight taper. He acted like he was the first to "discover" this taper.

Now for over a century the 9mm has been an exceptionally reliable round in guns made for it with the proper magazines for the 9mm. Proper mags for the 9mm in a single stack 1911 Government model have a spacer in the rear which places to 9mm forward in the mag. Mags made for the 38 Super are not useful for the 9mm. Folks have known this since 1948 when Colt first chambered the Commander in 9mm. Miller did not know this apparently and so blamed the 9mm. But the 9mm has no issues feeding with proper magazines. Miller created an issue where none had existed.

I can't begin to tell you about handloading specific bullets for your gun. I would load a heavier bullet so that it would work reliably in your gun and that may very on the gun and what I hope to do with it.

tipoc
 
The first US made 147 gr subsonic 9mm I know of was a JHP meant for sentry elimination with a silenced pistol or SMG. There were the usual rationalizations for a hollow point in military use, mostly that it was more accurate.

The cast 147s look an awful lot like that bullet with the hole filled in, generating a flat point.

Time marches on and the bullet makers tried other styles. I have shot a lot of 147 gr roundnose; cast, coated, plated, and jacketed. I have even seen 140-150 gr SWCs that would feed.

Mags made for the 38 Super are not useful for the 9mm.
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MY ammo in MY magazines do quite well with 9mm in Super clips. Not every such combination will work, but I have one that does.
 
Jim Watson said:
Mags made for the 38 Super are not useful for the 9mm.
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MY ammo in MY magazines do quite well with 9mm in Super clips. Not every such combination will work, but I have one that does.
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The only generality we should abide by is to not abide by generalities. I had a 1911 in 9mm that worked fine with several different .38 Super magazines, but I never found an actual 9mm magazine (with the spacer up the spine, or the Springfield Armory mags with the "integral feed ramp") that was reliable in that pistol.
 
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