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Stupid question... but what does "grain" size mean?

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Lighter bullets in any given caliber "usually" give higher velocities making longer shots, have less drop and easier to hit at longer ranges.

Actually, just the opposite. In match work the standard 62 grain load (.223) is never used in serious match work. Many use the 69 grain. When the distance opens up, most used the 80 grain load until Sierra came out with their 77 grain bullet. The idea is to keep the bullet supersonic. Speeds below that cause the bullet to become unstable.

 

As far as the 9mm in a carbine length, the 147 grain load was the preferred load for the H&K MP5. W-W has a 147 grain subsonic load specifically for that use in supressed firearms. The bullet will never get stuck in a barrel unless it were a squib load.

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The 9mm loads for the MP 5 are hotter than normal loads. They were made in Europe and are not recommended for use in some pistols. They were importing the stuff a few years ago and I remember reading the notes that it was not for use in pistols. Winchester may have used a powder not avail to reloaders for their sub loads. When I was looking into 9mm reloading I came across a few articles that read do not load 147 in 9mm carbines.

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The MM loads for the MP 5 are hotter than normal loads

 

True of some European loads. Not true of domestic loads. As 9mm handguns come in many shapes and sizes, the plus p plus loads are probably not the best. However my old S&W 659 could disgest anything without a problem.

 

We used the WW 147 grain loads in our MP5's after a recommendation from some local FBI firearm's instructors. They function fine in both the sub gun and handgun. Although the effectiveness in a handgun was not impressive in our real world experience. It was the reason for our switch to the 40S&W.

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"grain" Would be bullet weight, with 7000gr. in a pound.

 

Lighter bullets in any given caliber "usually" give higher velocities making longer shots, have less drop and easier to hit at longer ranges.

 

Thanks Urban Grunt, you learn something new everyday.

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Lighter bullets in any given caliber "usually" give higher velocities making longer shots, have less drop and easier to hit at longer ranges.

 

Lighter bullet weights are more susceptible to winds throwing them off course. For that reason, sniper rounds use bullets at the heaver end of the spectrum. 5.56 rounds use the Sierra Matchking 77 grain special production with a cannlure. 7.62 use either a 168 or 175 grain bullet in place of the standard 147 grain.

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147 gr bullets are not recommended for use in 9mm carbines. They have lower velocity and may get stuck in the longer barrel.

 

Now he tells me? I thought 147 gr would be good for bowling pins and steel at about 60 yards. The Range Office stopped me because he thought I had a squib. He couldn't see my bullets hitting the berm. They were probably hitting half way to the target. From now on, 115 gr. for my Storm.

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147 gr bullets are not recommended for use in 9mm carbines

 

Beretta has no such recommendation on bullets weights.

 

If anyone is firing a 147 grain load and the bullet cannot make 60 yards without hitting the ground there is more than the bullet weight as a problem. I've seen 147 grain 9mm commercial ammo shot from more than one style of carbine with zero problems. The slight decrease in bullet velocity will not affect the operation to any great degree. If a bullet load rated at 1000 fps second can't clear a 16 barrel there are other factors at play beyond the bullet style and weight.

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According to Federal's website their 147 gr FMJ 9mm should only drop about 2.50" at 60 yards. It certainly shouldn't be in the dirt at that point.

 

ShortTrajectoryGraph.aspx

 

 

147 gr bullets are not recommended for use in 9mm carbines. They have lower velocity and may get stuck in the longer barrel.

 

Now he tells me? I thought 147 gr would be good for bowling pins and steel at about 60 yards. The Range Office stopped me because he thought I had a squib. He couldn't see my bullets hitting the berm. They were probably hitting half way to the target. From now on, 115 gr. for my Storm.

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147 gr bullets are not recommended for use in 9mm carbines. They have lower velocity and may get stuck in the longer barrel.

 

Now he tells me? I thought 147 gr would be good for bowling pins and steel at about 60 yards. The Range Office stopped me because he thought I had a squib. He couldn't see my bullets hitting the berm. They were probably hitting half way to the target. From now on, 115 gr. for my Storm.

 

So what powder and how many grains are you using?

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We used the WW 147 grain loads in our MP5's after a recommendation from some local FBI firearm's instructors. They function fine in both the sub gun and handgun.

 

I also found that the velocity stays about the same for 147 gr ammo from handgun to MP5. Lighter bullets will pick up 50-100 fps going from a handgun to a MP5 (about a 9" barrel)

and 100-150 fps in a 16" barrel.

 

147 gr bullets are not recommended for use in 9mm carbines.

 

The problem with 147 gr bullets in 16" or longer barrels is not that it will not make it out of the barrel but the bullet may slow down compared to a handgun. Manufacturers make subsonic to stay subsonic (<1100fps) be it used in a handgun or MP5. When you put another 6" or more of barrel to go through barrel friction can slow it down 50-100 fps from those I've chronographed.

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Manufacturers make subsonic to stay subsonic (<1100fps

 

Probably closer to 950 in a 4 inch handgun based on our experience. Handloading would be the way to go using a slower powder and testing on a chronograph.

 

My thinking is the slower moving bullet allows the small powder charge to completely burn before the bullet leaves the barrel causing barrel friction to slow it down somewhat. But that depends on the makeup of the round itself. The subsonic worked best in the MP5's especially when suppressed. Supersonic rounds defeat the idea of a suppressor to a large degree.

 

But to cut down the need for different types of 9mm, we settled on the one 9mm load as lousy as it was in real use.

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Probably closer to 950 in a 4 inch handgun based on our experience. Handloading would be the way to go using a slower powder and testing on a chronograph.

 

Checked my notes and this is right on the money. Most factory subsonic loads were about 950fps regardless of barrel length. The highest velocity was WW in a Glock 17 at 990 fps. In a MP5 they all ran a little over 1000 fps. Through a Marlin 9 those tested ran 880-950 fps.

 

Of course you might get different results with diffrent firearms of the same make but it gives you an idea of what's really going on.

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