Difference between 124 grain and 147 grain?

[agalindo]

Originally Posted by TimXD9

This is an interesting point, and one I've thought about before.

When we're discussing 124-gr. vs. 147-gr. SD rounds in the same model from the same manufacturer (Speer Gold Dots for example) are we to assume the number of powder grains are the same in both cartridges? If so, it seems obvious to me that the heavier grained round will have lower velocity if the energy source (the amount of powder) used to propel both projectiles is the same.

Also, does a longer barrel permit a more complete powder burn, creating a higher velocity upon exit? If so, that would mean the average SD round would never achieve it's spec'd velocity from short barrel guns like the XD-SC, correct? And if that's true, do SD rounds designed for short barrels overcome that issue effectively?

I know practice, training, steady hands and well-placed shots will stop a BG, so a lot of this is just scientific conjecture, but I'm still curious. Besides being interesting to me, I think it's useful knowledge in that we should carry the best ammo possible in our firearms.

Grains is weight of the powder charge, not the number of individual powder grains or flakes. No sometimes different powder types are used, for sure different powder charges (grains weight not number of powder grains) are used for different bullet weights(grains).

Shorter barrels do effect velocity. 1" difference is not significant +- 50 fps. Bullets are designed to expand within certain velocity windows to take this change into account. The expansion window in a certain round can be between X ftps max vel to Y fps low vel.

Don't split hairs trying to get the no.1 A+ top scoring, best of the best of the best. Any of the quality HPs listed will work just fine. The difference between 124gr and 147gr is going to be measured in fractions of an inch penetration and expansion.

[fredj338]

Originally Posted by TimXD9

This is an interesting point, and one I've thought about before.

When we're discussing 124-gr. vs. 147-gr. SD rounds in the same model from the same manufacturer (Speer Gold Dots for example) are we to assume the number of powder grains are the same in both cartridges? If so, it seems obvious to me that the heavier grained round will have lower velocity if the energy source (the amount of powder) used to propel both projectiles is the same.

Also, does a longer barrel permit a more complete powder burn, creating a higher velocity upon exit? If so, that would mean the average SD round would never achieve it's spec'd velocity from short barrel guns like the XD-SC, correct? And if that's true, do SD rounds designed for short barrels overcome that issue?

I know practice, training, steady hands and well-placed shots will stop a BG, so a lot of this is just scientific conjecture, but I'm still curious. Besides being interesting to me, I think it's useful knowledge in that we should carry the best ammo possible in our firearms.

Sort of. Heavier bullets create more pressure so use less powder to reach max. pressure. Usually, that means they are also going slower. Manuf. do list vel. of their ammo on their websites. It is usually tested in a 4" test bbl. in a test machine. Your individual pistols vel. will very. In longer bbl.s you'll get higher vel. & shorter bbls. lower vel. In some calibers, you can lose as much as 75fps / inch of bbl. It's why Speer made GDSB, for the guys using subcompact guns to help insure expansion. Here is an example of expansion within a vel window. These are lead bullets, but the concept is identical for jacketed. You can see that just 30fps+/- is the diff bettween expansion & no expansion. I could tweek the alloy to get more expansion @ lower vel. but the bullet will fragment if pushed above 900fps. These were tested in bare wetpack.

[U.S. Patriot]

000

[AZXD]

Originally Posted by fredj338

Sort of. Heavier bullets create more pressure so use less powder to reach max. pressure. Usually, that means they are also going slower. Manuf. do list vel. of their ammo on their websites. It is usually tested in a 4" test bbl. in a test machine. Your individual pistols vel. will very. In longer bbl.s you'll get higher vel. & shorter bbls. lower vel. In some calibers, you can lose as much as 75fps / inch of bbl. It's why Speer made GDSB, for the guys using subcompact guns to help insure expansion. Here is an example of expansion within a vel window. These are lead bullets, but the concept is identical for jacketed. You can see that just 30fps+/- is the diff bettween expansion & no expansion. I could tweek the alloy to get more expansion @ lower vel. but the bullet will fragment if pushed above 900fps. These were tested in bare wetpack.

You just proved a point ... A properly designed projectile will perform best at it's designed velocity.
Bullet weight is secondary to the metallurgy used for the intended energy of impact.

[fredj338]

Originally Posted by AZXD

You just proved a point ... A properly designed projectile will perform best at it's designed velocity.
Bullet weight is secondary to the metallurgy used for the intended energy of impact.

I understand that. That's why shooting certain ammo in a subcompact 3" bbl. will not likely give you the results you want. mOst of those bullets are designed for 4"-5" bbl. vel. My point was even 35fps can dramatically affect bullet expansion or bullet integrety. One reason Speer does NOT recommend using their GDSB ammo in a 5" bbl. The bullet will over expand, it wont' fragment, because it is bonded, but it will expand & fold back on itself actually making smallerperm wound channel (yes I have tried it).

[AZXD]

Originally Posted by fredj338

I understand that. That's why shooting certain ammo in a subcompact 3" bbl. will not likely give you the results you want. mOst of those bullets are designed for 4"-5" bbl. vel. My point was even 35fps can dramatically affect bullet expansion or bullet integrety. One reason Speer does NOT recommend using their GDSB ammo in a 5" bbl. The bullet will over expand, it wont' fragment, because it is bonded, but it will expand & fold back on itself actually making smallerperm wound channel (yes I have tried it).

I agree, and that is why it makes no sense to say a particular weight of bullet will perform better, if all you look at is projectile weight.

Yet when you factor everything into the mystery equation, there is nothing to say that a heavy projectile will not expand properly out of a short barrel ... Except the manufactured.

But physics does tell us how much Stored Kinetic Energy will be lost at a given distance, and how much of the remaining energy will be dissipated into the intended target ... Doesn't it

[agalindo]

Originally Posted by fredj338

I understand that. That's why shooting certain ammo in a subcompact 3" bbl. will not likely give you the results you want. mOst of those bullets are designed for 4"-5" bbl. vel. My point was even 35fps can dramatically affect bullet expansion or bullet integrety. One reason Speer does NOT recommend using their GDSB ammo in a 5" bbl. The bullet will over expand, it wont' fragment, because it is bonded, but it will expand & fold back on itself actually making smallerperm wound channel (yes I have tried it).

The tests you did were with homebrew HPs right? Since it wasn't the premium SD ammo you tested it proves that cavity design and metallurgy are not the same with your HP and the premium stuff.

In a response to a question about which grain 9mm Ranger ammo to use in a short barreled pistol including 3.5" and 3", I got the following response from Winchester LE Ammo:

When we redesigned the Ranger T Series of ammunition we widened the velocity window under which the round would expand to allow for the slower velocities that shorter than standard barrels produce. What this means is that if you own a standard or sub compact pistol the round should have adequate expansion. In 9mm I would recommend the 147 grain bullet as it loses a lower velocity percentage than the faster lighter bullet in shorter than normal barrels. This is because the bullet has more dwell time in the bore and has a greater opportunity to burn the powder before the bullet exits the bore. Powder that is burned outside the bore does nothing for velocity. The lighter faster bullets generally have more powder to burn and since the lighter faster bullets have less time in the bore they are not efficient burners of powder in the shorter barrels.

We increased the velocity window under which the round would expand by increasing the size of the hollowpoint, tweaking the jacket thickness and the depth of the cuts on the inside of the jacket petal segments.

Sincerely,

Paul Nowak
Senior Technical Specialist
Winchester Law Enforcement Ammunition

From a post on another forum:

Originally Posted by RAM Engineer

For short barreled 9mm guns like the Glock 26 (w/ 3.5" barrel), are the recommended loads from the duty load thread still good-to-go?

Originally Posted by DocGKR

The 9 mm loads are generally tested in a 4" barrel; a half-inch shorter barrel is not going to change things...

[fredj338]

Originally Posted by agalindo

The tests you did were with homebrew HPs right? Since it wasn't the premium SD ammo you tested it proves that cavity design and metallurgy are not the same with your HP and the premium stuff.

From a post on another forum:

Geeze guys, read the posts. I never claimed my home cast HP has the same pref. level as a factory JHP. I am only trying to point out that vel. DOES matter, even 35-50fps loss can mean the diff between expansion & not. You have a better chance w/ a 124gr+PJHP expanding from a shorter bbl. than a 147gr in most cases. Premium doesn't mean it will expand at any vel. level. It means it is designed to expand & hold together at whatever vel. level it was tested. Since most are made for LEA, that would be 4"-5" bbls. NOT 3" subcompacts.
In a really short bbl, going to a bullet designed for that lower vel, like the SGDSB, will certainly be a better choice. If in doubt about the performance, at least run your own test in wetpack or the minimum of 3-4 1gal water jugs. If it doesn't expand there, it is not likely to expand in more fickle flesh.

[hotpig]

You are correct old 124+P bullets have a better chance of expanding out of a short barreled gun than a old 147gr.

Modern bullet technology has come a long way since you have been gone from the shooting world. Eleven years ago Winchester designed a 147gr bullet (RA9T)that expanded in a larger window of velocities.

Since then Federal and now Speer have followed suite with 147gr bullets that will work just as well in short barreled as long barrels.

[TimXD9]

Just an FYI: I successfully ran 20 rounds of 147 grain Win. SXT (aka Ranger) thru my new XD9sc Sun. afternoon. Didn't really seem like much difference in felt recoil between it and the Blazer aluminum case 115 grain practice ammo I used just before the carry ammo test.

I probably would have bought Speer Gold Dot Short Barrel 124 grain ammo for the new gun if I'd been able to find any locally. I already had a box of 20 rounds of the SXT on hand, and found 2 boxes at a local shop. Knowing SXT performs excellent as a SD round, I was happy to go with it instead of the GDSB anyway!

Now I just have to find more SXT or Ranger ammo to buy...