So I'm pretty new to guns, and understand that the grain is the weight of the bullet(correct me if I'm wrong). But my question is what is the best grain to use for my shield 40? I have some 165 and 180, but haven't been able to shoot it yet. Any advice would be much appreciated!

I shoot both in mine. Although I try to use 165 when I can, because I can notice a difference. Did I mention I love my shield!!!

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It may take a little experimentation for you to choose the best bullet weight for you. Yes, it is somewhat subjective.

Lighter bullets usually produce less recoil, depending on the powder charge. The powder charge will vary from brand to brand and depending on the intended purpose, target or self defense. Take that into consideration, but usually lighter rounds produce less recoil. This can be an advantage when you are trying to hit a target.

At the same time, with more recoil, heavier bullets tend to strike the target a little higher, relative to where your sights appear to be pointed. Although that seems counter intuitive the reason is that the greater recoil raises the end of the barrel before the bullet exits the bore, thus the gun is actually pointing a little more upward at a critical point in the shooting process.

The usual terminology is that the Point of Impact (POI) is higher relative to the Point of Aim (POA) with a heavier bullet, all other things being equal.

Some people find it easier to have the POI higher than the POA so they can see the center of the target on top of their front sight. This is usually referred to as "a 6 o'clock hold" because the tip of the sight appears to touch the edge of the circular bullseye at the point where the 6 appears on a clock face.

Finding any affordable ammunition is a good trick right now, so you may be limited in what you can play with before making a large enough purchase to have some inventory on hand for your convenience in the future. No hurry, unless you see a great bargain. But, even then, trying a few rounds first will help reduce your chances of disappointment.

Hope this helps!

Nice explanation Tuscon.

Bullet weight is like caliber choice, up to the user. What is best is very subjective, a slower heavier weight bullet, or a faster lighter weight bullet. I go against the majority, as I choose a very fast, lighter weight bullet. I use CorBon 40 S&W 135 gr JHP, for SD carry. It is loaded to maximum SAAMI specs, and has 1325 fps and 526 foot pounds of energy. The extra speed insures maximum expansion of the hollow point, while the energy will allow deep penetration. Since this ammunition is loaded for maximum pressure, while still staying under the SAAMI over pressure limits, there is more felt recoil, even with the lighter bullet weight, than with other 165 and 185 gr SD ammunition, I have tested. It is not uncontrollable recoil, just a noticeable increase.

When it comes to practice ammo, your choices are limited.

Bob

the 165 grs are very popular now, I'm slowly switching to the 165, use 180s before, the gun gets lighter with the 165s LOL

I found .40s to be too snappy for me in most sub-23 ounce guns, though I did prefer the heavier bullets (they may have recoiled more, but it wasn't as snappy) because I "felt" (and I know that's subjective) like my sights came back on target faster.
Another thing to consider is what will your practice ammo be? My 9mm practice ammo is usually 115gr, and sometimes 124gr, SO even though I prefer 147gr, I end up carrying 124gr defense ammo (since it shoots like or more like what I practice with).
At this point, shot placement being equal, I think a HIGH QUALITY round from 124gr to 180gr isn't going to make MUCH difference in ballistics--sure there are slight advantages to having a 165 over a 124, but then 8 wound channels is probably a slight advantage over 7 wounds channels. ;o) I'd just shoot a bit of both and see if you even notice a difference--if you prefer the feel of one, go with it. If not, then go with whatever you can get the most of for the best price (sticking to the high-quality stuff--and there are tons of good reviews and videos online reviewing ammo).

Looking down the road when the bug really bites you, consider reloading your own. When you go there your options become almost unlimited. As I have posed on other threads, my carry gun is a 40C. I shoot 165gr Hornady Critical Defense, pretty stiff recoil. For range use I load copper plated 165 LRN from X-Treme. You can load them down very light, as long as they will cycle the action. In my gun, 4.3gr HP-38 had a few FTF's, increasing to 4.5gr solved the issue. Point being you will have lots of options.

If you go this rout there are a ton of resources here to see you through it. Great hobby, and you may save a few $$.

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Jim

My carry ammo is 180gr HST, for practice I shoot whatever is available...

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