Accuracy and bullet weights??

[PNWguy]

Since starting to reload last year for .45 Colt, .40 S&W, and 10mm, I have noticed that some guns prefer lighter bullets vs. heavier bullets in regards to accuracy. Why is that? And to make it more confusing, some powders work better with lighter bullets vs. heavier bullets...

 

For instance, my XDS in .40 S&W will shoot 2 1/4" groups at 25yds with 155gr reloads and factory ammo. Put 180gr loads in it and the group sizes open up by 50% or more.

 

Any idea what the scientific explanation is for that?

 

I just bought a batch of 100 poly-coated 155gr bullets to experiment with in my .40 S&W and 10mm and am going to see if they are accurate in the G29, which for some reason is much more accurate with 180gr Hornadys and 190gr cast bullets than with the 155gr Hornadys.

[arkdweller22]

There are many factors that determine what a gun "likes". Rate of rifling twist is a big one as well as the actual bore size. Twist rate is usually optimized for certain common bullet weights. Throat depth on the barrel affects preference as well.

 

As an example: you see the bore size issue with 38 Super when a pistol has a true .356 bore and people shoot .355 bullets through it. Accuracy goes to pot and leading (if using lead) goes through the roof. Slug your barrels and figure out what is the actual bore size for each.

 

I'm sure more knowledgeable folks will come and give you a more comprehensive answer, but that's a start.

[Old School]

And honestly, sometimes it's what the shooter likes in addition to what the gun likes aka "it's the dope behind the gun and not the dope on the gun."

 

I can shoot .45 230 gr FMJ better out of a G21 versus a custom 1911. Kind of heresy for someone who goes by Old School, but it's just the way it is.

[ROB]

Could just be the quality of bullets being used too. Usually the advantage goes to longer heavier slugs with more bearing surface, provided all stuff being equal and correct rifling twist.

[sciolist]

If you're only looking at weight, within reasonable limits I think a lot of it's down to the shooter.

[jmohme]

I know that my TC really likes 55gr bullets in 223. Anything over that and accuracy suffers.

I am told that the 1:12 twist of the 14 inch barrel I am using its too slow and does not allow heavier bullets to stabilize.

[PNWguy]

The little XDS and it's 3.3" barrel not being able to adequately stabilize heavier bullets makes sense. But then the 4.5" KKM barrel and factory Glock 3.8" barrel in my G29 being more accurate with 180gr vs. 155gr would not be affected by stabilization...

[elsolo]

I have been told that barrel length has no effect in stabilization, a 2" barrel is the same as a 5"

 

Are you playing around with OAL with each bullet type, or just sticking to a specific length your magazine likes?

[PNWguy]

I stick with the OAL specified in the load. Most 10mm loads all call for an OAL for 1.260", no matter if the bullet is a 155gr or a 200gr. 135gr loads call for an OAL of 1.250", though.

 

.40 S&W is the same in that most loads call for the same OAL of 1.125"...

[csv]

I don't pretend to know **** about this but my 2010ish M&P 9mm is horrible with 115 gr. A lot of talk back then said the barrels were **** or they were made for heavier bullets, I don't know.

[Kilroy]

Barrel length, twist rate, bore diameter, bullet type/weight, powder type/amount, and weather conditions all matter. What also works great in one gun might be just the opposite with another of the same make/model.

 

I have two S&W 625" wheel guns and I have different loads for each one as they both shoot differently.

 

For the .40S&W I would have to say start out with the 180 or 200gr.

 

My 9mm's will work with anything, but I get the best accuracy with 147gr. I am starting to work with the 160gr and it is showing some possibilities.

 

No experience with the 45LC, but I would have to say try 250gr to start.

 

And everyone has their own opinion about powder and what works best for them. But in reality it takes a lot of time to truly work up a good load. Seating depth of bullet, chamber specs, velocity...and others. Keep a detailed record so you don't have to repeat your previous tests.

[RonS]

When I was loading for .357 and .44 magnums I had a 5 subject note book and kept a log of every load. Bullet, powder type and charge, brass (new-used & brand), primer and oal. Then when I was done shooting I would comment on how it performed. I learned a lot that way.

 

I'm a little more casual now, I put a sticker on the box with load details and that is about it.

[PNWguy]

I take pictures of every target I shoot with load information written on them. I used to have a notebook with all of my load data for my BPCR matches until my ex-wife threw it away and swore she has no idea what happened to it...

[Exit Plan]

I take pictures of every target I shoot with load information written on them. I used to have a notebook with all of my load data for my BPCR matches until my ex-wife threw it away and swore she has no idea what happened to it...

I found that 185 grain shoots much better out of a HK USP than 230 grain for some reason

[Exit Plan]

I found that 185 grain bullets shoot much better out of HK USP than 230 grain

[Danoobie]

IME, heavier bullets generally shoot better.

[minervadoe]

In my G20 and G29 10mm 155 grain and 165 grain plated loads, I was getting tight groups with Unique.  But, that powder did not work well for me with 180 grain plated rounds.  I had to switch to 800X to get any accuracy out of the heavier bullet.  The burn rates aren't that far apart on this chart (31 and 38). 

[Smokey45]

I've got half a dozen .40s, they're all more accurate with mid range weight bullets than with the heavier ones. I may have to revisit this as I'm about to change over to .40 and load a batch. I've got a few k Xtreme and Bayou in 180 I'll load this time. For some reason the 140gn Bayou have been the most accurate in my guns. 

s45

[Will Beararms]

I’ve had good luck with 180 grain JHP .40 caliber loads. 

[aimtrue]

I had the same experience as Old School, "I can shoot .45 230 gr FMJ better out of a G21 versus a custom 1911. Kind of heresy for someone who goes by Old School, but it's just the way it is."  My G21 was a highly accurate and reliable sidearm.

But, as age diminished my physical handling skills, I moved from the larger frame high calibers to the 9mm compact size pistols.  After owning and shooting many of the favored striker-fire pistols, I found that I could handle and shoot more accurately a M&P M2.0 compact.  It is now my EDC. 

This pistol  shoots most every type and weight of bullet well.  My accuracy with different weights varies insignificantly.  I simply adjust my grip and aiming point after the first few shots using any new box of ammo.

I have found the most consistent and accurate ammo to be 124gr HST.   My reading indicates that it is the best if not equal to the best ammo for pistol defense.

[Pax]

When it comes to loading for accuracy, there's much that can be said for what powders, bullets and primers one has on the shelf. The calibers I load for the most are 38 Super, .357mag and 10mm...but I also load for a number of other handgun, and rifle, calibers. The Super comes into its own with 0.356 and select 0.357 caliber bullets. Years ago a full charge of Power Pistol with 230gr Golden Sabers were very accurate out of two Colt 1911s, but had crap accuracy out of a Springfield 1911. Experimenting a bit, Universal gave good accuracy out of all three 1911s.

Experiment and enjoy.

[Collim1]

I hand load .38spl for accuracy. 

My 3” K frame shoots 148g HBWC over 3.2 grains of Winchester 231 in a ragged hole. The same load in my 4” model 66 yields surprisingly poor results. 

 

However the 66 shoots a 158g LSWC over the same powder charge with extremely good results. Every gun is different. 

 

My jframe shows no preference between the two. 

I haven’t even experimented much with different loads. A local shop sells the Win231 for cheap so I use it. It’s a little Smokey, but it’s consistent and is easy to clean.  

[Smokey45]

I'm looking for a workable minor PF loading (130-135) for a Glock 27 for IDPA CCP division. I bought a couple thousand Xtreme 180s from a friend who was getting out of .40 at a great price. I loaded 10 to run over the chronograph and group this week. I prefer the mid range bullets in .40 as I've had great results with them, but couldn't pass this deal up. I loaded this initial 10 with 3.1 gns of Clays. Hogdon says this load runs 732 fps out of a 4" barrel.  I'm anxious to see what I'm getting out of the 27.  I'm wondering if I can stabilize the 180s at that low velocity out of the Glock barrel. I plan to find out this week. Stay tuned kids!

s45

[Smokey45]

Ok, back from the range. The 180 Xtremes over 3.1 gns Clays averaged 675 fps and a 121 PF out of a Glock 27. Grouping was decent with no bullet yaw at 15rds.  Time to bump it up to 3.3 Clays. I'm looking for the 130-135 PF range. 

s45