Smith & Wesson Forum

Go Back   Smith & Wesson Forum > Ammunition-Gunsmithing > Reloading
o

Notices

Reloading All Reloading Topics Go Here


Reply
 
Thread Tools Display Modes
  #1  
Old 04-20-2017, 01:17 PM
Mr_Flintstone's Avatar
Mr_Flintstone Mr_Flintstone is offline
Member
Reduced Bullet Weight Reduced Bullet Weight Reduced Bullet Weight Reduced Bullet Weight Reduced Bullet Weight  
Join Date: Feb 2017
Posts: 125
Likes: 68
Liked 68 Times in 31 Posts
Default Reduced Bullet Weight

What effect does reducing the bullet weight (of similar type) by a small amount have on pressure and velocity? For example, if I have some 150 grain LRN for .38 special, and I use load data for 158 grain LRN, what effect should I expect? My limited understanding leads me to believe that the velocity should increase slightly, and the pressure should decrease slightly. Is this generally the case, or am I missing something?
Reply With Quote
  #2  
Old 04-20-2017, 01:25 PM
fredj338's Avatar
fredj338 fredj338 is offline
Member
 
Join Date: Feb 2006
Location: Kalif. usa
Posts: 6,836
Likes: 2,665
Liked 3,927 Times in 2,366 Posts
Default

With identical powder charge, you won't see much increase in vel but you will have less pressures. Rule of thumb when you don't have data for a given bullet wt; it is always safe to use heavier bullet data for a lighter bullet of the same mat'l.
__________________
NRA Cert. Inst. IDPA CSO
Reply With Quote
The Following 2 Users Like Post:
  #3  
Old 04-20-2017, 01:26 PM
Bugkiller99's Avatar
Bugkiller99 Bugkiller99 is offline
Member
Reduced Bullet Weight Reduced Bullet Weight Reduced Bullet Weight Reduced Bullet Weight Reduced Bullet Weight  
Join Date: Mar 2013
Location: North Florida
Posts: 3,097
Likes: 5,674
Liked 5,191 Times in 1,861 Posts
Default

As long as you understand that is a "general" statement, you are correct. You can "generally" use load data for a heavier bullet safely.
Bullet profile, cast vs FMJ, seating depth, among other things can turn being generally correct to being specifically dangerous.
__________________
Reg. Magnum wants/Rossi wallet

Last edited by Bugkiller99; 04-20-2017 at 05:15 PM.
Reply With Quote
The Following User Likes This Post:
  #4  
Old 04-20-2017, 01:27 PM
JHB51 JHB51 is offline
Member
Reduced Bullet Weight Reduced Bullet Weight Reduced Bullet Weight Reduced Bullet Weight Reduced Bullet Weight  
Join Date: Apr 2011
Location: Indiana
Posts: 362
Likes: 94
Liked 79 Times in 36 Posts
Default

The velocity will increase or decrease depending on the bearing length of the driving bands from one bullet to the other. Longer driving band may increase pressure but not a lot. Larger diameter will increase pressure also but 8 grains. in weight shouldn't make a lot of difference. Best to reduce your charge a little and work your way back up.
Reply With Quote
The Following User Likes This Post:
  #5  
Old 04-20-2017, 01:28 PM
rwsmith's Avatar
rwsmith rwsmith is online now
Member
Reduced Bullet Weight Reduced Bullet Weight Reduced Bullet Weight Reduced Bullet Weight Reduced Bullet Weight  
Join Date: Dec 2012
Location: (outside) Charleston, SC
Posts: 30,907
Likes: 41,495
Liked 29,147 Times in 13,778 Posts
Default The heavier the bullet is......

The heavier the bullet is, the less powder is used.

So shooting a 150 grain bullet with 158 grain data, any adjustment would be an increase in powder. Not making any adjustment would be safe and you could work up the load from there.

If shooting a 158 grain bullet with 150 grain data, any adjustment would be a decrease in powder. Knock off a couple tenths of a grain and work your way back up.

I usually ignore plus or minus 5 grains in the bullet weight. If the load is not near max I might ignore that altogether.
__________________
"He was kinda funny lookin'"

Last edited by rwsmith; 04-20-2017 at 01:31 PM.
Reply With Quote
The Following User Likes This Post:
  #6  
Old 04-20-2017, 02:14 PM
ArchAngelCD's Avatar
ArchAngelCD ArchAngelCD is offline
Moderator
SWCA Member
Absent Comrade
Reduced Bullet Weight Reduced Bullet Weight Reduced Bullet Weight Reduced Bullet Weight Reduced Bullet Weight  
Join Date: Dec 2006
Location: Northeast PA, USA
Posts: 8,877
Likes: 1,029
Liked 5,070 Times in 2,660 Posts
Default

Quote:
Originally Posted by Mr_Flintstone View Post
What effect does reducing the bullet weight (of similar type) by a small amount have on pressure and velocity? For example, if I have some 150 grain LRN for .38 special, and I use load data for 158 grain LRN, what effect should I expect? My limited understanding leads me to believe that the velocity should increase slightly, and the pressure should decrease slightly. Is this generally the case, or am I missing something?
Your general understanding is correct. As,said, when load data is not available for a bullet weight use data from the closest heavier bullet. In this case with only an 8gr difference or about 5% you will see little to no difference.
__________________
Freedom is never free!!
SWCA #3437
Reply With Quote
The Following 3 Users Like Post:
  #7  
Old 04-20-2017, 09:57 PM
rwsmith's Avatar
rwsmith rwsmith is online now
Member
Reduced Bullet Weight Reduced Bullet Weight Reduced Bullet Weight Reduced Bullet Weight Reduced Bullet Weight  
Join Date: Dec 2012
Location: (outside) Charleston, SC
Posts: 30,907
Likes: 41,495
Liked 29,147 Times in 13,778 Posts
Default My fingers are blabby......

Quote:
Originally Posted by ArchAngelCD View Post
Your general understanding is correct. As,said, when load data is not available for a bullet weight use data from the closest heavier bullet. In this case with only an 8gr difference or about 5% you will see little to no difference.
Well said, and you used about half as many words as I did but got the point across. Sometimes I think I just say too much.
__________________
"He was kinda funny lookin'"
Reply With Quote
  #8  
Old 04-20-2017, 10:57 PM
fredj338's Avatar
fredj338 fredj338 is offline
Member
 
Join Date: Feb 2006
Location: Kalif. usa
Posts: 6,836
Likes: 2,665
Liked 3,927 Times in 2,366 Posts
Default

Quote:
Originally Posted by Bugkiller99 View Post
As long as you understand that is a "general" statement, you are correct. You can "generally" use load data for a heavier bullet safely.
Bullet profile, cast vs FMJ, seating depth, among other things can turn being generally correct to being specifically dangerous.
The caveat was like mat'l/composition. Yes a 45/200gr lrn is diff than a 200gr jhp.
__________________
NRA Cert. Inst. IDPA CSO
Reply With Quote
  #9  
Old 04-21-2017, 08:51 AM
Mr_Flintstone's Avatar
Mr_Flintstone Mr_Flintstone is offline
Member
Reduced Bullet Weight Reduced Bullet Weight Reduced Bullet Weight Reduced Bullet Weight Reduced Bullet Weight  
Join Date: Feb 2017
Posts: 125
Likes: 68
Liked 68 Times in 31 Posts
Default

Thanks for the replies guys. The reason I asked is that I was going to make up some 200 grain .38 special super-police rounds, but my order for the 200 grain LRN bullets was cancelled due to a mix-up. When I tried again, they were out of stock, and all I could find was 190 grain LFP from Midway. I couldn't find load data for 190 grain, but Lee has data for 200 grain lead, and Lyman has data for 195 grain LRN. I figure data from either should be good for 190 grain LFP. There might be a slight difference in overall length due to the different point styles, but if I seat in the cannelure I should be OK shouldn't I?
Reply With Quote
The Following User Likes This Post:
  #10  
Old 04-21-2017, 12:20 PM
hdwhit hdwhit is offline
Member
Reduced Bullet Weight Reduced Bullet Weight Reduced Bullet Weight Reduced Bullet Weight Reduced Bullet Weight  
Join Date: Sep 2016
Location: North Texas
Posts: 804
Likes: 86
Liked 482 Times in 300 Posts
Default

Quote:
Mr. Flintstone wrote:
...if I seat in the cannelure I should be OK shouldn't I?
Using 200 grain lead bullet data with 190 grain lead bullets of the same diameter, composition and construction, you are probably going to be okay.

But note that it is not only bullet weight but composition and configuration that impact velocity and pressure. Two examples:
  1. If the lead in your bullets is made from a different, harder alloy than the bullets used to devleop the test data, it will take a higher level of pressure to get the bullet to engage with the rifling.
  2. If the bullet you are shooting has a hollow base then the propellant gasses will fill the hollow pushing its margins into contact with the rifling making it harder to move and thus requiring more pressure. If the bullets used to develop the load data had a flat base, they would not require as much pressure.

Begin with the starting load in your load data. Be alert to whether anything sounds or feels "off" when you shoot them and inspect the cases after firing for signs of pressure and then work up as indicated.
Reply With Quote
  #11  
Old 04-21-2017, 12:37 PM
Lee's Landing Billy Lee's Landing Billy is offline
Banned
Reduced Bullet Weight Reduced Bullet Weight Reduced Bullet Weight Reduced Bullet Weight Reduced Bullet Weight  
Join Date: Mar 2014
Location: Battery Oaks Range, S.C.
Posts: 1,847
Likes: 5,663
Liked 3,574 Times in 1,163 Posts
Default

Seating depth is important.
Reply With Quote
  #12  
Old 04-21-2017, 01:53 PM
fredj338's Avatar
fredj338 fredj338 is offline
Member
 
Join Date: Feb 2006
Location: Kalif. usa
Posts: 6,836
Likes: 2,665
Liked 3,927 Times in 2,366 Posts
Default

Quote:
Originally Posted by Lee's Landing Billy View Post
Seating depth is important.
Yes & no. OAL in small volume pistol rounds, like 9mm & 40, with fast powders, like faster than W231, can be problematic. In the larger revolver cases with medium to slow burning powders, OAL just isn't moving the pressure needle much, especially if not loading to max. Of course something like a 148gr WC is NOT the same as a 150gr SWC, but in general, the heavy bullet data for lighter bullets works fine & OAL doesn't affect much. Load to the crimp groove. If the OP is using 200gr LRN data for a 190gr LFP, as long as he isn't starting at max, he should be fine.
__________________
NRA Cert. Inst. IDPA CSO

Last edited by fredj338; 04-21-2017 at 02:02 PM.
Reply With Quote
  #13  
Old 04-21-2017, 03:37 PM
reddog81 reddog81 is offline
Member
Reduced Bullet Weight Reduced Bullet Weight Reduced Bullet Weight Reduced Bullet Weight Reduced Bullet Weight  
Join Date: Sep 2014
Location: IA
Posts: 1,716
Likes: 973
Liked 1,619 Times in 794 Posts
Default

Quote:
Originally Posted by fredj338 View Post
Yes & no. OAL in small volume pistol rounds, like 9mm & 40, with fast powders, like faster than W231, can be problematic. In the larger revolver cases with medium to slow burning powders, OAL just isn't moving the pressure needle much, especially if not loading to max. Of course something like a 148gr WC is NOT the same as a 150gr SWC, but in general, the heavy bullet data for lighter bullets works fine & OAL doesn't affect much. Load to the crimp groove. If the OP is using 200gr LRN data for a 190gr LFP, as long as he isn't starting at max, he should be fine.
What you say about 9mm OAL is true however I would say the same analogy applies to using 190 grain or 200 grain bullets in 38 special. With a 190 grain bullet you will have as much of the bullet in the case as you would with a wadcutter fully seated and maybe even more. Using 200 grain data should be fine. I would expect pressures to increase much faster going up in charges weights than they would for your average 38 special load.
Reply With Quote
  #14  
Old 04-21-2017, 04:57 PM
rwsmith's Avatar
rwsmith rwsmith is online now
Member
Reduced Bullet Weight Reduced Bullet Weight Reduced Bullet Weight Reduced Bullet Weight Reduced Bullet Weight  
Join Date: Dec 2012
Location: (outside) Charleston, SC
Posts: 30,907
Likes: 41,495
Liked 29,147 Times in 13,778 Posts
Default Just my two cents worth......

Cartridges based on those from black powder days, mainly rimmed revolver cartridges are MUCH less sensitive to deeper bullet seating than the rounds designed for semis that have small case volume and were designed for smokeless powder from the start. Pushing a bullet a little deeper in one of those will spike pressure dramatically.

.38 special (and subsequently the .357 magnum) .45 Colt and similar were all designed with black powder in mind.
__________________
"He was kinda funny lookin'"
Reply With Quote
  #15  
Old 04-21-2017, 05:28 PM
fredj338's Avatar
fredj338 fredj338 is offline
Member
 
Join Date: Feb 2006
Location: Kalif. usa
Posts: 6,836
Likes: 2,665
Liked 3,927 Times in 2,366 Posts
Default

Quote:
Originally Posted by reddog81 View Post
What you say about 9mm OAL is true however I would say the same analogy applies to using 190 grain or 200 grain bullets in 38 special. With a 190 grain bullet you will have as much of the bullet in the case as you would with a wadcutter fully seated and maybe even more. Using 200 grain data should be fine. I would expect pressures to increase much faster going up in charges weights than they would for your average 38 special load.
Again, 200gr data, it will take into account the longer/heavier bullet. Not like a WC at all. Unless he is feeding an old M10 or such, it should not be an issue, especially since all new loads should be worked up. again, OAL isn't going to come into play like to does in a 9 or 40, where the pressures are easily double & the case volume is half.
__________________
NRA Cert. Inst. IDPA CSO
Reply With Quote
  #16  
Old 04-23-2017, 09:40 PM
Warren Sear's Avatar
Warren Sear Warren Sear is online now
Member
Reduced Bullet Weight Reduced Bullet Weight Reduced Bullet Weight Reduced Bullet Weight Reduced Bullet Weight  
Join Date: Apr 2011
Location: Twin Cites, Minnesota
Posts: 5,141
Likes: 10,957
Liked 10,857 Times in 3,275 Posts
Default

Just a reminder; there will be no signs of excessive pressure evident in .38 Special loading, or any other caliber of similar pressure (45 ACP, 45 Colt, etc.) except for a cylinder bursting and the top strap hitting the ceiling.
Reply With Quote
  #17  
Old 04-24-2017, 04:50 PM
Mr_Flintstone's Avatar
Mr_Flintstone Mr_Flintstone is offline
Member
Reduced Bullet Weight Reduced Bullet Weight Reduced Bullet Weight Reduced Bullet Weight Reduced Bullet Weight  
Join Date: Feb 2017
Posts: 125
Likes: 68
Liked 68 Times in 31 Posts
Default

According to Lyman, the 358430 bullet has a length from base to cannelure of .412 inches. I just got my 190 grain Hunters Supply LFP today, and I measured the distance from base to cannelure on them, and I got .410 inches to the bottom of the groove. According to the Lyman load data, I feel pretty comfortable starting at the low end and working up. If the seat depth is the same, then all other things being equal but reduced weight, I should have pretty much the same or lower pressure.
Attached Images
File Type: jpeg image.jpeg (53.6 KB, 10 views)

Last edited by Mr_Flintstone; 04-24-2017 at 04:54 PM.
Reply With Quote
The Following User Likes This Post:
Reply

Thread Tools
Display Modes

Posting Rules
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
40 cal. S&W bullet weight martybee Ammo 6 08-31-2014 09:01 AM
Help with bullet weight Carrot Smith & Wesson M&P15 Rifles 8 01-27-2014 10:16 PM
Published bullet weight vs. actual bullet weight safearm Reloading 29 03-26-2013 05:45 AM
What weight bullet in a Md 439? cporfe Smith & Wesson Semi-Auto Pistols 3 05-27-2012 07:57 PM
Bullet weight vs Pistol weight oldracer Reloading 13 01-21-2010 03:13 PM

Powered by vBadvanced CMPS v3.2.3
smith-wessonforum.com tested by Norton Internet Security smith-wessonforum.com tested by McAfee Internet Security

All times are GMT -4. The time now is 01:33 PM.


Smith-WessonForum.com is not affiliated with Smith & Wesson Holding Corporation (NASDAQ Global Select: SWHC)