The Firing Line Forums

Go Back   The Firing Line Forums > The Skunkworks > Handloading, Reloading, and Bullet Casting

Reply
 
Thread Tools Search this Thread
Old May 10, 2019, 02:35 PM   #1
308Loader
Senior Member
 
Join Date: August 24, 2014
Location: Minnesota
Posts: 446
300 Blackout col

Working on 300 blackout loads with Hornady 150gr FMJ and CFE black. None of my books have data for it, so I'm bound to one source of data the hodgdon web site. The page shows 2.235 for COL, fits the mag and dummy round chambers fine. Dosent seem like much bullet in the neck, cases trimmed to Hornady book trim length 1.358. Hornady book shows 2.090 for 150FMJ, lyman shows 2.075, Nosler shows nothing in that bullet weight. The 2.090 seems to align with the crimp groove, but i do not plan to crimp so I guess that wont mater. the bullet From hogdons page is 150 IB, shouldn't make a difference with FMJ right? load data is based mostly on the bullet weight? guessing the longer COL is for case volume? Anyone have any experience using CFE Black? not married to the 150 FMJ just have plenty extra on hand for testing and plinking.

If it matters the rifle upper is 16" PSA 1-9 twist with pistol length gas system.

Thanks in advance for any input.
__________________
Just a dude with stuff.
308Loader is offline  
Old May 10, 2019, 02:57 PM   #2
Unclenick
Staff
 
Join Date: March 4, 2005
Location: Ohio
Posts: 16,501
In 300 BO, Hornady shows 2.090" COL for the FMJ and 2.210" for the IB. Hodgdon adds another 0.025" probably because it fits their gun well. The IB has no crimp cannelure suggesting seating depth, but the main difference is the FMJ has a shorter tangent ogive radius so its stubbier ogive won't let you put the tip as deeply into the bore as the IB's longer secant ogive does before the bullet makes contact with the throat.

So, no, bullet weight isn't everything. The geometry has to be considered, too. There's an article by Allan Jones titled Practical Effects of Bullets on Pressure that shows same-weight bullets can cause pressure to vary 30% if you don't load to match them correctly.

50 years ago it was mostly true that weight alone told you what you wanted to know, but there were no secant ogive or VLD shapes or copper solids and the like back then. Bullet variety has expanded immensely since that time.
__________________
Gunsite Orange Hat Family Member
CMP Certified GSM Master Instructor
NRA Certified Rifle Instructor
NRA Benefactor Member and Golden Eagle
Unclenick is online now  
Old May 10, 2019, 03:34 PM   #3
308Loader
Senior Member
 
Join Date: August 24, 2014
Location: Minnesota
Posts: 446
thanks nick, that was my concern.
__________________
Just a dude with stuff.
308Loader is offline  
Old May 10, 2019, 03:47 PM   #4
rg1
Senior Member
 
Join Date: November 6, 2001
Posts: 1,081
Advice from other 300 BLK loaders for AR magazines was to measure the bullet and place a mark where the bullet measures .250" (out on the tapered tip) and seat the bullet until the mark lines up with the hump on the inside of the magazine. A standard .223 Rem neck is about .250". This will align the BLK case so that it's straight in the magazine and not tilted inward and for more reliable feeding. That works for standard GI magazines and close for others. A recommended oal for 150 Hornady 150 FMJ's was 2.065". For Sie 220 gr HP's a recommended length is 2089", Nosler 125 BT to 2.085", Hornady 130 SP's at 2.010". I load 147 gr. military FMJ's to 2.130" to 2.140" but they have a different profile to Hornady 150 FMJ's. You should be fine seating the Horn. 150 FMJ's to 2.090". Take into account your charges if you seat a lot shorter than the data in your manual.
rg1 is offline  
Old May 11, 2019, 04:00 AM   #5
Mobuck
Junior member
 
Join Date: February 2, 2010
Posts: 6,847
"the bullet From hogdons page is 150 IB, shouldn't make a difference with FMJ right? load data is based mostly on the bullet weight?"
NO!!! Bullet construction ia a variable not to be assumed as constant.
Mobuck is offline  
Old May 11, 2019, 10:04 AM   #6
308Loader
Senior Member
 
Join Date: August 24, 2014
Location: Minnesota
Posts: 446
"You should be fine seating the Horn. 150 FMJ's to 2.090". Take into account your charges if you seat a lot shorter than the data in your manual."

Sounds reasonable, but how would I calculate what a starting charge would be? reduce hodgdon start charge by ?%? or start at their starting load and know I wont be able to get to the max? If I were to try and contact Hodgdon would they have more data than is aproprate for this bullet construction?
__________________
Just a dude with stuff.
308Loader is offline  
Old May 11, 2019, 04:44 PM   #7
Unclenick
Staff
 
Join Date: March 4, 2005
Location: Ohio
Posts: 16,501
CAUTION: The following post includes loading data suggestions beyond or not covered by currently published maximums for this cartridge. USE AT YOUR OWN RISK. Neither the writer, The Firing Line, nor the staff of TFL assumes any liability for any damage or injury resulting from the use of this information.

When I wrote: "Hornady shows 2.090" COL for the FMJ and 2.210" for the IB," this was for identical powder charges in Hornady's book. One of the limitations is that Hornady steps velocity up in evenly spaced blocks and some of their bullets will be getting closer to the velocity claimed for a charge weight than others. Going from 2.09" to 2.235" increases the difference to 0.145", but the Hornady 150 grain FMJ is 0.178" shorter than the IB, so you actually have more space in the case with the 150-grain FMJ at 2.090" than you do with the IB at 2.235". As a result, the case has almost 0.6 grains more water capacity under the bullet when loading the FMJ to that shorter COL than the IB does at its longer COL.

Using QuickLOAD to make a comparison, it turns out you need about 2% more powder with the shorter FMJ bullet loaded to that shorter COL than you do with the IB loaded to Hodgdon's COL. So you would multiply all the Hodgdon charges by 1.02 from start to top to compensate for the using shorter bullet even at 2.090". With most of the supersonic velocity loads, it'll be around 0.3 grains higher charge weights. Not a lot.
__________________
Gunsite Orange Hat Family Member
CMP Certified GSM Master Instructor
NRA Certified Rifle Instructor
NRA Benefactor Member and Golden Eagle
Unclenick is online now  
Old May 11, 2019, 05:35 PM   #8
308Loader
Senior Member
 
Join Date: August 24, 2014
Location: Minnesota
Posts: 446
Ahh I see. Thank you for taking the time to explain, also taking the time to run QL comparison. I guess I assumed... well I don't rightly know what I assumed now that I see what you meant. Thank you.
__________________
Just a dude with stuff.
308Loader is offline  
Old May 12, 2019, 11:46 AM   #9
Ralph Allen
Senior Member
 
Join Date: January 21, 2007
Posts: 426
You can google 300 Blackout reloading data and come up with current pages from Nosler, Accurate and Sierra. I printed out the pages from the above sites and they have all the pertinent info. The Sierra has the most variety on bullet weight.
Ralph
Ralph Allen is offline  
Old May 12, 2019, 06:51 PM   #10
308Loader
Senior Member
 
Join Date: August 24, 2014
Location: Minnesota
Posts: 446
Right but I'm using Hornady 150gr FMJ. I called Hornady and they have no load data for CFE BLK, said the powder was too new. As stated above and confirmed, all 150gr bullets are not the same. the Sierra 150fmj looks close but is it the same construction as the Hornady?
__________________
Just a dude with stuff.
308Loader is offline  
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 03:09 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
This site and contents, including all posts, Copyright © 1998-2018 S.W.A.T. Magazine
Copyright Complaints: Please direct DMCA Takedown Notices to the registered agent: thefiringline.com
Contact Us
Page generated in 0.05786 seconds with 10 queries