The Firing Line Forums

Go Back   The Firing Line Forums > Hogan's Alley > Handguns: General Handgun Forum

Reply
 
Thread Tools Search this Thread
Old April 27, 2017, 02:44 AM   #1
simonrichter
Senior Member
 
Join Date: December 3, 2011
Location: Austria
Posts: 757
Cartridge impulse - slide weight - spring force

Is there a formula for calculating the spring force in a straight blowback handgun with a given cartridge impulse and slide weight?

Thx
__________________
"Get off of my lawn!" Walt Kowalski
. ISSC PAR .223
simonrichter is offline  
Old April 27, 2017, 06:36 AM   #2
kozak6
Senior Member
 
Join Date: June 16, 2005
Location: AZ
Posts: 3,113
http://www.orions-hammer.com/blowback/
kozak6 is offline  
Old April 27, 2017, 02:15 PM   #3
ShootistPRS
Senior Member
 
Join Date: January 3, 2017
Posts: 1,583
Kozak,
That is a great resource! Thanks.
ShootistPRS is offline  
Old April 28, 2017, 02:42 AM   #4
simonrichter
Senior Member
 
Join Date: December 3, 2011
Location: Austria
Posts: 757
I still don't get it - if the spring force was irrelevant for the blowback action, why would you have to change the spring e.g. when changing caliber in multi-caliber pistols?
__________________
"Get off of my lawn!" Walt Kowalski
. ISSC PAR .223
simonrichter is offline  
Old April 28, 2017, 05:56 PM   #5
Snyper
Senior Member
 
Join Date: December 16, 2013
Location: Eastern NC
Posts: 3,047
Quote:
if the spring force was irrelevant
It's not irrelevant.
It's just not what holds the bolt in place alone.
It's purpose is to cushion the blow, and return the bolt to battery.
__________________
One shot, one kill
Snyper is offline  
Old April 28, 2017, 11:09 PM   #6
James K
Member In Memoriam
 
Join Date: March 17, 1999
Posts: 24,383
Most blowback pistols and rifles will work fine without any return spring at all, and some have been made that way, including a single shot rifle and a single shot pistol, both .22. At least one .32 ACP pistol has been made with no return spring. A few pistols made for use with suppressors have a padded bolt and no return spring so as to keep the bolt clatter to a minimum. Of course, the bolts have to be returned to battery by hand.

Jim
James K is offline  
Old May 2, 2017, 04:56 AM   #7
Hal
Senior Member
 
Join Date: October 9, 1998
Location: Ohio USA
Posts: 8,563
Quote:
I still don't get it - if the spring force was irrelevant for the blowback action, why would you have to change the spring e.g. when changing caliber in multi-caliber pistols?
Is there such a critter as a multi caliber blowback?
I'm not sure on this one....
Hal is offline  
Old May 2, 2017, 11:41 AM   #8
carguychris
Senior Member
 
Join Date: October 20, 2007
Location: Richardson, TX
Posts: 7,523
Quote:
Originally Posted by Hal
Is there such a critter as a multi caliber blowback?
The HK HK4 was offered as a 4-caliber kit with .22LR, .25 ACP, .32 ACP, and .380 ACP barrels. It was also offered in 2-caliber centerfire/rimfire combos, most commonly .22LR and .380 ACP. The pistol incorporated a mechanism to switch the firing pin position as needed for rimfire and centerfire, although I don't recall the design details.

Additionally—although factory caliber-change kits may not have been offered—many blowback pistols offered in both .32 and .380 with barrels that aren't fixed to the frame can be switched between calibers easily. For example, the Beretta 81 and 84 can exchange calibers with a simple barrel and magazine swap; the recoil springs are actually the same!
__________________
"Smokey, this is not 'Nam. This is bowling. There are rules... MARK IT ZERO!!" - Walter Sobchak

Last edited by carguychris; May 2, 2017 at 01:04 PM. Reason: Beretta Pico deleted because it's locked breech
carguychris is offline  
Old May 2, 2017, 05:03 PM   #9
Hal
Senior Member
 
Join Date: October 9, 1998
Location: Ohio USA
Posts: 8,563
Thanks Chris!

I didn't know such a critter was out there.
Hal is offline  
Old May 3, 2017, 07:32 AM   #10
5whiskey
Senior Member
 
Join Date: October 23, 2005
Location: US
Posts: 3,649
Quote:
For example, the Beretta 81 and 84 can exchange calibers with a simple barrel and magazine swap; the recoil springs are actually the same!
I'm sure there are others, but add the Astra 4000 to the list. It also had a separate slide for .22lr. Neat little gun and a good example with a full kit (all components for .22, .32, and .380) used to fetch about 2 grand or so in good shape. Despite being neat, it suffers from the same quality issues that many other Spanish pistols faced in the middle of the last century.
5whiskey is offline  
Old May 3, 2017, 04:41 PM   #11
44 AMP
Staff
 
Join Date: March 11, 2006
Location: Upper US
Posts: 28,677
Quote:
Is there such a critter as a multi caliber blowback?
M3A1 "Greasegun". WWII .45acp blowback SMG, had a conversion kit (barrel, bolt assy, and mag) to convert it to 9mm Luger.

I forget which volume its in, but in one of the volumes of "The Machine Gun" (col Chinn) there are formulas for calculating bolt mass & spring tension needed for blowback operation of various cartridges.
__________________
All else being equal (and it almost never is) bigger bullets tend to work better.
44 AMP is offline  
Old May 5, 2017, 11:25 AM   #12
Hal
Senior Member
 
Join Date: October 9, 1998
Location: Ohio USA
Posts: 8,563
Chinn Vol 4,...it's in the link up above by kozak6

Really neat info - in addition to that info.
Hal 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 08:21 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
This site and contents, including all posts, Copyright © 1998-2021 S.W.A.T. Magazine
Copyright Complaints: Please direct DMCA Takedown Notices to the registered agent: thefiringline.com
Page generated in 0.07287 seconds with 8 queries