3djedi Posted March 18, 2014 Share Posted March 18, 2014 I've been reading on here that if you increase OAL you reduce pressure. But I just read in the hornady reloading book if you increase oal it increases pressure. As you get the bullet closer and closer to the rifling there is "Less running start" for the bullet and pressure increase to get the bullet moving down the barrel. Totally confused now. Sent from my SAMSUNG-SGH-I747 using Tapatalk Link to comment Share on other sites More sharing options...
Sarge Posted March 18, 2014 Share Posted March 18, 2014 Worry more about the pressure increasing with a shorter oal. That is a certainty. Link to comment Share on other sites More sharing options...
rtp Posted March 19, 2014 Share Posted March 19, 2014 (edited) I'm assuming this is for pistol loads? Two ways to increase pressure, assuming a constant of bullet and powder. Compress the powder or space it has to burn/expand in further, or make it harder for the bullet to get out of the barrel. The first is accomplished by shortening the OAL, the second by a tighter barrel (not so likely unless you routinely swap them? ), or by pushing the projectile out (longer OAL) to the point it's contacting the lands. Doing a plink/max OAL test and backing off slightly removes #2 from the equation, assuming you aren't swapping barrels often, while the former (shorter OAL) is in your control. http://www.czfirearms.us/index.php?topic=34225.0 As an example, I have a short chamber in my PPQ, so loading at 'min' published load for WSF with 124gr JHPs still puts me up towards published max velocity. Edited March 19, 2014 by rtp Link to comment Share on other sites More sharing options...
3djedi Posted March 19, 2014 Author Share Posted March 19, 2014 From what I understand from reading hornady is increasing OAL closer to the rifling will increase accuracy, increase velocity, and increase pressure. It said reducing charge is recommended. Sent from my SAMSUNG-SGH-I747 using Tapatalk Link to comment Share on other sites More sharing options...
3djedi Posted March 19, 2014 Author Share Posted March 19, 2014 I reread it and I did misunderstand. Its talking about an OAL to the point the bullet us touching the rifling. That's when pressure increases significantly. But it says it is the most accurate at this point. It's also talking about rifles. I dont know if this applies to pistols... Sent from my SAMSUNG-SGH-I747 using Tapatalk Link to comment Share on other sites More sharing options...
3djedi Posted March 19, 2014 Author Share Posted March 19, 2014 How does barrel length effect pressures? I see all load data is for 4" barrels. How significant of a difference in pressure and velocity of a 5" barrel? Sent from my SAMSUNG-SGH-I747 using Tapatalk Link to comment Share on other sites More sharing options...
Youngeyes Posted March 19, 2014 Share Posted March 19, 2014 As Sarge said, decreasing the OAL will certainly increase the pressure. For regular shooting and even competition the posted OAL is fine.You vary it only to assure that your loads feed well. Some serious rifle shooters will measure the headspace to reduce the bullet "jump" to increase accuracy. IMO this is very unnecessary in pistol shooting. Link to comment Share on other sites More sharing options...
Youngeyes Posted March 19, 2014 Share Posted March 19, 2014 How does barrel length effect pressures? I see all load data is for 4" barrels. How significant of a difference in pressure and velocity of a 5" barrel? Sent from my SAMSUNG-SGH-I747 using Tapatalk Effectively nothing. Link to comment Share on other sites More sharing options...
3djedi Posted March 19, 2014 Author Share Posted March 19, 2014 (edited) Ok thanks! Sent from my SAMSUNG-SGH-I747 using Tapatalk Edited March 19, 2014 by 3djedi Link to comment Share on other sites More sharing options...
RDA Posted March 19, 2014 Share Posted March 19, 2014 I've been reading on here that if you increase OAL you reduce pressure. But I just read in the hornady reloading book if you increase oal it increases pressure. As you get the bullet closer and closer to the rifling there is "Less running start" for the bullet and pressure increase to get the bullet moving down the barrel. The only time I know of increasing OAL to increase pressure would be if your OAL was longer than your chamber allows and when chambering a cartridge, the bullet is jammed against the rifling prior to being fully seated causing bullet setback and increasing the pressure. Link to comment Share on other sites More sharing options...
RPatton Posted March 19, 2014 Share Posted March 19, 2014 I've been reading on here that if you increase OAL you reduce pressure. But I just read in the hornady reloading book if you increase oal it increases pressure. As you get the bullet closer and closer to the rifling there is "Less running start" for the bullet and pressure increase to get the bullet moving down the barrel. The only time I know of increasing OAL to increase pressure would be if your OAL was longer than your chamber allows and when chambering a cartridge, the bullet is jammed against the rifling prior to being fully seated causing bullet setback and increasing the pressure. Not exactly true. If you load a rifle with the bullet just touching the lands it will cause pressure to spike as the bullet has more resistance to movement. When I started reloading back in 1968 it was one of the first mistakes I made with an 8MM Mauser. I would assume that a semi-auto pistol would experience the same problem. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now