OAL and accuracy?

[bigtattoo79]

Does OAL affect accuracy? I have a load that works pretty good but someone was telling me that a longer OAL is better for accuracy "I know about not hitting the rifling and how to check it".

Thanks

[Bshooter]

I prefer to load to a length that is just short of the rifling. I have found that the longer the bullet you can fire in a particular weapon to be more accurate. That same bullet might not be as accurate in a different weapon. Work the load up and stick with it for that weapon.

[CocoBolo]

If we exclude the most important factors the human and the discharging device, Powder, bullet, primer, brass, and yes OAL all have an affect on accuracy.

You can find your max oal by taking a case and sizing it then start a bullet in th case. Next with the barrel push the round all the way into the chamber. Remove it measure it and subtract .01 from the measurement. Next verify that the length will fit in the mag. This is the max oal for that bullet in that gun. Now you are on your way just start then then decrement the oal on each group of 10 and shoot them on a rest at 50 yards measure group size. Not happy change powder charge weight, then change to different powder, start over again. Not happy change bullets start over again. For the test to have meaning you need to use the same primer and equivalent brass, aka all same head stamp with same history. Not happy change to different primer start over again, Not happy change primer start over again.

If you look around there is one guy that puts out a spread sheet on all his testing and it will give you some insight into how all these factors affect accuracy, as well as the benefit of his testing to eliminate those loads that don't measure up.

My basic accuracy test at 15 yards is the A Zone in a uspsa target. If I can shoot 10 shots into the head A zone with at least 8 hitting in the Azone Free style then load is good enough for a Local USPSA match Level I. For major matches Nationals, Sectionals, I take the time to shoot the 50 yard test.

Be sure to do you testing only with components you can get on a regular basis, isn't much fun when you develope the worlds most accurate load with bullets you can't get when you need them, or they are too expensive to shoot. I'm sure some Sirrea's would be real accurate.

[Sarge]

But with certain guns it is not always the longest round that is the most accurate. My Glock 34 was most accurate at 1.13 my M&P liked 1.15. When I mentioned that to several other reloader/shooters they said often times a minor PF load will be more accurate at shorter oals in a given gun.

[Trident]

But with certain guns it is not always the longest round that is the most accurate. My Glock 34 was most accurate at 1.13 my M&P liked 1.15. When I mentioned that to several other reloader/shooters they said often times a minor PF load will be more accurate at shorter oals in a given gun.

Sarge, and to make this more confusing what bullet profiles were you using RN or HP ? In my recent testing, and the post I made a few days ago, I found that MG CMJ and MG JHP had significantly different free bore differences of over .045. Meaning I could load the JHP to as close as .005 free bore and still fit in the mag but the closest I could get the CMJ was something like .045 before it would not fit into the mag. Something to consider.

[Hi-Power Jack]

Probably true in his gun, with his load.

Not true with myload in my gun.

I developed a nice 147 grain MG load for my BHP

and it was more accurate at 1.12", but didn't

feed real well - loaded it out to 1.13" and

it fed great, but wasn't "quite as accurate",

but accurate enough

Guess it depends on Your Gun, and Your Load.

[rhyrlik]

Does OAL affect accuracy? I have a load that works pretty good but someone was telling me that a longer OAL is better for accuracy "I know about not hitting the rifling and how to check it".

OAL affects accuracy by changing the internal ballistic properties of your round. It affects peak pressure, how pressure builds, and the time the bullet spends in the barrel. In my Glock, 1.130" is more accurate with 147's than 1.110". Primers affect accuracy the same way. For example, in a certain load, FC-100 primers produce much larger groups than CCI-500 primers. This is all gun/load specific, though.

[Red Ryder]

But with certain guns it is not always the longest round that is the most accurate. My Glock 34 was most accurate at 1.13 my M&P liked 1.15. When I mentioned that to several other reloader/shooters they said often times a minor PF load will be more accurate at shorter oals in a given gun.

I agree Sarge. Accuracy speaking, my G17 really likes 1.130 to 1.135 using 124gr MG CMJs. My XDM prefers the same bullet with the AOL at 1.150. If I go shorter on the XDM, accuracy is decreased. Loading Longer has no affect. Loading Longer for the G17 decreases accuracy and reliability. I have not tried loading shorter with the G17 because I had excellent accuracy at 1.135.

The real question is what affects accuracy the most in a bullet recipe. That answer would provide the most helpful info when working up a load. That would be what you would change first. But, thanks to Brian Enos, we have available to us a plethora of relatively reliable bullet recipes that have been tried and found to be true all over the country by reloaders and shooters alike! Every load should still be worked up but at least we have fairly good references to guide us in the process. Imagine what it was like 30 years ago.