What distinguishes 50 vs 25yd cartridge accuracy?

[Mikelo]

You'll often hear / read Bullseye shooters describe a given cartridge as being accurate at 25yds, but not 50yds. So they work-up a load for 25 and another for 50.

So why are some cartridges accurate at 25yds, but not 50yds?

[2650 Plus]

The scoring rings are the same size at 25 and 50 yards. The degree of difficulty is much greater at fifty yards and requires a higher degree of accuracy to score well. The problem is very different at 25 yards as the short range targets are shot in sustained fire strings of five shots per string. Recovery and reaquiring the hold allow the shooter considerably more lee way and still enable shots within the ten ring. Many shooters delibertly hand load soft loads to make it easier to control the centerfire and 45 parts of our national match course. I apoligise for this long winded explanation and its just my opinion. Good Shooting Bill Horton

[Isabel1130]

You'll often hear / read Bullseye shooters describe a given cartridge as being accurate at 25yds, but not 50yds. So they work-up a load for 25 and another for 50.

So why are some cartridges accurate at 25yds, but not 50yds?

Short answer, almost everything works at the 25 yard line. Two factors for accuracy at the 50 yard line are the gun and the load. A rack grade 45 will seldom hold the ten ring at 50 yards. It will usually need to be accurized with a match barrel, trigger job and often machining a better slide to frame fit, match bushing etc. Some gunsmiths test match barrels for accuracy before they even put them in a gun. Then you start fine tuning with proven loads that work in other guns similar to yours to find what works well in yours. One of the things bullseye shooters do is to find a load that shoots well at the 50, that is as light as possible so that your softball loads at the short time will still reliably action the slide so you don't end up with alabis. They fine tune their loads so both work for their intended purpose without having to change out the spirng in the gun in between slow fire and sustained fire. At the 50 yard line there are three things in a cartridge that have a big effect on accuracy. Type of powder and charge, type of bullet and the consistancy of the bullet manufacturing process. Swaged and jacketed bullets generally shoot better than lead cast and are easier to develop loads for. The OAL (seating depth) of the bullet also is very important. Primers and brass are the least important factors IMHO. Isabel

[fc60]

Greetings,

I machine custom barrels for the 32 S&W Long, which are attached to the frame with no moving parts. Testing factory European barrels at 50 yards revealed the bullet was destabilizing, as evidenced by what some folks refer to as "keyholing". Experimentation showed that a barrel with a faster rate of twist tends to stabilize the bullet better and X ring sized groups are more easily attained.

The 32 and 38 HBWC bullets are described by ballisticians as "dynamically unstable". I do not recall if the 45 ACP match bullets are stable or not.

Regarding the 45ACP, we tested 1911 barrels several years ago in a rigid fixture to find the most accurate ones. What we discovered is that if the barrel is correctly machined with quality components they all shot X ring groups. Yes, some shot a little better; but, not by much. It was the AMMUNITION that was the key factor. This is why it is important to test your loading components and tweak them for the best results.

Even commercial ammunition varies. Talk to a Military shooter and ask them about the "ammo shack". Here they test various lots of ammo from the commercial companies and order entire lots of the best shooting ammo. We do not have this luxury and, fortunately, by reloading, we can produce some very accurate ammo.

By the way, where do you suppose those lots of ammo that do not shoot well end up? (Hint, they do not pull the bullets and start over.)


Cheers,

Dave Wilson

[Mikelo]

Thanks for the detailed responses.

So let's say that I worked up a load and bullet combination capable of holding the X ring on a 50yd target reduced for 25yds, assuming a 45 caliber bullet. That is, this cartridge is capable of X ring accuracy when shooting to 25yds on a properly scaled slow fire target.

Can I assume that the same cartridge will maintain this degree of accuracy when shooting to 50yds - with the appropriate sight adjustment?

Or is it that the accuracy may degrade due to the increased distance? - e.g. due to the change in velocity.

I've read about this phenomenon w/ 9mm, for instance. That you can develop a very good 25yd cartridge, but the accuracy at longer ranges may degrade significantly. I think that this is due to the bullet's interaction with the 'sound barrier'.

[Isabel1130]

Thanks for the detailed responses.

So let's say that I worked up a load and bullet combination capable of holding the X ring on a 50yd target reduced for 25yds, assuming a 45 caliber bullet. That is, this cartridge is capable of X ring accuracy when shooting to 25yds on a properly scaled slow fire target.

Can I assume that the same cartridge will maintain this degree of accuracy when shooting to 50yds - with the appropriate sight adjustment?

Or is it that the accuracy may degrade due to the increased distance? - e.g. due to the change in velocity.

I've read about this phenomenon w/ 9mm, for instance. That you can develop a very good 25yd cartridge, but the accuracy at longer ranges may degrade significantly. I think that this is due to the bullet's interaction with the 'sound barrier'.

The second statement is correct. Accuracy degrades over the increased distance. And some loads and bullets are fine at 25 but you will see tipping when the bullet does not go in nose first (there will be a keyhole pattern)and some types of ammo and powder charges end up with flyers. If you see ragged holes at the 50 it is a good sign that the bullet is doing something it should not be doing which can be caused by both an incorrect twist rate in the barrel/and or lack of uniformity in the bullet or iincorrect powder charge or a combination of these factors. 9mm will not generally shoot well without changing the twist rate on the barrel and a guy on bullseye L said he NEVER found a lead 9mm bullet that would shoot at the 50 yard line, only the jacketed ones. Tipped bullets is a common problem with both a 32 or a 38 at the 50 yard line unless the factory twist rate of the barrel in changed and you load very carefully with the right bullets. I have stood by shooters at matches twice now who were shooting 38 semi autos at the 50 and observed this both times. Isabel