How many rounds to switch to a new load?

[RickT]

My wife and I are switching from 147/WSF to 115/N320. Yes, its SC so no PF. Setting aside accuracy considers and potential issues going below the book minimum load how many rounds downrange would make you comfortable with using a new combination in a match, 1000?

[Youngeyes]

Once I have a load that meets my expectations on accuracy, recoil, feeding and chrono, I shoot a couple of hundred and I'm good to go. I'll wind up shooting more than that in practice, but I would shoot a match after the initial 200. Be careful on the below minimum loading. Booms can happen on an under loaded round.

[safeactionjackson]

I'd say 200 is fine if you haven't seen any issues.

Recently ran a batch of 400, and had an issue about every 30-50 rounds.

Tweaked my load, ran a few hundred without issue.... good to go for matches!

~g

[AzShooter]

Run a couple hundred to see if they function correctly and go where you want them to. Then you are good to go. You don't need to run 1000, you can tell in 100. I recently switched from147 to 125 and 135 for less recoil and faster time to target.

[Brooke]

Run a couple hundred to see if they function correctly and go where you want them to. Then you are good to go. You don't need to run 1000, you can tell in 100. I recently switched from147 to 125 and 135 for less recoil and faster time to target.

Wow! You might want to rethink that!

There are many references available to show that when different bullets are shot at the same power factor, the heavier bullet produces less recoil force. The heavier bullet also requires less powder to achieve that power factor which accounts for much of the difference. Recoil force is associated with both acceleration of the bullet and with the force of gas escaping the barrel. Since a light bullet requires more powder, more gas is generated. Look at all the empirical, experimental, and theoretical data available on the internet. This is really a settled issue, well beyond the argument stage.

On the topic of time to target...with 9mm rounds of 115 gr and 147 gr bullets both loaded to 125 pf, the muzzle velocities are 850 ft/sec with heavy bullet and 1087 ft/sec with the light bullet.The differences in time to target for a 10 yd target is 0.007 sec and for a 50 yd target 0.036 sec. These are completely negligible for any practical purpose. Your reaction time to any event related to the target is way longer. More on the order of 0.14 sec or longer.

Gut feel for stuff often leaves you mistaken.

[Yeti]

After all testing and the load is finalized...100+ perfect rounds.

If something less than perfect occurs or anything odd or unexpected happens, it is more. If for any reason I need to change the load...100+ again.

I know for some this may not be enough. IMHO the odds are high that if I shoot that many with absolutely no issue the load will be good to go. The gremlins can always come from somewhere else, but I feel confident enough.

Gotta concur with Brooke on the heavier bullets. However much of it is perceived and some of it is just personal taste.

Edited December 3, 2015 by Yeti

[RickT]

Thanks. 100 makes sense at 0.1gr above what will cycle reliably. I reloaded rounds for this weekend's math at 3.8gr N320 which I knew would cycle flawlessly. At the same time I practice with a mix of 3.5 and 3.6 grain which also cycled flawlessly through 300 rounds although we had some issues with the 3.5gr at the last match - go figure. I'd have my wife shoot more than that since she seems to experience a few more problems; the slide on her 9mm 1911 has never felt as slick as mine and I believe that is the major factor. I'm also going to be switching lubes which should improve the slide action

[Yeti]

You have a pretty stable temperature year round (unlike some of us) but you may want to consider +0.2gr as a buffer.

It messes with your time and your head to have a stoppage during an event.

Aaaand if it is your wife!? You are in the doghouse buddy.

[rowdyb]

Once everything is set and initial load development is done and I think, "alright, this is my load" at that point if I shoot 2-300 and nothing goes wrong I call it good and don't look back. My development process can take up to a 100 rounds 'wasted' in figuring out exactly what I want from that combo of projectile, powder and gun.

I find that if problems do show they occur when you're first making the load or later when something happens during the reloading process itself. The degree to which your original 'recipe' is good can be discovered really quickly. Then it's just being able to repeat that process over and over again.

[RickT]

My process is pretty solid - over 30K rounds of our previous load without a hiccup. I'll need to account for his/her competition and backup guns; sounds like 200 rounds in each of our #1 guns, less than one practice session, and 50 rounds through each of the backups as a sanity check.

OTOH, why is an old fart bothering with all this. I have no idea.

[motosapiens]

with no chrono requirements, i'd be happy with one practice session without hiccups.

I usually like to do at least 2 separate chrono trips (sometimes 3 or 4 if I'm fine-tuning the powder charge).

But I never really have any trouble getting my guns to run and feed. It's purely an issue of sight adjustment, accuracy and making pf reliably.

[LilBunniFuFu]

Run a couple hundred to see if they function correctly and go where you want them to. Then you are good to go. You don't need to run 1000, you can tell in 100. I recently switched from147 to 125 and 135 for less recoil and faster time to target.

Wow! You might want to rethink that!

There are many references available to show that when different bullets are shot at the same power factor, the heavier bullet produces less recoil force. The heavier bullet also requires less powder to achieve that power factor which accounts for much of the difference. Recoil force is associated with both acceleration of the bullet and with the force of gas escaping the barrel. Since a light bullet requires more powder, more gas is generated. Look at all the empirical, experimental, and theoretical data available on the internet. This is really a settled issue, well beyond the argument stage.

On the topic of time to target...with 9mm rounds of 115 gr and 147 gr bullets both loaded to 125 pf, the muzzle velocities are 850 ft/sec with heavy bullet and 1087 ft/sec with the light bullet.The differences in time to target for a 10 yd target is 0.007 sec and for a 50 yd target 0.036 sec. These are completely negligible for any practical purpose. Your reaction time to any event related to the target is way longer. More on the order of 0.14 sec or longer.

Gut feel for stuff often leaves you mistaken.

He might be talking about splits. If you have a good grip on the gun the lighter snappier ammo should have you back on target sooner. Meaning you can "double" without too much thought of the second shot. But for us mere mortals the heavier bullet are overall more helpful.

[RickT]

For SC the lighter bullets seem to be the way to go. These light 115gr loads just barely move the sights and yet our 1911s will cycle if I just barely hold onto my gun. Our WSF load behind 147gr Bayou is as low as we could go, but definitely more sight movement. Of course there are lots of other powders out there, but life's short, I can get N320 for now and have 16 lbs of HP-38 as backup for which I have not worked up a load.

There's a lot out there discussing the danger of below-book loads, but any instances referenced appear to relate to rifle cartridges loaded with small amounts of pistol powder or similar exercises. At most I'm only going 10% below book and N320 is pretty fluffy stuff so it's not as those I have 3 grains of powder rattling around in the case.

[CZ85Combat]

Try 115 with N310

[RickT]

Try 115 with N310

I'll probably do that next time I order powder. It's not listed by VV, but I suppose it might burn cleaner at the very low end and it appears to be more available..

[t0066jh]

I know the original post was in regard to Steel Challenge......but it's also about reloading.

For USPSA, I wanted a softer load and developed a load that took me from 131 Power Factor to 127. All was well until I had to shoot a string in a classifier that was 6 shots weak hand......the gun wouldn't cycle......my grip wasn't strong enough to provide the resistance necessary. Back to 131 PF.

My point:... for me, I've got to test the load under all circumstances.

Edited December 14, 2015 by t0066jh

[nwhpfan]

I was shooting 3.6 TG with 125 from a Glock 34 with no problems but was needing to switch because I was running out them. I had a few thousand 147 which is what I was going too. I loaded 3g of BE which is a very popular load and thousands of people have shot millions of rounds with no problems....so once I shot a few hundred rounds to verify the charge ran my gun properly I made the change without much thought or worry... I did hold back a few hundred rounds of 125 just in case but in the end, it was fine. I did have to swap the front sight which I was prepared for and really...I go back and forth a little anyway.

[9x45]

When I switched from Bear Creek 125TC's to Bayou 125 TC's in October 2014, I loaded 15 rounds and shot them out after the match. Made one adjustment to the OAL, going from 1.125" to 1.100" and that was over 14,000 rounds ago. Since the powder charge and bullet weight were the same, I didn't chrono until a few months ago, and both loads chrono at around 1,150 fps, mixed cases. At near a 144PF there is never a worry of not making minor.