Load won't cycle action, just reduce OAL?

[Deavis]

I am experimenting in the low end of the powder range and I've finally found a load that won't cycle my weapon consistently. I'm trying to develop loads that are super easy to shoot in 9mm for beginners or just for low-stress plinking. The casings usually fail to extract without feeding the next round, or are thrown just directly in front of the gun. Tried it in another gun and saw the same exact thing (XD-9 and HK-P2000)

I was thinking that I could just reduce the OAL of the load in thousandth of an inch increments to increase the pressure slowly. If I do that until I found the point where the load had sufficient pressure to cycle the action, I would have the absolute low-end with that powder charge. As long as I don't make the load shorter than the minimum length, I don't think there will be any issues with that.

What do you guys think? I know what velocity the test gun showed at hi/low and I know what velocity mine showed at high so I'm hoping to find a similiar offset at the low end. The load I'm running is ~3.5-3.8gr (3.5/4.8 from Lymans 48th) of 231 with an MGB 115gr JHP, a WSP primer, and a 1.090"OAL.

 

[Mal H]

As long as you don't decrease the OAL to a point less than the minimum as you stated, I guess I don't see anything seriously wrong with what you propose.

But, I am puzzled why you would want to try that method instead of increasing the powder load 1/10th grain at a time until it cycles your gun consistently. I think the increasing powder method would give you much more consistent results than decreasing the OAL. By trying to increase pressure/velocity of a round by decreasing the OAL, you are depending more on variables such as bullet purchase in the case, exact dimensions of the OAL, etc., than you do by increasing the powder weight.

 

[Rockstar]

You could also try decreasing the recoil spring weight to compensate for the lighter loads. At some point, you'll reach a point of diminishing returns.

 

[Deavis]

Mal,

Your suggestion is very good but it doesn't help me with the 100 rounds of each 1/10 increment that I've already loaded that won't cycle! It starts cycling reliably right around 4 grains.

My goal is to just get some data and look at how OAL is affecting the feel and the performance of the load. With that many rounds per split I can do a ton of experimentation and get plenty of data. Of course, it sucks when the load doesn't work out well but if I'm worried, I'll only load 50 of it. That gives me two 25 round strings worth of data to play with if I don't want to stretch it out over more strings.

Rockstar, I hadn't considered replacing the spring just yet. Want to keep the gun stock and not have to remember which spring is in there.

 

[saltydog452]

Reducing the over all length to improve function in a 9X19..

I respectfully offer this comment.

I recently bought a Browning Hi-Power that seems to have a feeding problem. The seller of the Browning hasn't seen fit to answer my e-mails or phone calls.

One of the loads that I tried was Cor-Bon 115 JHP. The Cor-Bon load has worked well in my Kahr K-9, P-9, & the Colt version of their P-9.

The used Browning has some feeding problems, but I figure that can be corrected. The thing that causes me some concern is that the Cor-Bon load in its travel into the chamber didn't quite make it that far.

Upon extraction, the Cor_Bon round just didn't look guite right. I dug out the trusty Brown and Sharpe dial calipers and the calipers verified my 'eye-ball' obversavation.

The Cor-Bon loaded round had been forced back into the case by .023.

The 'Cliff Notes' version of this post is that the OAL that you start out with ain't exactly the same as what is fired in the chamber.

So, if you have a 'hot' round thats marginal as to safety, by ther time it makes it up through the magazine and up the feed ramp and into the chamber, it just may be a little short with a bit higher pressure.

Thats just a suggestion for those who insist on loading semi-auto rounds to their max.

The OAL just don't necessarily stay that way.

salty.

 

[larryw]

So when working up a load, you load 100 of each increment? Interesting, I hadn't considered that approach: I load 10 of each to get a baseline on functionality and then go back to look at the promising loads.

How do you plan on conducting your experiment? Will you take a sample from each batch of 100 (how many total cartridges are we talking about?), bump it down a thou; take another sample, bump it down a couple thou; etc? And then do this for each batch of 100?

If you choose to go this route, I will be very interested in hearing your report, especially with regards to pressure and how it correlates to powder charge and internal volume variations (within the limits as pointed out by Mal)

But my spider sense is tingling and this sounds like a recipe for disaster: I recommend a bullet puller, a soda or two, and comfy chair instead.

 

[Mal H]

Like larryw, I hadn't considered that you had loaded 100 or more of the light loads. Try your experiment with OAL variations. Again like larryw, I would be interested to see if it makes much difference in vel and therefore in cycling the action.

 

[Deavis]

larryw,

Normally I load 100 of each round that I want to experiment with. When I am pushing the high end, I will only load 50 at a few tenths away from the max at first. Once I verify those are within the limits of what I expected, I'll load up to the max to see how it performs. I think that many people do a big disservice by only loading 10 of a round because how do you make a meaningful comparison to other loads?

Typically, I'll go out with a few favorites and the new loads. First, I fire a couple over the chrono to be sure it isn't "crazy" hot. Then 1 full mag of each one just to feel it out. How was the recoil? Did I like the feel? How dirty is the case does the primer look ok? Did it feed the whole magazine? Does it have too much flash or smoke? Then I'll run a string of 25 for each new load over the chrony and use the favorite or some WWB as a baseline for that day. Then I'll try out each new load versus each other with a staggered magazine load to really compare the feel of the load. After that I'll shoot a ten group of each for accuracy sitting on a rest to see how they do. 10 rounds just isn't enough to evaluate a round, get a solid statstical data set, and to make sure that your loading setup is consistent.

Anyhow, my plan is to drop the OAL in .001 increments within 10 round groups. I know what the velocity was on a max load (max pressure) so if I appear to be getting velocities close to that then I'll know I should be wary of trying the next lowest OAL. I'll have to do some calculations to be able to come up with a rough case volume/pressure/OAL relationship. I guess I could dig through my rinker book and see if I can find something useful in there.

I'll keep you guys posted and if it blows up, I'll be posting pics. Speaking of which, I need to post that pic of the Glock 10mm brass that blew out a few weeks ago. Blew out right over the feedramp! The casing, what is left of it conformed to the feedramp perfectly. Too bad I couldn't find the casehead anywhere

 

[TooTaxed]

You can reduce OAL only so much before the short cartridges alone cause feeding problems...they will jam on the chamber mouth regardless of how heavy a load of powder you are using. This is somewhat of a trial and error proposition, as different bullet types require different OAL ranges.

Best to increase powder 0.1-gr until you get reliable functioning and the slide remains back at the end of the clip load. I've found this varies by gun model. My CZ-75B Tactical in 9-mm Luger functions reliably on 3.4-gr #231 with either a 115-gr RNP Ranier or 125-gr Bear Creek moly RNL bullet, with the slide remaining open at the end of the string. My Taurus PT-99 Tactical requires 3.8-gr #231 to be similarly reliable.

 

[hals1]

I don't think playing with OAL is going to help. Your gun is recoil operated. What you need is to transfer enough energy to the barrel/slide to make the action work. This depends almost entirely on the momentum of the bullet/powder (velocity times mass). You gotta increase the powder charge or maybe reduce spring pressure. If you really want to shoot light you also have to lighten the slide.

Increase the powder charge or get a .380 or 9x18.

Just my $.02.

 

[caz223]

Interestingly, I had something like that happen.
I always did all my load development for 9mm using my CZ75.
I tried out a new load that had almost no recoil and cycled the slide 100%.
I got a chance to shoot a steel plate match, and the results were very promising.
So, I cranked out several hundred rounds for long term testing.
A week or so later I happened to be out at the range, and wanted to shoot my sig 228.
Loaded it up, and not once did it fully cycle the slide.
stovepipe, jam, empties not extracting, etc.
It didn't occur to me that my CZ was undersprung, and the sig was NOT.
I still have those really light loads laying around for training use, but I want all my ammo in each caliber to work in all my guns (In their respective caliber.).
I am watching this thread, I never even suspected that reducing OAL could have an effect on the velocity, and therefore, the cycling of the slide.
I would like to know if increased PRESSURE has any effect.....
But I suspect it does not.
Let us know, I'm very interested......

 

[Zak Smith]

I don't think playing with OAL is going to help. Your gun is recoil operated. What you need is to transfer enough energy to the barrel/slide to make the action work. This depends almost entirely on the momentum of the bullet/powder (velocity times mass). You gotta increase the powder charge or maybe reduce spring pressure.

This is not really correct.

Decreasing the OAL will increase pressure and velocity.

It might or might not do so enough to make those 100's run in your gun.

I suggest using a reasonable OAL for reliability's sake (ie, 1.130" nominal in 9x19), and then adjusting bullet mass and powder charge until it has the recoil characteristics you want and will run your gun.

If you want to shoot underpowered loads a lot, consider getting a less strong recoil spring for your pistol.

I found that a CZ would run at around 85 PF, but it was reliable at 100 PF.

 

[Deavis]

Okay, so here is what I've got lined up for this weekend. I took the cartridges which were assembled with an OAL of 1.090" OAL and decreased the AOL in increments. I just ran them through the seating die as I stepped it down. Then I measured them and sorted them into bins. I've got 20 of each distribution bin. The step down in 5 thousandths of an inch increments.

So I've got... 1.085"-1.090", 1.080"-1.085", ... 1.020"-1.025".

I'll chorno them all and see how the velocity is increasing with decreasing seating dpeth. I bet I could back out some characteristics of the powder's burning rate if I was more careful about measuring case volume, bullet size, etc. The goal... functioning without blowing up! Then, of course, remembering to increase the powder charge next time!

I'll post results next week.

 

[saands]

NOTE: The following post cites PREDICTED numbers from a SOFTWARE MODEL that deals with interior ballistics. Like ALL models, this one (strictly speaking) is wrong, but I have found it to useful inspite of it not being 100% accurate. It is my experience that it is quite good at predicting what will change when one parameter (such as OAL) is changed at a time ... in this light I will offer its output ... YMMV, etc.

Deavis,

I ran your numbers through QuickLoad (an interior ballistics model) and here's what it predicts:

first I wanted to get a baseline for the model's functioning with 9x19 and 231 so I ran the max load you mentioned:

OAL 1.090 with 4.8 gr 231: 30,216psi and 1181 fps

That looks pretty good as most max loads listed in the books are sitting at 10-15% under max pressure.

Now, onto the 3.8 grain charge predictions:

1.090" : 18,700 psi and 996 fps
1.020" : 24,800 psi and 1052 fps ...

I'd say that you aren't likely to do any damage to anything and if they feed, you will likely find a usable load out of this experiment. As the SaltyDog points out ... changes in OAL (especially in short straight walled cases where the percent change is mush greater than in long and/or bottlenecked cases) can really make your pressure climb especially if you are already in the hot-load region ... just for grins I ran the model with the 4.8gr charge and 1.020" OAL and QL predicts more than 42,000 psi (34,000 is my listed max for the 9x19)

Good luck,
Saands

 

[Bronson7]

As several members have already posted, the correct solution is a lighter recoil spring.
Bronson7

 

[contactcole]

Reduce recoil spring weight

As several members have already posted, the correct solution is a lighter recoil spring.
Bronson7

This is the correct answer IMHO.

The easiest and safest option for light charge loads is reduced recoil spring weight. Reducing OAL is more unpredictable in pressure build up. Also, reduced OAL could effect feding irregardless of powder charge weight. Reliable cycling is a designed, balanced correlation between load dimesions, load energy and slide resitance (mass and recoil spring weight).

 

[Al Norris]

Deavis wrote:
I'm trying to develop loads that are super easy to shoot in 9mm for beginners or just for low-stress plinking.

Ok, maybe I'm all wrong in my thinking. Maybe I'm wrong in my understanding of ballistics.

By decreasing the OAL, to that which cycles properly, you will be increasing pressure, velocity and felt recoil.

By increasing the powder charge, to that which cycles properly, you will be increasing pressure, velocity and felt recoil.

One of the problems I see with reduced OAL, as has been already observed, is reliable feeding. Ignoring that, for the moment, I would think you are defeating the stated purpose when such reductions will increase the recoil.

Or am I wrong? (wouldn't be the first time...)

 

[Deavis]

Guys, I'll say it one more time, I don't really care about using a lighter recoil spring.I simply want to see how low I have to go with the OAL and still cycle the gun. Thanks for the input on the springs but I'm absolutely, positively, not going to put a lighter spring in there. This is simple an experiment and I'm doing it for the pure enjoyment of it. I'll get some data on how OAL affects velocity with 231 in my gun. I already know that this load is not something I'll duplicate so why not use it to learn something?

Anyhow, for anyone not interested in the recoil spring, I was finishing up chronographing (read holding the unit and writing down notes) some 10mm loads and my buddy managed to pop my sensors on the very last 10mm set. I should have brought the replacement sensor housings since he was going to be shooting all the 10mm through but I forgot to grab the bag. On the bright side the sensor housings look ok and only one lens fell thorugh, so I think I can reuse them with a new set of screws I would be mad but he is paying for the replacement and his hand was bleeding from the pounding of the 10mm loads. He said, "I want them hot, let's see how they go." I admit it, I enjoyed watching him sweat his way through the boxes.

The 9mm testing will have to wait but just for fun I ran 5 through at the 1.070" OAL and everyone of them cycled but the brass was still ejected forward. Hopefully some solid data on them in the next week or two.

Saands, thanks for the data, we'll see how close they actually come to it!

 

[saands]

I AM interested, so consider it my pleasure ... I WAS hoping that you would post the results. When an opportunity to learn presents itself, I try to take advantage of it. Since reloading is SO non-linear, I saw this as a GREAT way to cross-check QuickLoad's interior ballistics model. Thanks for collecting the data

Saands

 

[Bullet]

Quote -
"This is simple an experiment and I'm doing it for the pure enjoyment of it."

Sometimes some people forget about the fun. In my opinion this is what it's all about.

 

[contactcole]

Deavis: I think reading your additional posts the question you are asking is, How little of a given powder charge will cycle the slide with a stock recoil spring?. The question you initially posed was in regards to creating the lowest energy load your gun can reliably cycle. Two different questions. Two different answers.

If you have a load that's too just a hair too light to cycle the slide, you are correct that decreasing OAL will increase pressure and energy enough to very likely get it done. The thing to keep in mind is that decreased OAL can create pressure spikes that are more inconsitent than just increasing charge weight. However, it's often easier to do this than disassemble components.

Simply formula to conceptualize:

If X = lightest recoil energy to cycle your slide with standard factory recoil spring, clearly all loads that reliably cycle the slide MUST be >/= X.

(Assuming same components)

A) Standard Load x Standard OAL = X

B) Reduced Load x Reduced OAL = X

Recoil energy must be the same in A and B. Recoil is not reduced by decreasing both load and OAL.

I, and I think others, were answering the "least (felt) recoil" question, whereas reducing OAL relates to reducing powder charge load.

That's the great thing about reloading: Tweaking loads to suit wants, needs, curiosity and whims. Keep us posted.

 

[Deavis]

I think reading your additional posts the question you are asking is, How little of a given powder charge will cycle the slide with a stock recoil spring?. The question you initially posed was in regards to creating the lowest energy load your gun can reliably cycle. Two different questions. Two different answers.

Yes, the point was, at first, to find a very low felt recoil round using the stock gun (I could always shoot a smaller caliber, but that wasn't the point of the exercise!) I just happened to start with a 3.8gr load and a 1.090" OAL because that was listed in the manual. From there I increased charge and changed powders to see what I liked.

When the 3.8gr loads fell through due to the inability to cycle, I figured why not find out what OAL I had to run with the load to cycle the gun. I'm trying to turn some bum loads into something that yields some useful data

For my purposes, I am not reducing the powder charge, just the OAL. I am relying on the reduced volume to increase the pressure of the load. I'm curious to see how the felt recoil changes as OAL drops. I will not, as your 2nd formula indicates, be changing the powder load at the same time as the OAL. This OAL is fairly short already and I'd rather lengthen it up and work from there. More data, more data!