Comp for 9mm pcc

another reality is that nobody wants to load different for pistol and pcc. and not a lot of folks shoot open (or shouldn't, anyway - a stupid class that is the antithesis of ipsc). so, if not developing a load specifically for a compensator then you are developing a load for a standard or production pistol and pcc.

in this case, you want to load a heavy bullet and a slow powder. you want everything to slow down. there are two hits when you pull the trigger; the initial bang, and when the slide (or bolt - this is the pcc forum) hits the end of travel. shoot a light bullet and a hot load and these two hits happen a the same time and make for a snappy round with lots of flip. slow it down with slow powder and a bullet with a lot of momemtum and the two hits happen consecutively which creates a push instead of a snap - easier to control.

of course i am not a db with a bazillion posts so take it for what you paid for it ...
 
Haha, I know what you mean - Open division isn't really my thing either. But as a test ground for new tech, stuff that seems weird and impractical but eventually becomes really useful, it seems to work. Don't we have Open to thank for the modern miniaturized red dot, for example? Other stuff too, like gas pedals, base pads, mag wells, others that I'm forgetting... None of the latter floats my boat but I'm glad they exist, and I wonder what weird and wonderful developments will come from Open division guys pushing the limits in the future.

You're probably right that most people probably don't want to develop two different loads for pistol and PCC. But I'd guess that the top tier guys do (even if they're not in Open). You just can't get perfectly optimized results from both handgun and PCC with a single load, they are different animals. But you can probably get pretty close, and "good enough" is good enough for most of us. In the US, you see solutions like 16" PCC "barrels" that are actually just 4.5" barrels with permanently attached sleeves to make the "barrel" length reach their magic number of 16". That way the rifled portion of the PCC barrel is the same length as the handgun barrel (or very close).

I think everyone agrees that when it comes to a member's post history, it's quality that matters - Not quantity. Please excuse my ignorance, but what is a "db"?
 
Johnl you asked about lead build up in a comp

The answer is yes. I plugged up TK comp on a S&W 22lr pistol. You have to keep it clean
Since my experience where I didn't pay attention to the comp I now clean my comps after each shooting trip to the range. Clean your comp and you should be ok. Don't and you will find your comp plugged eventually if my experience with my .22 comp is replicated in my 9mm carbines. I don't use lead in the two Trudeau has yet to ban and they don't feed my FP lead bullets I cast.

Take Care

Bob
 
alpining said:
What is a bad ######? All the ones I've met have been pretty good.
Click to expand...

It's just like getting good fish at the market...... sniff test, you will know when it's bad.... unless you have long covid or an otherwise non functioning sense of smell!
 
I removed the comp and shot the gun then reinstalled the comp and shot the gun, the gun shot flatter with the comp.
What you are suggesting a 3oz comps weight will reduce the barrel rise a noticable amount. I ask you will a feather.atrached to the barrel reduce recoil? Your answer is likely yes as you are adding weight and it is obvious to all that adding weiht will9 reduce muzzle rise. You might want to investigate how much weight you need to add to prevent muzzle rise then let' us know if the 3oz weight falls within your calculation. My bet it isn't.

Tale Care
Bob
ps. The calculations expressed earlier regarding pressure estimates are just that. The amount of psi would obviously vary depending upon the gas generated. The latteris not a constant.
 
Glad to see you're still in this thread Bob.

I think you've written up the reasons for your position very well. I hope everyone reading appreciates the time and effort. I particularly appreciate it because it shows me that you have been acting in good faith - You haven't been dodging the question. You haven't been evasive in your replies. And you're not trying to hide anything behind vague or irrelevant "lawyer-proof" statements. Even though we disagree on the topic at hand, I respect you all the more for your approach.

Nobody here has tried a direct comparison between using a comp and using an equivalent dead weight on an NR 9mm PCC. It's not particularly difficult, and it's "interesting" to consider why manufacturers haven't done this and made their results public: "Hey customers, look how well our comp works!"

Shooting flatter with a comp vs. no comp simply doesn't answer the question - If you think it does, then we're simply never going to agree. By the laws of physics, gas pressures at the muzzle for an 18" barrel is much, much lower than for a 10" barrel - If you think they aren't, then we're never going to agree.

I can't really add anything at this point, except to again remind everyone that many other forums have lots of information on this topic if they care to look it up themselves. As for this thread, readers can decide if what they've seen here amounts to evidence of anything at all.
 
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alpining said:
Glad to see you're still in this thread Bob.

I think you've written up the reasons for your position very well. I hope everyone reading appreciates the time and effort. I particularly appreciate it because it shows me that you have been acting in good faith - You haven't been dodging the question. You haven't been evasive in your replies. And you're not trying to hide anything behind vague or irrelevant "lawyer-proof" statements. Even though we disagree on the topic at hand, I respect you all the more for your approach.

Nobody here has tried a direct comparison between using a comp and using an equivalent dead weight on an NR 9mm PCC. It's not particularly difficult, and it's "interesting" to consider why manufacturers haven't done this and made their results public: "Hey customers, look how well our comp works!"

Shooting flatter with a comp vs. no comp simply doesn't answer the question - If you think it does, then we're simply never going to agree. By the laws of physics, gas pressures at the muzzle for an 18" barrel is much, much lower than for a 10" barrel - If you think they aren't, then we're never going to agree.

I can't really add anything at this point, except to again remind everyone that many other forums have lots of information on this topic if they care to look it up themselves. As for this thread, readers can decide if what they've seen here amounts to evidence of anything at all.
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For heavens sake. Of course the pressures are lower with the longer barrel. The question I'd ask is are
they enough, and don't concern yourself by what I think, their are folks here that aren't quoting what they read, they are experiencing the effect of the comp. The pressure figures you reference aren't absolutes.

Your silly test, exhibited by you asking what affect a 3oz comp might have on muzzle rise when you are dealing with a rifle that weighs in at 128oz/8lbs., really!

Lastly over my chrono:
10" FX9 5gr CFE high VEL 1299
18.5" RAVEN CFE high VEL 1298
Shot the same day temp 15C

Hodgdon Powder tables suggest chamber pressure to be 33,000PSI

I am sure you have read where velocity increases X with every added inch of barrel but......it appears not always. Forget your dead weight test, your quoted pressure levels developed mathematically. Do some real world testing yourself then come and tell us of your results. Buying a $125Cdn comp might be a source of enlightenment. Davinci/TK are calling.

BTW if anyone does tie a 3oz weight to their rifle and finds it has no affect on barrel rise would you believe him? One of my watches I wear weighs exactly 3oz. and I do have a naked 18.5" FX9 UPPER. I'll see if I can do a video for you. You might just have to take my word for it.

Take Care

Bob
ps I never left it, just put you on my ignore list.
 
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Well, then I'm glad you took me off your ignore list.

Thanks for clarifying, I'm glad we agree that the pressure at the muzzle is going to be lower in the longer barrel. From your post, #53 in this thread
Canuck44 said:
...If gas pressure has some affect on the velocity of the bullet , and I think it does, then it would appear there is little significant difference in the driving factor ie pressure given the velocities are for all practical purposes the same. ...
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I take that to mean you think the pressure difference at the muzzle is not enough to make a significant difference in the comp function, am I right? The numbers we have to work with say that the muzzle pressure for the shorter barrel should be somewhere in the ballpark of double that of the longer barrel. I can't call that insignificant, however you look at it.

(BTW, I think it should be noted that we've been ignoring the "quantity of gas" part of the problem. But for simplicity's sake I think we can get away with it as long as we're keeping that constant: By sticking with "typical 9mm factory ammunition").

Regardless, I think your question is right on the money: How much muzzle pressure is enough to drive a comp on a 9mm PCC with any meaningful effect?

Ever since page one in this thread, we've been talking about it. And nobody has really gotten close to answering it as far as I can tell. It seems obvious that at some point, a 9mm barrel is too long and the muzzle pressure drops too much for the comp to work as a comp in any meaningful way. How about a 72" barrel? Of course, the pressure has to be way too low, the comp can't function as a comp. 36" barrel? Gotta be too low. 18" barrel? Well now I'm not sure, and I'd need to see some evidence before forming an opinion. 10"? It seems like the comp should work as a comp, but even so, we shouldn't just assume that it does.

The way I see it (feel free to correct me if I'm wrong), the difference in our positions is that you started with the assumption that the comp must still be working as a comp even with an NR 9mm barrel. So you tried your NR 9mm with a comp and without one. You found a difference in muzzle rise. And you say the difference can only be due to effect of the comp working as a comp. This would be true only if you also assume the mass of the comp has no significant effect. Those are two assumptions that I'm not willing to make.

Adding 3oz to the end of a three foot lever does have an effect on dampening any rotation of the lever. It's relatively small, sure, but so is the muzzle rise due to recoil on a typical NR 9mm PCC.

The only objective way I can think of to rule out the effect of dead weight is to compare muzzle rise with a comp and with an equivalent dead weight.
 
There is no normal factory load.

We do have Hogdon Powder chamber pressures to go by.

We are told max. 9MM velocities occur between 10" and 11". I suggest for all practical purposes there is no significant fall off or gain in velocities between 10" and 18" barrels. Much depends on the powder burn rate of the powder used. The latter is true when it comes to pressure levels. You can't assume pressure fall off is a constant between powders nor can you assume pressure levels are a constant.

You hang on to your dead weight premise. Have you considered the weight of the shooters arms, his/her strength to hold the firearm level? Your concern about the 3oz weight of a comp is entirely misplaced. Move on.

Take Care

Bob
 
Heavy rifles shoot flatter and softer. The comp design has a lot to do with gas velocity. So a properly designed comp that is efficient for the gas levels present is paramount. The gas action will help reduce muzzle climb.

Combine both factors and you have a combination effect that results in positive gains.

I think you are both right.

From my video experience, titegroup works my comp the best on a 19.5in barrel. Kinda weird since it's relatively quick. And a 19.5in barrel with a heavy comp was the flattest shooting configuration ive tried so far. Just a bit long for IPSC...
 
Canuck44 said:
There is no normal factory load.

We do have Hogdon Powder chamber pressures to go by.

We are told max. 9MM velocities occur between 10" and 11". I suggest for all practical purposes there is no significant fall off or gain in velocities between 10" and 18" barrels. Much depends on the powder burn rate of the powder used. The latter is true when it comes to pressure levels. You can't assume pressure fall off is a constant between powders nor can you assume pressure levels are a constant.

You hang on to your dead weight premise. Have you considered the weight of the shooters arms, his/her strength to hold the firearm level? Your concern about the 3oz weight of a comp is entirely misplaced. Move on.

Take Care

Bob
Click to expand...

(I was trying to keep things simple with my ammo comment. Doesn't seem to matter for this discussion anyway)

You're absolutely right that outside of a lab, we have to rely on theory to get numbers for gas pressure at the muzzle. Quickload will tell you your approximate muzzle pressure for any given powder and bullet combination. It's very well established and widely accepted, so I don't know why you'd have a problem with it. If you just don't like the numbers that you see, that's fine: You can easily do a real-world test for yourself to see if the gas pressure at the muzzle of an NR 9mm PCC is enough to make a comp work: By comparing muzzle rise with a comp, and with an equivalent dead weight.

Just kidding, I know you are satisfied with your assumptions and you aren't interested in that kind of test. That's fine. I don't expect to convince you at this point, I'm just fleshing out our differences.

I absolutely do consider the weight of the shooter's arm, their strength, etc.. Don't you? What do you think is going on when a skilled shooter is able to virtually eliminate muzzle rise just by using good technique? They use muscle and bone to anchor the forend to the mass of their arm, and to the mass of their shoulder and torso as much as they can, as solidly as possible. Notice how they tend to reach as far forward as possible, to get the most leverage?

I was going to move on from dead weight, leverage and inertia, but you keep making it interesting. Thanks!
 
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FarmerDanz said:
Heavy rifles shoot flatter and softer. The comp design has a lot to do with gas velocity. So a properly designed comp that is efficient for the gas levels present is paramount. The gas action will help reduce muzzle climb.

Combine both factors and you have a combination effect that results in positive gains.

I think you are both right.

From my video experience, titegroup works my comp the best on a 19.5in barrel. Kinda weird since it's relatively quick. And a 19.5in barrel with a heavy comp was the flattest shooting configuration ive tried so far. Just a bit long for IPSC...
Click to expand...
Thanks Dan, I for sure welcome more input in this thread. I've been wondering if Bob and I should switch to PM. I wonder what that would be like...

I agree that comp design matters. But only when there is enough energy from expanding gas at the muzzle for the comp to actually work as a comp (for simplicity sake, I'm going to start calling this "gas energy" in this thread). If there isn't enough "gas energy", then the design of the comp doesn't matter one bit. The comp still works to dampen muzzle rise, but only because it adds dead weight. As you (and many others) have found, the heaviest comp will tend to work best. However, this doesn't tell us one way or the other if there is enough gas energy to make the comp work as a comp (you could still be seeing the results of both factors at work).

AFAIK, outside of a lab the only way to test whether or not there is enough gas energy at the muzzle of an NR 9mm PCC to make the comp work as a comp is to compare muzzle rise with a comp and with an equivalent passive weight. If the comp works better than an equivalent muzzle weight, then there is enough gas energy, and obviously the comp is working as a comp. If it doesn't work better, then there not enough gas energy, and the comp is effectively a dead weight. Apparently nobody here has done this test (or if they have, they don't want to talk about it). I haven't either, because: It's been done plenty of times elsewhere, and by enough different people with enough different long barrel 9mm PCC setups to convince me that there is not enough evidence to support the theory that there is enough energy from expanding gas at the muzzle to make a comp work as a comp.

Still, I can't say that it definitely doesn't, because "Not enough evidence that it does" is not the same thing as "It doesn't". It's problematic to prove a negative.

It's interesting to hear that a fairly fast powder works best for your setup (similar to what madcow found). What it also shows is that comps on PCCs simply don't work the same way as they do on pistols. Maybe there's something different about the PCC that we can't account for. But if you're not tied to the assumption that there must be enough gas energy and so the comp must be working as a comp, there's a pretty simple alternative: There's not enough gas at the muzzle to get the comp to work as a comp, so all you're really seeing are differences in the overall recoil impulse due to different bullet/powder combinations.
 
Alright. I did some testing.
Platform: 16.1" barreled FX9 with hydraulic buffer system.
Ammunition: CCI Blazer Brass 124gr
Muzzle devices:
1) thread protector
2) bird cage
3) Tandemkross game changer pro
4) Devinci Diesel 9mm Slant
5) 3oz of stainless steel zap strapped to the barrel at the muzzle with thread protector on

Results:
The thread protector alone performed the worst followed by the birdcage, the 3oz of ss lowered the muzzle rise all be it not a ton. The tandemkross was noticablely better. The heavier Davinci was a huge difference.

Synopsis:
Both weight and gas forces contribute to the decrease of muzzle rise in the 16.1" FX9. The weight alone was not enough to counter the muzzle rise.

Conclusion:
If you want to maximize the reduction of muzzle rise, get a heavy top ported comp.

Cheers,
ADC
 
TL/DR:

Lots of people say that "shoots flatter with a comp than without a comp" is all the evidence you need. That is only true if you assume there is zero passive effect from the added weight of the comp. There's an easy way to test it, it's been done plenty of times elsewhere, and I think the consensus is that comps don't work better than dead weight on NR 9mm PCCs.

However, there are good reasons to have a comp on an NR 9mm PCC (just not this one).
 
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