Test Loads for 9mm... Pressure Signs

[Sinjin]

Sinjin,

... These are commercial cast bullets. ...

WCK, what hardness are the bullets you are buying?

[Sinjin]

... But sizing at .400 I could seat them normally ...

happy7,

Your experience sounds very similar to mine. My only worry about sizing down is leading. I'm already getting some now. I was actually consideing the possibility of trying a bigger boolit to solve that problem. If I can get the .356 to shoot without leading, I may consider sizing to .355 to see what happens.

[happy7]

I also had some leading initially when I used a fast powder. I ascribed this to the shallowness of the rifling in the XDm barrel. When I went to the slowest powder listed for a 40 and this dissapeared and did not return when I started sizing to 400. Just my experience. Again may not apply to the 9mm.

[Windy City Kid]

WCK, what hardness are the bullets you are buying?

Sinjin,

I never checked the hardness on those commercial cast 9mm 147gr. FP BB bullets. I would think they are about 16 or 18 bhn.

I got them from S&S Casting.

Here is a link to thier web site.

http://shop.snscasting.com/product.s...3&categoryId=1

[Sinjin]

I also had some leading initially when I used a fast powder. I ascribed this to the shallowness of the rifling in the XDm barrel. When I went to the slowest powder listed for a 40 and this dissapeared and did not return when I started sizing to 400. Just my experience. Again may not apply to the 9mm.

This gives me hope! I don't have a ready source of WSF or Blue Dot, but I do have some HS-6. Is that considered a relatively slow powder for pistol? 3N37 looks similar to WSF. Anyone here used 3N37 with cast boolits for 9mm?

[mike in co]

sorry to dissagree, but recoil is based on bullet weight( bullet weight squared x velocity.).....the lighter, the quicker is the second shot. so ideally go with a 115 and high velocity........as most cast are not light, do a 120/125 at 1100/1050. for nra action i do 124's at 1050, for club ipsc i do 135 jacket/135 cast at 1000 fps( casue i have a 9x21 that i shoot at 1200 with 135's).......i shoot alot more 124's than the 135's.


heavy means a slower second shot........and its accuracy AND speed that counts.

[Lee]

Shouldn't that be something like (bullet weight x velocity squared) ??
That's the gist of the atom bomb (e=mc2) and in the Lee handbook muzzle energy is velocity(fps) x velocity(fps) x bullet weight(grains) divided by 450436 = muzzle energy in foot lbs. I guess I would think that the muzzle energy going THAT way would be counteracted by the opposing recoil energy generated by the (weapon/hand/body weight x rearward velocity x rearward velocity) going the OPPOSITE way

Or am I missing a portion of the math/logic on this one??................

[mike in co]

Shouldn't that be something like (bullet weight x velocity squared) ??
That's the gist of the atom bomb (e=mc2) and in the Lee handbook muzzle energy is velocity(fps) x velocity(fps) x bullet weight(grains) divided by 450436 = muzzle energy in foot lbs. I guess I would think that the muzzle energy going THAT way would be counteracted by the opposing recoil energy generated by the (weapon/hand/body weight x rearward velocity x rearward velocity) going the OPPOSITE way

Or am I missing a portion of the math/logic on this one??................

i'll wait for someoen else on the formulae.

but i ran the numbers on a 135 pf on a 2lb gun for 115,125 and 147 bullet wieghts.....in a recoil tool.....( in quick load)

guess what......no significant difference......


ok and the funny part, i heard it in a gun rag long ago...and i shoot 135/124 and soon to be a 140hp.....

just goes to show ya...
i know in ealry ipsc...they use to smoke 115's.......oh well

mike in co

[Linstrum]

Lee has it, the basic physics formula that gives kinetic energy, which recoil is related to, is 1/2 Mass times Velocity squared or
Ek = 1/2MV^2.
The reason why the 1/2 doesn't appear in the bullet energy formula is because it has already been factored out mathematically but it is represented as part of the calculations that arrived at the "fudge factor" number 450436.

Like he said, Einstein's famous equation is related, ultimate energy of ALL matter is

E = MC^2, so if you remember that then it will help you to remember the other by adding 1/2 to the front of it. The "C" in Einstein's is also velocity, the velocity of light.


rl631

[HORNET]

Recoil is determined by momentum (mass X velocity). The principle is conservation of momentum: equal & opposite reactions per Isaac Newton. Note that, for direct comparison purposes, the conversion factors from weight to mass cancel out making the math easier.
Weight1 x V1 vs. Weight2 x V2...the units are a mess but they can be cancelled as well. Too early for this, need coffee.....

[Sinjin]

I seem to recall reading, somewhere, that the blast of propellant gases exiting the barrel, after the bullet, was a large component in 'felt' recoil (EDIT: which is to say that all of the ejecta exiting the muzzle contributes to the recoil, not just the bullet). If that is the case, then isn' it possible that two loads, using different powders and bullets, could have the same muzzle energy but different amounts of recoil?

EDIT 2: which leads one to hypothesize that recoil should be related to the total energy released by the burning powder, sans thermal, regardless of the weight or velocity of the bullet.

EDIT 3: leave it to good old Wikipedia: http://en.wikipedia.org/wiki/Recoil, according to which the key quantity relating to recoil is momentum, not energy.

[mike in co]

the tool in quickload actually does several calculations...bullet, gas, gun weight, etc.....
like i said in our cases there was no significant differences

[Linstrum]

Thanks Hornet, yeah, need coffee, too. It has been a long time since I had to do any calculations with forces acting on two different masses. Then there is a bit of the energy lost to bullet friction also. It is not simple at all.

rl633

[fecmech]

I think I read over on the Brian Enos forum that when using the .45 in IPSIC or IDPA he used a load of 3.5 Clays and a 230 gr bullet to make major that way as opposed to the 200 gr swc at the higher velocity. He claimed less shot to shot disturbance and quicker times than the "snappier" 200 gr load.

[Siggy226]

Sinjin, I have the exact same mold and I'm using W231, which is supposedly the same as HP38. I too am noticing flat primers starting at around 3.8-3.9. And it becomes flat at 4.0. But my slide on my P226 doesn't lock most of the time at 3.8-3.9. I think it'll lock most of the time at 4.0. Crimp is just enough to get rid of bell and a little more.

I found that the barrel doesn't like anything higher than 1.085-90 OAL. So I seat it behind the rifling at around 1.070-75". There's really not much room to play with but these bullets appear to be very accurate to me. But I don't know how bad these flat primers can be. American Eagles get flat primers when I fire them and I just notice flatting at around 3.9 with these cast bullets, plus the slide doesn't lock back all the time. Wouldn't hot loads be able to lock slide all the time!?

As for lead fouling, I'm getting some, but I don't know what is acceptable. I doubled lubed some bullets with Xlox and will try those out next. I'm noticing that the almost the first half of the barrel (from breach end) don't have much fouling and it begins after that. So maybe I need more lube. I can hardly see the lube with 1 coat unless I compare it with non-lubed bullet. NOting to compare with, but i think it's smokey enough already.

[Ricochet]

Recoil momentum of the gun = momentum of the bullet + momentum of the ejecta (powder gases and any unburned powder.) The unit of momentum in the English system is pound-seconds. (NOT "foot pound seconds," as Elmer Keith and others have used in the shooting literature.) A pound second of momentum is the result of pushing steadily with 1 pound of thrust for 1 second. Momentum of the ejecta is tricky to ascertain. Usually we use published estimates of average velocity of the powder gas and the mass of the powder charge, as it's generally a lot less than the momentum of the bullet and errors are fairly small.

Unfortunately, some clueless bozo many years ago decided it would be appropriate to express recoil in terms of foot pounds of energy, which differs with the weight of the gun. You have to use the momentum equation and the weight of the gun to determine the free recoil velocity of the gun, then use the 1/2mv2 formula to come up with the free recoil energy. That's meaningless anyway, because you're not normally letting a gun recoil freely, you're holding it and moving with it.

[StarMetal]

Sinjin, I have the exact same mold and I'm using W231, which is supposedly the same as HP38. I too am noticing flat primers starting at around 3.8-3.9. And it becomes flat at 4.0. But my slide on my P226 doesn't lock most of the time at 3.8-3.9. I think it'll lock most of the time at 4.0. Crimp is just enough to get rid of bell and a little more.

I found that the barrel doesn't like anything higher than 1.085-90 OAL. So I seat it behind the rifling at around 1.070-75". There's really not much room to play with but these bullets appear to be very accurate to me. But I don't know how bad these flat primers can be. American Eagles get flat primers when I fire them and I just notice flatting at around 3.9 with these cast bullets, plus the slide doesn't lock back all the time. Wouldn't hot loads be able to lock slide all the time!?

As for lead fouling, I'm getting some, but I don't know what is acceptable. I doubled lubed some bullets with Xlox and will try those out next. I'm noticing that the almost the first half of the barrel (from breach end) don't have much fouling and it begins after that. So maybe I need more lube. I can hardly see the lube with 1 coat unless I compare it with non-lubed bullet. NOting to compare with, but i think it's smokey enough already.

As for the leading....your accuracy will tell you when the leading is too much.

Primer flatness isn't always a perfect method to determine pressure. Many primers are soft and get flat easily. If you think the 231 is too hot to function the Sig then try a different powder.

Joe

[Siggy226]

As for the leading....your accuracy will tell you when the leading is too much.

Primer flatness isn't always a perfect method to determine pressure. Many primers are soft and get flat easily. If you think the 231 is too hot to function the Sig then try a different powder.

Joe

Hmmm... I'm still a little confused.

My slide doesn't lock back reliably, does that mean I'm not in the 'hot' zone yet? Is this an acceptable method to tell that my loads are not hot?

Factory ammo cycles my P226 reliably.

TIA!

[Ricochet]

Most semiauto pistols are recoil operated, so are dependent on the recoil momentum discussed above. If the pistol operates normally, the momentum of the load is sufficient. If it doesn't, the total momentum may be low, or the resistance to the recoil thrust may be low (i.e., held with a loose grip.) Doesn't tell you anything directly about pressure.

[Siggy226]

Ricochet: thanks for the input. I read your momentum topic above and I got a little lost. LOL!

FWIW, my Sig P226 only seen 700rds (of that, maybe 50rds were factory). Not sure what is going on except that it cycles perfectly fine with factory ammo.