.45 ACP +P, .45 Super and .45-08 Heavy Boolit Load Data?

[robertbank]

Originally Posted by DRNurse1
"Interesting thesis but a bit misdirected. The spring absorbs the rearward energy created when the boolit is moving down the barrel. More mass to move, at the same velocity yields more energy to absorb. The recoil spring for the 185 gr SWC I use is about 12# but the one for the 230gr RN is 22#. You are correct that the force has to go somewhere when the slide returns to battery, so there is more forward force in the heavier spring. The trade off being 'felt recoil' (lighter spring yields more felt recoil) and the battering your gun receives by not absorbing the rearward force in the spring.

Either way, the energy has to go somewhere. Those darned physics guys, any way."

The highlighted statement cannoy be true. The barrel does not unlock until the bullet has left the barrel and any spring compression would be insignificant until after the bullet has gone.

Take Care

Bob

[Bearbait in NM]

Bob,

Kinda a yes and no to that. There is some amount of spring load that first tenth of an inch or so. But clearly not the bulk of the poundage that the spring exercises when fully compressed at full rearward position. If you shoot Rowlands or Supers with conventional Wolff springs of whatever weight, you will find that the the Wolff springs take a shorter over all length set pretty quickly. I personally feel that in the 1911, the flat firing pin stop and correct main (hammer) spring is more important than this little bit of "locking" spring load, but I did switch over to ISMI chrome silicon springs, as they do not get this shorter OAL set as quickly as the Wolff's. And in my Rowlands, a 20lb ISMI works great.

The 1911, imho is absolutely at the edge of design with Rowlands, Supers and probably 10mm, although I have not owned a 10. The idea that the energy has to go someplace is correct. With the flat fps mod, more stress on the hammer, hammer pin, mainspring and housing (and parts). With ultra heavy recoil (action) springs, definitely a lot more stress on the barrel lugs, cross pin etc. The other consideration that is often neglected on the recoil spring is the possibilty of bullet setback when feeding. Been down this road, and have one blown out slide as my reward.

With over a half dozen Rowland fits since about 2000, and fiddling with the 45 Super for the last 3 or 4 years, my idea of a proper build is to address the fit of the barrel upper and lower lugs, run a flat firing pin stop with 25lb main (hammer) spring, a 20 lb ismi recoil spring and the barrel comp on the Rowland or the comp on a Super if pushing the Super into Rowland territory, which can be done safely. These days, I find myself carrying my 45 Super with 250 grainish lead or plated bullets doing right around 1075 fps. And my S&W 625PC does just fine with this range.

Craig

[longbow]

Finally an update! Nothing very earthshaking though.

I got hold of my friend who I haven't seen since about this time last year.

He has settled on a 255 gr. SWC after getting some feed ramp work done on the gun but is using new .45 ACP brass and just slightly heavy loads. he says he is getting just under 1000 FPS with the 255 gr. boolits and feeding is good.

He had some trouble with his .45-08 brass bulging when he seated boolits. He said it appeared that the cases had not been reamed to correct diameter. In any case he dropped the .45-08 idea and just settled on stout loads under heavy boolits.

And here I was looking forward to some load development! Oh well.

Anyway, thanks to all who posted and especially those who provided info and load data.

Longbow

[45r]

If his 45 wears out he might want to get a 10mm.
I like it over my 45.

[StrawHat]

Finally an update! Nothing very earthshaking though.

I got hold of my friend who I haven't seen since about this time last year.

He has settled on a 255 gr. SWC after getting some feed ramp work done on the gun but is using new .45 ACP brass and just slightly heavy loads. he says he is getting just under 1000 FPS with the 255 gr. boolits and feeding is good.

He had some trouble with his .45-08 brass bulging when he seated boolits. He said it appeared that the cases had not been reamed to correct diameter. In any case he dropped the .45-08 idea and just settled on stout loads under heavy boolits.

And here I was looking forward to some load development! Oh well.

Anyway, thanks to all who posted and especially those who provided info and load data.

Longbow

Thank you for the update. He should be well served with the heavier boolit in the ACP brass.

Kevin

[NavyVet1959]

Well, here's what my G21 looked like after the conversion. I call it a .45 SUPER +P+ since even though it's built to the .460 Rowland pressure level, I'm using normal length brass in it.

[DougGuy]

Heh 5 pages of posts, y'all have made this SO MUCH HARDER than it really is. USE A .45 WIN MAG AND TELL YER BUDDY TO GET OVER IT!



EDIT: Find these on Gunbroker Groo! vvvv

[Groo]

Groo here
Yaw but their not made now [ darn]

[longbow]

I have no argumnet about going .45 Win Mag. but my buddy wants to use what he always uses and that is his Dlask 1911 in .45 ACP. That's his choice.

Me, I would go at least .44 mag. in a revolver.

Different strokes.

Longbow

[robertbank]

Doug Guy Longbow is on the other side of the 49th. Gunbroker is for all intent and purpose not an option.

Longbow if your friend is really getting 1,000 fps using a 255 gr bullet then he is way over pressure for the 45acp case. The gun will take the pressure the case won't.

Take Care

Bob

[lar45]

The TZZ Isralie Military brass is rather strong. It's thicker so you'll have to reduce your load some, but it should take the pressure.

[huntersdog]

Great post! Ton of great information in this thread.

[huntersdog]

Well, here's what my G21 looked like after the conversion. I call it a .45 SUPER +P+ since even though it's built to the .460 Rowland pressure level, I'm using normal length brass in it.

The a pretty reliable setup there, with the lone wolf barrel and comp.

[NavyVet1959]

The a pretty reliable setup there, with the lone wolf barrel and comp.

I just need to find an appropriate holster so that it will not snag when I'm drawing it if I need it while hog hunting. That compensator snags on the standard kydex open bottom style holster.

[kingrj]

Acctualy 300 Savage is correct and that is the way my 45 Super is set up. The lug engagement was increased so that the pressure is lower when the pistol unlocks. I run an 18.5 pound spring. I shoot Buffalo Bore and Underwood 255 grain flat point 45 Super and get around 1080 FPS a very good hard hitting load from a 1911.

As a .45 Super fan I have read reams of post regarding the requirement of a super stiff recoil spring to allow an stock .45 acp to handle the increased power of the Super..Being an engineer I just had to find out for myself so I started with conservation of momentum and calculated final slide velocity at the recoil stop for my Smith and Wesson 4506 using a 200 grain bullet at 900 fps and then at my chronographed Super load of 1230 fps. The force on the slide/barrel unit prior to unlock with the acp load is 3821 Newtons of force..With the Super load it is 7153 Newtons! By comparison the 18# recoil spring puts only 17 Newtons of resisting force on the slide/barrel unit at firing!!! The TOTAL energy absorbed by the recoil spring at full slide travel is defined by the equation KE=1/2K(x squared) where K is the spring constant and "x" is the distance in meters it is compressed. With the 18# spring the total energy absorbed during slide recoil is only 1.2 Joules as compared to the energy of the slide at lock back of 18.7 Joules!!! As you can see it doesn't matter how big a recoil spring you install on your Super...it only has a minimal effect on the final energy the slide has when it hits the end stop. By comparison the standard acp load hits the stop with 9.5 Joules of kinetic energy...So lets "change" the spring from an 18# to a 28# recoil spring and run the simulation again for the super load. This absorbs a little more energy and the final slide energy is "only" 18.0 Joules!!! You would have to put a 100# spring on these guns to get a substantial reduction in battering of the gun on recoil..So...SLIDE/BARREL MASS is the critical factor in a successful Super convertion..NOT recoil spring. Some have recommended stronger main springs and square bottom firing pin stops to 1911 guns. This is a logical and good mod and if I was converting a 1911 I would do the same but super heavy recoil springs only batter the gun on closing and force one to use high power magazine springs so the closing slide does not overstrip the cartridge. NOTHING you can do to a normal .45 acp will decrease the effect of the much higher momentum impulse of the .45 super and its resulting increased wear on the gun other than adding lots of slide/barrel mass. The only way you can make a gun "live" with the much higher pressure .45 Rolland is by fitting a heavy comp on the barrel. If anyone is interested I have made a spread sheet calculator for calculating slide velocities for any combo of bullet weights, slide weights, barrel weights, powder charges, spring rates..I have it on dropbox and can share if you want to play with it.

[akraven]

If anyone is interested I have made a spread sheet calculator for calculating slide velocities for any combo of bullet weights, slide weights, barrel weights, powder charges, spring rates..I have it on dropbox and can share if you want to play with it.

Kingrj thank you for applying your engineering knowledge so we have a true idea whats going on with facts rather than just guesstimates. I would really like to look at your spreadsheet calculator. Have to you looked at/calculated the effects of a comp? It doesn't change barrel/slide mass but changes the effect of slide speed. Thanks again for your work!!

[Artful]

Well as long as we are stirring an old cold pot. 20+ years or is it 30 now back in the late 80's, I was reading Dean Grennell's 45 Super stuff, at first I didn't have 451 brass or trimmer accessories so I took a page from Dean's early experiments and loaded my heavy loads in WW2 steel cases and changed out my standard spring to a Detonic's double spring with stronger firing pin spring.

I was loading hard cast RCBS 255 SWC over BlueDot loads to spitting distance of 1,000 fps.
And the pistol as set up would still function with HardBall ammo. Eventually I got set up to cut down 308 or 451 cases. But by then I had moved to overloading 45 colt in Ruger Blackhawk, enough that the cylinder pin was moving forward.

If you friend wants to 45 superize his pistol at this point I think you should look at 460 rowland conversion parts, as I have not seen ACE customer 1911's offered in quite some time.

[kingrj]

Kingrj thank you for applying your engineering knowledge so we have a true idea whats going on with facts rather than just guesstimates. I would really like to look at your spreadsheet calculator. Have to you looked at/calculated the effects of a comp? It doesn't change barrel/slide mass but changes the effect of slide speed. Thanks again for your work!!

This link https://www.dropbox.com/s/7st1nsoqn0...ator.xlsx?dl=0 Will get you into my drop box and allow you to download this file. The numbers listed for barrel weights and slide weights as well as the distances for unlock and total slide travel are specific for a full sized 4506 but can be changed for any browning type action auto... I have NOT included calculations for the effect of a comp because I would have to teach myself fluid dynamics (i am an electrical engineer LOL!) in order to be able to calculate the reverse thrust provided by a comp. AND the actual design of the comp, nozzle configurations, gas pressures etc are so varied that it would require a great amount of work to add this into the program. However..I am retired and like a good challenge so I may look into that! The basic theory for my calculator is simply the totally elastic conservation of momentum transferred from the bullet to the slide/barrel unit. The slide/barrel unit travel together for the unlock distance then the slide continues at that same velocity (assuming that the bullet has already left the barrel prior to unlock) I then calculate the kinetic energy of the slide then subtract the total kinetic energy absorbed by the recoil spring during the slide travel which results in an adjusted final kinetic energy and velocity for the slide when it hits the stop. You will notice some additional calculations below the actual spread sheet where I calculate the bullet time in the barrel, acceleration rate of the bullet and make sure that the bullet has left the barrel prior to unlock! I suppose it is possible to use a heavy enough bullet to unlock the barrel prior to leaving the barrel (a very bad thing indeed!) but I have not played around trying to determine it...

[akraven]

Thank you Kingrj for the spreadsheetcalculator. I will spend some time playing with that!

[kingrj]

It may appear from my two previous post that I am discouraging the "conversion" of the .45 acp to .45 Super. Nothing could be further from the truth and I am a Super fan! I deer hunt with my 4506 Super and I have had NO durability issues with the gun but then again I don't shoot it 5,000 times a year either. My point was that just changing the recoil spring is NOT going to reduce the recoil impulse of a Super to the normal ACP level...And some increase in gun wear is likely to be experienced if many rounds are fired through the gun...I however, suspect my Super will easily outlive me and I don't worry about it.