Bullet grain VS Recoil Spring

[TJW]

Can someone explain why 230 grain .45 acp bullet fired from a Commander size 1911 with standard 18 lbs recoil spring works fine, but has FTF issues with a 175 grain .45 acp bullet?

[Gringo Bandito]

Have you checked the extractor tension? Have you tried multiple mags?

[jericho89]

Can someone explain why 230 grain .45 acp bullet fired from a Commander size 1911 with standard 18 lbs recoil spring works fine, but has FTF issues with a 175 grain .45 acp bullet?

good question. I have seen this with a gold cup with compensator and a standard 16lb spring. Works like a charm with 230 but put a 200 in there and it would not cycle. To the point that even with an 8 lb spring it would not cycle.

[noylj]

Calculate the momentum (power factor). Mass goes down faster than velocity goes up and I'll bet the 185gn load has a lower PF than the 230gn load.
Momentum is what pushes the weight of the slide back and compresses the recoil spring and the main spring. All need to be in balance.
A 185gn standard load will run about 950fps, for a PF of about 176. A 230gn standard load will run about 850fps, for a PF of about 195. Quite a difference in momentum. Even if you load them to a target velocity of about 775fps, that would be a PF difference of 144 vs 178. So, if you are "sprung" for a PF of 175-200, that light 185gn has too little momentum for the slide weight and spring weights.

PS: all my Gold Cups cycle 200gn loads just fine with the standard recoil spring. If you can't get a 1911 to cycle with an 8lb spring (do they actually make 8 lb recoil springs), there is something wrong with the gun or the load is beyond light and approaching squib.

[CSACANNONEER]

It has to do with powder type and powder charge just as much as bullet weight.

[TJW]

Great answer noylj. Unfortunately I have to shoot indoors with frangible 175 grain .45 acp on occasion to qualify. This is the only ammo available in 45 acp. My .45 acp's all seem to have failures to feed with this frangible 175 grain rounds. But I have no problems with 230 grain ball ammo at outdoor ranges. This is like a physics question and was looking for a sensible explanation.

[hermosabeach]

recoil is a funny thing...

Many AR mags work fin with a semi auto gun but will not work fine in a machine gun. The bolt moves faster in a machine gun and the mag spring does not have enough power to move the next round all the way up so the bolt can stop, miss a round or induce a malfunction as it pushes a round forward when it is not in the complete upper position.


If a lighter / faster 185 is speeding up your slide, it could be a mag.

it could also be that the round is not pushing the slide all the way rearward...

What malfunction are you seeing? Type 1,2 etc. FTF is a bit vague?

What profile is the 175 grain bullet? Is it a feed ramp issue?

[Chief-7700]

Could it be the shape of the bullet?

[JustEd]

Less recoil causes the slide to cycle slower or possibly not even push the slide fully to the rear.

[CSACANNONEER]

I once had a problem feeding one certain type of 185gr cast bullet in one of my 1911s. I had 5000 rounds and it took me at least 3000 rounds to figure out that it wasn't the gun or the ammo. It was one Wilson Combat magazine that I occasionally used. I got rid of the magazine and didn't have another problem. So, don't just assume it's your recoil spring. There are many other possibilities.

[rsrocket1]

noylj hit it on the head. If you match the momentum of your 230g loads, you likely have greater success in cycling and feeding so long as you aren't getting things like a 3 point jam. A 3 point jam is caused by the geometry of the bullet, the magazine feed lips and the ramp of your barrel, any or all of those could be the cause.

Are you able to hand cycle these 175g loads without jamming?

Back to momentum. A 230g bullet under 5.0g Bullseye @850 fps gives a PF of 195.5. You would need that 175g bullet going 1117 fps in order to give you the same momentum. A slower powder like BE-86 or Power Pistol might be able to give you that speed without going over pressure.

[TJW]

Thank you rsrocket1, noylj, and JustEd, you guys have explained what I was trying to figure out. I know the problem is not the gun, recoil spring, or magazines, as all are brand-new, and problem is with multiple 1911 platforms. The problem only occurs with this Wichester frangible 175 grain ammo (Winchester only makes 45 acp frangible in 175 +P grain). Unfortunately I have to use it indoors for qualification. I have heard that lighter bullet grains require lighter pound recoil springs to cycle the slide properly, I just wasn't sure of the reason why. There's math (science) behind it, which effects the cycling operation. The momentum and cycling time explains it. I just don't want to change out recoil springs when I qualify indoors

[CSACANNONEER]

Thank you rsrocket1, noylj, and JustEd, you guys have explained what I was trying to figure out. I know the problem is not the gun, recoil spring, or magazines, as all are brand-new, and problem is with multiple 1911 platforms. The problem only occurs with this frangible 175 grain ammo (230 grain not available). Unfortunately I have to use it indoors for qualification. I have heard that lighter bullet grains require lighter pound recoil springs to cycle the slide properly, I just wasn't sure of the reason why. There's math (science) behind it, which effects the cycling operation. The momentum and cycling time explains it. I just don't want to change out recoil springs when I qualify indoors

I'd be far more concerned about a "brand new" piece of equipment than one that has prove itself. The magazine I spoke of earlier was a new and highly respected brand but, it still had issues with one certain bullet profile at one seating depth. I did not play with my COAL to try to get that one magazine to work with the bullet profile though. Your feed rap or feed lips may not like the profile you're using.

[TJW]

From Looking at the specs of Winchester's 230 grain .45 acp JHP ammo vs Winchester's 175 +P grain frangible, it appears that the 175 grain frangible although a faster round, it produces 13% less energy. Would it make sense to reduce the recoil spring lbs by 13% when using the frangible? That would mean changing from 18 lbs recoil spring to 15.5 lbs recoil spring.

[noylj]

I'm surprised. Energy is v^2 while momentum is just v, so a light bullet usually gains enough velocity to have a higher energy, but lower momentum. If it can't even gain enough energy to overshadow the heavier bullet, it doesn't sound like a winner.