'Oversize' Cartridges & Tight Chamber on 45ACP

[MMH]

I have a 1911 with a tight chamber. When I load cast bullets the outer diameter of a lot of the cartridges is at 0.474" and will not chamber easily.

The 0.474" is measured where the the base of the bullet would be - about 1/4" below the case mouth. SAAMI lists maximum cartridge diameter of 0.473" at the mouth and 0.476" at the base (actually just above the extractor groove). So my cartridges may be a little oversize, but close. The bullets are 0.452" in diameter and I measured the case thickness which is between 0.010' to 0.011". At 0.011" the cartridge OD would be 0.474".

The minimum chamber dimensions as listed by SAAMI is 0.474" at the mouth and 0.4796" at the base. So it appears that my chamber is at the minimum SAAMI dimensions.

I am debating about putting lapping compound on a swab and running it in a drill to open the chamber of my 1911 up a little. Is this a bad idea? SAAMI only lists minimum chamber dimensions, not maximums. Does anyone know what typical dimensions are for guns set up for reliable feeding?

 

[jk80]

Use your barrel removed from the gun as a chamber gauge and adjust your taper crimp down another thousandth or two until it is correct.

 

[SSL]

Try seating and crimping in separate steps and use a Lee Factory Crimp die. The Lee die crimps and sizes the case/bullet combo to "factory" dimensions. That includes "case bulge" caused by the bullet body.

 

[MMH]

Try seating and crimping in separate steps and use a Lee Factory Crimp die. The Lee die crimps and sizes the case/bullet combo to "factory" dimensions. That includes "case bulge" caused by the bullet body.

I will try this. I never used a crimp die before. Thanks!

 

[DirtySteve]

I will try this. I never used a crimp die before. Thanks!

The Lee Factory Crimp die is the best thing ever in pistol reloading..

 

[SSL]

I will try this. I never used a crimp die before. Thanks!

Just back your existing seating/crimp die out and adjust the seating stem to seat only. Adjust the Lee die for the amount of final crimp you want. That also eliminates the shaving of the lead bullets when the seating/crimp die tries to close the case mouth as the bullet is still being seated into the case. The Lee die crimps and gives a "final sizing" to the completed cartridge. It may not sound like much, but .45 ACP bullet diameter is usually considered to be .451". Nothing wrong with you using .452", but it might be a little tighter fit in your chamber. The Lee will actually swage the bullet slightly and may very well cure your problem.

 

[jcm800]

You can taper crimp a 45 acp with a 06 type FL die if you already have one.
I used a 280.... 308 type may work as well. Obviously, take out decapping rod first.

 

[MMH]

...but .45 ACP bullet diameter is usually considered to be .451". Nothing wrong with you using .452", but it might be a little tighter fit in your chamber...

I was under the impression that FMJ bullets were sized to 0.451" but cast were sized to 0.452". I may be wrong, but that is what I thought.

 

[SSL]

I was under the impression that FMJ bullets were sized to 0.451" but cast were sized to 0.452". I may be wrong, but that is what I thought.

That's the general case to seal the bore and engage the rifling better, but that extra .001" might make the difference in chambering in your gun if it is tight. No harm, the Lee die should iron it out without problems. I use the Lee on all my handgun cartridges for crimping except for one. One of my .44s has an oversized bore and I use .4335" cast bullets in it. I have to use a spare standard seating die to crimp cartridges for it. Otherwise the Lee swages the bullet down too far in the process of crimping and "after sizing" and the gun leads.
My main point is try everything else before permanently altering your chamber.

 

[6bra1k]

Use your barrel removed from the gun as a chamber gauge and adjust your taper crimp down another thousandth or two until it is correct.

no

 

[6bra1k]

he has a problem.\lead is typically .001 bigger than a jqcketed..and his chamber is too small for a cast load.
more crimp will just bulge////a lee fcd will make the lead bullet too small in dia but will allow it to chamber most likely/
the answer is if you want to shoot cast you need to get the chamber cut a little larger

 

[Jdne5b]

It (lee factory crimp die) will also swage the lead bullet undersize and contribute to leading and possibly accuracy issues. The FCD is a crutch for proper sizing, seating and crimp and usually hides issues instead of solving them.

 

[jk80]

he has a problem.\lead is typically .001 bigger than a jqcketed..and his chamber is too small for a cast load.
more crimp will just bulge////a lee fcd will make the lead bullet too small in dia but will allow it to chamber most likely/
the answer is if you what to shoot cast you need to get the chamber cut a little larger

I've used this method for years loading on a dillon 550 using dillon dies with a taper crimp and have never had a problem with case bulging or leading. Guess if you're careless enough it can happen.

 

[6bra1k]

I've used this method for years loading on a dillon 550 using dillon dies with a taper crimp and have never had a problem with case bulging or leading. Guess if you're careless enough it can happen.

you do not have his gun with his chamber...it is bullet dia loaded case dia look at his post

 

[Walt Schmidlin]

Have you access to R-P 45ACP brass? The cases are typically thinner. Worth a try if all else fails before changing the chamber dimensions.

 

[dellet]

I would probably measure brass fired in that chamber, and see if a bullet might just slide in with thumb pressure.

Depending on bullet profile, if it has a smooth transition from nose to bearing surface, seat one upside down and see if the flat base is distorting the case in some way. Could always take the corner off the base of a bullet, but that may still seat crooked.

It does not take much off center to cause the described problem

Might also run the cast bullets through a .452 sizer, no guarantee that they are round either.

Lots of things to check before altering the chamber.

 

[jk80]

you do not have his gun with his chamber...it is bullet dia loaded case dia look at his post

Yes, and it can apply to any chamber. We're talking cast bullets in a pistol round not a jacketed bullet in a match chamber. If factory rounds fit its a AMMO problem. I'll stand by my answer.

 

[spudgun]

My Sig 1911 Tac op, .45 ACP had this issue also.

I was using cast lead and some coated bullets. Even though they would do the plunk test in the case gauge I noticed a slight bulge in the case where the cast bullet was seated.

What I ended up doing was taking my case sizing die and removed the de caping pin.

I ran all 500 rounds back through my sizing die.

Now only about 1-2% will not go into battery and it just takes a nudge with my thumb and they seat in the chamber.

It worked for me...

 

[6bra1k]

My Sig 1911 Tac op, .45 ACP had this issue also.

I was using cast lead and some coated bullets. Even though they would do the plunk test in the case gauge I noticed a slight bulge in the case where the cast bullet was seated.

What I ended up doing was taking my case sizing die and removed the de caping pin.

I ran all 500 rounds back through my sizing die.

Now only about 1-2% will not go into battery and it just takes a nudge with my thumb and they seat in the chamber.

It worked for me...

and you undersized the bullets by resizing.
there is a reason cast bullets are bigger and even the saami spec shows it

 

[6bra1k]

Yes, and it can apply to any chamber. We're talking cast bullets in a pistol round not a jacketed bullet in a match chamber. If factory rounds fit its a AMMO problem. I'll stand by my answer.

cast bullets in 45acp are typically .001 bigger than a jacketed bullet. it makes a bigger round ON PURPOSE. same answer look at the ammo spec, cast bullet is .001 bigger. people that do cast bullets do this all the time and a cast round will be bigger. sizing them smaller ruins the cast bullet