chamber question

[SSL]

Just a thought...are you crimping the bullets? If so, it sounds like some of your cases may be a bit long and causing the necks to be expanded by the force of the crimp process. .223 really doesn't need a crimp if the neck tension is right, but If you want to crimp it is essential that the cases are all trimmed to the same length.

 

[K22]

I said out of 50 only about10 will not chamber, the neck will not go in the case gauge. The rest of them go in the case gauge perfectly and do chamber perfectly. The bullets are Hornady 55 gr soft points, could some of them be out of spec and be stretching the case neck too big ? I measured the bullets and they are .224 and the case neck with bullet seated is .254 to .256

.254 to .256 is .001 to .003 over the maximum of .253. This can create a dangerous high pressure condition.

Not trying to get preachy but get a copy of the Lyman Reloading Manual and read it. It will give you a better understanding of critical dimensions and processes in reloading.

I stand by my suggestion - don't use cases fired from unknown sources - start with new cases and avoid a bunch of problems.

 

[Uncle Ed]

The last batch of 500 once fired 5.56 Lake City cases I bought were sized first with a small base die. I also paused for 4 seconds at the top of the ram stroke to reduce brass spring back. After sizing each case is checked with a JP Enterprise case gauge that is closer to SAAMI minimum diameter. These cases are fired in three different 5.56/223 rifles without any problems.

There is nothing wrong with using once fired or range pickup brass as long as they are sized and gauged properly. With range pickup brass if the case still has a crimped primer you know its once fired.

Save $$ By Using Lake City 5.56x45mm Once-Fired GI Brass​

http://bulletin.accurateshooter.com/2019/10/save-by-using-lake-city-5-56x45mm-once-fired-gi-brass/

Accuracy Potential of Mil-Surp 5.56×45 Brass​

So, how accurate can previously-fired GI surplus brass be in a good National Match AR-15? Well, here’s a data point from many years ago that might be of interest. A High Power shooter who wrote for the late Precision Shooting magazine took a Bill Wylde-built AR match rifle to a registered Benchrest match. His first 5-round group ever fired in a BR match was officially measured at 0.231″ at 200 hundred yards. This was fired in front of witnesses, while using a moving target backer that confirmed all five rounds were fired.

He recounted that his ammo was loaded progressively with factory 52gr match bullets and a spherical powder using mixed years of LC brass with no special preparation whatsoever. Obviously, this was “exceptional”. However, he had no difficulty obtaining consistent 0.5-0.6 MOA accuracy at 200 yards using LC brass and a generic “practice” load that was not tuned to his rifle.

 

[divingin]

I said out of 50 only about10 will not chamber, the neck will not go in the case gauge. The rest of them go in the case gauge perfectly and do chamber perfectly. The bullets are Hornady 55 gr soft points, could some of them be out of spec and be stretching the case neck too big ? I measured the bullets and they are .224 and the case neck with bullet seated is .254 to .256

Are you sure it's the neck that is holding the case from entering the gauge?

There are several common problems that cause over-spec bulges: Insufficient neck sizing (neck too large - that will usually show by not holding a bullet); Insufficient body sizing (usually can be fixed by screwing the die down a little more, but may require a small base die for brass that has been blown out); bulges at or just below the shoulder (often cause by over-crimping, where the force applied to crimp the case mouth into the bullet distorts the shoulder/body junction or completely collapses the shoulder. Can also be caused by sizing the neck too small resulting in excessive seating force, which does the same thing.)

I would seriously doubt that a single lot of bullets would do this, as they would need to be a few thousandths oversize (which is a lot for a bullet.) Quick test is to measure the outside diameter of the necks of those that don't fit, and compare with those that do. If they're comparable, you're looking in the wrong place.

 

[Uncle Ed]

Sounds like your seater die body may be screwd in just a little too much and is causing the shoulder/body junction to slightly mushroom out. Usually you can feel this with your fingers just by rubbing your fingers toward the mouth end of the case. Back out your seater die a half turn and then readjust the seater stem inward to give desired seating. Longer cases will cause the problem, especially if your on the hairly edge.

Frank

THIS above, a longer case will start to crimp when seating the bullet, this will cause the crimp to bulge.

Make sure all your cases are trimmed to the same length and raise the seating die to prevent crimping.