Bolt hard to close

Many reasons apply. Brass fired in a different gun. Load to hot, expanded the web area of the case. FLRS dies not set so the press cams over when sizing. Cases need trimming. Loaded round neck diameter to large. Get your micrometer and start measuring the difference between rounds that chamber and rounds that don't.

Get a Wilson cartridge case gauge. That will make it very easy to see where your problem is.

I have an SC 1903-A3 that will not chamber brass that has been fired in either of my Garands, even after full length re-sizing.
However, you might look to see if you are occasionally collapsing the shoulder when seating a bullet. This defect can be subtle if you aren't looking for it and don't notice a slight increase in force while seating.
HTH

Doug

Screw the sizing die down until it contacts the shell holder just as you have done.

Then screw it down another 1/8 to 1/4 turn until you feel a definite "bump" when the press linkage cams over.

The way you have it now, you are not full-length sizing the harder cases so the shoulder isn't getting pushed back where it belongs.

PS: You can try the sized cases in your rifle to see if they fit before you load them.

rc

Screw the sizing die down until it contacts the shell holder just as you have done.

Then screw it down another 1/8 to 1/4 turn until you feel a definite "bump" when the press linkage cams over.

The way you have it now, you are not full-length sizing the harder cases so the shoulder isn't getting pushed back where it belongs.

PS: You can try the sized cases in your rifle to see if they fit before you load them.

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+1...

I agree with RCModel.....try chambering the sized...but not loaded brass. If the bolt closes easily on all the brass, then the problem is you are seating the bullet tip too long. If not closing on the empty sized brass, the problem is the brass and the sizer die.

If the brass your using is once fired from a machine gun, that streaches the crap out of the brass and you may continue to have issues unles you switch to a small base sizing die.

Yes, exactly what rc model says.

If the brass your using is once fired from a machine gun, that streaches the crap out of the brass and you may continue to have issues unles you switch to a small base sizing die.

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That is true. And what is also true, is that different brass, of different thickness, of difference hardness, all springback slightly differently. I have observed work hardened brass, CAVIM brass, require a slightly different amount of sizing to get them to the "Go" line on my Wilson gage.

I have also measured brass fired in different chambers, and they require different amount of sizing to end up at the same length.

Maybe I am too ham fisted, but I can't say I have ever felt the "bump" while sizing brass.

But I can measure shoulder set back with a cartridge headspace gage.

In my opinion, if you are sizing for a gas gun, you have to have one of these. And if you are sizing for a bolt gun, you should have one of these.

If you can't measure what you are doing, you don't know what is going on.

Get the small base die, keep your cases trimmed to length, and you should rid yourself of that issue. Once you fire the suspect cases in your rifle you shouldn't have that issue with them anymore.

However like was mentioned if they have been loaded several times they could be work hardened and springing back more than they should be. If that is the case you might look into picking up some replacements.

Case Gage

Get a Wilson cartridge case gauge. That will make it very easy to see where your problem is.

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Absolutely. Cost is around $12, depends on where you buy it. You can use it from one operation to the next - see first if all brass fits after just sizing - then after bullet seating - then after crimp - so you can find out where good brass goes bad

Use real caution if you're chambering live rounds to check them. It's easy to touch the trigger while you're distracted for just a second. I witnessed an accidental discharge while someone else was doing just that.

I won't say that I never use the "see if it'll chamber" method - but I'm damned careful when I do, and use gages for all the stuff I load a lot of or have had particular problems with.

I think I'd buy the gage before buying the undersize sizing die - your problem could be at bullet seating or crimping instead of at full length sizing.

Like others have mentioned, the F/L sizer die needs to be screwed down past 'just touching' the shell holder, to fully size the case.
There should be some 'tightness' felt as the ram linkage cams over. (without a case on the full ram stroke, as per RCModel's recommendation - 1/8 to 1/4 turn).

The other thing to check is if all your cases are within max length spec.

But I can measure shoulder set back with a cartridge headspace gage.

In my opinion, if you are sizing for a gas gun, you have to have one of these. And if you are sizing for a bolt gun, you should have one of these.

If you can't measure what you are doing, you don't know what is going on.

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+1

I use Redding Instant Indicator Case Comparators for my rifle loads but any accurate method to measure the headspace will do. The Redding comparators are pricey but they can be used to make a number of measurements such as headspace, seating depth, ogive etc

You will find that the shoulder of a fired case moves forward, and how much it moves will depend on a number of factors such as case pressure, the size of the chamber compared to the SAAMI standard, type of brass etc. It may take three, four or five firings before the case shoulder needs to be bumped back a couple of thousandths.