What's my problem?

[adiredneck]

Why is it that I can load 50 rounds and 1/2 of them chamber hard? All brass is within spec as far as my trim-to length. Several calibers. Same head stamp brass.

I've been having accuracy issues with the 30-06 and 7mm-08 lately. I wondered if the hard chambering is causing my groups to open up?

I just bumped my sizing die for the 7mm-08 in by about an 8th of a turn. I loaded a dummy round and it is much better now. I won't be able to test until next weekend.

Is the problem my press? I have a Hornady Lock n load single stage press. I suspect it's the press, or specifically the quick change bushing. This happens with 3 or 4 calibers from 22-250 up to the 30-06. I do have an old Rcbs Partner press that I use strictly for my Forster bullet puller. I suppose I could try taking the quick change bushings off a sizing die and see if the problem goes away. Any suggestions?

 

[Broz]

Lowering the sizing die a little would be a good place to start.

Jeff

 

[MagnumManiac]

Why is it that I can load 50 rounds and 1/2 of them chamber hard? All brass is within spec as far as my trim-to length. Several calibers. Same head stamp brass.

I've been having accuracy issues with the 30-06 and 7mm-08 lately. I wondered if the hard chambering is causing my groups to open up?

I just bumped my sizing die for the 7mm-08 in by about an 8th of a turn. I loaded a dummy round and it is much better now. I won't be able to test until next weekend.

Is the problem my press? I have a Hornady Lock n load single stage press. I suspect it's the press, or specifically the quick change bushing. This happens with 3 or 4 calibers from 22-250 up to the 30-06. I do have an old Rcbs Partner press that I use strictly for my Forster bullet puller. I suppose I could try taking the quick change bushings off a sizing die and see if the problem goes away. Any suggestions?

This type of variation is nearly always caused by differing brass hardness, the harder brass springs back more than the softer brass.
This is why we anneal our brass necks and shoulders, it keeps spring back even across our brass.
I've had this same issue, I, too, thought it was the press, but found after annealing case necks it was easier to keep them all .001"-.003" shoulder bump.
I suggest you try annealing your case necks first and see how that helps.

Cheers.
gun)

 

[dkhunt14]

Whenever I size I measure the headspace on the case out of the gun. Using a Stoney point headspace gauge and a caliper. Now I set my die up to bump the shoulder .002 to .003. I then take the fire control out of the bolt and check to make sure the bolt closes on a case without resistance. After a couple of firings you will have to anneal. When you anneal you may have to back off the die a little because they will bump a lot more. I set up my dies with a little bit of cam and then lock the die ring. Now I use die shims and change the shims to change the amount of bump. I can easily change my die bump by changing the shims. Matt

 

[Broz]

Can also be caused by some brass growing at different rates. Some needing bumped and not getting it due to die setting and some that don't need it yet that will chamber fine.

Jeff

 

[cowboy]

Why is it that I can load 50 rounds and 1/2 of them chamber hard? All brass is within spec as far as my trim-to length. Several calibers. Same head stamp brass.

Does all your brass have the same number of firings?

 

[adiredneck]

Does all your brass have the same number of firings?

Unfortunately, no. It does not. I am religious about case trimming, but not on keeping the brass sorted by firings. I am just trying to get some decent groups with the 7mm-08 for deer season. It's certainly accurate enough for adirondack hunting at around 2" groups, but disappointing. I was just wondering if I am getting some pressure changes with the variations in the way the cartridges chamber that is opening up my groups.

I can start by annealing a small batch of brass. I have 8 pieces on the bench right now. I could start there.

By the way, I only FL size my brass.

 

[Broz]

By the way, I only FL size my brass.

That's fine, but how do you tell if you need to size more or less. A hard bolt close on some could be a flag to indicate some shoulders have grown forward, and if you die is not set properly low enough it will not correct the issue. The less x fired rounds have not grown to this point yet but will. And yes the ones that chamber tight could indeed be having more pressure and effect velocity.

Jeff

 

[adiredneck]

I know this is tabu in certain circles, but after I bumped my sizing die a tiny bit, I sized a dummy round with no primer and did the masking tape trick on the head stamp. The bolt closes hard on the 2nd layer. Keeping my fingers crossed..

A set of cartridge headspace gauges are on my Christmas list.

 

[ShootnMathews]

I had this exact same problem happen on my 6.5-284. Some closed hard and others easy. After acquiring my headspace comparator gauges I found that even with my die screwed all the way down I was getting zero bump on the shoulders. I screwed my die down a touch more and cammed over tight on it and now get .002" bump on the shoulder. All rounds chamber easy now and my loads evened out a lot.

But even with some tighter than others the gun still shot 1/4 MOA with an occasional wild flyer. Now it shoots one hole with no flyers.

 

[Broz]

I know this is tabu in certain circles, but after I bumped my sizing die a tiny bit, I sized a dummy round with no primer and did the masking tape trick on the head stamp. The bolt closes hard on the 2nd layer. Keeping my fingers crossed..

A set of cartridge headspace gauges are on my Christmas list.

This sounds good, as long as you used a case that was closing hard before sizing.

Jeff

 

[adiredneck]

Any suggestions on a decent headspace gauge?

Hornady has a nice kit, with several bushings included, but the reviews are mixed.

 

[Broz]

Any suggestions on a decent headspace gauge

A case that closes tight. Then size lowering die till easy closure. Then do the tape trick to be sure you didn't go too far.

Or I use the Hornaday with different bushings on a good caliper.

Jeff

 

[Lefty7mmstw]

Are you using an expander ball?? If so, how heavy is the expander ball pull through the neck?? High amounts of pull can actually pull the neck out a bit at times and will mess up even chambering in otherwise good brass. Also make sure to get the carbon out of your case necks with a good brush.
I'd start to segregate your brass based on firing count also as others have said. I am the pot calling the kettle black on this as I haven't been the best at waiting to reload a box until every round is shot, especially the 100 round boxes.