308 tight chambering in bolt gun


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rich0372
November 14, 2008, 08:04 PM
I have been loading 308's and some of the rounds are chambering kind of tight. It pushes in the chamber no problem but, some not all, are kind of tight locking the bolt down. I notice it more on my second reloads more than the first reloads. I'm trimming them to 2.005 and seating the bullets to an overall lenth of 2.800 for the 168MK's and 2.775 for the 150MK's both Sierra. I'm using a RCBS competion die set with a full lenth sizer.

I've measered the thickness of the round compared to a factory one and the sized round is around .002 to .003 of an inch thicker at the base and basicly the same where the bullet is seated.

Will this damage the gun? does it put to much stress on the bolt? It's not like I have to force it but it is tighter than a factory which is almost lose. They are also shooting very accurate.

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ants
November 14, 2008, 08:11 PM
It is very likely that the shoulder of the brass case needs to be pushed back a couple thousandths of an inch (this is called "bumping" the shoulder). The case stretches slightly with each firing, and the shoulder gets pushed forward a little bit each time. After a while you need to push it back.

Assuming you use a full-length sizing die, raise the ram to the top and tighten your die down until the bottom of the die just touches the shell holder, then lower the ram and tighten the die down another 1/4 turn. (Some reloaders do a 1/2 turn.) This will bump your shoulder back. If you do the 1/4 turn and the case is still a little tight, try another 1/4 turn.

Let us know if that helps.

Walkalong
November 14, 2008, 08:14 PM
It could be you are not pushing the shoulder back enough any more when sizing. The brass gets "work hardened" after a while and the shoulder "springs" back more than it did when it was new and dead soft. If so you can adjust the sizer down a tad more.

Another possibility is over pressure has expanded the case heads a bit too much, but it does not sound like it.

I would try sizing a bit more and see if that fixes it.

It puts more wear and tear on the gun to continually have to push down hard on the bolt to chamber rounds.

Agh...ants and I were typing at the same time. He must be faster. He gives good advise. :)

rich0372
November 14, 2008, 08:17 PM
I already trimmed a bunch of brass that I aready sized. Should I run them though the full length sizing die again? and if I do will I have to trim again?

Walkalong
November 14, 2008, 08:19 PM
Try a couple and check to see if they chamber OK. If that works, resize the rest to match. You won't need to trim again.

rich0372
November 14, 2008, 08:21 PM
Thanks for the fast reply I'll let you know if it helps

SlamFire1
November 14, 2008, 08:45 PM
Your problem is very common because without cartridge headspace gages, you don't know how much you are sizing the case. With a gage, you can measure. I like the simple "G0", "No Go" gages, like this Wilson gage.

I use gages to set up my sizing dies, because I have found that the directions that come with sizing dies, the "touch the shell holder and give a quarter turn" are rubbish. Sometimes, the die is too long. And sometimes the shoulder is pushed back to much.

http://img.photobucket.com/albums/v479/SlamFire/Reloading/ReducedWilsongagemeasuringnew308bra.jpg

Remo-99
November 14, 2008, 08:51 PM
It sounds like your chamber is a tight one, which is not entirely a bad thing, if your aware of it and can make the reloaded rounds so they fit well.

Being that those dies are competion FL, they may only size a minimal amount.

I like to feel a very 'slight' resistance when chambering a round, but too much force will wear on the bolt locking surfaces, over time.

If adjusting FL sizing doesn't fix the issue, Are you crimping at all?
As an over crimp may bulge the case neck enough to give chambering difficulties, as well.

Walkalong
November 14, 2008, 10:32 PM
I use gages to set up my sizing dies, because I have found that the directions that come with sizing dies, the "touch the shell holder and give a quarter turn" are rubbish. Sometimes, the die is too long. And sometimes the shoulder is pushed back to much.Yep, best way to check if you are sizing to SAMMI specs or not. That way you know it will fit any decent chamber.

Most folks just tweak their sizer until their reloads fit their rifle, which is just fine, and good for brass life and accuracy.

I like to do that if accuracy is the #1 goal. If reliability is the #1 goal, using a case gauge is the way to go.

rich0372
November 15, 2008, 07:24 AM
well that fixed it adjusted the sizing die and loaded 20 rounds they all chamber perfect.Thank you so much for everyones help.

Now what do I do with the 60 or so cases I already primed and the 80 rounds I loaded will it be OK to load them and fire them?

With a gage, you can measure. I like the simple "G0", "No Go" gages, like this Wilson gage.
Yes I have to get one of these I been looking for one I guess I have to order one.

Remo-99
November 15, 2008, 07:34 AM
primed cases, just run them through the sizer again and reuse the primers.
Loaded rounds can be pulled and resized or shot as is, it's up to you.
I would most likely be pulling and re-doing them.

rich0372
November 15, 2008, 07:37 AM
But don't I have to lube the cases before I resize them again and will that ruin the primers?

Remo-99
November 15, 2008, 07:46 AM
small amounts of lube on the cases and a little in the necks.
If your got any doubts whether lube has affected the primers, toss them, if you wish, whats a few bucks anyway.

paperpuncher49
November 15, 2008, 09:29 AM
Just raise the depriming rod to a point that the expander ball still gets inside the case but the primer does not get ejected at full stroke. If necessary, remove the depriming pin. If you are using a lube such as RCBS Case Lube 2 which is water based it will not contaminate primers. Skip lubing the inside of the neck, they will size properly without lube on the inside. I sometimes just run a brush down the mouth of the case and skip lube anyway. It helps if you spend the bucks and get a carbide expander ball. Hornady makes one for RCBS dies, and Redding makes their own. Not sure about Lee, but I avoid Lee products due to several bad experiences in the past.

jeepmor
November 15, 2008, 09:29 PM
I had this problem once also. Now, everytime I resize necked cartridge cases, I verify it by chambering the empty case before I get rolling onto the production mindset.

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