Why are my 308s sometimes hard to chamber?

[bobotech]

I am loading for a gas gun, a Saiga 308. When I let the bolt fly forward, it will chamber the rounds fine but other times, they won't lock up easily unless I let the bolt fly forward.

I am resizing them with RCBS dies that are set to touch the bottom and slightly tightened beyond that so that the press has a slight cam over feel to it. I am trimming them to 2.008 or so. I am using 150 grain boat tail bullets. I am giving them a fairly heavy factory crimp with the Lee crimping die.

Any ideas?

What could I be doing wrong?

 

[MCMXI]

bobotech, I'm not familiar with the Saiga but two possibilities come to mind. Do you have any way to measure the headspace of your reloads and your Saiga chamber? A Redding case comparator works VERY well for this ... you can compare the chamber and cartridge headspace to a SAAMI standard. The RCBS die is all the way down so you're full-length sizing the cases but if the headspace of your Saiga chamber is less than the SAAMI standard, you may have a problem with your current set up and may need a body die to bump the shoulder back even further.

Another possibility is your magazine(s). Can you easily strip off rounds from the magazine(s) by hand. You can bend the magazine lips up/out to change the amount of force required to strip rounds off the follower. Many feeding related issues can be traced to the magazine. I had to mess with one (of three) AI magazine for feeding-related issues with my .308 bolt action.

 

[30Cal]

If you're not able to measure how much you're sizing your cases, correctly setting an FL die is guesswork. I highly recommend using a case gage/comparitor whenever you use a FL resizing die.

Do you need to crimp (how much do your un-crimped bullets move)? Overdoing it will bulge the shoulder.

 

[bobotech]

I am wondering if I am overcrimping them. I do crimp because I'm using a mag fed gas gun and I just feel safer with crimping.

I will do another batch with less crimp and see.

I should get those case comparator tools soon but that will have to wait til the end of the month.

 

[rcmodel]

Get a black Magic-Marker or a candle.
It is way much cheaper!

Color one of the tight rounds, or smoke it with the candle, and chamber it by whatever means necessary.

Then eject it, and see where the shiny spots are.

Where that is, is where the problem is.

Another thought.
Not sure if the SAIGA extractor snaps over the case rim after the round is in the chamber or not?
If it does, and you ease the bolt shut like you indicated, you have to smack it to pop it over the rim.

rc

 

[bobotech]

It does "snap" over the case rim. What I have been doing to test is is to smack the bolt to get the case to hook into the extractor then I try to ease it into the chamber. That is when i have the problem. If I let the bolt slam home, it closes fine but it just makes me slightly nervous. I really don't want to have an out of battery experience.

 

[rcmodel]

If I let the bolt slam home, it closes fine but it just makes me slightly nervous.

Maybe something is just dragging a little when you ease it shut?

Could just be a lubrication issue in the carrier, op rod, piston, bolt, or trunnion block. Could also be the mag, or top round in the mag dragging on the bolt carrier.

Do the "coloring" test I outlined, and if you don't have any tight spots showing up on the case or bullet, it is something else.

rc

 

[bobotech]

Will try that tonight.

Thanks.

I had to do the coloring test when starting to reload for the K31 a while back. The OAL wasn't correct in the book because the bullet hit the rifling . Had to figure out the correct depth of the bullet. What a pain. LOL

 

[Hummer70]

It is not uncommon to find FL dies that don't size FL. You need a chamber type case gage to know for sure. They can be corrected by chucking die in lathe and cutting off .005 to .010" from bottom of die and re-radius the bottom. I have 56 sets of dies and have had to cut about a dozen of them.
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