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Discussion Starter · #1 ·
I am having a problem with pressure in my g2 contender in a .204 carbine. The primer is cratering and I am 2.5 grains under max load. Im using 28gr of aa 2520 with a 32g v-max in rem brass. I have backed off the lands twenty thousanths. All my brass is new and trimmed to 1.84. All other case measurements are matching up. Should I keep backing off powder or switch powders? Am I overlooking something or am I just being overcautious? Any info will be appreciated.

regards, Dane Braley
 

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Keep in mind that each gun will have its own max load, not necessarily what the book says. What primers are you using? Lots of folks have switched to Rem 7 1/2s or CCI BR primers because they have stronger cups.
 

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I am having a problem with pressure in my g2 contender in a .204 carbine. The primer is cratering and I am 2.5 grains under max load. Im using 28gr of aa 2520 with a 32g v-max in rem brass. I have backed off the lands twenty thousanths. All my brass is new and trimmed to 1.84. All other case measurements are matching up. Should I keep backing off powder or switch powders? Am I overlooking something or am I just being overcautious? Any info will be appreciated.

regards, Dane Braley
What primers are you using? Have you tried using Remington 7 1/2?
 

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A couple of things to check.

Do you have the same problem with factory ammo, or did you check?

Either way, I am having a similar problem, though not maybe quite as bad) in my 204 and I will tell you what I was told by a couple of fellas.

1. With a micrometer, measure the necks and body of the cases before and after shooting to see if your chamber neck or body might be a little tight. You can also check for case head expansion this way.

2. Check the rifling in the barrel. My barrel's rifling has some hefty lands which may be some of my problem. If you can see a line where the reamer stopped cutting the lands, that would be an indicator. This is very apparent in my barrel.

3. Check to see if you are jump to the lands is a too close. Ammo from the factory may be set for some jump and if you don't have it, I think it can impact the chamber pressure (some argue this).

I have backed mine off some, but may have to more based on what I am seeing. Oh well, I guess the barrel will last longer.

Good Luck.
 

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Discussion Starter · #6 ·
I have not yet shot any factory ammo. But I may try using remington 7 1/2 primers. I am using winchester wsr primers. I'll fool around with it some tommorow and see if I can eliminate this problem. Thanks fellas.

Dane Braley
 

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If I were you I'd try some CCI-450 primers. In my experience with AA2520 it needs the small mag primer.

Accurate Arms lists 29grs of 2520 as the top load at least according to the data over on rugerhunting.com.
 

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If you use Mag primers...

If I were you I'd try some CCI-450 primers. In my experience with AA2520 it needs the small mag primer.
back off the load and work it up again.
 

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That's OK

Thanks Steven!! I sometimes forget or should I say assume, that people who post on here should know that.
No problem -

Once tried to just deduct 1 1/2 gns of powder to compensate for changing to a magnum primer. Nothing damaged, but the accuracy was disastrous.

I always hope that people out there are smarter than I am, but just in case...
 

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No problem -

Once tried to just deduct 1 1/2 gns of powder to compensate for changing to a magnum primer. Nothing damaged, but the accuracy was disastrous.

I always hope that people out there are smarter than I am, but just in case...
I had a a load in a .223 once using 50 Nos BT and AA2520 that put 5 shots darn near in the same hole at 100yds, but the SD was sky high. Traded that rifle to my dealer who substituted CCI-450's for the Fed 205M and the SD came way down, same load just different primer. He shot the hell out of that rifle out in SD.
 

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Jim makes a good pointabout the WSR primers being soft. Everytime I have run into pressure problems with the 204 Ruger or 20 Tac even without primers cratering I have had very loose primer pockets the next reloading and two firings at this pressure will usually render the case unusable. If you are not gettng loose primer pockets I would assume it the soft primers and switch to a Rem. 71/2.

Rodney
 

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Headspace

Good advice here about primers. I've found headspace problems on both Contender and Encore barrels, if you are shooting new brass here is what I'd try.

Neck size only your fired brass (back off your full length die if you have to) and load the same components as before and see if that changes your pressure signs. I know that Thompson's need full length sizing but if you have excessive headspace it can cause prematured cratering. That said, I don't put much faith in cratering as a sign of excess pressuse in bolt actions. The Contender can be finicky though.
 

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Discussion Starter · #16 ·
Well, here's the skinny. I reloaded some more bullets today w/ rem. 7 1/2 primers and they are still cratering. So, I ran to the local store and picked up some factory ammo, and you guessed it, they (Hornady 40g V-max) are cratering too. No signs of pressure elsewhere though. In my bolt action rifles this never was a problem. Could this be the contenders trait? This is my first one.

Thanks, Dane Braley
 

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I hear about this a lot with T/Cs and .204s (I moderate over on the .204um). I think that it's due to minimum cartridge size, stuck in a SAAMI chamber. Most companies are making their brass undersized a LOT now, it's safe enough, but loose in the chamber, and that makes it look like excessive pressure when it's more likely headspace issues due to dimensional problems. That's my take on it, anyway. I might be wrong, since I don't own one, but several of the posters there have had troubles with it.
 

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Saving brass

I hear about this a lot with T/Cs and .204s (I moderate over on the .204um). I think that it's due to minimum cartridge size, stuck in a SAAMI chamber. Most companies are making their brass undersized a LOT now, it's safe enough, but loose in the chamber, and that makes it look like excessive pressure when it's more likely headspace issues due to dimensional problems. That's my take on it, anyway. I might be wrong, since I don't own one, but several of the posters there have had troubles with it.
I've seen that in other cartridges and the problem can be two-fold.

1. The manufacturers are saving a little bit on brass by making the cases to the bare minimum sizes.

2. The factory gun makers may be starting out with reamers that are just a little on the large size. That way, they can get a few more sharpenings out them before the reamers are below tolerance. Headspace may be pushing the upper limit. Be sure that on their no-go guage it is acceptable.


You combine the 2 in one gun and you have an issue that not only looks like a pressure problem, but it really is. Safety factors are compromised, but as long as no one gets hurt, it's ok. Right?! :eek:

The majority of GQ public shooting don't even know what to look for half the time and the other half don't care as long as it goes bang.
 

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I'm not sure I see the connection with the "cratering" though. If you have a +spec chamber it should reduce pressure as there is a bigger volume for the gases to fill. I can see the small brass causing protruding primers, but cratering is usually always a high-pressure indicator, or a problem with the firearm, or a too-soft primer. I've never heard of near-excess headspace causing cratering. Would it be possible for him to have a -spec chamber, causing high pressure?
 
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