Reading Primers during Load Development

[Argon3119]

Working up a new load for my 223 using H4895 Rem 71/2 primers and 69SMK's seated to a COAL of 2.255. I was performing an initial OCW work up from 24.2 to 26.0g in .3g increments. (Hodgdon's data says 24 min and 26 max).

Stopped shooting at the 25.7 increment because of cratering. While discussing this with a fellow shooter, he observed that this F-C brass has been crimped and is therefore coming off the same line as LC mil brass. Because of the lower case capacity I should reduce the stated max by 10% to 23.4.

Shown are representatives of some of the loads.
25.7 - where I stopped, also slight ejector marks
25.4 - good node
24.5 - good node
24.2 - starting

Even the starting load's primers have a small lip which you can catch with a fingernail. All the other loads I use are about like this. My question for those more experienced is, are all of these loads over pressure like this guys says? Or can I get by with either of the middle loads, which show slight lips but don't show much flattening? I'd like some advice before I go chrono anything too hot.

 

[nosualc]

What type of gun were you shooting this out of? Bolt vs. AR15 vs. Other.

-nosualc

 

[Argon3119]

Bolt, savage model 11.

 

[Drop Port]

Cratering in a factory rife is not necessarily pressure, a loose fit firing pin often craters at much lower pressure. Flat primers can also come from excessive head space. You need to take all things into consideration as not to get a false pressure sign.

 

[Mega]

Reading the first post I immediately thought this has got to be a Savage. Common problem cratering primers from too much clearance around the firing pin even with those thick cup Remington 7 1/2's.

There are a few solutions around if you search. I'm not a Savage person but have seen the problem with several Savage rifles even with very mild loads.

Besides the Savage problem, even with other rifles, primer cratering is only one of the indicators for excess pressure.

 

[nosualc]

Bolt, savage model 11.

Thought so. Savages are infamous for slopping bolt/firing pin clearance.

Using primers as a primary pressure indicator is problematic. Too many variables like pin/bolt clearance, hardness of primer cups, etc. That said your primers don't look flattened at all, and absent other indicators I think you're fine.

Do yourself a favor and avail yourself of the best deal in guns today. Send your bolt to Gre-Tan rifles and have them bush it. Very inexpensive, and the service is great. If you send it on a monday, you'll have it back by friday. Otherwise, switch to a harder primer or live with the cratering.

-nosualc

 

[Argon3119]

I had thought this might be an issue with factory tolereances aftet reading some similar posts about savages and remingtons. And I have read about the gre-tan bushing. Sounds like a good thing while this rifle hibernates during deer season.

The 25.4g load had a consistent POI with neighboring increments along with a good group, should I continue development with this one looking for other pressure signs.?

As far as reducing lisfs by 20%, I have not heard of reduced case capacity with military 5.56 capacity vs. 223 brass, only with 7.62 vs. 308, but looking for other people's input. This lot of F-C brass is consistently 2g heavier than my non-crimped F-C, though.

 

[Argon3119]

How appropriate that gre-tans video showing his bushing process uses a savage bolt as an illustration. Thanks for the suggestion!

 

[Mega]

In general the .223R / 5.56mm cases are a different capacity even between themselves. If you swap any case brand work up your loads again from a safe starting point. A common military case used here in Oz is the ADI .223R and is very high quality. ADI = Australian Defence Industries, the same mob that makes the ADI AR Powders sold by Hodgdon.

The problem I can see if you continue with load development with those primers cratering like they are without fixing the issue is you risk having a Primer Pierce which may perhaps damage your bolt face. I'd get the bolt fixed first.

 

[Argon3119]

That seems to be the consesus of what you guys are saying and what I have read elsewhere. Bush the firing pin, then reevaluate. Thanks!