Pressure Signs

[HK Dave]

Howdy folks. I'm new to reloading and am working up my first load for one of my ARs. Wanting to play it safe.

From left to right it's 24gr, 24.5gr, 25gr of Varget pushing 77smk loaded to max magazine length. (Rem 7 1/2 primers)




At 24.5gr, one of the primers looks like it flattened a bit, but the rest look fine to me.

At 25gr, I think I can make out the beginning signs of a tiny bit of cratering but it's really subtle... not sure if I'm just seeing things by being overly cautious.

What do you folks think?

[HK Dave]

Crappy phone pics.

[JagerDog]

Those all have room to go up if you want to.

[HK Dave]

Looks like it right? Most of my factory ammo has more pressure signs than this. :P

Wish it wasn't blowing like the end of days at Angeles couple days back... could have chronoed. :P

[koehn,jim]

They look ok to me but remember the pressure spikes in a hurry. temp. will also affect pressure was the day cold or hot.

[HK Dave]

The day was about 80 or so with winds at 20-30mph.

Given that I don't shoot past 600 yards with 223, maybe backing it off to 24.5 gr should be fine, considering it wont have too much trouble getting there.

[GeoffLinder]

25 gr under a 77 is getting near max. Pictures aren't clear but it looks like one or two in the middle might be getting near the pierce point. Even when primers aren't flowing, they can pierce in the firing pin dimple. I'd say you are getting near max for that combo and don't have a lot of room to move up in charge level. 24.5 is what I consider safe max in my .223 Wylde chambered 1/8 JP barrel. Above 25 gr under a 77gr is getting near or at compressed charge point due to how deep a 77 goes into a case even at max mag length.

[HK Dave]

Thanks Geoff. Ok I'm going to back off to 24.5. At 25 gr the powder is pretty crunchy.

I'm running a Shilen Ultramatch 1:8 stainless wylde.

Seems most reports online have people maxing out at 24.5. I assumed the pressure signs would be some obvious flattening or cratering. I better read up some more about pressure signs.

[GeoffLinder]

Thanks Geoff. Ok I'm going to back off to 24.5. At 25 gr the powder is pretty crunchy.

I'm running a Shilen Ultramatch 1:8 stainless wylde.

Seems most reports online have people maxing out at 24.5. I assumed the pressure signs would be some obvious flattening or cratering. I better read up some more about pressure signs.

Check the velocity when you test too. Knowing this also helps ascertain where you are. Getting near or over 2700-2750 FPS is also a sign that you are near or at max for this bullet in an AR. I have heard of folks safely getting high 2700 fps range, but my max delivers me 2725ish and I settled on just around 2700 as an accuracy node worth stopping at.

[HK Dave]

Will do... been a while since i pulled out the chrono. Thanks Geoff.

BTW what barrel length are you getting 2725?

[GeoffLinder]

Will do... been a while since i pulled out the chrono. Thanks Geoff.

BTW what barrel length are you getting 2725?

20"

[JagerDog]

Thanks Geoff. Ok I'm going to back off to 24.5. At 25 gr the powder is pretty crunchy.

I'm running a Shilen Ultramatch 1:8 stainless wylde.

Seems most reports online have people maxing out at 24.5. I assumed the pressure signs would be some obvious flattening or cratering. I better read up some more about pressure signs.

With the high winds, pretty hard to gauge accuracy..but that's what I'd be hunting for. You've still got headroom based on the primers. They're barely ironing out. Be nice to see where it can go, but for target work it's not important.

[GeoffLinder]

With the high winds, pretty hard to gauge accuracy..but that's what I'd be hunting for. You've still got headroom based on the primers. They're barely ironing out. Be nice to see where it can go, but for target work it's not important.

I disagree, I doubt there is very much headroom left there. Above 25.0 of Varget under a SMK 77 is a gray area in most any AR and there is evidence of cratering in the firing pin dimple in several of the cases in his photos.

[ExtremeX]

Just some food for thought...

I have never used Remington primers, but from the brands I have used (Winchester, Tula/Wolf, CCI 400, 450, #41) all seem to flatten out but some more than others.

I found only looking at primers isn't always the best way to figure out of you are at a max load or not.

Even at near max load I don't always get flattened primer or flow similar to whats you would see on factory M193 or M855.

[GeoffLinder]

BTW, from the pics it looks like you have not removed the crimp ring on a lot of those cases. I would swage or ream that crimp ring out. Primers will seat better that way, a couple cases show signs that the primer went in a little catywampus.