Is a slightly “hot” round bad for your gun?

[Shooter14854]

Hey everybody sorry for the dumb question, I just got started reloading.

i recently did some .308Win load development and found 44 grains of Accurate 2495 (paired with Hornady 150gr BTFMJ 2.735 COL) ran best. Some of my brass has some mild-moderate extractor swipe. According so Accurate’s load data the load maxes out at over 46gr. My question is, is shooting a load that’s slightly “hot” and making mild-moderate extractor swipe marks bad for your gun? Or do I just need to be especially careful when charging the case and seating the bullet as to not make the round even hotter

if it helps I’m shooting a 18in barrel AR10 that I purchased new from Palmetto about 6 months ago. Thanks for the help. This forum has been great for advice since I got started loading!

 

[MEHavey]

Ejector wipe/brass-flow (if that's what you're actually seeing) means pressures in the mid 70s.

[But...] as low as you are (relative to published load data), you may be seeing other ejection-force
marks rather than actual metal flow

 

[Shooter14854]

Ejector wipe/brass-flow (if that's what you're actually seeing) means pressures in the mid 70s.
As low as you are (relative to published load data), you may be seeing other ejection-force
marks rather than actual metal flow

good to know! What type of other ejection type marks are you talking about? And are they something I should be concerned about? Again I’m really sorry for the newbie questions.

 

[NMexJim]

Look up AR dwell timing. If you changed the barrel from a longer length, your dwell time may be off.

 

[Charlie98]

There are differences in .308 load data... there is data for bolt actions, primarily, and 'gas gun' or service rifle data. Your AR-10 would be a 'gas gun.' Typically, that load data is a little less than the full-house data, mostly because it's intended for target or match shooting, developed to cycle gas-operated rifles. I also have used gas gun data in .308 for my Savage 99 lever action... feeding a steady diet of full-up .308 can damage a rifle like the 99.

My Hornady #7's service rifle data, with the Hornady 155grn A-Max, lists 43.5grn AA2495 as their 'service rifle' max. Oddly enough that particular charge is .2grn higher than their standard .308 load data with AA2495, which also includes the bullet you are using now, just for reference.

Personally, I wouldn't go beyond the Hornady data... just my .02 worth... unless you just had to have the extra velocity. You say your 44grn load 'ran best...' I would ask in what context? Did lesser loads not cycle the action? ...or did the 44grn load show better accuracy?

 

[twarr1]

There will be some who disagree, but ejector brass flow is a better indicator of high pressure than primer ‘flattening’
(If indeed it’s flow, as @MEHavey alluded to)

 

[243winxb]

https://www.thehighroad.org/index.php?media/albums/high-pressure-signs.148/

mild-moderate extractor swipe

On 308 factory ammo @ 62,000 psi , its not a common thing.
May be caused by ("other ejection-force marks") excessive head clearence, wet, oily chamber or the ejector plunger hole has rough* edges. But high pressure is the most common cause. May not be an issue. Watch for loose primer pockets in 5 or less reloads.

Photo- Brass flow into the ejector hole can be a sign of high pressure.. The right brass shows light flow.. This can be seen on some factory fired brass.. Showing higher pressure moving to the left. Until the pocket expanded and primer fell out.

 

[243winxb]

Auto actions that open to soon may show high pressure signs. As said in Post #4 dwell time. The difference in port pressure. Adjustable gas block helps.


The use of suppressors on rifles, Hornady- Pressure signs https://www.hornady.com/support/superformance-in-gas-operated-firearms

 

[MEHavey]

...ejector brass flow is a better indicator of high pressure than primer ‘flattening’

Correctomundo Grasshoppa !
Take look at 243win's photo's in Post#7

 

[Random 8]

In a gas gun, it can be bad for your rifle. This is well known among service rifle shooters who push loads to the limit and suffer premature wear of components. If you really like the load, AND you need the extra velocity, AND you're willing to consider parts of your upper to be expendable (as many aforementioned service rifle shooters do,) proceed with caution. If not, you may be happier backing off a fuzz or working with a powder such as R15, 4064 or Varget with a more friendly pressure curve.

No experience with your AA powder, but I have found ball powder in general to run a bit hot in higher temperatures.

 

[Hooda Thunkit]

No experience with your AA powder, but I have found ball powder in general to run a bit hot in higher temperatures.

I don't know if this is appropriate or not, but Accurate 2495 isn't a ball powder. It's a single base extruded powder, meant to mimic IMR 4895.
https://shop.hodgdon.com/accurate/accurate-2495r

 

[Howa 9700]

Recently picked up a copy of Hodgdon's 2021 annual reloading guide. What I missed the fist time through was a small table of loads for military rifles in 308.....right behind the regular 308. Only 4 bullets listed, but what caught my eye was in no case did the pressures get to the 50,000 level. All topped out in the 45,000 psi range. Regular loads often loaded up to 60,000 level. So for these gas guns, they had backed the loads off a lot.