.243 velocity with 90 grain bullets

People, some wise council.

I gave a late model Sako L579 in .243. With 90 Ballistic tips and 90 grain ELDX's I am loading them up to book max (which is 44.5g of 2209) and chronographed the results at 3220 fps.
The rifle has a 22 inch barrel.
The book speed is 3187 fps for this load in a 24 inch barrel. According to my thinking I am getting more pressure than the book because I am getting more velocity in a two inches shorter barrel.
Off setting this is the notion that we have no pressure signs on the cases, and the .308 is rated higher pressure in the same rifle and cases (62K over 60K)

So its a hot load, but where do you draw the line. Case life will suffer perhaps, but accuracy is excellent, 0.5 - 0.75 of an inch.

I would like to forget I own a chronograph. When I didnt have one I would have just forged ahead

In a Rem Model 7 using 90gr Speer hot cor 44.5gr 2209 gave 3016 fps. Think it is a 20” barrel. No pressure signs.

Your logic is sound. There's no speed without pressure. If you're getting above book velocities with a shorter barrel than they used, the chances are you are above the amount of pressure they got too. Pressure goes up very quickly for small increases in speed once you start getting up towards max. And primers and brass don't always show it.

You could do what most would do and ignore it - as it doesn't look like you're anywhere near a catastrophic failure. But personally I would back it down closer to 3100. It'll probably shoot just as well dialed down a notch.

You can download yourself a copy of GRT too and use that to sanity check your loads.

Sako A7 with 22" barrel and 44 gr 2209 gives me 3160 with the 90gr ELDX. I didn't get any pressure signs for that load or 44.5, but 44 grains shot slightly better so went with that.

Minuscule differences in bore tolerances from rifle to rifle will result is differernt presures for the same load. (this is why you are told never to swap hand loads between rifles). If you're not getting any signs of excessive pressure then there probably isn't any. Be thankful that you have a "fast" barrel that is accurate.

I will see how the cases last with this load. I am loathe to give up good velocity AND good accuracy...

One of my accurate .243W loads uses Norma brass, Hornady ELD-X 90 gn, Federal 210 Primer, AR2209 43.80 gn for 3250 fps from a 1:9 twist, 22 inch barrel
I thought it a hot load but repeated firing of the same brass ( maybe up to 5 X ) has not shown indications ( yet ) of overpressure. So, I think I'm good. I think a tendency sometimes with AR2209 is to render higher velocity with slightly less than max charges and without excessive pressure. I have found AR2213sc ( in other cals ) is the same.
In any case your intended course of action is what I would do. Keep shooting and loading the same brass for a while and see what the brass tells you. My guess is you'll be fine.

Quote:

---

Originally Posted by JohnDuxbury

People, some wise council.

I gave a late model Sako L579 in .243. With 90 Ballistic tips and 90 grain ELDX's I am loading them up to book max (which is 44.5g of 2209) and chronographed the results at 3220 fps.
The rifle has a 22 inch barrel.
The book speed is 3187 fps for this load in a 24 inch barrel. According to my thinking I am getting more pressure than the book because I am getting more velocity in a two inches shorter barrel.
Off setting this is the notion that we have no pressure signs on the cases, and the .308 is rated higher pressure in the same rifle and cases (62K over 60K)

So its a hot load, but where do you draw the line. Case life will suffer perhaps, but accuracy is excellent, 0.5 - 0.75 of an inch.

I would like to forget I own a chronograph. When I didnt have one I would have just forged ahead

---

Greetings @JohnDuxbury,
You would only lose around 50 fps from your shorter barrel so this is no biggy. You are around 100 fps faster than the book data. It looks to me that you have a miss match in your powder speed. AR2209 was sped up for some reason around 2,000 so you will be getting more pressure as you suspected. I just looked up the Hodgdon/ ADI data which I think that you are using and see that the pressure is in CUP so this is the data for the older and slower powder. I tested the two powder lots in my 6.5 and the new stuff produced about 80 fps more speed in line with what you have experienced so it is up to you whether you drop the load back or not. Your choice.
Regards Grandpamac.
PS. I crunched the numbers and pressure would be just over 53,000 CUP with your current load. Not major.

Greetings again,
Looking at the ADI data I see that the Hornady 87 grain projectile is listed with pressure in PSI. I expected the load of AR2209 to be the same or a little more than the 90 grain Speer but it was actually 1 grain less at 43.5 grains for 3,190 fps and 58,300 PSI. It appears that this is the later and faster AR2209 powder and book max for the 87 and 89 grain flat base or Nosler BT projectiles should be considered as 43.5 grains and perhaps a little less for the longer spitzer boat tail like the ELDX.
Regards Grandpamac.

Hi Grandpamac, I have discovered the slower and faster 2209 as well and have both on hand. Interesting that you mention it. I have a tin of 2209 a few years older that produces slower results, and with smaller carridges like the .243 I have to add another grain to get to what the more recent powder will do, and sometime 1.5 - 2 grains in big cartridges like the .30/06 or 9.3x62.

I have no pressure signs showing at the moment, I will continue and see what case life results,.

Quote:

---

Originally Posted by Butch73

Sako A7 with 22" barrel and 44 gr 2209 gives me 3160 with the 90gr ELDX. I didn't get any pressure signs for that load or 44.5, but 44 grains shot slightly better so went with that.

---

44gr is spot on . 2213sc can give you even tighter groups.