280 AI Results with 175-180g bullets

7mmAI said:

Nosler brass CA ridgeline 175 EH
Retumbo 62 gr got me 2911
N560 60.6 gr got 2917 fps
Retumbo load at 60, 61, 62 gr of retumbo were all touching so that was my first real trial handload after breaking in. Might have just hot the easy button. Not sure i need to push for more than 2911 fps with a 175gr. Bolt lift was easy on all.

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I would keep it there.

I bought but several boxes of ELD-X 175gr and M 180gr bullets. But decided to try Berger 150 and 168gr Classic Hunter bullets. I have loaded up several tests loads. With IMR 7828ssc H4831sc and RL22. I have H1000 on hand but haven't opened it. I was planning on buying some Grand Retumbo and Winchester 6.5 powder. But didnt know much about the 3. My rifle has a 1@8 26-inch barrel.

Currently compiling a build list for 280AI project built around the 175EH. It would be interesting to hear some details regarding chambers and COAL in for some of these loads that are at or near 3K fps MV for the 175EH. Custom reamer or SAAMI? which I have yet to make a decision on.

tomcat818 said:

Currently compiling a build list for 280AI project built around the 175EH. It would be interesting here some details regarding chambers and COAL in for some of these loads that are at or near 3K fps MV for the 175EH. Custom reamer or SAAMI? which I have yet to make a decision on.

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Loads with a 175-180gr that are "at or near 3k fps" appear to be well above the top loads listed in most reloading manuals.

tomcat818 said:

Currently compiling a build list for 280AI project built around the 175EH. It would be interesting here some details regarding chambers and COAL in for some of these loads that are at or near 3K fps MV for the 175EH. Custom reamer or SAAMI? which I have yet to make a decision on.

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Looking at the case cut photo above I'd say that .280 AI is long throated.

Off the top of my head max COAL for 280 AI is 3.330 The magazine in my CA Ridgeline will let me seat that bullet way out. The 175 berger EH hits my SAAMI chamber lands at 3.450. I have my loads seated to 3.422

Barrel is 25 inches so that helps a bit.

Ok that makes sense with that much freebore and IIRC @lancetkenyon is also shooting a CA Ridgeline 26" barrel and getting some impressive velocities. I read about a custom reamer someone had made for the 175EH seated with the bottom of the bullet bearing surface\start of boatail at the neck shoulder junction and allowing for seating .020" off lands. Someone on a different forum asked him to compare the custom reamer print with the SAAMI spec and there was about .140 thou added freebore which is close to your Ridgeline chamber dimensions.

When considering load data one should make sure they are comparing apples to apples. Otherwise, if you have a chamber cut tightly to SAAMI specs and are taking load data from someone with a chamber like yours or cut with a custom reamer with longer freebore pressure signs will stop you before getting close to target load data velocities. It would make more sense if those soliciting load data gave the COAL measurements of a dummy round to the lands or jams and ask for load data for chambers of similar length.

Out of curiosity how does this rifle shoot factory loads at SAAMI COAL?

Thanks for the reply 7mmAI

Have not and will not shoot factory loads. Handloading is all of the fun for me. The 280 rem factory federal for the brass are the only factory I will shoot. I am only at 22 rounds through the gun. Just finishing up break in... I will say i have another 280 ai and it was put together by a pretty precise gunsmith and the chamber in this CA is tighter than my other 280. Brass must be sized about an extra .003-.004 to fit in the CA.

7mmAI said:

Have not and will not shoot factory loads. Handloading is all of the fun for me. The 280 rem factory federal for the brass are the only factory I will shoot. I am only at 22 rounds through the gun. Just finishing up break in... I will say i have another 280 ai and it was put together by a pretty precise gunsmith and the chamber in this CA is tighter than my other 280. Brass must be sized about an extra .003-.004 to fit in the CA.

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Headspace I presume?

Yes my hornady comp with the .33 cal insert so it hits the shoulder indicates the shoulder must be pushed back an extra 3-4 thousandths. Had to polish that much off a shell holder to get it to chamber.

Shot some more retumbo 175 EH loads today. Only loaded up 3 at 61.7 gr and 3 at 62.2 gr. Temps were 30 degrees. I noticed that 1/2 gr diff in powder added very little more velocity. 61.7 2911 and 2918 and one missed reading. The 62.2 was 2914 and 2924 with one missed reading. Was shooting at 300 yrds at steel with a 10x max scope and no exact aiming point so not a true test of precise or imprecise load. 61.7 was about 3 inch group and 62.2 was 2 inch group. Think I will swap out that scope for something with maybe 5-10 more x's to pick the load and then for hunting might go back to the leupold LRH 3.5-10 1 moa per click scope

Primer choice can make a huge difference with Retumbo, try 215, cci 250, and Win Mag if you can find them. You never know.....

I keep going up till I find pressure, In fact, I WANT to find pressure to establish a base line to stay away from. Sounds like the hotter the load, the more accurate it is...keep on truck'en!

I work up loads with high powered scopes, the Sightron III 10x50, then swap out for my hunting scope. This builds a lot of confidence.

Keith

Here's some rather conservative data provided by Berger for their bullets.