260 rem pressures

[Coldfinger]

I finally got into 6.5 diameter. Picked up a 260rem from member. Just wondering what pressure spikes I should be noticing. Right now I'm cutting the same hole during pressure testing. I started at 41 gns h4350 and am sitting on 44 gns now. Launching Berger 140 elite hunters. Lapua lrp brass CCI Br2 primers.
No bolt lift resistance at all. But I know customs can hide pressure.

 

[just_jon]

QL and GRT estimates 44 grains of H4350 at 69,878 and 68,925 psi, respectively. SAAMI max pressure is 60,191. QL and GRT data is based on a COAL of 2.8" and case capacity of 53.5 grains of H2O.

 

[lancetkenyon]

I don't see any visible signs that I would be worried about.

 

[Coldfinger]

QL and GRT estimates 44 grains of H4350 at 69,878 and 68,925 psi, respectively. SAAMI max pressure is 60,191. QL and GRT data is based on a COAL of 2.8" and case capacity of 53.5 grains of H2O.

It's jumping a country mile to get to magazine length feeding but still cuts holes. There might be something to this 6.5 craziness I've ignored all my life

 

[MagnumManiac]

I don't see any signs of excessive pressure, but I would expect Varget to give better performance, it did in my 260 before I went AI with it, then H4350 shines over everything else.
What COAL/CBTO are you running?
My rifle is a REM 700 VSSF II, so mag length is restricted.

Cheers.

 

[VinceMule]

44g with 140s are very popular among the 260 guys. 44.5-45.5 in the AI. Every chamber/barrel will be different

 

[ShtrRdy]

Primers look fine. Do you have a velocity measurement? That's another piece of information we can use to infer pressure.

 

[Coldfinger]

Primers look fine. Do you have a velocity measurement? That's another piece of information we can use to infer pressure.

Not yet it rained all day. Don't have a garmin crono yet.

 

[Coldfinger]

Primers look fine. Do you have a velocity measurement? That's another piece of information we can use to infer pressure.

Not yet it rained all day. Don't have a garmin crono yet

I don't see any signs of excessive pressure, but I would expect Varget to give better performance, it did in my 260 before I went AI with it, then H4350 shines over everything else.
What COAL/CBTO are you running?
My rifle is a REM 700 VSSF II, so mag length is restricted.

Cheers.

I don't see any signs of excessive pressure, but I would expect Varget to give better performance, it did in my 260 before I went AI with it, then H4350 shines over everything else.
What COAL/CBTO are you running?
My rifle is a REM 700 VSSF II, so mag length is restricted.

Cheers.

I'm at 2.90" but got to get a tad deeper to not bind in Accurate mags. It's a surgeon action and bottom metal.

 

[MagnumManiac]

I'm at 2.90" but got to get a tad deeper to not bind in Accurate mags. It's a surgeon action and bottom metal.

OK, you should be good, I'm a tad shorter than you, but the AI chamber hides pressure real well. I'm at 49g H4350, no pressure signs. When mine was standard 260, I maxed out at 42g H4350 with 150g BT. Mine is 30" 8" twist.

Cheers.

 

[Lionel Boyd Johnson]

When I'm developing loads for a hunting rifle that I want to be able to feed from the magazine, I start my OL length tests just short of the magazine length assuming that the chamber would allow longer seated bullets. That way, I only have to test for best OL length in one direction - shorter.

 

[Pootyng]

43-45 grains of N160 with 140 sst is what I hunted deer with until I switched to a Grendel. I think it was 2700 from a 26" Austrian Mauser. I don't remember the coal but there is no limit on that action for the 260.

 

[Doom2]

The case on the right is showing an extractor(?) mark at 11 o'clock so you are probably above the 60KSI point. But my take is that your worst worry would be brass life.

 

[cajun]

Fwiw Berger lists 40.8 gr with that bullet and powder. 2.8 coal.
Nosler doesn't list H4350 with 140 but has 43.5 with 130 gr. Berger uses quickload for a lot of their data so I would guess the above QL estimates are pretty accurate.