6.5x284 to a 6.5 SAUM/GAP

[Jgraf]

I have a single shot Rem 40x rifle chambered in 6.5x284. It has an 8 twist Bartlien 5R Rem Sendero contour 26" length. I am contemplating rechambering it to 6.5 SAUM/GAP.
Is that possible? Is it worth it? I was thinking I could go for 3000+ fps vs. the 2800 fps I get now.
I have another 40x action with a magnum bolt face that I would mate the barrel to.
Thank you for your input.

 

[ShootDots]

I have a single shot Rem 40x rifle chambered in 6.5x284. It has an 8 twist Bartlien 5R Rem Sendero contour 26" length. I am contemplating rechambering it to 6.5 SAUM/GAP.
Is that possible? Is it worth it? I was thinking I could go for 3000+ fps vs. the 2800 fps I get now.
I have another 40x action with a magnum bolt face that I would mate the barrel to.
Thank you for your input.

It can easily be done>>>>with modifications. The 6.5 x 284 is a tiny bit longer, so you will have to trim some threads off. This REALLY means you need to cut off the threads and re-thread the barrel. Then you will have to open the boltface from .473 to .532. These modifications are easily done. However, you will have to pay a good 'smith to get them done. Then comes the question. Both of these firebreathers will eat throats up. How many rounds are already on your 6.5 x .284? if you have over 500, I would get a new barrel and start afresh! The cost for rechambering is the same as doing a new barrel, minus the crown>>>which I would have done on a rechamber anyhow! Food for thought..

 

[FatBoy]

2800 with a 6.5x284? How long is the barrel. I run just under 3000 and have seen shooters run 6.5x284 up to 3200fps out of a 30" barrel.

 

[ShootDots]

2800 with a 6.5x284? How long is the barrel. I run just under 3000 and have seen shooters run 6.5x284 up to 3200fps out of a 30" barrel.

Hello Chris, OP says he has a 26" barrel..

 

[FatBoy]

Hello Chris, OP says he has a 26" barrel..

Missed that. I'm getting 2835 from a 6.5x47L with 142s and H4350 with no pressure. 2800 seems slow. I wouldn't change calibers until I explored the limit's of the x284. I would expect 2900-2950 with something like h4831sc or n160.

If it's a tight bore, or something else that would cause higher pressure sooner then maybe no, but if there is a condition that causes pressure it'll still be there with a SAUM.

 

[ShootDots]

Missed that. I'm getting 2835 from a 6.5x47L with 142s and H4350 with no pressure. 2800 seems slow. I wouldn't change calibers until I explored the limit's of the x284. I would expect 2900-2950 with something like h4831sc or n160.

If it's a tight bore, or something else that would cause higher pressure sooner then maybe no, but if there is a condition that causes pressure it'll still be there with a SAUM.

You are absolutely correct my friend!

 

[Jgraf]

Thank you for all the replies. I have things to think about for sure. I've tried H4350, R17, and Retumbo. I've been to 2900 fps but with pressure signs.
How much does jam/jump affect pressure and/or velocity? I try to use minimal jump.
P. S. I'm shooting Berger 140's.

 

[ShootDots]

Thank you for all the replies. I have things to think about for sure. I've tried H4350, R17, and Retumbo. I've been to 2900 fps but with pressure signs.
How much does jam/jump affect pressure and/or velocity? I try to use minimal jump.
P. S. I'm shooting Berger 140's.

I have a fair amount of experience with the 6.5 x 284 but not to the same degree that Chris has. But I will give you my 2 cents worth. It is MY opinion that the 6.5 x 284 is a fairly stout overbore and is better served with slower powders. With H4831SC you could do well. However, with H1000 I think you could do better! I tried Retumbo and got excellent velocity, however, my e.s.'s were in the 30f.p.s. range. There is a new host of powders out there these days. I would not hesitate to try RL-26. It is in the correct burn rate range, burns clean (from what I hear) and adds 40+ f.p.s. for the same pressure! It is at least well worth a try..

 

[FatBoy]

I wonder if you're dealing with a carbon ring? How many roujds down the pipe? Have you ever JB'd the throat?

I would take a look at what Ben is saying. My first 6.5x284 was a tight bore at 26". I had pressure issues for sure and recall that rifle shot at 2850. Swore off tight bores for over bores after that. If. 15 years ago n170 was about as slow as anyone went that I knew, with n165 being the AMU powder, and most of the rest of us shooting h4350 or h4831sc.

If you can get your hands on some slower powder, try it for sure. Worse that will happen is you're out $30 and get no extra MV.

Also, I run Retumbo in my 300WMs. I found that Remington 9 1/5Ms were the ticket to single digit ED. Not getting the speed I was hoping for with the 230 OTMs, but I am also running 26" so I have handicapped myself.

 

[Tucker65]

I just purchased a Cooper model 52 with a 26" barrel. I'm getting right at 3000 fps using 55gr of Reloader 26 with the Berger 140's 015 off the lands. I tried different seating depths and the worst group I got was about 5/8". 015 was the sweet spot with one hole group about the size of a 30 caliber hole. I haven't tried this load yet at distance yet but I'm hoping it will be good.

 

[JLT]

Thank you for all the replies. I have things to think about for sure. I've tried H4350, R17, and Retumbo. I've been to 2900 fps but with pressure signs.
How much does jam/jump affect pressure and/or velocity? I try to use minimal jump.
P. S. I'm shooting Berger 140's.

Give RL-26 a try in the 6.5-284. Start at 52 grains behind a 140 and work up to ~54 and you should start seeing the velocities you want. I'm well over 3,000 fps with RL-26 and 140s with no pressure signs at all.

 

[rifleman700]

I have a single shot Rem 40x rifle chambered in 6.5x284. It has an 8 twist Bartlien 5R Rem Sendero contour 26" length. I am contemplating rechambering it to 6.5 SAUM/GAP.
Is that possible? Is it worth it? I was thinking I could go for 3000+ fps vs. the 2800 fps I get now.
I have another 40x action with a magnum bolt face that I would mate the barrel to.
Thank you for your input.

With H1000 you will double your barrel life over a 6.5x284. Yes its that good. Call GAP and have them do your work. They have more history with the 6.5 4S than anyone. George pioneered the use of H1000 in it.

 

[markgrabowski]

Thank you for all the replies. I have things to think about for sure. I've tried H4350, R17, and Retumbo. I've been to 2900 fps but with pressure signs.
How much does jam/jump affect pressure and/or velocity? I try to use minimal jump.
P. S. I'm shooting Berger 140's.

Yeah there's something going on with the chamber if you are getting pressure signs at such low velocities. Carbon ring, too much neck tension due to neck wall thickness, etc. maybe you have a VERY fast lot of powder???

 

[Zero333]

I've had early pressure signs with a particular lot of Lapua brass. Tho my issue was with a 308win. But you never know.

First and second reload was normal and good. Third reload got heavier bolt lift with the same load that was good before. Dropped down 2gr to the next node. All was good for a few more reloads, and then started getting heavy bolt lift again as well as accuracy got very erratic.

Switched to Winchester brass and all we good again !

 

[Drop Port]

Thank you for all the replies. I have things to think about for sure. I've tried H4350, R17, and Retumbo. I've been to 2900 fps but with pressure signs.
How much does jam/jump affect pressure and/or velocity? I try to use minimal jump.
P. S. I'm shooting Berger 140's.

How many rounds are on the barrel? what were your pressure signs? What was the load data where you saw pressure?