284 win getting low velocities

Hello you lot,


What sort of velocities are you guys with short barrels (17 inch)? rifle is a Tikka t3 7mm08 re-chambered.

I'm only getting 2640 fps over the chrono and load is 51.5gr of Reloader 17, fed 210 primer, norma brass and 162 ELD-m. This load is definitely hot in this barrel with extractor marks at 52.5gr during development.

I've been hoping to get around 2800 fps no cigar yet.

Any tips? the rifle isn't as long throated as long as some i've seen on here but would that make much difference?

magnum primers worth a try?


Cheers

The .284 is an overbore cartridge and is designed for longer barrels with moderately slow powder (factory ballistics are based on 24" barrels). You could carefully work up some loads with a slightly faster powder but you are never going to reach factory velocities with a 17" barrel. 2600 fps is a perfectly respectable velocity for anything out to 250-300 metres.

Who rechambered it, what is the neck diameter of your chamber, and what brass are you using abd what's the diameter of the neck on a loaded round.

I've been thru all of this with my 17" 284 and finally sorted it. I run a 162g Amax at 2700 now, which goes very well.

I opted to use the tight neck reamer .317. And after necking up 6.5-284 lapua brass, the base of the neck measures .319. It needed neck turning right down into the shoulder to remove that thicker section from where some of the shoulder material was formed into the base of neck.

the short barrelled 284 win has become somewhat of a trend here as its pretty efficient and can work well in a short barrel.

the rifle is built to shoot up to 600m or so which should be quite doable.

thanks for the tip though mate!

your original posts on your 284 was one reason that I wanted to do the conversion! rifle is set up similar to yours.

Greg at custom guns in Invercargill did the chamber and the throat isn't a tight neck. I wanted a little more room to play with with different brands of brass/ I don't have a neck turning set up.

Brass is factory Norma .284. can check diameter of a loaded round tomorrow

Measure the neck diameter of the fire cases, then measure the neck diameter of neck with bullet seated and pm me. Happy for you to call me for a chat about it all.

That does seem a little slow. That said, it is only a 17 inch Barrel and 2650 with the eld m is still plenty to reach out to 500.

Norma brass is softish and I notice does tend to stamp a little easier than lapua.
If it shoots as is I wouldn't worry. Animals not going to no5ice that extra 50 fps

Have you verified your fps by shooting at range?
My Chrony reads 70-75 fps slow under all conditions.

I’d agree a 162 travelling that ‘slow’ is still fast...

hi kiwi303.

I have a 284win 20 inch tikka 7mm08 barrel, gun works did the work. only managed about 2670 with 51.5 gr rl17 hitting pressure signs.
that was lapua brass necked up. seems low like yours compared to what others have been getting, a suppressor for me might increase it a bit. i assume yours is suppressed? I'm planning on trying 2213sc so will let you know how that goes, can't imagine it going much faster.

How will adding a suppressor increase velocity?

I've heard of it increasing velocity, weather its true or not I'm unsure. some guy at a gong shoot was claiming 90 fps increase on his rem mag. i will find out when i get one for my 284.

Quote:

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Originally Posted by c-dog

hi kiwi303.

I have a 284win 20 inch tikka 7mm08 barrel, gun works did the work. only managed about 2670 with 51.5 gr rl17 hitting pressure signs.
that was lapua brass necked up. seems low like yours compared to what others have been getting, a suppressor for me might increase it a bit. i assume yours is suppressed? I'm planning on trying 2213sc so will let you know how that goes, can't imagine it going much faster.

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Read my posts above about neck diameter in your chamber.

Hey GWH, did your right neck affect pressure/velocity? Did you have trouble chambering them before neck turning?

Tight neck

GWH
The fired neck was about .313 and about .311 with bullet seated. Its hard to get an accurate reading measuring the top of the shoulder as it is hard to see weather its ment to be the shoulder taper or not towards the neck. It does.increase slightly so maybe neck turning will help drop the pressure.

In response to the discussion about the need for neck turning, -presumably the only reason to do this is if you get pressure signs with loads that are well under what should be a maximum load?

I have a 16” 284 which I am struggling to get decent velocities from. Currently up to 55g of 2209 with a 140g Sierra GK and only getting 2650. Super-accurate and no pressure signs but seems to be a lot of powder for modest velocity. My 23” 7mm08 gets more speed with the same projectiles and only 41g of 2208. Am not completely confident in my chrono but even with a bit of error it is still slow. Will try re17 next.

Quote:

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Originally Posted by stevodog

Hey GWH, did your right neck affect pressure/velocity? Did you have trouble chambering them before neck turning?

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Yes i got excess pressure signs (heavy bolt and case head stamping) at very low powder loads. Once i turned the necks right down into the shoulder i could then run a more normal (higher) powder load and sure enough increased velocity without seeing the excess pressure.

Quote:

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Originally Posted by rossm-96

In response to the discussion about the need for neck turning, -presumably the only reason to do this is if you get pressure signs with loads that are well under what should be a maximum load?

I have a 16” 284 which I am struggling to get decent velocities from. Currently up to 55g of 2209 with a 140g Sierra GK and only getting 2650. Super-accurate and no pressure signs but seems to be a lot of powder for modest velocity. My 23” 7mm08 gets more speed with the same projectiles and only 41g of 2208. Am not completely confident in my chrono but even with a bit of error it is still slow. Will try re17 next.

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man this one is really a case of trying to reinvent the wheel isnt it...... guys have used longer barreled rifles with run of mill cartridges for ....well for ever to keep velocity high.remember fellas used .303 with full length barrels to do some rather long shots back in the day...not the ones that had been cut down for bush work.
you can go so far by changing case...but only so far....
guess its a bit like changing motor and tyres on a car but leaving gearbox the same.....

Quote:

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Originally Posted by c-dog

GWH
The fired neck was about .313 and about .311 with bullet seated. Its hard to get an accurate reading measuring the top of the shoulder as it is hard to see weather its ment to be the shoulder taper or not towards the neck. It does.increase slightly so maybe neck turning will help drop the pressure.

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Is that .313 on a fired case neck before resizing, if so you have an extremerly tight chamber, like a very tight match chamber. Might pay to re-measure.

Quote:

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Originally Posted by rossm-96

In response to the discussion about the need for neck turning, -presumably the only reason to do this is if you get pressure signs with loads that are well under what should be a maximum load?

I have a 16” 284 which I am struggling to get decent velocities from. Currently up to 55g of 2209 with a 140g Sierra GK and only getting 2650. Super-accurate and no pressure signs but seems to be a lot of powder for modest velocity. My 23” 7mm08 gets more speed with the same projectiles and only 41g of 2208. Am not completely confident in my chrono but even with a bit of error it is still slow. Will try re17 next.

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That is very slow, im at 2700 fps with the 162 Amax in my 17" 284 with 52.5gr of H414. And have run up to 54gr of 2209 with the 162 amax.

Great thread...hope you guys get your 284s cooking soon. Thanks for the schooling on neck size and turning GWH.
The necks on mine are even through to the shoulder at 0.3230 so I guess I can rest my wee brain now.
Out of interest, what neck turning gear are you using?

So unless requested otherwise, why don't gunsmiths do .284 chambering with bog standard not shit and ordinary reamers that match ordinary off the shelf dies?

Quote:

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Originally Posted by Tahr

So unless requested otherwise, why don't gunsmiths do .284 chambering with bog standard not shit and ordinary reamers that match ordinary off the shelf dies?

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AS far as im aware they do, when i found out the smith had two reamers (saami spec .321 and the tighter neck of .317) i opted for the .317, as over the years the 284 brass has got thinner on the necks for some reason, and i notice on my other 284 with the .321 neck that the necks get over worked alot fire forming all the way out from .313 to .321 and ive had some split the necks, annealing obviously helps.

So i thought id go with the tighter necked reamer to work in better with the brass that's available today. There is also a different in the 'lead' of that reamer to i believe.

I was told that they cut different chambers for modern bolt action rifles vs the older lever actions that the 284 was designed for. Not sure if that explains why some bolt action chambers are cut so tight.

Thx for all the replies to my earlier questions.

Quote:

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Originally Posted by rossm-96

In response to the discussion about the need for neck turning, -presumably the only reason to do this is if you get pressure signs with loads that are well under what should be a maximum load?

I have a 16” 284 which I am struggling to get decent velocities from. Currently up to 55g of 2209 with a 140g Sierra GK and only getting 2650. Super-accurate and no pressure signs but seems to be a lot of powder for modest velocity. My 23” 7mm08 gets more speed with the same projectiles and only 41g of 2208. Am not completely confident in my chrono but even with a bit of error it is still slow. Will try re17 next.

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Yeah that seems super slow. I'm at 2750 in a 19 inch Barrel with the 162's and 52.7 414. 55gr 2209 sounds light behind a 140. Maybe stoke her up a bit.

Adi lists max load for 2209 and a 140 as 57 gr. They have it as a compresed load. Maybe try 2208 or go to a heavier projectile get that pressure up a bit. Will be shooting alot of unburnt powder out the end with that 2209 load.

The 284 is best with 150gr plus imo

Thx Nick. That max load data from the adi website is different to my nick Harvey book which lists the max for 140g prom with 2209 as 54.5.will have to use the adi data in the future.

Anyway have loaded some 150g Sierra GK’s with Re17 to see how that goes. I am still wary that my cheap chronograph is under- reading but can’t be more than 50-100 FPS.

Cheers Ross

Quote:

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Originally Posted by rossm-96

Thx Nick. That max load data from the adi website is different to my nick Harvey book which lists the max for 140g prom with 2209 as 54.5.will have to use the adi data in the future.

Anyway have loaded some 150g Sierra GK’s with Re17 to see how that goes. I am still wary that my cheap chronograph is under- reading but can’t be more than 50-100 FPS.

Cheers Ross

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Yeah the 150's over rl17 will get things humming. Fella on the other forum getting 2900ish with the same load

Quote:

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Originally Posted by Nick-D

Adi lists max load for 2209 and a 140 as 57 gr. They have it as a compresed load. Maybe try 2208 or go to a heavier projectile get that pressure up a bit. Will be shooting alot of unburnt powder out the end with that 2209 load.

The 284 is best with 150gr plus imo

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That's the exact load I get. I could go a bit faster, but this was best accuracy wise that I was happy with. 57gr or 2209 gives me 3040fps out of a 19.5 inch barrel using a 140gn Berger VLD Hunting..

I had pressure at low speeds on mine, was getting an internal donut at the neck/shoulder junction, neck turn and cut slight relief into this area to let brass flow into void and prevent buildup on inside. Been a couple of guys on here with same issue and same fix

Quote:

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Originally Posted by distant stalker

I had pressure at low speeds on mine, was getting an internal donut at the neck/shoulder junction, neck turn and cut slight relief into this area to let brass flow into void and prevent buildup on inside. Been a couple of guys on here with same issue and same fix

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Yep same, here's my original post about my problem https://www.nzhuntingandshooting.co....chamber-32589/

Quote:

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Originally Posted by GWH

Yep same, here's my original post about my problem https://www.nzhuntingandshooting.co....chamber-32589/

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Lol on my phone and didn’t see there was another page with solution already posted ��

Quote:

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Originally Posted by Nick-D

Yeah the 150's over rl17 will get things humming. Fella on the other forum getting 2900ish with the same load

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Progress report: Managed to get to 2750fps with 53.5g Re17 and 150g SGK. Still very accurate (.5 moa). Got pressure signs at 54 (sticky bolt but no issues with doughnuts in the case neck.) This is a good improvement on the 2209 loads but I still need to verify the chrono by measuring real drop vs predicted drop at longer range. Thx again for all the help. Ross

I reckon you'll find your chrony is slow. Gunwerks have a good free ballistics solver/truer on their website that you can use to true velocity

Thx. Had a look at gunwerks. That will be a big help!