Joules

[Pewpewpetie]

Hi all, I'm currently on a dmr build and my local site allows 420fps/ 1.68j on a .2g bb or 290fps/1.68j on a .43g, if the barrel is over 457mm/18inches. My question is which would get a better effective range? The longer barrel on .43 or the shorter.

[Asomodai]

Shorter. Longer barrels struggle to move and hop the heavier the ammo you go. 

[Iceni]

You would see a slight difference in a long and short barrel, but nothing that would prevent the gun functioning.

@400fps you are in stock USA gun values. All the guns we can buy at 350fps, well they sell just as well over the pond at 400fps. In fact, the guns we buy are typically downgraded to 350fps (TM Excluded).

Shorter/Longer barrel it makes very little difference provided it's volumed correctly to the gearbox. A longer barrel will have a slight FPS increase but it'll be marginal.

Heavier ammo is always a problem for AEG's. To hop it you need harder buckings so they don't wear out as fast, but also more accurate hop control so you are not constantly over/under hopping. It's why hops that can be locked in position are king in bolt action guns. Do you need that @400fps, nope. Simply moving from soft 50-degree rubber to a slightly harder 60 degree should be more than enough. If you find the 60 wears quickly then you simply go up in hardness again to a 70.

You are not going to be able to hop sniper weight BB's in an AEG based DMR. 0.43g BB's might have the weight but they certainly don't have the speed at 290fps. Add in distance and you will have many problems trying to hit a target. A more realistic value would be 0.3 - 0.35g BB's that will keep the gun over 310fps.

A bolt action shooting at 500fps with 0.2's (2.37J ) is still getting 350fps with 0.4g bb's. It's the combination of the speed and weight that work.



The best modification you can make outside of the hop rubber, inner barrel and mainspring would be a Pre-cocking mosfet. It'll take the gun and make it instant. 

I personally don't feel there is any reason to go beyond this, and upgrades to 400fps DMR specs for the UK market are pretty much just clever marketing to make you part with cash for no reason.

 

[Adolf Hamster]

Cant hop sniper weight bb's at 400fps?

 

*Looks at 1j m4 that can lob .48's*

[Iceni]

8 minutes ago, Adolf Hamster said:

Cant hop sniper weight bb's at 400fps?

 

*Looks at 1j m4 that can lob .48's*

Those BB's are travelling so slowly that by the time they get there the game has ended. What are you chronoing those at 210fps?

I don't think I would even attempt to play at that speed, nevermind advise it. I'd love to see the video tho - feel free to post your kill cam with it.

[Adolf Hamster]

32 minutes ago, Iceni said:

Those BB's are travelling so slowly that by the time they get there the game has ended. What are you chronoing those at 210fps?

I don't think I would even attempt to play at that speed, nevermind advise it. I'd love to see the video tho - feel free to post your kill cam with it.

 

Still a lot faster than folk can run.

 

You just learn the lead and it's fine, you wont be hitting the ferrets running crosswise between cover but the whole point is that your far enough back you have team mates in between.

[Pewpewpetie]

9 hours ago, Iceni said:

You would see a slight difference in a long and short barrel, but nothing that would prevent the gun functioning.

@400fps you are in stock USA gun values. All the guns we can buy at 350fps, well they sell just as well over the pond at 400fps. In fact, the guns we buy are typically downgraded to 350fps (TM Excluded).

Shorter/Longer barrel it makes very little difference provided it's volumed correctly to the gearbox. A longer barrel will have a slight FPS increase but it'll be marginal.

Heavier ammo is always a problem for AEG's. To hop it you need harder buckings so they don't wear out as fast, but also more accurate hop control so you are not constantly over/under hopping. It's why hops that can be locked in position are king in bolt action guns. Do you need that @400fps, nope. Simply moving from soft 50-degree rubber to a slightly harder 60 degree should be more than enough. If you find the 60 wears quickly then you simply go up in hardness again to a 70.

You are not going to be able to hop sniper weight BB's in an AEG based DMR. 0.43g BB's might have the weight but they certainly don't have the speed at 290fps. Add in distance and you will have many problems trying to hit a target. A more realistic value would be 0.3 - 0.35g BB's that will keep the gun over 310fps.

A bolt action shooting at 500fps with 0.2's (2.37J ) is still getting 350fps with 0.4g bb's. It's the combination of the speed and weight that work.



The best modification you can make outside of the hop rubber, inner barrel and mainspring would be a Pre-cocking mosfet. It'll take the gun and make it instant. 

I personally don't feel there is any reason to go beyond this, and upgrades to 400fps DMR specs for the UK market are pretty much just clever marketing to make you part with cash for no reason.

 

Currently running a zci 363mm barrel with flat hopped prowin and easily lifting. 4g at 415fps on. 2g. My question is would the longer barrel firing. 43g at 290fps be any better

[Samurai]

Barrel length doesn't matter if the volume is balanced for it.

 

Aim for a 320-350 fps with the weight you use, that's the sweet spot. So if your gun shoots harder, increase the BB weight so it shoots this fps. Then balance the barrel/cylinder volume for it. Barrel length over about 300mm won't give you anything extra.

[Pewpewpetie]

30 minutes ago, Samurai said:

Barrel length doesn't matter if the volume is balanced for it.

 

Aim for a 320-350 fps with the weight you use, that's the sweet spot. So if your gun shoots harder, increase the BB weight so it shoots this fps. Then balance the barrel/cylinder volume for it. Barrel length over about 300mm won't give you anything extra.

320 with. 4g? Site limit is 415fps and will be way over as they test the shorter barrels on. 2g