barrel length and burn times

D

David N

Well-Known Member
Off shopping tomorrow. looking at powders for my T3 .223 20" barrel. planning on loading 50Gr Ballistic tip.

I know they shop does not have any N133 but has other powders. Since reading about reloading I have notice that people talk about burn times and unspent powder leaving the barrel or making the mod fowl.

Is it to simple to say a shorter barrel requires a faster load than a long barrel? I guess the optimum is to have all the powder burnt by the time it leaves the barrel. If it not just about the powder will different primers have an affect.

or am I over analysing and just get something there .
 
Yes you are overanalysing :)
See if your gun shoppe has Vihtavuori N130 which will cover you from 40 to 60grain bullets, it's quite a 'fast' powder and pretty much any primer will ignite it. I think you'd have to get things very wrong to have unburnt powder fouling the mod.
 
David N said:
Is it to simple to say a shorter barrel requires a faster load than a long barrel? …….

or am I over analysing and just get something there .
Click to expand...
With barrels becoming shorter and shorter this certainly is worthwhile a consideration.
RWS is even making a business out of it with their 'Short Barrel Ammunition'.
I've seen stub barrels as short as 16" because people want to limit the overall length incl. the moderator. But to my mind this is really overdoing it.

Personally I would not go any shorter than 20", for a 308 that is. For the .270 I feel that anything shorter than 23" would be a castration.
 
Rider said:
With barrels becoming shorter and shorter this certainly is worthwhile a consideration.
RWS is even making a business out of it with their 'Short Barrel Ammunition'.
I've seen stub barrels as short as 16" because people want to limit the overall length incl. the moderator. But to my mind this is really overdoing it.

Personally I would not go any shorter than 20", for a 308 that is. For the .270 I feel that anything shorter than 23" would be a castration.
Click to expand...

I wanted a short barrel rifle for woodland stalking. I chose the 308 because it’s perfect for this application.

16” barrel, 150gn @ 2700fps. Dropped a 170kg Red Stag without issue.
 
Some alternative suggestions:-
Alliant AR-Comp *C *T - 100.% case fill @ 24.6gns; M.V. 20inch barrel =3300fps; 99.% powder burnt in 20inch barrel; pressure 45000psi. (.223 SAMMI MAX 55000psi)

Alliant Reloder-10x *C - 95.8% case fill @ 23.0gns; M.V. 20 inch barrel =3250fps; 99.% powder burnt in 20inch barrel; pressure 48125psi.

This would be my choice and I do use this load in T3 rifle.
Vihtavuori N120 *C - 91.6% case fill @ 21.3gns; Chron'd M.V. 20inch barrel 3330fps; 100.% powder burnt at 15inches (a snipers dream); pressure 47000psi

Best Regards
RoyR
 
Last edited:
Rider said:
Personally I would not go any shorter than 20", for a 308 that is. For the .270 I feel that anything shorter than 23" would be a castration.
Click to expand...

If you regard barrel length by caliber 20" 308 would be equivalent to 14.5" 223. If by volume, 10.5" 223.

Above not considering case volume at all. I get very good velocity from 12.75" 223.
 
Rider said:
Oh, I'm sure it did. But with just a few inches more on the barrel your mod would live longer and even be more effective, which I find the more valid argument.
Click to expand...

I'm not suggesting it's a better option for everybody, but "MY" criteria, was the shortest practical barrel, where powder burn is nigh on 100%.

Noise may be louder, but it's never been loud enough to give a second thought. By how many shots do you think the life of a mod would be reduced, with a 16" barrel, as against a 20" barrel ?

There is no "right", or "wrong", just what suits you best.
 
Residues in the mod will be down to the chemistry of the powder and what is left after the burn. There is some unburnt powder that makes it out of the barrel with low pressure 'pistol' type chamberings. I have not looked into the higher pressure rifle rounds though, so can't comment on those.
Certainly pistol powders like Bullseye are filthy. You get a thick light grey mank over anywhere that the burn can get. Used to be a pain in the days of pistols.
Loading magnum powders in pistol cals can really throuw a lot out unburnt, if you don't have enough pressure. For example if loading below the starting load.
22rf can be as bad, for residue. In a semi auto, where the brass in on the way out whilst the burn is still going on, the deposits build up and turn any oil around the bolt into black paste. And what comes out of the end really builds up on the mod.

I did an experiment on an indoor range, after some concerns about unburnt powders being left on the range floor and the explosion srisk.
After a weekly clean up, where probably 50 shooters had been through, with mixed rinfire, 'pistol cal' rifles and muzzle loaders (loading 777). I took a sample and tried to burn it. There were a few twinkles from the odd flake of unburnt, but it really was a tiny amount.


Pistols themselves were not banned in the UK. But extra rules were added, that a firearm must be of a minimum size and barrel length. So effectivly banning them.
Till someone thought of putting a longer barrel on a pistol and a silly arm brace/counterweight, to get the length up.

The gun size restriction didn't apply to muzzle loaders, we've always had those.
And of course, someone started modifying modern revolvers with a ML cylinder, and we now have full power 357 revolvers, that just take a bit longer to load.
 
So have come back with Ramshot X-Terminator. No idea if its good, bad or indifferent but at £35 felt it was in my price range, will get me started and if any good easy to get more as its local.
 
Morning David N.
A suggested starting load for 223, with 20inch barrel, Ramshot X-Terminator; 50gn V-max; case trim length of 1.750"; assume Form Fired case capacity of 30gns, COAL 2.235"
Sammi Max pressure for .223 quoted at 55000psi

Starting Load.
Ramshot X-Terminator 24.8grains @ 93% case fill; estimated 42000psi @ MV 3020fps. powder burnt in 20inch barrel around 88% - expect about an 18inch flame out the end of barrel. If shooting daylight hours just moderator fouling. If shooting at night, every creature within 1/2 mile in front will know your position, especially if a second shot is required; as in dispatching a Vixen with fox cubs in tow. Dispatching the Vixen first, cubs are in disarray, and with no muzzle flash, I've dispatched 4 of the cubs before survival instinct kicks in and the remaining cubs scarper. One time a cub actually ran towards me - dispatched. Try doing that with an 18inch flame, muzzle flash!

Working load. (slowly work up to this load, checking for any over-pressure signs)
Ramshot X-Terminator 25.9grains @ 96.7% case fill; estimated 48000psi @ MV 3150fps. powder burnt in 20inch barrel around 91% - expect about a 14inch flame out the end of barrel.
Personally, I would not use this powder, I believe there are better choices for 223 with 50gn V-Max.

Please feel free to ignore all the above!

Best Regards
RoyR
 
Last edited:
This is just my understanding of it based on my own experience and reading up, but hopefully its of some use.

If you take it to extremes pistol powders are really fast burning and are designed to get a bullet up to speed really quickly in a very short barrel, and the cartridge cases are very open - There is no shoulder and the case is not wine bottle shaped, its just a straight walled almost bucket like shape. This means that the very fast expanding gases can get out quickly, act on the projectile quickly and you dont end up with over pressure.

Then if you go the other way with cartridges like .25-06 which are a large case capacity with a small bullet you need a slower burning powder to avoid over pressure (If you were to use a faster powder you might blow the gun up as the gases cant get out the small case neck quickly enough) and a longer barrel in order to allow the powder to keep acting on the bullet for longer.

The powder usually will all burn but if you cut the barrel down shorter then you'll get a lot of muzzle flash, snappy recoil and a lot of noise, plus sub optimal velocity. If the powder has all been able to burn in the barrel then you have attained peak velocity and whats coming out the end is just exhaust gas and no flame.

This is why .25-06 is often a 24" barrel and most of the complaints I've read about the cartridge being too loud or unpleasant to shoot have been from people who have a 22" or shorter barrel.

Equally .308 is a relatively smaller case with quite a big neck so you can use a faster powder in this than you would in .25-06, but still not as fast as you would use in a pistol. And you can often find .308s in 18-20" barrels.

Hope that was of some use and those in the know feel free to correct me if I have anything wrong!
 
You must log in or register to reply here.

Similar threads

308 with 18" barrel load data help needed
Replies
17
Views
2K
Strike
S
For Sale: BR2 LR, CCI-400 SR and Small pistol Primers - Lots of Brass - Lots of Powders + more
2 3 4
Replies
61
Views
9K
Razzdogg
R
Quickload / GRT - powder choice/data question...
Replies
6
Views
1K
Qwertyzmate
Qwertyzmate
Owt better than 308 for short barrel?
2 3 4
Replies
61
Views
6K
tim@tcs
tim@tcs
.22LR barrel length and rifle options
Replies
12
Views
2K
suburban bushwacker
suburban bushwacker
New Avon Arms
Back
Top