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View Full Version : Barrel length/ powder burn rate?



CYanchycki
09-10-2008, 03:16 PM
Here is the gun. Rem 700 243Win with 20" barrel 9.25"twist. It stabilizes 105 A-Max no problem at 200 so I take it they should be okay out further. Will find out possible this weekend.

What I want to understand is what dictates the choice in powder selection for a given weight bullet. I mean in theory according to the reloading manuals one uses a faster powder for the lighter bullets and as you go up in weight the powder choice goes to a slower burning powder.

What effect does the length of the barrel have on this choice?

Say using RL 22 in a 20" tube versus a 24" tube. The longer tube should burn better and more efficient than the shorter would it not? Or is the length a non issue when soosing the powder?

H4831, RL22, RL19 are a few choices for the heavy bullets in the 243.

Since I have a short barrel I do not think I will be able to get up to around 2950 without geting into the extreme load ends with the short barrel. I am hoping I can make it to 2900 and I would be quite happy.

I hope it makes sense what I am trying to put across.

Calvin

jackie schmidt
09-10-2008, 03:43 PM
The rules haven't changed. If you want to go faster, more powder behind the bullet will do the job. But, that dictates a slower burn rate, which in turn dictates a longer barrel.

It is no big chore to push that same A-MAX 105 grn bullet 3000 fps out of a 6BR with a 1-8 twist and a 28 inch barrel. That says something about efficiency.

If your bullets are stable at 200, they will continue that way all the way to sub sonic velocity. The bullet has no idea what the barrel length is, it just knows velocity and twist rate.

With your short barrel, powder selection will be criticle, maybe one of the VV hIgh Energy powders, (N540-N550), would be the hot ticket. 2900 certainly seems reasonable.

But like I said. Free lunches are hard to come by. Reloader 22, 4831, etc are probably too slow with you 20 inch barrel, the muzzle blast might sound like 3000+ fps, but a Chrono would probably tell a different story.........jackie

CYanchycki
09-10-2008, 06:26 PM
I kinda thought that. Just wanted to be sure that I was not thinking wrong.

The gun is actually for Coyotes mainly. It is the Rem 700 youth model. Shorter stock 12", short barrel 20". It is compact and light plus easier to shoulder with about 6 layers of clothes when it gets -30deg celcius.

I have a good 55gr load for coyotes and wanted to work up a good heavy load for whitetails.

Easier to carry and shoot than my 30-06. I am a recoil Wuss.......

Calvin

expiper
09-10-2008, 07:01 PM
Hi Carl...I have shot a few .243's over the years...and many with short bbls...and 4895 is excellent.....and of cours try 4350...it is the old standby in a 243....Roger

Cliffy
09-10-2008, 08:14 PM
Hodgdon H4350 is only slightly slower-burning than IMR 4350, yet staying inside an inch at a 100 yards with a .243 Winchester caliber remains easy with light bullets. I like Barnes 62 grain Varmint Grenades for coyote, yet I'm sure better combos exist for Benchrest competition. For a really slow-burn I've used Alliant RL-25, but velocity is sacrificed for recoil felt as a smooth push. RL-22 is best left for 100-105 grain hunting bullets. H4350 is velocity-hound's powder, and I love it. cliffy

CYanchycki
09-10-2008, 09:02 PM
2900 certainly seems reasonable.



2950 was no problem either out of the 20" barrel. I may try up to POSSIBLY another 1/2 gr but that would be about it for RL19.

With that light sporter weight barrel and that much powder 3 shots is all she can handle in a row. Pretty toasty to the touch. If a round sits in the chamber for a while she cooks and the velocity gives a slight jump, enough to start to feel a bit of bolt lift.

Will be okay by time our deer season comes around.

Anyways thanks again for clarifying for me Jackie.

Calvin

Chisolm
09-10-2008, 10:05 PM
FYI
I was getting 3/4" groups at 200 yds with 105 A-maxes at 2900 out of a 10 twist and when I went to 600 only 2 out of 5 would make it on the paper. No problems with 87 V-maxes though.

James