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-   -   Factoring barrel heat in match loads? (https://www.calguns.net/calgunforum/showthread.php?t=1510147)

smoothy8500 02-10-2019 10:19 PM

Factoring barrel heat in match loads?
 
Considering barrel heat and course of fire in F-class, or especially PRS where quite a few rounds are fired within 120 seconds, is incorporating a hot barrel part of load development? I have always "warmed up" a barrel with a handful of sighters before doing any load testing. Part of the load development is running test loads round-robin at a slightly faster pace than what would be experienced at a match. I would think seeing how the rifle/loads shoot "hot" would be a more accurate representation of performance on a match.

Kwikvette 02-11-2019 7:21 AM

Tag

longrange1 02-11-2019 1:58 PM

i DO NOT...if your having POI shifts as the barrel heats up you need to run a heavier contour...if your running a heavy contour and having POI shifts theres something else going on...from cold bore to 35 rounds shot back to back ive never had POI shifts unless the round sits in a hot chamber for 30+ seconds.

smoothy8500 02-11-2019 5:58 PM

Quote:

Originally Posted by longrange1 (Post 22654476)
ive never had POI shifts unless the round sits in a hot chamber for 30+ seconds.

No changes in POI except for hot chambered rounds like you mention. I was just curious since I see a lot of posts where people are concerned with keeping the barrel cool between shots regardless of barrel contour.

longrange1 02-12-2019 4:16 AM

heat is what kills barrels so thats more of why they are doing what they can to cool barrels between strings.
as you probably know in F-class when the flags drop its like 20 rounds of machine gun fire so those big bore barrels get hot fast especially when its 80-100deg and is also why they are changing barrels around a 1000 rounds.

im building a 6BR right now...it will be my tactical rifle so that i can try and get a little more barrel life out of my BRX...ive found over the last couple of years that using the same rifle for 3 different types of shooting kills barrels pretty quick and a few have gone prematurely.

smoothy8500 02-12-2019 5:50 AM

Quote:

Originally Posted by longrange1 (Post 22656453)
as you probably know in F-class when the flags drop its like 20 rounds of machine gun fire so those big bore barrels get hot fast

Yes, heat is an unavoidable issue in most competition.


Quote:

Originally Posted by longrange1 (Post 22656453)
im building a 6BR right now...it will be my tactical rifle

Just curious how you are getting consistent ejection. I built a 6mm BR NRA prone (sling shooting) and the short cases pop out of the Rem 700 extractor early due to the extremely short length. Not an issue since there's no "rapid fire", but I would think in other comps it would be an issue.

longrange1 02-12-2019 6:45 AM

i do not run factory actions...im running curtis customs actions with mini 14 extractors...ive shot 6.5x47-6CM-6BRX on this action with no issues with anything..before this i had a surgeon 591 and never had any issues with it.

i have not actually shot the BR yet but i dont see it being an issue.

LynnJr 02-15-2019 8:23 PM

Something is wrong if you can't cycle a 6BR case out of your gun. I ran a 700 at the nationals one year and the cases flew right out.
300 Whisper brass is another story.
It's thin and short so if you cycle it slow the case mouth sits at 3 O'clock and will pop out of the extractor.
If your shooting a hotrod cartridge you will get sticky bolt lift at around shot 7 or 8 if your running them as fast as possible. That's why some chamberings that work in some disciplines don't get used in other disciplines.
If your running a 6BR heavygun with 30 grains of powder in 30 seconds for 10 shots your putting 300 grains of powder down the barrel. I don't know the BTU per grain of powder in Varget but it is most likely around 4000.
If your running a 6mm-06 at 57 grains of H1000 that's almost double the powder down the same size bore and roughly double the number of BTU's.

OpenSightsOnly 02-16-2019 6:50 AM

Quote:

Originally Posted by smoothy8500 (Post 22656545)
I built a 6mm BR NRA prone (sling shooting) and the short cases pop out of the Rem 700 extractor early due to the extremely short length. Not an issue since there's no "rapid fire", but I would think in other comps it would be an issue.

Folks who use 6BR for XTC, Eliseo R5, have the Sako extractor.

smoothy8500 02-16-2019 8:19 AM

Quote:

Originally Posted by OpenSightsOnly (Post 22673026)
Folks who use 6BR for XTC, Eliseo R5, have the Sako extractor.

Yes, they come out ok when ejected quickly and slow extraction is the issue. The Sako is an option I looked at. Another is "lengthening" the stock ejector pin by moving the roll-pin notch back .015 to .030 inches allowing it to stick out further from the boltface.

longrange1 02-17-2019 4:13 AM

why not just buy a piece of spring stock and make the ejector spring slightly longer that would make it stronger or if its an older action with lots of rounds through it replacing it with a new factory spring may do the trick

smoothy8500 02-17-2019 9:36 AM

It seems the poor ejection of the 6BR is pretty well documented with "longer" ejector fix as the common solution. Here's a pretty good explanation.

http://forum.accurateshooter.com/thr...shers.3883455/

longrange1 02-21-2019 9:39 AM

Quote:

Originally Posted by smoothy8500 (Post 22676719)
It seems the poor ejection of the 6BR is pretty well documented with "longer" ejector fix as the common solution. Here's a pretty good explanation.

http://forum.accurateshooter.com/thr...shers.3883455/

thanks smoothy if i have the ejection issue i will try this but like i say i run axiom actions...they are 3 lug so i dont think the neck will ride in the lug race...if it will quit snowing for a minute my smith will get my barrels done.

smoothy8500 02-21-2019 3:13 PM

Nice!


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