.243 minimum loads

[kbfife]

Hi Guys,

 

In my .243 I have been mainly using the lighter weight bullets in the 55gr to 70gr range, and have been generally loading them up to and near to the maximum powder charge. Some freinds of mine have made me conserned about the wear these fast bullets are causing to my barrel. So because these fast loads are not really needed as I dont shoot past 200m, what I want to know can I load a box of nos bt 55gr .243 with a charge of Varget that is below the recomended minimum dose?

 

Whats the thoughts on loading below the recomended minimum loads in general, in an attempt to reduse barrel damage?

 

Thanks

 

Keith

[1967spud]

if you go to far below lowest load needed you can run in to dangerous pressure probs, i ould run them at either minimum stated loads or just above but never below them, as for wearing out your barrel yes the light bullets travelling faster will wear it quicker as you are using more powder( its the powder that wears the barrel not the bullet) but they should shoot tighter groups and flatter

 

its often said that the most accurate loads are some times the highest or just below in the pressure curve i.e. near maximum stated loads

 

if you are shooting live animals you owe it to them that you are using the most accurate load you can acheive fior that gun/bullet combo

 

 

just be cautuos though what may be a maximium load in your mates gun may not be in yours always always work your loads up

[Andrew]

The best powder for reduced loads is IMR or H 4895. One of it's hallmarks -now largely ignored in the quest for Fast- is that you can safely load it to 3/5 (60%)of whatever is listed as a maximum load.~Andrew

[njc110381]

I don't understand why people try to get the absolute maxmum power from any given calibre? Ok if it gives the best accuracy and you need that then fair enough, but unless you're shooting a comp does it really matter if you are shooting MOA or half MOA? Either way it's a Dead target inside 200 yards or more.

 

I run all my guns at just over start load. All my rifles shoot MOA or better. Once my factory ammo for the .338 runs out I'll probably load it very lightly. As long as it shoots ok it really doesn't need to be running at full throttle!

[Mash67]

matters if your trying to shoot a crow at 400yrds

[njc110381]

But he's not!

[Andrew]

Reduced loads save barrels, brass, and can be just as effective as full power loadings if game and range is adjusted. I've been shooting them all of my life.~Andrew

[Laurie]

Keith,

 

Hodgdon produce a list of 'Youth Loads', ie lighter bullet and slightly reduced charge loads to reduce recoil and it's available on their website under the 'Data' menu on the homepage

 

Hodgdon Reduced Loads

 

Most Hodgdon reduced loads use H4895 as mentioned by Andrew which is a very flexible powder in these applications in this cartridge size, so you can safely drop down a lot from the usual maximum for that powder with whatever bullet is being used - 20% reduction would be a good starting point. A downside can be badly sooted cases because of poor case obturation in the chamber, although sometimes changing primer make and model can overcome this.

 

The normal rule for safe, efficient, and accurate light loads is to 1. use the lightest bullet that is suitable for the quarry, 2. use a slightly faster burning rate powder than would normally be used with such bullets. So if you'd normally use Viht N160, see if you can find a listed load for that bullet weight with N140, then go for the starting load, or starting load minus a little.

 

With the sort of bullet weight you're using I had very good results in a .243 Ex-police Parker-Hale M87 tactical rifle a few years back with Viht N130, a powder that would normally be regarded as far too fast burning for the .243. It gave superb accuracy with the 70gn Sierra HPBT MatchKing target bullet.

 

Your friends are way off line in telling you that you'll wear your barrel out faster with high velocity light bullet loads. Assuming suitable powder grades and charges are used for both light and heavy models, the primary determinant of wear and tear and barrel life is the pressure they produce. Barrels fdon't wear out though friction but through the effects of intense heat and pressure on the throat area that affects the barrel steel at the the molecular level. In fact, if a 55gn load at 3,800 fps and a 100gn load at 2,900 fps require the same maximum chamber pressures (but using different powders vis a vis burning rates), the heavy bullet load will wear the barrel out significantly quicker. This is because the heavy bullet has more inertia and takes longer to start moving down the barrel so the throat is treated to high pressures and temperatures for a longer period. Also, the heavy bullet needs a slower burning powder to stop pressures peaking too quickly before the bullet is moving fast down the barrel, but this has the effect of extending both the time the barrel is subjected to peak stress and the length of throat / barrel subjected to it. This can be quite marked in cartridges that see users handload large variations in bullet weight, such as fast twist barrel .223 Rem where a shooter might routinely switch between 55s , 69s, 75, and 80s. The higher the percentage of 80s through the barrel, the faster its throat erosion.

 

Load light bullets, and keep pressures down and barrel life can be significantly extended.

[1967spud]

well put laurie

[kbfife]

Some very good information there guys, thanks for taking the time to explain it to me.

 

So rule of thumb would seem to be use a light bullet with a light charge of a fast powder? For giving long barrel life.

 

 

Because my tikka t3 has a short barrel only 20" in the .243, would it be wise to use fast powders anyway to ensure a complete burn?

 

The rifle is mainly used for foxes out to a max 200m, so I quite like the 65grn VMax and 55grn BTip. Is Varget a good powder for this weight of bullet? I have H414 aswell, but I think thats for the heavier bullet weights.

 

 

Regards

 

Keith

[1967spud]

i use 414 for a 55 g nosler and its fairly potent

[Laurie]

So rule of thumb would seem to be use a light bullet with a light charge of a fast powder? For giving long barrel life.

 

The best rule of thumb is to use the right bullet for whatever you're shooting at and a suitable powder. If light bullets suit your shooting, and from what you say, they obviously do, then stick with them as your mates' view that you're wearing your barrel out fast is simply wrong.

 

Barrel length and powder burning rate is generally speaking not that much of an issue providing the loads are sensible, or unless the barrel is really short. Slow burning powders can still produce high MVs in this situation, but they don't give 100% burn, so you usually get a much louder muzzle blast, and potentially flash too.

 

For interest, I ran five powders through QuickLOAD with the 55gn Nosler BT in a 20" barrel with loads at two charge levels - a low one that gives a light, low pressure load around 40-44,000 psi and a full pressure one that gives 55-57,000 psi to see what the powder burn percentage runs at.

 

AA-2015 35.6gn......3,135 fps......99.1% burn

40.5gn......3,489 fps.......100%

 

Viht N135 39.5gn.....3,209 fps......99%

43.5gn.....3,495 fps.....100%

 

Viht N140 40.5gn.....3,229 fps.....98.2%

44.0gn.....3,477 fps.....99.2%

 

H4895 40.0gn.........3,263 fps.....94.3%

43.5gn..........3,531 fps....97.8%

 

Varget 41.5gn.........3,250 fps.....93.1%

45.0gn........ 3,511 fps.....96.8%

 

H414 45.5gn ...........3,258 fps ... 88.2%

49.0gn .......... 3,531 fps.....93.0%

 

 

You can see that with a light bullet, you get a little extra velocity with the slower burning powders, but at the expense of using a lot more and from Viht N140 onwards with a less that 98 or 99% burn rate, especially with the starting or low load. Remember, all charges listed give similar maximum pressures, so are pretty well equivalent in this sense.

 

Accurate Arms 2015 is a short-stick powder that is a fast-burner lying between H/IMR-4198 and Reloder 7 on the fast side and H322 / Viht N130 on the slow side, but is very flexible in light loads or light bullet loads.

 

With a near 100% burn in 20" of barrel at only 39,600 psi pressure you can see that light bullet / light load works really well with a fast-burner like this while H414 needs another 10gn of powder to run at 44,000 psi and give another 100 fps MV, but only 88% is burned. The odds are that this load won't work very well at these pressures and burn rate.

 

NOTE - these are QuickLOAD results, only a computer model at the end of the day, and not guaranteed to work or even be safe in real life, but it's usually pretty close in the .243.

 

Personally, I'd say Varget is a little on the slow-burning side for the 55s and won't be far out for the 65s. In either case, it should give you pretty good results, so as long as the rifle shoots well, I wouldn't buy anything else unless you can't resist a bit of experimentation - and that way lies damnation, or at any rate, shot-out barrels!

 

I hope these thoughts help.