Varget gr. variance yields same result:more experimenting

[ronas]

Rifle is OBR 556 with 16" barrel. I sometimes shoot this rifle to 600 and 800 yards. Bullet is 77gr Nosler Custom Competiton. FPS for 77 gr. is around 2450 with 24 gr of varget, other amounts not chronographed.

When reloading with LC brass I do not weigh either bullets or brass. Varget is dispensed with RCBS Chargemaster.

When shooting at 100 yards, with bipod and rear bag there is no difference when loading 24, 24.3 or 24.6 grains of varget. All groups are 3/4 MOA sometimes a shade more sometimes a shade less, which I attribute to operation error. All groups are 10 shots.

So has anyone else found that amount of varget not critical when you are near gr weight where rifle shoots good.

This make work out well because if precise weight not critical then I can load using 650 or at least dispense powder with powder measure.

[the86d]

I need to test accuracy of M855, M193, and 40 Grain V-Max reloads out to about 250yd in my 20" 1:8, as I have yet to have time. Currently I load them all with 26.2 grains of Varget. Now you are making me set a date to test these out this far and see if I need to adjust any loads... now that I have a functional scope mount.

When I was working up I didn't notice a difference in my groups, now that you mention it, at 100yd.

[darksands]

I think the major differences come into play at longer distances. At 100yds it's not going to show as much as 300+ as velocities and bullet drop changes over time. I'm no physicist so take with a gran of salt.

[huckberry668]

Are you saying the accuracy doesn't change or POI or bullet drop don't change?

I'm thinking, accuracy may not be affected but velocity will change so POI might. Bullet drop out to longer distances will definitely change at least slightly.

[D.carden]

I'll throw this out there.....

-16" barrel with Varget-

You have short barrel and using a slow powder... There's a good chance that the 16" barrel can only burn "X" amount of a slow powder while the bullet is still in the barrel regardless of safe charge weights (to a point). Basically, you ran out of run-way to launch the bullet any faster. Without the chrono'd velocity of the other loads, its hard to judged the out come..... More powder may be just muzzle blast after the bullet exits the barrel....!!! A faster burning powder might show some changes in POA/POI....... Just someth'n to think about

[damndave]

Like Darksands said. Itbe the same at 100 yrds, but when you stretch it out to 300+, you will most likely see the difference.

[ronas]

You have short barrel and using a slow powder... There's a good chance that the 16" barrel can only burn "X" amount of a slow powder while the bullet is still in the barrel regardless of safe charge weights (to a point). Basically, you ran out of run-way to launch the bullet any faster. Without the chrono'd velocity of the other loads, its hard to judged the out come..... More powder may be just muzzle blast after the bullet exits the barrel....!!! A faster burning powder might show some changes in POA/POI....... Just someth'n to think about

Varget with CCI 450 small rifle magnum primers was best as far as accuracy and 100% functioning of the action. I tried several other powder, blc2 and H335, and a couple of others. They all caused problems with jams and or cycling. I thought maybe something wrong with rifle. Called Larue and they said before sending rifle back shoot it with Federal Gold Metal Match and see how it works. I did shoot and single loaded each round to see if bolt locked open and it did. Nothing wrong with rifle just needs more along the line of 556 loads, rifle has Wydle chamber

[GeoffLinder]

D.Carden is correct about un-burned powder in shorties masking POI variance.

Also, 100 yards is nowhere near enuff distance to see POI changes due to powder drop variances. You need to look at 300 yards or more to see any vertical stringing due to small powder drop variances. If you chrono, you should be able to see SD tighten and loosen depending on charge uniformity but it won't show on paper at short ranges.

[ronas]

If you chrono, you should be able to see SD tighten and loosen depending on charge uniformity but it won't show on paper at short ranges.

Unfortunatly I do not have a chrono

[NotEnufGarage]

As said above - 16" barrel and 100 yd range.. Both too short to show differences between loads with small powder variations, heavy bullet and a slow powder.

[Red_daggs]

I'll throw this out there.....

-16" barrel with Varget-

You have short barrel and using a slow powder... There's a good chance that the 16" barrel can only burn "X" amount of a slow powder while the bullet is still in the barrel regardless of safe charge weights (to a point). Basically, you ran out of run-way to launch the bullet any faster. Without the chrono'd velocity of the other loads, its hard to judged the out come..... More powder may be just muzzle blast after the bullet exits the barrel....!!! A faster burning powder might show some changes in POA/POI....... Just someth'n to think about

I agree exactly. Varget burns rather slowly, you can switch or find a good mix and you would see a difference. When I use varget for my .308, I use a magnum primer to ignite faster because of this issue. I think R-15 works a bit better, but I haven't tried it on 5.56. But I did just get a pound of CompAR powder from alliant, should be interesting.

[RandyD]

I do precision reloading and do a lot of reading on 6mmBR.com which is where precision shooting and reloading are discussed in fine detail. Given that, I would second what the posters have said above; 100 yards is too close to determine the variances of your powder charges. Search the internet on ladder tests and use the ladder test. Also, a 16 inch barrel may be too short to effectively burn the powder charges that you are using. Have fun experimenting. It is enjoyable.

[ronas]

Yesterdays experiment. Wind 5-10mph so I only shoot test ammo at 300 yards.

Well the the 24 and 24.3 grain rounds were noticebly lower, like 1" to 2''. and greater than 1 moa.

The 24.6 gr. rounds measured 2 1/2" and 2 of the shots were higher than the 24.8 gr. shot rounds.

The 24.8 gr. shot rounds meaused 2" group with two of the shots lower than the 24.6 gr rounds.

Conclusions: It seem that 24.8 grains is best and max. load. I do need to get load chronographed. Hodgen data shows max at 23.7 varget is max. That is really not as relevent as one might think. It is for sami spec. chamber mine is not. It is for barrel 50% longer than mine. It is for a bolt gun that does not need gas pressure to cycle.

With two of the 24.6 rounds printing higher than two of the 24.8 rounds I am thinking barrel harmonics or operator error. My vote is operator error. But I think it does show I should most probably stay at 24.8 gr.

An other opinions?