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Jay1

6BR Benchmark Loads

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I get 3100fps with 87gr vmax with v135

2750fps with 105 amax with varget

 

105's varget RL15 v150 seem more popular powders to use

 

I use benchmark but in my 223 ackley

 

Gaz

Gaz - Are you shooting the 87g vmax out of 1:8 twist? I might give them a go also!

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Thanks Onehole -

 

Same as myself, 5thou off works for everything I've tried so far and that's exactly where I'll start this Friday.

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Yes 1/8 twist for 87gr and 105gr

 

I've also had the 105gr at 2750fps out to 900 yards, 87gr out to 500 at present but so much fun

 

Gaz

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I'll defo have to give the 87g a go, looks a great short - middle range head with a pretty good BC for the weight too.

 

Roll on Friday, ill end up with the xsearcher mounted before I'll want to call it a day :D

 

What was your come up for 900.....around 30moa?? How did they perform?

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Hitting gongs not a problem and they wasn't all that big, but now I stick to 600 mainly and closer it's plenty for what I do

 

Gaz

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Looking for your opinions on my approach tomorrow.

 

The plan was to zero the rifle while breaking in the barrel and then straight to 300m firing line to shoot the varied loads, pick the best one and tweak, shoot again and if happy go out to 600yds and see how it performs but now the weather forecast has changed quite a bit.

Wind speed 30km/h gusting to over 60km/h - should I start at 200yds?? My thinking is the wind could make a mess of it at 300, 200 should show me the charges that look to be working or just drive on as planned??

 

My approach for the .308 was the same but instead of going out to 600yds I'd go straight to 1000yds with the best loads. I know I do it backwards to some / most as I only go to the chrony when I've found a load that shoots well first. I always go with results on paper instead of the chrony!

 

Thoughts?

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I,m not much help I,m afraid,,,I,ve usually got some 90-95 neckturned heads to blow in as well as break a new barrel in {20-30ish shots usually] and don't take much notice of whats happening until they are all reloaded in a fireformed state.

What I would say is just stick to 200 given the wind variance and shoot with the flags if there are any,,,,,,,,I only pick my final load in next to no wind,,,,needs some planning for sure!! 200 is usually good enough for this.Others may do it well different but this is me and may take a few sessions to nail it,,,,,,thats why I don't like fussy cals and barrel burners,,,O

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It was a long day today and I got off to a less than ideal start. I couldn't find my bipod adapter so couldn't use my evo bipod but I borrowed a harris and hit the 25yd zeroing range, fitted the rail and scope, found paper and after a quick barrel break in I hit the 100yd line. Got my 100yd zero and moved down to 300mts, all loads were 5 shot groups shot prone at 300m.

 

The wind was fishtailing from 5-7 at around 20-25mph. I started at 27.7g Benchmark working up to 30.7g. Nearly all loads produced 1/2moa vertical or better, the worst was 2/3moa and the best measured .4inches. Same POA for each group so only measuring vertical. I threw a few shots (called them bad) but included them anyway. No pressure signs which is always a good thing and even more so as the best load happened to be the hottest. Normally I would run with the best load and start playing with neck tension and seating depth but as there was no signs of pressure I decided to call it a day and continue to increase the charge the next day.

My guesstimated speed is around the 2750 mark on the last 3 loads, based on coming up 5moa from 100y - 330y.

Not a bad start and with the groups tightening up on the last 3 loads - maybe suggesting I'm nearing the speed I need to be at, as advised previously by the good members here.

The next day out should be very interesting!

 

Thanks again for your replies and advice - you were all bang on the money!!!

 

For anyone reading this and thinking about jumping straight in with the hottest load, please note I worked up VERY slowly.

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Jay ,,,can you tell me your barrel length and chamber spec please,,,neck and freebore and distance to lands for your loaded round ,,,,,I have some Benchmark and would like to experiment,,

In addition,,,I don,t think barrel length, powder burn and bullet weight has been examined here on UKV,,,,,,,ie shorter barrel heavy head needs a slightly faster powder than norm? probably?,,,long barrel ,heavy head,,slower powder,,usually,,,,,may raise this on a separate Topic,,,,,O

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Jay ,,,can you tell me your barrel length and chamber spec please,,,neck and freebore and distance to lands for your loaded round ,,,,,I have some Benchmark and would like to experiment,,

In addition,,,I don,t think barrel length, powder burn and bullet weight has been examined here on UKV,,,,,,,ie shorter barrel heavy head needs a slightly faster powder than norm? probably?,,,long barrel ,heavy head,,slower powder,,usually,,,,,may raise this on a separate Topic,,,,,O

PM sent Onehole

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Jay ,,,can you tell me your barrel length and chamber spec please,,,neck and freebore and distance to lands for your loaded round ,,,,,I have some Benchmark and would like to experiment,,In addition,,,I don,t think barrel length, powder burn and bullet weight has been examined here on UKV,,,,,,,ie shorter barrel heavy head needs a slightly faster powder than norm? probably?,,,long barrel ,heavy head,,slower powder,,usually,,,,,may raise this on a separate Topic,,,,,O

I'm not using a 6br but in my 16" barreled dta srs covert I've found really heavy bullets loose less speed than light bullets do. That's using a fairly slow for cal powder, only used 1 powder with the 208's but I've tried several powders with lighter bullets.

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I'm not using a 6br but in my 16" barreled dta srs covert I've found really heavy bullets loose less speed than light bullets do. That's using a fairly slow for cal powder, only used 1 powder with the 208's but I've tried several powders with lighter bullets.

Danny,do you think that might be the generic effect of "BC"- the lower BC ultra velocity bullets lose out -beyond medium range/400ish-because they shed that initially high velocity much faster...

 

It is possible that choosing an optimum powders for velocity in short barrels,as per suggestions for light/heavy bullets,will reduce the difference,but probably not by much-compared to the BC effects.

 

gbal

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Jay I have been using benchmark for a long time in my 6mmbr, but I use 70. And 87 gr with great results, I will check my data ASAP I'm back home tomorrow after a family shoot and will post my findings,

 

I have to say my br is a1/9 not a 8 twist,

 

From memory it's 31 gr of bench mark over a sierra 87 gr spritzer, works very well out to 600 yards for me,

 

RSC

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Danny,do you think that might be the generic effect of "BC"- the lower BC ultra velocity bullets lose out -beyond medium range/400ish-because they shed that initially high velocity much faster...

 

It is possible that choosing an optimum powders for velocity in short barrels,as per suggestions for light/heavy bullets,will reduce the difference,but probably not by much-compared to the BC effects.

 

gbal

I'd have to agree, BC is king when it comes to retaining velocity down range, with that said though - you'd be very surprised at the speed you can achieve out of shorter barrels. I had a blueprinted remmy 700 in .308 with a 20in barrel and I easily reached 2900fps (47.4g benchmark) with 155 palmas, I shot it out to 900yds holding 1/2 moa vertical.

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Jay I have been using benchmark for a long time in my 6mmbr, but I use 70. And 87 gr with great results, I will check my data ASAP I'm back home tomorrow after a family shoot and will post my findings,

 

I have to say my br is a1/9 not a 8 twist,

 

From memory it's 31 gr of bench mark over a sierra 87 gr spritzer, works very well out to 600 yards for me,

 

RSC

Do you know what speed your doing out of interest? I plan on using 87g myself out to 3/400yds and 105amax 500yd plus. I'm running a 1:8 twist but hear lads are having good results with 75g - 115g pills.

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Do you know what speed your doing out of interest? I plan on using 87g myself out to 3/400yds and 105amax 500yd plus. I'm running a 1:8 twist but hear lads are having good results with 75g - 115g pills.

Jay I'll have a look when I get ome tomorrow

 

RSC

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Jay I'll have a look when I get ome tomorrow

RSC

Just had a look at my notes onmyphone,and the last time we ran it over a chronograph it was around 3980 to 3105 with the 87s

 

RSC

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Update...

 

Another round of load development today and its looking like 29.2g Benchmark and touching the lands is whats working best, still playing with seating depth and neck tension though.

I took it out to 600yds today and it held 1/3moa vertical - happy with that as still shooting off a harris bipod so room for improvement my end.

I still haven't run them over the chrony but from 100y zero its 5moa to 330yds and 14moa to 600yds so I'm at around 2750fps.

 

If anyone would like more details/info please ask here or PM.

 

Onehole - Have you started with Benchmark yet? Very Interested to compare results!

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Update...

 

Another round of load development today and its looking like 29.2g Benchmark and touching the lands is whats working best, still playing with seating depth and neck tension though.

I took it out to 600yds today and it held 1/3moa vertical - happy with that as still shooting off a harris bipod so room for improvement my end.

I still haven't run them over the chrony but from 100y zero its 5moa to 330yds and 14moa to 600yds so I'm at around 2750fps.

 

If anyone would like more details/info please ask here or PM.

 

Onehole - Have you started with Benchmark yet? Very Interested to compare results!

Hi,,no not yet may take some time to get round to this,, work, weather and playtime don't seem to roll out in the right order at the moment,,,doh,,,,,,,O

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Danny,do you think that might be the generic effect of "BC"- the lower BC ultra velocity bullets lose out -beyond medium range/400ish-because they shed that initially high velocity much faster...

It is possible that choosing an optimum powders for velocity in short barrels,as per suggestions for light/heavy bullets,will reduce the difference,but probably not by much-compared to the BC effects.

gbal

I'm talking about initail velocity not down range. I personally think in my rifle the very heavy for cal bullets loose less initial velocity than lighter bullets do in the shorter barrel. If you see what I mean

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I'm talking about initail velocity not down range. I personally think in my rifle the very heavy for cal bullets loose less initial velocity than lighter bullets do in the shorter barrel. If you see what I mean

I had to have a think about it, in my head the opposite seems more likely but I might still be looking at this arseways :D

  • The lighter bullet will be traveling faster than heavier one at the early stage of flight
  • The lighter bullet will accelerate at a higher rate than the heavier one

So if you then shorten the barrel would that not exaggerate the trend??

Do the heavier bullets benefit more from the longer barrel - I mean, will they have a higher percentage increase in velocity over the lighter bullets?

 

Sorry if I'm reading this all wrong...

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Not sure mate there is logic to what you say but I find I can drive a 208 nearly as fast as I can a 175 in my barrel

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I'm talking about initail velocity not down range. I personally think in my rifle the very heavy for cal bullets loose less initial velocity than lighter bullets do in the shorter barrel. If you see what I mean

Sorry,Danny...I can't get this clear...I take "initial velocity" to be muzzle velocity,,and "downrange velocity" to be any velocity at some distance from the muzzle,and this downrange velocity will decrease steadily with such distance.

 

Heavy bullets will have lower velocity that lighter bullets from the same cartridge/barrel (to SAAMI specs-it would be possible to reverse velocities with much reduced loads for the light bullets,but I take it we are talking about 'standard' loads,,even 'hot' loads for both bullets.)

Short barrel will reduce both light and heavy bullet velocities compared to a longer barrel-just how much is only known by comparing equal loads in short and longer barrel for each bullet--the effects may not be equal,but the difference in effects is unlikely to be large.

 

Sooooo....I still struggle with "heavy bullets lose less initial velocity" (than light bullets) "BUT i'm not talking about downrange'??

 

Do you mean that the heavy bullets still achieve closer to the muzzle velocities that they would achieve in a longer barrel,than do the lighter bullets in the same short barrel?

ie though the heavies in the short barrel are slower at muzzle,than the lights in the same barrel,their muzzle velocities are less reduced (absolute or percentage?)....the performance loss is reduced for the heavies?

If so,it would take a bit of chrono - ing to see if any such differences were maintained "downrange".

 

I suggested that BC comes in-the advantages of fast and light,do not last,and there is some point "downrange" where higher BC bullets (typically longer/heavier) become superior.

Though complex,BC and velocity (and weight,therefor) are in an "interactional' relationship with distance-effects switch round if you like,unlike the simple linear relationships of velocity and distance-velocity just reduces as distance increases,maybe at different rates,but it always reduces as time of flight/distance increases.

(I think that's why 40 g speedsters give way to 75g for long range varminting.....)

 

We may be in initial agreement?though so far,I'm not sure about any BC complexities?

 

Cappucino needed!

 

g

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Do you mean that the heavy bullets still achieve closer to the muzzle velocities that they would achieve in a longer barrel,than do the lighter bullets in the same short barrel?

 

Yes that's what i seem to have found mate. May only be my rifle but thus far I can throw the really heavy bullets nearly as fast as the lighter bullets and not a million miles from guys using barrels much longer.

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