How can I improve this load?

woodmaster

Well-Known Member
I've been re-loading for 2 years and had good success with both 22-250 and 6-5x55. Achieving ammo which out performs the factory stuff I started with. I now only use re-loads. However I have recently bought a .308 Heym with 23" barrel and a shot count of 40 rounds.
Using some once fired federal cases full length sized and trimmed, cci #200 primers, and speer 150 gn SPBT (2022) bullets.
I started with
45gn Varget and worked upto 47gn (stated max load) with a COL of 2.700"
Results were 3 shot groups as follows.
45gn= 2 5/8"
45.5gn= 1 7/8"
46= 2 3/16
46.5= 3/4
47= 1 13/16"
So from this I took the 46.5 gn load and played with the COL begining with 2.650 upto 2.800 in 0.05 increments.
Groups were.
2.650=15/16"
2.700=1"
2.750=1 1/2
2.800= 1 3/4.
Admitidely this was prone of my rucksack at 100 yds and wold have been better of a nice bench. I do have access to a range but only when my mate can attend, so I just wanted to crack on.
I should also say this rifle is un-moderated and I am just getting to grips with the extra recoil compared with the 6.5.
1" group is all I need for hunting so not looking for clover leaf etc but can shoot 1" fairly consistently with the 6.5. My question. Is there anything else that could be done to improve this initial loading?
Would a flat base bullet nearer the lands make much difference?
Any idea's would be welcomed.
Thanks.
 
3/4" is perfectly acceptable, if you can replicate that consistenly then I'd stick with that one.
Anecdotally, I'd be suprised to see such a swing in groups due to a half grain of Varget (46 to 46.5) as it's quite a slow powder.

I take it you're chamfer/deburring the brass before loading it?

Boat tails are forgiving in this respect, flat base aren't and if you're chamfering isn't sufficient you'll have some issues when seating i.e. little slivers of copper visible at the seated case neck.

My preference is to play with length first and then powder. Reason is primarily that I've found my rifles to be quite charge tolerant once the length is right. Also, shortening a load near max will bump pressure quite quickly, conversely, lenghtening a low charge will drop it quickly.

Good work, enjoy!
 
Can't comment on the 308 aspect and relative lengths, but if the groups get bigger as you lengthen the OAL what happens if you shorten them from 2.65"
 
Thanks Milligan. Yep all cases chamfered after length cut. I'm yet to fire more than one group of the same load/spec so difficult to say if consistent. Couple of the best targets had 2 touching and one straggler to make the group. Where as the other loads were all evenly spaced leading me to develop the former. I have never thought about doing things the other way round with COL first. I'll make a few of the best two up and see if repeatable. On another note why is it that this .308 which weighs the same as my 6.5 firing a bullet only 10gn heavier gives noticable more kick? Is one 308 likely to give more kick than another of the same weight?
 
Not tried yet brewsher. Looks like the down ward trend may be better but at current COL charge is compressed. So since I've never had to compress powder before didn't want to go to far.
 
..
Results were 3 shot groups as follows.
45gn= 2 5/8"
45.5gn= 1 7/8"
46= 2 3/16
46.5= 3/4
47= 1 13/16".

I would explore the powder weights a bit further before doing anything else. I would load up as before and try 46.1, 46.3 46.5 and 46.7. Then review the results. I would also try one other powder (N140 perhaps?) and see how that fairs. I would only tweak the seating once I felt happy I was in a good place for powder weight.

I would also highlight the following article that a more scientifically minded Forum member has brought to my attention - Group Size Analysis

If you agree with the logic in this article, then you should apply a correction factor of 1.158 to your group sizes. Have fun. JCS
 
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If your after better accuracy then i would say that the bullet/powder combination isnt the best. Either try a different bullet or different powder.
 
I would explore the powder weights a bit further before doing anything else. I would load up as before and try 46.1, 46.3 46.5 and 46.7. Then review the results. I would also try one other powder (N140 perhaps?) and see how that fairs. I would only tweak the seating once I felt happy I was in a good place for powder
Plus 1 for the above.

Everyone seems to have there own system for developing a new load, I would normaly shoot a powder ladder first and then mess about with seating depth, before finaly going back to fine tune the powder weight again.
I was speaking to an acquaintance recently who uses a slightly different method to get his initial powder weight. He has access to an accurate chronograph, instead of shooting a powder ladder at paper at 300m or more meters, with the inherant variations that can creep in, he shoots his ladder through the chronograph. What he looks for is a group of weights that give the same or similar velocity for example

45.5 2760 fps
45.7 2785 fps
45.9 2815 fps
46.1 2825 fps
46.3 2830 fps
46.5 2836 fps
46.7 2857 fps
46.9 2886 fps


This table is hypothetical and for demonstration purposes only, but you can see that the velocities between 45.9 and 46.5 are fairly similar. His assertion is that this represents an accuracy node and by taking the middle powder weight and playing around with seating depth he manages to get good accuracy without having access to a range in excess of a 100m.

I haven't got a chronograph, but its now on the top of my wish list
Dcg
 
The simplest thing to do would be to try a different bullet.

The Speer spbt is a good bullet and accurate in my 06 but for some reason hornady interlock and barnes TSX are much better. Conversely I have never been able to get the same grouping from Nosler partitions or Accubonds.

For the bullets the rifle seems to like just about any appropriate powder willl yield a good load, for the ones it doesn't like i have tried several powders without significant improvement.

Try a flat base bullet if speer is the brand you can get most easily or shop a little further afield.

Of course different rifles may be more sensitive to powders than bullets but in my experience the experimenting to find the right bullet makes the whole thing easier and cheaper.
 
Good advice here. I'll try a few of them out and see how I go. TBH I'm happy with a 1" group for hunting deer as I've never shot one more than 160 yds away. So only likely to be about 2" off target. At that range I'd be going for a nice safe HL shot if off sticks so likely to be my lack of marksmanship rather than ballistics that produce poor results. If in a good high seat I'd be happy for Head/neck shots. I do wonder if really it's just more practise with this rifle that is needed, however I do find I not that keen on putting too much lead down range before my shoulder says it's had enough. I'll try tinkering a bit more and just test half a dozen at a time to reduce fatigue problems.
 
woodmaster

In my limited experience, a good load results from the happy collision of a number of factors:

Your rifle and scope
Your brass preparation
Your reloading technique
Your choice of brass and bullet
Your choice of powder and primer
Your load testing method

Good luck. JCS
 
... TBH I'm happy with a 1" group for hunting deer as I've never shot one more than 160 yds away. .

A couple of things to consider. When things go tits up, and the deer has run off another 200 yds and has momentarily stopped, you want to be confident you can hit it. Secondly, no matter how well I shoot in practice, I know when I'm out in the wind and the rain and I'm cold and wet, I'll shoot at least twice as badly as I do on a summers day on the range.

Regards JCS
 
woodmaster; I do wonder if really it's just more practise with this rifle that is needed said:
Just a thought, but you should be allowing your barrell to cool down between shots and shooting five shot groups. I reload 308 for a friend of mine for his Sako 85 light weight hunter, and although not particularly pleasant to shoot without the moderator it's not uncomfortable after 20 or 30 shots if your taking your time between strings. I'm not familiar with the Heym, but I wonder if all is well with the rifle, things like excessive headspace etc could cause it to "batter you". My advice would be to have a moderator fitted by an experienced gunsmith and wether the rifle is new or new to you, I'd have him check the rest of it over at the same time.
 
DGC. I do let the barrels cool between groups. But I'm still finding the recoil on this rifle more than expected and my shoulder agrees after 20 shots. The rifle is new to me and had only previously fires 27 shots from new. So you could say it's as new. I wonder if it's normal for one rifle of similar design and weight to kick more than another. Not fired another 308 for some time so can't really remember what recoil was like. It is booked in to Norman Clarke to have a mod fitted and hidden cap but in general I will use it without. It would make it nicer for load development to have a mod or brake. I'll have him give it the once over while it's there.
 
DGC. I do let the barrels cool between groups. But I'm still finding the recoil on this rifle more than expected and my shoulder agrees after 20 shots. The rifle is new to me and had only previously fires 27 shots from new. So you could say it's as new. I wonder if it's normal for one rifle of similar design and weight to kick more than another. Not fired another 308 for some time so can't really remember what recoil was like. It is booked in to Norman Clarke to have a mod fitted and hidden cap but in general I will use it without. It would make it nicer for load development to have a mod or brake. I'll have him give it the once over while it's there.

What Heym model is it? I've had several of the more common SR20N model - including a .308.

Do you have an idea when yours was made? If not, the first 2 digits of the 5 digit Serial No (NNnnn) will help. These aren't turned out by the million like other makes.
 
I have recently bought a .308 Heym with 23" barrel and a shot count of 40 rounds.

First things first. Unless you know it's only fired 40 rounds, treat that with a pinch of salt. Give the barrel a thorough cleaning with a good copper solvent.

Secondly, elminate human error as far as possible. Support the foreend with either a benchrest or a sandbag (and I mean a heavy one filled with sand) or a bipod resting on soft ground to avoid bipod bounce. The butt needs to be in your shoulder but supported underneath by a back bag. If you don't have a back bag, use a sandbag. This arrangement will hold the rifle very steady. So any variation of shot won't be the result of the rifle wobbling around. Next, concentrate on your trigger control: no snatching and be sure to follow through. (I have a bad habit of snatching the trigger. Geting someone esle to load and hand you the rifle - sometimes with an empty chamber but you won't know - is an excellent way to find out whether you're a snatcher.)

So from this I took the 46.5 gn load and played with the COL begining with 2.650 upto 2.800 in 0.05 increments.

Bullet seating depth is one of the most influential parameters, far more so than choice of primer or powder or, within reason, powder charge. But if it's shooting 5-rounds groups of an inch at 100 yards then, as you say, that's quite reasonable. (An aside: it seems that an awaful lot of people claim to have standard factory rifles that group to a half inch. Just because a rifle throws half inch three or five round group now and then doesn't make it a half inch rifle. It's all to easy to say "that one's a flyer so I'll ignore it". The flyer is part of the group, and if it opens the group up to two inches then it's a two inch group.)

I should also say this rifle is un-moderated and I am just getting to grips with the extra recoil compared with the 6.5.

I suspect from what you say that you are probably flinching in anticipation of the recoil. Perhaps get someone else to shoot it - off a firm support - and see how it performs? If it consistenty shoots better in your friend's hands then you will have your answer. A Deccelerator butt pad would help if recoil is an issue.

-JMS
 
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try h4895 45gr this is my sako fed 210 primers lap case's fully prep inc flash hole cut, useing gage from OG 2.3055 c.o.a.l (not base to tip) bullets are s/PRO HUNTER 150 FBSP i get 1/2 moa @100 so your 3/4 is not to far away ,your rifle may not like hot loads mine hates max plus and it also hates tsx hav't tryed ttsx yet as can't find anyone with same rifle that is getting a good result ?anyone !

or v150 44gr all same

i have a sako
I've been re-loading for 2 years and had good success with both 22-250 and 6-5x55. Achieving ammo which out performs the factory stuff I started with. I now only use re-loads. However I have recently bought a .308 Heym with 23" barrel and a shot count of 40 rounds.
Using some once fired federal cases full length sized and trimmed, cci #200 primers, and speer 150 gn SPBT (2022) bullets.
I started with
45gn Varget and worked upto 47gn (stated max load) with a COL of 2.700"
Results were 3 shot groups as follows.
45gn= 2 5/8"
45.5gn= 1 7/8"
46= 2 3/16
46.5= 3/4
47= 1 13/16"
So from this I took the 46.5 gn load and played with the COL begining with 2.650 upto 2.800 in 0.05 increments.
Groups were.
2.650=15/16"
2.700=1"
2.750=1 1/2
2.800= 1 3/4.
Admitidely this was prone of my rucksack at 100 yds and wold have been better of a nice bench. I do have access to a range but only when my mate can attend, so I just wanted to crack on.
I should also say this rifle is un-moderated and I am just getting to grips with the extra recoil compared with the 6.5.
1" group is all I need for hunting so not looking for clover leaf etc but can shoot 1" fairly consistently with the 6.5. My question. Is there anything else that could be done to improve this initial loading?
Would a flat base bullet nearer the lands make much difference?
Any idea's would be welcomed.
Thanks.
 
Hi Sinstral. Mine is a SR21 with the first digits of serial being 2107. I am reliably informed of the shot count and the guy would have had no reason to try and kid me. The blacking is still on the bolt lugs, and barely a scratch on the steel mag from the retaining clip to name a few. I do wonder if I am flinching a little. I have been careful to ensure my trigger technique is as it should be. I may give the 4895 a try as I can also use this in the 22-250 and have some good loads from a previous batch. I should see my mate at the weekend and may get a few different bullets, but for now I think I'll load up as said and give it a go at the bench with some good sand bags.
And for my own peace of mind I think I'll try another similar 308 just put my mind at ease that mine is no different. It's not an un-pleasent rifle to fire but as said is noticeable after a dozen shots or so.
 
I prefer to use a short bipod and a rear sand bag to test ammo,ideally I would test off of a front and rear sandbags off a bench,that's as steady as you can get,if your ammo is good you will soon know
 
Hi Sinstral. Mine is a SR21 with the first digits of serial being 2107. I am reliably informed of the shot count and the guy would have had no reason to try and kid me. The blacking is still on the bolt lugs, and barely a scratch on the steel mag from the retaining clip to name a few. I do wonder if I am flinching a little. I have been careful to ensure my trigger technique is as it should be. I may give the 4895 a try as I can also use this in the 22-250 and have some good loads from a previous batch. I should see my mate at the weekend and may get a few different bullets, but for now I think I'll load up as said and give it a go at the bench with some good sand bags.
And for my own peace of mind I think I'll try another similar 308 just put my mind at ease that mine is no different. It's not an un-pleasent rifle to fire but as said is noticeable after a dozen shots or so.

Woodmaster,

On looking up the SR21 model it seems to have the same thin .555" barrel, and stock as the earlier SR20, although everything else has been changed. I had 3 of these earlier models in .243, .270, and .308 in the continental 'schnabel tip' style too. They were very light, so did keep you on your toes in the beefier calibres. My SR40 .222 has exactly the same length & taper barrel so maybe these are a stock item.

What I did notice about these Heym rifles was that they were custom throated like Weatherby's, and sometimes used non-standard twist rates. Heym make their own barrels, and everything else of course. Anyway, when I replaced them with LH Tikka's I had to redo all my OAL measurements as the new throats were much shorter by 4-5mm. My OAL with 130gr Sierra SP bullets in the Heym .270 was 88mm, and with 150gr Sierra SP in the Heym .308 was over 2.900". I know that Speer bullets have a different shape ogive and aren't so pointy .... but Sierra always shot better so I stuck with them.

Just thought I'd mention this in case you haven't already checked out your barrel.
 
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