Bullet Jump

[redding]

After years of using the same bullet, (.308 Sierra 2130 150 grn) supplies have dried up.

Now using Sierra 2125 150 grn boat-tail, and struggling to get a decent group.

 

I loaded them to the same seating depth/same powder & primer as the old bullets but the group is crap so I need to start messing about with seating depth.

Out of interest I pulled a bullet from a factory Winchester 150grn and measured depth to lands (from Ogive) and how deep Winchester have seated them. (they group as well/bad as my "new" reloads.

 

I was shocked to see that they have a jump of 0.189 thou! any comments?

My plan is to start my reload depth at that and work out from there, the current crap reloads have a 20 thou jump.

 

I may, of course need a new barrel (Sauer 2007 & a many thousands of rounds down it) at the last rifle inspection & service I was told that there was slight pitting but probably not enough to affect accuracy, normally the rifle has been giving 1/2 MOA at 100 yds.

 

Any comments would be appreciated.

 

 

[Scotch_egg]

Have you continued using exactly tbe same powder charge weight?

 

What powder are you using?

 

I would recommend loading to 2.80 OAL in a sporting firearm and only adjust powder weight to start in .3 increments whilst safe to do so. Keeping an eye out for pressure signs etc

[redding]

Have you continued using exactly tbe same powder charge weight?

 

What powder are you using?

 

I would recommend loading to 2.80 OAL in a sporting firearm and only adjust powder weight to start in .3 increments whilst safe to do so. Keeping an eye out for pressure signs etc

Yep same charge weight, powder RS40, but tried RS52 yesterday same crap grouping.

[Scotch_egg]

As per my last post. Change the charge weight in .3 gr increments from a starting load and watch for pressure signs.

 

Only change one variable at a time.

 

 

Your hunting rifle will have a pretty long throat to suit a range of bullets including heavier and longer bullets i.e. 180gr.

[Andrew]

After years of using the same bullet, (.308 Sierra 2130 150 grn) supplies have dried up.

Now using Sierra 2125 150 grn boat-tail, and struggling to get a decent group.

 

I loaded them to the same seating depth/same powder & primer as the old bullets but the group is crap so I need to start messing about with seating depth.

Out of interest I pulled a bullet from a factory Winchester 150grn and measured depth to lands (from Ogive) and how deep Winchester have seated them. (they group as well/bad as my "new" reloads.

 

I was shocked to see that they have a jump of 0.189 thou! any comments?

My plan is to start my reload depth at that and work out from there, the current crap reloads have a 20 thou jump.

 

I may, of course need a new barrel (Sauer 2007 & a many thousands of rounds down it) at the last rifle inspection & service I was told that there was slight pitting but probably not enough to affect accuracy, normally the rifle has been giving 1/2 MOA at 100 yds.

 

Any comments would be appreciated.

 

 

 

I sincerely believe that it's a myth that bullets MUST have a short jump to the lands to be accurate. ~Andrew

[LukeSoutherner]

Andrew, you might find this UKV post helpful. I certainly did. Not managed to get out and p[ut it into practice yet, but will update on results when I do. Up to this point I have always kept the seating depth the same and played about with the powder charges, but I have set up some loads at a mid-weight for my .308 (44r N135) and varied seating depth by 0.010" for several loads from touching the lands and heading backwards (if that makes sense). Not had a chance to shoot them yet.

 

The Houston Warehouse Project article from the above post was fascinating.

[gbal]

Redding,remember commercial reloads will be to SAAMi specs to ensure magazine feed in rifles which may vary a tad....do Winchester load their 150 with Sierra,or Ballistic Silvertip? I know you are just curious,but 'similar' bullets do vary,as do barrel's preferences for bullets.If you possibly can,check with a few of the previous 'good load'.A stalking rifle does not need sub .5 moa-it needs first shot to POA.

gbal

[Murph]

I sincerely believe that it's a myth that bullets MUST have a short jump to the lands to be accurate. ~Andrew

Plus 1 on this. I have a load in 223 - 53 gr vmax which is loaded at factory length roughly 2.265. This load is 220 thou off the lands! Best group at 100 yards 0.180 inch for 5 shots. Any load i have with a big jump like this I use a lee factory crimp die which halves my es and sd.

[Andrew]

Plus 1 on this. I have a load in 223 - 53 gr vmax which is loaded at factory length roughly 2.265. This load is 220 thou off the lands! Best group at 100 yards 0.180 inch for 5 shots. Any load i have with a big jump like this I use a lee factory crimp die which halves my es and sd.

A big Plus One on that, too.~Andrew

[redding]

Plus 1 on this. I have a load in 223 - 53 gr vmax which is loaded at factory length roughly 2.265. This load is 220 thou off the lands! Best group at 100 yards 0.180 inch for 5 shots. Any load i have with a big jump like this I use a lee factory crimp die which halves my es and sd.

Thanks all for the help.

I will start again with the Winchester factory jump of a 0.189 thou and work from there.

 

GBAL. I understand and agree that a stalking rifle does not need sub .5 moa grouping, but I like to be able to put a group together with that level of accuracy, if have that accuracy @ 100yds it correspondingly helps with smaller groups at longer ranges, say out to 400 yards.

 

Being a bit thick here, is POA not the same as .5MOA accuracy?

[gbal]

Redding, I agree that more precision,rather than less,is desirable-as it increases confidence in the rifle.

 

I don't think stalkers should really be concerned with grouping at 400y,since shooting at that distance is getting iffy-one reason being that group size is just not linear-the 1/2 inch 100 rifle is generally not a 2" 400 yard rifle,though it will be better than a 1" 100 y rifle-too many other factors,ignorable at 100y come in significantly by 400y. The 100% hit zone performance for a 1/2 inch rifle is lost around 250y in field conditions....

 

POA-point of aim-means placing the bullet where you want it (aim it)-it's an accuracy term. MOA is a precision term,it measures the group size without reference to where that group is.

"Of course" zeroing means getting you XMOA group centered on your POA-typically about an inch high at 100y,in stalking rifles.

When zeroed,a .5 MOA rifle will of course place all it's .5 MOA shots within 1/2 inch of POA-super.

 

The issue arises though in stalking,that not all rifles will put their first,'cold' shot in the subsequent group-though most will be 'close enough'.

The point is though that it is this first 'cold bore' shot that matters-it has to be 'accurate'-or at least know to be consistently pretty close to POA-it is very likely the only shot taken.If another shot is necessary,really .5 moa potential is largely irrelevant,given the performance of modern stalking rifles and ammo.

 

So sub 1/2 inch grouping is desireable,but secondary to where the first cold barrel shot goes-agreed,these will often be close enough,but how would you feel about a 400y shot cold bore,with a rifle that often put it's first shot 1" (variably) out of the subsequent .3 group? Less confident?

If your rifle puts first shot within 1/2 inch of the subsequent group,not an issue at stalking ranges,especially if it's consistent,and you can allow for it.

 

For the fortunate,it may not be a big deal,but Litz,eg,spends nearly 300 pages on the distinction between Accuracy and Precision,though it's not required reading !

 

A sub .5 moa group centered on point of aim will do very nicely,IF one of those is the quarry shot.

 

gbal

[redding]

Cheers GBAL, now I understand the difference.

It seems the longer I fiddle about with accuracy, grouping, MOA etc the more new stuff I learn.

 

Regards

[gbal]

Cheers GBAL, now I underatand the difference.

It seems the longer I fiddle about with accuracy, grouping, MOA etc the more new stuff I learn.

 

Regards

"....and so say all of us..!"

 

Now ,in his other book...... :-)

 

g

[silentsoulsleave308holes]

My most accurate gun is my longest jumping gun by miles and I mean miles although it's best group to date witnessed and signed by a number of respected shooters was x5 rounds 22thou. It's a 308 seated at 2.810 155 amax 44gr variety br2 primer. By 22thou I mean set caliper to 308 then zero and measure group

[gbal]

My most accurate gun is my longest jumping gun by miles and I mean miles although it's best group to date witnessed and signed by a number of respected shooters was x5 rounds 22thou. It's a 308 seated at 2.810 155 amax 44gr variety br2 primer. By 22thou I mean set caliper to 308 then zero and measure group

The 'standard' way to measure group size is outer edge to outer edge of furthest apart shots,minus calibre (centre to centre of furthest shots comes to the same,but centres is a little more difficult to put callipers on accurately simultaneously.We get some interesting numbers/photos on here sometimes. :-)

 

Rifles can of course be individual,ineresting depending what 'miles off' means ...

"...and measure group' seems a tad vague? If " 22 thou" means .022",its phenomenal esp for a 5 shots,30 cal,even as a one off...and it would have to be 'edge to edge,minus' ......How does the rifle aggregate,over several groups? 'Miles worse',or close?

Interesting,though.

gbal

[silentsoulsleave308holes]

The group looks like a one 308 shot at paper with just the slightest open one side. Just a few months before I did a group with skanys rifle that HE posted that was x5 rounds 86thou that was witnessed and signed by a lot of people. If you measure outside to outside then minus the cal it's the same thing isn't it. Interesting though how I just posted trying to help ànd get jumped on yet ask for help myself about quick load 100 plus people read and no one helps nice one

[redding]

The group looks like a one 308 shot at paper with just the slightest open one side. Just a few months before I did a group with skanys rifle that HE posted that was x5 rounds 86thou that was witnessed and signed by a lot of people. If you measure outside to outside then minus the cal it's the same thing isn't it. Interesting though how I just posted trying to help ànd get jumped on yet ask for help myself about quick load 100 plus people read and no one helps nice one

Thanks, can I ask please, you say your .308 rounds are seated at 2.810, is that CBTO or COL, if its CBTO how much of a "jump" is that.

I thought the Winchester factory round with a 0.189 jump was ridiculous but obviously not.

I am going right back to basics now and going to load up a series of charge weights increasing by 0.5 grns with them all seated with a 0.180 thou jump and see what happens. If I can get a decent group I will then fiddle with increasing charge weights, I intend to start mid way from min to max.

[silentsoulsleave308holes]

It's col. I went back to basics many years ago after visiting the world's largest ammo manufacturer and realised a few things. I am on my way from work to the indoor range. When I get home later I will measure the jump for you if need be for other people I will find those groups and post them and contact witnesses to post too and m show how when you zero caliper closed then open to your cal then zero then measure overall group.this gives centre to centre sorry don't mean to have a rant just can't believe someone who doesn't know me would out of the blue have a go at me about stuff . The measuring gives the same value. I did say groups were signed and witnessed by respected shooters . Sorry redding not having a go at you of course

[redding]

It's col. I went back to basics many years ago after visiting the world's largest ammo manufacturer and realised a few things. I am on my way from work to the indoor range. When I get home later I will measure the jump for you if need be for other people I will find those groups and post them and contact witnesses to post too and m show how when you zero caliper closed then open to your cal then zero then measure overall group.this gives centre to centre sorry don't mean to have a rant just can't believe someone who doesn't know me would out of the blue have a go at me about stuff . The measuring gives the same value. I did say groups were signed and witnessed by respected shooters . Sorry redding not having a go at you of course

Thanks, I appreciate this.

I am interested as to how to measure, accurately, COL, I ask because sometimes the tips (lead) of bullets are slightly deformed.

Sorry about all the questions but I am always ready to learn.

[gbal]

ssl,"furthest edges apart minus calibre' was my explicit prescription,and indeed it is the same as yours;and 'if it's .022,it's phenomenal' likewise-it's a statement of fact,There was no 'jumping on intended' and reads to me like admiration....some of us may have done it for two,three shots-but not many for 5.

There are/were around 20/30 shooters at 100y UKBRA competitions.Each shoots 5 or 6 5shot groups,and there were 5(or 6) competions per year-call it 500 groups shot per year.These include some of the very best shooters ,under excellent conditions,with top gear,in UK .I seem to recall that the number of 'screamer ' targets shot ( 5 under .1") was no more than one per year,or thereabouts,and almost all were with a 6PPC,.Whatever,this is the basis for suggesting .022 is 'phenomenal',and any perusal of world records would simply consolidate that.It does happen )mostly in the Houston tunnel,and even then,it wasn't by any means a given!)

I accept that you mean 5 shots from a 308 in one hole little bigger edge to edge than calibre (explicitly,308+.022) to be exact,.330 .Outstanding.

But as in all these things,consistency,and near replication, matters.

 

Rather than 'jumping on you' I was suggesting how good .002 was-we're well into world record territory-especially if closely repeated,reasonably often.There is a world of difference,and indifference,between 'skeptical' and 'septical' commentary.

Hope you can sort out the "OAL?" and "miles off' issues.

Personally,I think it's all a bit OTT,except as a matter of principle,influencing optimum calibre and so forth....

 

g

[silentsoulsleave308holes]

Then please except my apologies as I read it you were being hostile.it seamed that way to me and that's my mistake. The gun has shot many sub .1 groups and is the cheapest rifle I ever picked up.i bought another that is basically brand new been sat in armoury so now have two lucky me they are quite rare as they are between a cadet and m84 so I have two spare sets of target flat top sights for m83 m84 m85 both quick detachable for sale if you know any one. When I did the group with skanys m84 x5 rounds .086 he posted it on here .he hadn't had the gun long and got it only coz how well mine shot and he wasn't sure about how it shot so I asked him if I could shoot it with the loads that I asked him to load for it instead of the other loads he had been playing with and I done the nice group. The first three rounds were truly in the same hole one the last two opened it slightly. The group is on here somewhere just look up skanys. I have been on here for years and years now I am not a noob to the site. When I done my 22thou I look every where on the net to see if it was a record. I couldn't find if it was but what I could find is that it wouldn't count as it would have had to have been done at an affiliated br club at least I think that's right if memory serves. It's something like that anyway. The miles off thing is my jump to lands. I got a looping jump in my 308 that is my most accurate shooter. Work that out when other people including myself with other guns go stuffing bullets in or near the lands. Actually there is science to back it up but I Nintendo thumb typing on this dam smart phone.

 

Redding buy a stoney point or hornady oal gauge and seat the best looking tipped bullet to the depth you want. Then insert the correct collet for your cal into the holder and attach to a vernier and close vernier and zero. Now open it and measure the bullet and case you just made and write the figure down in your reloading manual. Now next time you adjust your die for some reason and have to set it back for those lead tip bullets you have a comparative head measurement instead of the col measurement so it won't matter how messed up the lead tip is as it will be measured off the copper jacket Instead.

[baldie]

I remember buying my fist AX a couple of years ago. First thing I did was measure the Leade. There was 0.100" from a magazine length loaded round to the throat. So I loaded up 10 x 10 round batches of ammo and lengthened them by 0.010" per batch.

 

The aim was to simply shoot 100 rounds through the gun on a day off and enjoy it.

 

There was not a scrap off difference on the paper between them all. I sometimes think its possibly because its a 7.62...but I doubt it.

 

The bullet is a 167 scenar and it seems to work in any .308.

 

I was testing my new AW 338 yesterday. I already know it loves the lock base bullet at mag length and bought [what I assumed to be ] 3 boxes from the supplier. They had put scenars in by mistake. These will only shoot well on the lands which is useless in a magazine fed rifle.

 

Bullet shape has a lot more to do with accuracy than people think.

 

I would rather have a round that shoot reasonably well at mag length any day of the week.

[Ronin]

 

 

I was testing my new AW 338 yesterday.

 

 

 

Practice for the Fly Dave ?……….

[Andrew]

I remember buying my fist AX a couple of years ago. First thing I did was measure the Leade. There was 0.100" from a magazine length loaded round to the throat. So I loaded up 10 x 10 round batches of ammo and lengthened them by 0.010" per batch.

 

The aim was to simply shoot 100 rounds through the gun on a day off and enjoy it.

 

There was not a scrap off difference on the paper between them all. I sometimes think its possibly because its a 7.62...but I doubt it.

 

The bullet is a 167 scenar and it seems to work in any .308.

 

I was testing my new AW 338 yesterday. I already know it loves the lock base bullet at mag length and bought [what I assumed to be ] 3 boxes from the supplier. They had put scenars in by mistake. These will only shoot well on the lands which is useless in a magazine fed rifle.

 

Bullet shape has a lot more to do with accuracy than people think.

 

I would rather have a round that shoot reasonably well at mag length any day of the week.

I now start all my loading with the parallel side of the bullet at the base of the neck and work from there -that or OAL listed with the data. I seldom move very far away from that datum, if I move at all. Like you, in the majority of rifles, with most bullets, I found there just wasn't any difference. I think a good, accurate load comes from choosing good component balance and quality (consistency) of assembly. Distance to the lands is not always that important.~Andrew

[silentsoulsleave308holes]

One of the most important or probe rely the most important thing I found that changed my grouping and spread over the chronograph. Consistency etc etc was using a bronze brush in a drill to scrub put the necks to rid them of alllll carbon deposit so when sizing they are spoon consistent. So consistent on seating and so consistent on tention . Some body once asked me how can he reduce his shot to shot spread as he was getting around 160 to 180 sometimes. I asked if when his brass was new did they all size nice and snug and seat bullets nice and snug and now the brass has been fired a few times does it seem that some size too easy some are tight and some are slacker seating bullets and some are tight. He looked really shocked and said that's exactly like that. I said I bet you either clean your necks with a nylon brush or not at all. The bronze brush in the drill getting the case neck internal glee ming sorted it