120gr 7mm08 troubles- #62 potential issue

I don't go by charts.

I go by what I have seen on my targets.

Can you tell us of some of your test results please?



These just happen to be sitting on my desk.

You need a recommenced minimum twist to stabilize a particular weight of bullet.

Please tell me why I only have loss of stability/accuracy on the heavier bullets in my 7mm chamberings? In the 7/08 I have loaded and shot for anything from 100 "poor" quality hollow points up to 168gr high quality target bullets.My loss of accuracy came from the high quality target bullets , that is where one determines the bullet weight has exceeded the parameters of the rifle and chambering and barrel.

As for optimal , your rifle will tell you.You won't find many 7/08 that won't shoot a 120gr "optimal" if it doesn't then I can almost assure you you have a rifle problem or operator problem, not bullet.

Guys will push their varmint rifles to the very edge trying to squeeze that last bit of velocity out of them with light bullets.The extreme case, the bullets will disintegrate from over spin , while obtaining accuracy the whole time up until then.


coleman1495 said:
Here is the quick reference chart from Berger: http://www.bergerbullets.com/pdf/Quick-Reference-Sheets.pdf

It shows a 1-10 twist as being optimal for 140-168gr depending on the bullet. 1-9 twist is definitely too fast to be optimal for a 120gr. The more uniform a bullet is the less effected by overspin. Soft point bullets are not going to be extremely uniform. A 1-9.5 twist still won't shoot a 120gr bullet optimal. Those twist rates are designed to be optimal for ~>150gr.
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WhelanLad said:
The Result

IMG_20170106_194004_559.jpg~original
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Way to stick on it.

All the posts on the 120 weight makes me want to test some myself.

Regards
Ronr
 
The first 7mm-08 i got had a 18,5'' barrel.
To get high velocity i went with 120 Ballistic Tip and Varget. Results weren't up to my expectation and i tried IMR4350 next. Better but not too much. Just above the 1moa mark.
I sold the rifle for another more powerfull compact. But soon i grab another 7mm-08 with 20'' tube.
Then i tried the BT and some other bullets with both powder. The Speer 145 BTSP gave excellents results with either ( 44 of IMR4350 and 41 of Varget )
Speed is around 2700 fps for both load...

Stabilisation problems can occur when using lighter boattail , VLD type bullets with shorter bearing wall for a given caliber.

The Sierra 120 Prohunter has a long bearing wall considering his weight and i'm confident it can be stabilized easily with a good choice of propellant and primer.

( Go with slower burning rate powder Whellan . Your 22'' tube and twist are fine . Primer then...)

Longer and heavier bullets like VLD or monometalic TTSX need fast twist to stabilize properly and i don't think there can be '' too much'' fast twist or any '' over-stabilization ''.

Bullets malfunction ( explosion or fragmentation in flight ) occurs when '' over spinning '' is induced by excessive high speed on thin jacketed varmint bullets.

Quality big game bullets are not prone to those malfunctions when used within their advertised parameter.

Every rifle has its preferences for a diet too.


https://sierrabulletsblog.com/2015/05/07/understanding-twist-bullet-stabilization/
 
A bit of an update fresh from the mountains ,..
I was lucky this morning after a few mishaps , a mature doe stood broadside long enough before turning off at about 100m to give the Sierra a chance to hit home.
I aimed for just behind the shoulder- at the shot she turned broadside again an took off without much fuss.

Long story short i found her 200m away but had fallen into the multiple blackberry bushes an i was unable to recover her..or a Bullet!

Good blood trail out only one side , would of loved to have follow the bullet path an find it.

Hmm
WL
 
I checked my load notes...120gr Sierra Prohunter 2.780" COAL CCI250 39.5gr W748 Frontier Brass. 2480fps. 1.4" 5 shot group. Low recoil was the goal. Intended as a short range deer round for the kids. Rem700 Mtn...22" bbl. Heats up pretty quick so I don't fire more than 2 shots before a long wait... Or I end up with an even longer wait while it cools.
 
wilbar said:
I checked my load notes...120gr Sierra Prohunter 2.780" COAL CCI250 39.5gr W748 Frontier Brass. 2480fps. 1.4" 5 shot group. Low recoil was the goal. Intended as a short range deer round for the kids. Rem700 Mtn...22" bbl. Heats up pretty quick so I don't fire more than 2 shots before a long wait... Or I end up with an even longer wait while it cools.
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2500 fps mate, that is tamed down a bit, but proberly for the better for the projectile an aiding penetration! I like it.

the noise of my 120 load in the mountains is like a true pop gun..admittedly its nice to shoot though!! I'm at a bit of a cross road with what is ideal for me... but I have loose Regs that a 130gr .277 is minimum for the Game I hunt.... 120gr .284 falls under that, so even with a TTSX 120gr .. the line has been drawn in the sand at that number.

the little deer are 100gr .243 so the 120s are fine for this application, which will be happening around mid Feb until April, then i'll switch over to the 140gr Woodleigh (maybe even 160gr) for the Winter and Big Deer.

my loads must be around or on 2900fps

WL
 
There are two things I would like to suggest ,First being trim length of Brass can cause tight cases for bolt lift and accuracy issues. Second would be try to torque you mounting screws if your gun is not glass bedded. This would just remove the variables that could loosen up your groups. I have a reduced recoil load for my son that is 37.5 grains of varget with a 139 grain hornady that shoots sub moa. I found that if I overtightened the stock mouting screws it would change how the gun shot.
 
WhelanLad said:
I rekon I had another thread askin about seating depths and such to see if it would help Bring a 120gr Sierra into reasonable contention for a Hunting Load....

So I shortened up the COAL and re-loaded a few Charges wich showed promise.. I didn't gain too much but had one group at a bit over 1.5 inch ..

there seemed to be a common trend, few close an one out. So I continued loading and shooting Groups of 3, incase it was me. but seemed often than not I couldn't improve.


So Today I've started on a New Batch of Brass, to work out a load for these 120gr... NNY Brass - Kimber Montana 84m -

The Data I have says from about 42.5 - 44 gr ? of AR2208 (VARGET to You)
so I tip toed around 42gr after none of the above charges worked, an now have dropped right down to 41gr too see if that can slow things up a bit but give me a decent accuracy.


This wouldn't be unsafe?

also this wouldn't be unheard of if my particular Rifle didn't like said 120 bullets? ey?

good evening from Australia

WL
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Well mate, just have to introduce you to the ways of the CGN. On this blog they don't make 1.5" groups. Oh, they make them alright, but the 1.5" becomes .42" and often carries the remark, "What should I be doing to tighten it up?" And six young guys on here will give hints for making better groups!
I recently did considerable testing on a Tikka and a Savage, both in 7-08 calibre. The data you have on 42.5 to 44 grains of Varget with 120 grain bullet, is a very low velocity load, no wonder it is not accurate. My Tikka only made 2700 fps with 44.5 grains of Varget and a 130 grain bullet! The same rifle was shooting 130 grain bullets comfortably to 3,000 with Norma powder.
I was a very active shooter, often in competitions, throughout the glory days of shooting, the 15 to 20 years following WW2. There were so many great shooters throughout the world at that time and they gave out good advice. Not any good quality riflemen would put up with a rifle that changed POI as the barrel warmed up. However, on the CGN it is constantly seen to wait between shots until the barrel cooled! If the rifle has a good barrel and is properly bedded, usually with tension under the barrel at the front of the stock, it will keep the same group as the barrel warms up. If the rifle will only shoot a good group by waiting between shots, it is not an accurate rifle. The era I speak of also spawned the famous remark by Townsend Whelan, "Only accurate rifles are interesting!"
So, if I were you, I would pay very little attention to people on the CGN telling how to shoot and reload, with the exception of the odd expert on there. Instead, I would get some top quality books on the subject, written by riflemen in the years following WW2 and follow them diligently. One of the very best is, "The Accurate Rifle," written by Warren Page, often referred to as the greatest rifleman, ever. Jack O'Connor also wrote top of the line books on rifles, shooting and reloading, as of course, did many others, at a time when shooting and shooters was a mainline, admired hobby.
 
Lot of truth to that H4831. 140's work so well in the 7-08, it really isn't worth the farting about it takes with the 100/120 bullets. Too short a shank and the only thing gained is a bit of speed, 150-200fps or so, and you lose on the downrange end. Stick to the one load and shoot it. Once you have the shooting part down, the load becomes less of an issue. I shot 140 Partitions as hunting loads, 140 Ballistic tips shot the same, so I used those for everything else. Same powder charge for both. For seriously punching paper I used 168gr Sierra.
And I do not believe those dented cases are underloads of slow powder, that will collapse the shoulder in my experience. There is a full crease thru the neck base and up to point of the shoulder, to the dent in the side, which is usually longer, with underloading, and you can see the pressure path pretty clearly, don't see it there on those.
 
Whelan, I'm cheering you on your endeavors.


H4831 said:
Not any good quality riflemen would put up with a rifle that changed POI as the barrel warmed up. However, on the CGN it is constantly seen to wait between shots until the barrel cooled! ...
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Myself I am coming to that way of thinking. A 3rd yr starting on year 4 reloader (using a press) like myself can get caught up in the hype. It's like reading books about raising kids...this is what should or shouldn't be done regarding barrel cooling etc. ... if a parent follows all the hip literature and hearsay their kids will be just fine. Right? As time and reloading/testing goes on the practical pieces of this puzzle seem to become more prevalent and distance themselves from the lesser points. I hope I'm getting better but the things I used to concern myself with is just stuff in the noise now thanks to a few here patient enough to explain and let me run my course.

H4831 said:
Instead, I would get some top quality books on the subject, written by riflemen in the years following WW2 and follow them diligently. One of the very best is, "The Accurate Rifle," written by Warren Page, often referred to as the greatest rifleman, ever. Jack O'Connor also wrote top of the line books on rifles, shooting and reloading, as of course, did many others, at a time when shooting and shooters was a mainline, admired hobby.
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I'll look for those books H, thanks for that.

209jones said:
140's work so well in the 7-08, it really isn't worth the farting about it takes with the 100/120 bullets. ... Stick to the one load and shoot it.
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I think you already have a 140 load Whelan and that you are trying alternatives to see what they are like in the field, but I believe there is merit regarding 140's as being optimal.

Aside: The stick to the one load way of thinking is something I've recently converted to. C-fmbi had some words of wisdom that really resonated for myself. I was caught up in a "load for this" and a "load for that" but his words were to the effect of learning what one load does in all conditions. For me that's learning more about this 7-08 . (Close/far, standing/moving, broadside/quartering - lets see what this does) assuming proper caliber for the game hunted of course. BUT I still want to try 120's as stated earlier for some experience at the range to learn more from.

Regards
Ronr
 
Quote Originally Posted by H4831 View Post
Not any good quality riflemen would put up with a rifle that changed POI as the barrel warmed up. However, on the CGN it is constantly seen to wait between shots until the barrel cooled! ...

Bruce, there aren't very many rifles out there that will shoot consistently from a cold barrel to a hot barrel. Two or three rounds of consistently accurate rounds is about it for many sporting rifles. Milsurps on the other hand seem to do well and maintain acceptable accuracy over a lot of shots.

All sorts of reasons for this.

Like you, I am blessed with a FEW rifles that could care less how cold or hot the barrel is and for some reason they just don't gather enough fouling to make any difference in POI.

On the other hand I have other rifles that put their first shot in a different place than the fourth or fifth round. Usually for most hunting situations it isn't enough to make much difference.

Then there are the folks new to the game that have their new Savage/Winchester/Remington etc along with a reasonable scope and they don't know what is going on inside the barrel when a round goes down, let alone 20-40 rounds in quick succession. Same goes for proper maintenance to keep the POIs consistent. Example, freshly cleaned rife put back in the safe after a day at the range and left there for a couple of months. It comes out of the safe and into the pick up. When the person gets to where they want to hunt, they get out of the PU and load the rifle. A bit later a buck comes along that is close to 300yds away but presents a nice easy broadside shot. BANG. Miss. Bang. Miss. This buck is a newbies dream, he just stands there looking to see where the noise is coming from. WTH. How did he miss???

Well the newbie made the final scope adjustment after shooting several rounds in a row when the barrel may have been to hot to touch. When that barrel cooled all sorts of changes occurred. Also, the fouling in the bore was no longer there and maybe the newbie had a new box of ammo. Where that first shot went will be anyone's guess, maybe the same for the second shot. This is pretty much the normal scenario for an off the shelf rifle.

I often give people the advice to sight their rifles in for a first cold shot. The reason for this is because it's the only shot where you can control conditions. I have a Ruger #1 chambered in 338-06. That rifle puts its first shot from a cold barrel just over an inch high from its 200 yd sight in. At 300 yds it's about 3 in above where it should be placing the bullet. This is OK if the shooter knows what's going to happen and compensates for it. Most shooters don't pick up on this. They feel that the last shots they took will be where the rifle will shoot from a cold bore. That means a miss or worse a wounded animal.

As you well know, the first shot is usually the best and most important shot a hunter gets. That's the shot the shooter should be preparing for. The rest is mostly superfluous as most with any experience shooting game has found out.

It's the first round from a cold barrel that does the job.

The other thing is shooting from a fresh barrel. Most rifles throw that first and often the second or third round before they settle down. Even bench rest rifles have this issue and the shooters are allowed to shoot a few fouling rounds before they settle onto their score target. Some folks will shudder at this but with the rifles I hunt with I sight them in just before the season opens and unless something makes it necessary I don't clean the bores until the season is over.
 
Well Gerald, the first thing that comes to my mind is that you are not an old time shooter! It would have put more meaning into the sentence you copied, if this had preceded it.
"I was a very active shooter, often in competitions, throughout the glory days of shooting, the 15 to 20 years following WW2. There were so many great shooters throughout the world at that time and they gave out good advice."
You completely missed out on this fabulous era of shooting. Had you gone through it I'm almost certain that you too, would not put up with a rifle that wouldn't hold its point of impact as the barrel heated. I've had to re-bed the action and barrel of nearly all the bolt action rifles I've had from some years back. And every bolt action rifle I have had was made to keep the same group as it warmed. If it wouldn't, I certainly wouldn't have it!
In the great shooting period, there were lots of competitions for centre fire sporting rifles and everyone of them required multiple shooting, as the barrel heated. Even the turkey shoots the farmers put on, competing for live turkeys, often required multiple shots. So where would you have been with a rifle that changed POI as it warmed?
Cheers and good shooting,
Bruce
 
Bruce, I'm not knocking what you're saying and I copied/pasted that quote from another reply. I will go back and read your full post.

Just so you know, I started shooting single shot 22rf when I was 7 years old. That was close to 60 years ago. I didn't move onto centerfire rifles until my early teens. The rifles were full stocked milsurps. The thing about them was that they mostly behaved and did what they were supposed to do. Very seldom were any of them tack drivers, especially with the surplus ammo I shot. I shot in DCRA competition as well as Hunter Bench Rest. The DCRA shooting I did, wasn't quite as demanding as the HBR shooting but then again, I wasn't as serious about the DCRA shooting. The main reason behind that was time constraints and a 24/7/365 work cycle in my main place of work. I still have a couple of those DCRA rifles, a No4 MkI* Longbranch chambered for 303 Brit and another No4 MkI* Longbranch chambered for 7.62x51. They both shoot better than I can hold and they have been properly bedded and maintained. Both will shoot ammo they like very well and POI doesn't change from a cold barrel to a hot barrel. Both of them throw the first two rounds from a cleaned to the steel bore.

As for HBR shooting I also gave that up after a very good friend of mine passed away. We built our own rifles for that game and did very well. It was just never the same after my bud passed on.

All of the rifles I hunt with will shoot round after round into acceptable hunting groups, cold or hot. I attest that to several things, proper bedding, medium weight barrels that are free floating.

Most shooters have no idea what we talk about when we mention bedding and free floating barrels. Mod 7 Remington rifles and similar style are notorious for changing POI and having groups open up after as few as three rounds. Not a thing can be done to fix it either until the pencil thin barrels are replaced. That being said, Mod 7 rifles will shoot directly to point of aim from rifles that have been sighted in with fouled and cold barrels for the first and second shot.

The rifles of the "golden years" were mostly very well made and had the looks and reputations to prove it. What amazes me is how good even the off the shelf rifles really were. Most of that has to do with the exceptionally good bullets we enjoy today.

I remember a meat shoot in Westwold that went very well with a Brazilian full stock 1908 Mauser and a Martini 22rf. The winning shots that day ranged in the 1.5 in group range. There were some very good shooters there. They weren't surprised by their groups and took what they got. That was over fourty years ago. They had different classes of shooting then. Off the shelf rifles with scopes and without scopes.

The competition set up for scoped rifles allowed the iron sighted rifles to be used as well but only iron sights were allowed in the other. That was around the time the Juenke guage was marketed. What it did was measure bullet jackets for concentricity over the whole jacket. This led to much more accurate bullets. I especially remember that match because one of the competitors was upset that I was shooting an as issued milsurp in a sporting class rifle match. He felt that the full wood offered me an advantage over their shorter sporting stocks.

To sum this meandering up, I have done a lot of shooting on different venues, rifle/shotgun/trap/handgun etc. I am not one of those folks that just instinctively hits everything shot at. I have to work at it.

I have exactly two rifles that will shoot to POA from a clean barrel and still maintain accuracy over a string of ten rounds shot in rapid fire timed style. All of the rest need to be fouled first and depending on their barrel weights/bedding will shoot to POA when cold and might start to open up the group when and if they get shot enough to warm up.

In all honesty, I only shoot two off the shelf rifles as purchased. A Tikka T3 and a Remington 700. Everything else has been worked over from bedding and trigger to setting back barrels to clean up those nasty barrels that were installed in the seventies and eighties on most of the commercial rifles offered due to cost cutting.

You're right, the standards changed on firearms manufacture and what could be expected of them. Then again, with the advent of better bullets the accuracy bar was also raised.
 
I was just going off an ADI powders guide on the Powder charges for the 120gr, 2208 etc. Min and Max.

my rifle wouldn't work correctly if I keep stoking higher charges, I think my Kimber is a bit different to the other 708s out there ;) I like it.

I dislike the loads I'm trying in 120gr.... an once gone wont be back.

Great information here
 
Bearhunter, I'm not questioning that you have done a lot of shooting. Interesting that you first shot a 22 when you were seven. That is the same age that I first shot a 22! An older brother let me shoot at a grouse, twice, and I missed the grouse both times! However, my 22 event occurred in the very early 1930s.
What I am saying is you had nothing to do with this great period of shooting in the world, following WW2. You may not have even talked to anyone who knew it from personal observation. That makes it so hard for me in writing of it, because there probably is not another person on the CGN with personal observation about it.
Just think of it this way. In the years of WW2 there were no civilian firearms manufactured. At wars end a great many service men returned from war, from not only Canada and the USA, but from many other countries as well, including Australia, New Zealand and many countries in Europe, who wanted to get shooting and hunting. There was a tremendous rush to get firearms and everything related to them, on the market. BC sold more hunting licences when it had a population of 1.5 million, than they did when they had 4.5 million population!
Every descent sized town had shooting clubs and shooting was likely participated in by more people than any other sport. The gun writers of the big three magazines, Warren Page of Field and Stream, Townsend Whelen of Sports Afield, Jack O'Connor of OUtdoor Life and Elmer Keith, among many others, were writing articles and books which are highly sought after today. In short, it was the greatest period ever, in the world of shooting.
But what's the use of me talking to myself about it?
Cheers, Bruce
 
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