450 vs 7 1/2's

Rflshootr

Member
Has anyone ever chronoed loads to see the difference between 450's and 7 1/2's in a 6BR. Is there much difference in velocity or SD?
 
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Justin, I think he knows that we are jerking his chain. I'm certainly not the best speller, but Mickey Coleman stayed on my A$$ about it. A pet peeve of his.

Had to edit my post-spelled it seller instead of speller.
 
well I guess you'd dip 'em in a chrome tank? Then the lone ranger wouldn't have anything on us bench rest shooters. ;)

And I'll bet if somebody thought it would give them an "edge", they'd probably try it.
Ok I'll play nice and take that part out.
But I am a pretty good speller....just not a very good typer :p
 
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Could be pertinent

Back in the day when I was seriously chasing the Badge, and the High Master, I did a lot of testing at 600 yards. In the mid 90s, when I was doing all these on a ranch near Laredo, I spent hours and days testing my 600 loads at 600 on different occassions. This is of course on .223. Tested different bullets, powder and every available primers I could get my hands on.

Bottom line, the 450s came out about the same as the BR4s in terms of grouping at 600. I opted to use the 450s because back then nobody was using then especially on the lowly .223s, and they are much cheaper. I emptied the LGS of their 450s. I use the same primer on my .223 1000 yard load.

When I said grouping, with multiple groups, the 450s grouped the smallest, roundest (if there is such a word) the 7 1/2 grouped tighter width wise, but the groups were diagonal from 730 to 130 about edge to edge inside the 6 inch X ring, whereas the 450s grouped around half the X ring. Though it repeated, I did not bother to tune out the diagonal groups of the 7 1/2

No chrono data, most of the times we tested at night when the wind died down, lights on the target. The concrete bench was set conveniently just outside the ranch house, we load and shot.
 
So were the pressures pretty close to the same with the 450's and the 7 1/2's other then maybe some minor tuning or was there a significant change in the powder charge between the 2?
 
I have not

nor with the 30 BR I shoot. In reading Ken Waters' book of compiled articles he wrote over the years, there is references where he changes primers and reports 18-20 or so fps diff between the two. In a hunting rifle that prolly won't make much diff, but in a target rifle it may change the tune.
 
I'm sure there are primers that are not good...had some. As far as good primers go, I wouldn't mix up a bunch and try to shoot them competitively. Pretty sure I don't even understand the question here as well. Sure, one primer may produce different velocities than another but how do the holes in the target paper look? Velocities ain't what you should be looking at...look at the dadburn bullet holes!
 
Justin, I think he knows that we are jerking his chain. I'm certainly not the best speller, but Mickey Coleman stayed on my A$$ about it. A pet peeve of his.

Had to edit my post-spelled it seller instead of speller.

Butch,

I wish I had had Mickey Coleman on my arse about spelling. I had nuns. Mickey with a toothache and high on crack would be more pleasant than Sr. Patricia...


Nez,

I experienced something similar with 7 1/2's in a Contender chambered for .223. The first two shots would be a dot, and the next three went vertical. Every time. I switched to 400's and got nice, round groups. I've shot 7 1/2's in other guns and never had it happen again.

Go figger'...

Justin
 
Wilbur I was more looking for a comparison of consistency between the 2 different primers in velocity with the same powder charge and if one gave more velocity and/or consistency (ES) with the same powder/bullet combination. Maybe I didn't word it right in the beginning.
 
I beat around the bush there a little but that's exactly what I thought you wanted to know. What I'm thinking is why would you care? Help me out a little here....really. I understand the question but don't know why you're asking. In short - It seems important and I don't know why.
 
Well what started my thinking process, if you can consider it to be one, is that I have been having trouble getting a 6BR to shoot well. This is my first experience with a 6BR and the thing is as finicky as I don't know what. I've gotten 1 bullet to shoot fairly well, a sierra 70 match. Everything else is just junk. All over the net is how easy these things are to tune and how great they shoot. I've checked the gun to make sure I didn't screw up somewhere along the build and can't find anything there. All the components are top shelf names. So I guess I'm trying to research data to try and decide where to go next. There are a million load combinations out there which I neither have the time nor the resources to try them all. At the same time, I realize what works in one rifle doesn't work in another. I am looking at the primers that I am using (7 1/2's) as suspect at the moment and was trying to get some data on what seems to be the most consistent for the application. Maybe I just got a $350 junk barrel and I'm chasing my tail. I haven't given up on it yet, but I'm close. So I'm trying to make an educated decision instead of just throwing this, that and the other down the barrel.
 
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OK, I understand. Forget about those primers for a moment and tell us about your rifle:

Barrel maker
Barrel twist rate
Action
Trigger
Action glued in?
Stock
Any particular details
Tuner?
etc...

What powder and bullets have you tried? I can't help there but others can and likely will. What size group will the rifle shoot (best and average) and at what yardage? Do you use wind flags?

If you have already posted this stuff, please copy the link(s) here so we can view them.
 
Krieger 8 twist 26", P1000 single shot action, Jewell trigger @ about 8 ounces, laminated stock 2 1/2" forend, glass bedded not glued. Scope is Leupold 6.5x20 side focus w/target knobs.
Powders...H4895, 8208, varget, H335 and BL-C2. Just got a lb of Benchmark but haven't tried it yet.
Bullets....70 BT, 70 Sierra match and 70 blitzking, 75 V-Max and 95 VLD. Fire formed with 100 interlocks (didn't expect anything here anyway).
Groups at 100 yards mostly with flags...not always.
Sierra match was the most consistent averaging .5's with a few groups in upper .2's &.3's. The best group was .281.
Other bullets from upper .5's to close to 1".
One thing I haven't done is seated the bullets out further then touch....no jam other then for fire form.
Also have only used the 7 1/2 primers except for fire form which was WSR.
Lapua brass, necks skim turned, weight sorted, sized for .002 neck tension with .003 clearance to chamber with loaded round.
Right now the barrel has close to 400 rounds thru it. The reamer is zero free bore.
So what should I try from here? Jamming(didn't really want to do this)? Different primers? Heavier bullets? Throat it out a little? Heavier neck tension?
The rifle and the 2 best groups out of almost 400 rounds in the pics.
And btw, the bipod was for the pic only. Groups were fired off of a rest.
 

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Since the groups pictured are similar in shape, do you have another scope that you could try? I don't think that's the problem but if you have another it would be a good thing to do just to rule out the scope. PM me your address and I'll send you some hand swaged bullets....enough to see if they shoot any better. The twist rate of your barrel is much greater than what you would need for these bullets but they're good bullets nonetheless.

How much powder did you use to shoot those groups? Have you worked with that powder such that you know the absolute maximum load...the load that you would be willing to shoot rather than the load that goofs up your cases?

I'll ask...is H4895 a typical powder for the 6BR? If it is, just use that powder for a few trips to the range so you can keep it somewhat simple....alternatively, pick a powder.
 
I do have a 12x42 nightforce I could throw on it. The Leupold was brand new for that rifle. I doubt that is the problem either, but years ago I did have a Vari-x 3 6.5x20 that was bad out of the box and had to be sent back.

The 2 powders I had the most luck with were 8208 and Varget. Those 2 groups happened to be Varget. The problem with either powder or the rifle is that it won't agg. I'll get a good group, then a pretty bad one and vice versa with no consistency. Sierra lists the max at 32.1 and Hodgdon at 34.0. I worked the load in half grain increments to find the node, and then went .2 on either side and found 32.5 to be the best. I never went all the way to the top to find out where it gave excessive pressure but judging from what I was seeing, it is close to the top at 32.5 which is between what Sierra and Hodgdon data says. I'm relatively sure that I can't reach the next node without wrecking cases.
As far as H4895, it's in the recommended burn rate range for that bullet weight but I didn't have much luck with it. On the burn rate chart it is just below 8208.

I appreciate the bullet offer and will send you my info, but I'll expect you to let me pay you for what you are willing to part with. I just don't do "free rides". Never have.
 
Are you shooting over flags? How are you holding the rifle? Have you tried a milder primer, with its own powder charge workup? What about less neck tension. In the past, I have always worked my varmint rifles with bullets seated .006 to .010 into the rifling, without any problems. I did the workup that way. Once a charge weight has been sorted, I have found that seating depth has a large influence on accuracy. What you want is not the issue. Ask your rifle what it wants. I have seen a lot of steel time and components wasted by shooters who did not do that.
 
Krieger 8 twist 26", P1000 single shot action, Jewell trigger @ about 8 ounces, laminated stock 2 1/2" forend, glass bedded not glued. Scope is Leupold 6.5x20 side focus w/target knobs.
Powders...H4895, 8208, varget, H335 and BL-C2. Just got a lb of Benchmark but haven't tried it yet.
Bullets....70 BT, 70 Sierra match and 70 blitzking, 75 V-Max and 95 VLD. Fire formed with 100 interlocks (didn't expect anything here anyway).
Groups at 100 yards mostly with flags...not always.
Sierra match was the most consistent averaging .5's with a few groups in upper .2's &.3's. The best group was .281.
Other bullets from upper .5's to close to 1".
One thing I haven't done is seated the bullets out further then touch....no jam other then for fire form.
Also have only used the 7 1/2 primers except for fire form which was WSR.
Lapua brass, necks skim turned, weight sorted, sized for .002 neck tension with .003 clearance to chamber with loaded round.
Right now the barrel has close to 400 rounds thru it. The reamer is zero free bore.
So what should I try from here? Jamming(didn't really want to do this)? Different primers? Heavier bullets? Throat it out a little? Heavier neck tension?
The rifle and the 2 best groups out of almost 400 rounds in the pics.
And btw, the bipod was for the pic only. Groups were fired off of a rest.

Flags yes, mostly except times when conditions were near dead. Always 7 1/2's. Holding the rifle as if in the field, not free recoil. Using .002 neck tension. Tried .001, made it worse. Didn't do any jam for fear of bullet pulling if the round needed to be removed. I have seated deeper in the case but a light touch was best. I'll try some jam & see what it does.
 
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