Hot Barrel Accuracy, cold barrel not so much

JMB is my Hero

JMB is my Hero

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So I am at a loss. I handload for my A-Bolt in .270 and have found a load it loves.....with a hot barrel. Shooting with a cold barrel(10-15 minutes between shots) I get an almost 2" group at 100yards. Shoot fairly rapidly(every 15-20 seconds), and it will consistantly push through one ragged hole at same distance. For the record I'm loading 140 AccuBonds, pushed by 52.5gr of H4350, Fired by CCI Benchrest primers.
Over the years I've probably only pushed 1000 rounds or so through the old girl, and the barrel isn't contacting anything I can find, so I am at a loss.
I am appealing to the greater knowledge of the group here. Can someone give me an idea what the hell is going on?
 
By shooting fairly fast you are likely shooting in conditions that are the same, and your position doesn't change much. With 10-15 minutes between shots things change, light, wind, mirage, position, hold etc.
 
"...every 15-20 seconds..." Too fast for a hunting rifle. It needs to have its best accuracy out of a cold barrel.
"...the barrel isn't contacting anything I can find..." Look at the bedding anyway. It may be touching a pressure point when it's hot but not when cold. Or touching when cold and not when hot. Check it with a hot barrel. Run a $5 bill under the barrel. Where it stops is where the pressure point is on your rifle. If the 'Fin' runs all the way to the chamber area, the barrel is free floating. It may not be when cold though.
Barrels are daft things. Some like a pressure point, some don't. The one in your rifle may be too small. Easily fixed with a bit of bedding material.
"...52.5gr of H4350..." According to Hodgdon's site, that's half a grain over max. Isn't enough to cause any grief though. All manuals will give slightly different data too. Load manual data reflects tests done on a specific day using specific components.
 
Harmonics change with the heat. Heat causes expansion etc. Conditions, would have to change drastically to open a group by 2 inches at 100 yards.

Most rifles, have a load they like with cold barrels and one with hot barrels. For hunting rifles, go for the cold load. Load it for accuracy, not any particular velocity.
 
My criteria for a purely "Hunting" rifle is the first shot out of a cold barrel. As long as the second shot is not 2-3" away, I'm good to go. The first shot is usually the one that really counts IMHO. Eagleye.
 
Maynard. I considered the variables possibility. The hold I can see, I'm sure it changes to a certain extent. This rifle and I, we've been doing this together for 15 years, and this is new to me. The wind I take care with, it's one of the few variables I can work around.
Sunray. I realise I want to find a load that shoots the best out of a cold barrel. I only found that it shoots well hot out of frustration. I had shot the 2" group with the first 3, and got mad because things just haven't been working out. So I rattled off the other 3...into one hole. I have checked the float on the barrel, it does start making contact about 2" or so ahead of the reciever. And as for the max recommended powder charge, I had worked this load up in .5 gr increments and so for no signs of excessive pressure.
bearhunter. I typically try all my loads out of a cold barrel, when I'm hunting I'm looking to only take one shot. I just can't seem to find a decent(ok I try for sub MOA) load these days.
Eagleye. I feel similar. Except I want under an inch. A lot to ask I know.
I've handloaded for it since I was 15, so 13 years I guess. So I have a little experience, but am by no ones estimation a master. I appreciate the the help guys I guess I'm just wishing there is some miracle cure for my frustration.
 
At what stage of shooting after you have cleaned your barrel? Are you worst groups with a clean barrel or dirty?
Just throwing it out there, Had one barrel that shot better after a few fouling shots.
 
I think I had 6 or 9 shots through before the last group. Ya, I find that I need 2 or 3 shots through the barrel before it starts to get consistent. I'm pretty fussy about cleaning, but I'll usually put about 20 rounds down the barrel before I clean it.
 
JMB is my Hero said:
I think I had 6 or 9 shots through before the last group. Ya, I find that I need 2 or 3 shots through the barrel before it starts to get consistent. I'm pretty fussy about cleaning, but I'll usually put about 20 rounds down the barrel before I clean it.
Click to expand...

I have put over 800 rounds down my .308 target rifle without cleaning, and still won matches with it. Cleaning the bore is over rated.
Is your action bedded?
 
JMBH, There are a lot of reasons, why rifles won't shoot under an inch.
The main reason, for most rifles, is the bullet jackets. Bullet jackets, need to be as concentric as possible. Until the use of Juenke Thickness Testing machines, jacket thicknesses were hap hazard to say the least. Not all that many years ago, 4 inch groups from a hunting rifle, were considered acceptable.

To make extremely concentric jackets, takes a lot of expensive quality control. Bullets, need to be cheap to make and distribute. The better they are, the more expensive they are. There are other factors as well. Many bullets, like partitions aren't especially accurate. They are plenty good enough for hunting purposes and give excellent performance at any range. Don't expect sub minute of angle groups out of them.
Commercial chambers can also be on the generous side and may or may not be concentric to the bore. You name it. Hand loading can only do so much. It won't work magic. If you are lucky enough to have one of those rifles, that everything just seems to be perfect with, great. Most of us aren't that lucky and we wring the best results we can out of what we have.
We can also get into other things, like run out on the loaded bullets, etc.

If as you said in your original post, the bullet from the cold barrel, hits 2in high, you should try a bit of fore end pressure against the barrel. It's an old trick, but it still works If you have a fishing scale, pull up on the barrel with about 2kg of force and put a pad between the barrel and fore end. It is amazing how well it can work, even with plastic stocks.
 
maynard. Yes the action is bedded. It was from the factory, so I imagine it's not the most stellar job. I've contemplated doing it myself, but up till now I'd had no issues.

Bearhunter. I suppose I should mention that I had a load worked up with the 140gr AccuBonds using IMR 4831 that shot a rather consistent 3/4". Lost my Reloading Log though, so it's kinda hard to remember what the particulars are. That and I wanted to try Nosler brass. I have a fair amount of H4350 around so I thought I'd give it a shot also.

All in all. Lower performance than what I am used to. I've got an LEH elk hunt that ends on the 30th so maybe after that I'll have more time to play with this. I do appreciate the help, a sounding board is a hell of a thing to help a guy out. Especially when your sounding board has a collective experience level such as this.
 
bearhunter said:
JMBH

If as you said in your original post, the bullet from the cold barrel, hits 2in high, you should try a bit of fore end pressure against the barrel. It's an old trick, but it still works If you have a fishing scale, pull up on the barrel with about 2kg of force and put a pad between the barrel and fore end. It is amazing how well it can work, even with plastic stocks.
Click to expand...

JMBH,
Don't dismiss the above as it has worked for me on my .270 Win..
 
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