Bullet base below neck Accuracy? Plan

[joeb33050]

I have a Savage M10 308 Win. that must have 314299 base/gas check seated below the neck for the cartridge to go in the gun. I want to have this barrel throated to get the base/GC up into the neck.
This rifle then offers the unique opportunity to test whether it is less accurate with the bullet base below the neck or with the bullet base up in the neck.
Thus, I want to perform a test of this rifle, before and after throating.
My 308 Win. 314299 accurate loads are 16-20 IMR4227, and 18-20 A5744.

I would plan to load some of each, shoot, record the results. Keep going until I’m in the 100 yard five shot average 1”-1.25” range. Get Pat to throat the barrel, put it back on, shoot the same load/s, record and compare the results.

Looking for thoughts or criticism regarding the test plan.
Thanks;
joe b.

[StarMetal]

I have a Savage M10 308 Win. that must have 314299 base/gas check seated below the neck for the cartridge to go in the gun. I want to have this barrel throated to get the base/GC up into the neck.
This rifle then offers the unique opportunity to test whether it is less accurate with the bullet base below the neck or with the bullet base up in the neck.
Thus, I want to perform a test of this rifle, before and after throating.
My 308 Win. 314299 accurate loads are 16-20 IMR4227, and 18-20 A5744.

I would plan to load some of each, shoot, record the results. Keep going until I’m in the 100 yard five shot average 1”-1.25” range. Get Pat to throat the barrel, put it back on, shoot the same load/s, record and compare the results.

Looking for thoughts or criticism regarding the test plan.
Thanks;
joe b.

Joe,

On that Savage 10 in 308, are you sure that the fat nose of the 314299 isn't allowing it to enter the bore thus requiring deep seating. Try a bullet nose in the muzzle. If it is very tight or hard to push it, then the nose is too fat. Remember the 314299 was made for fatter bores, 303 British, etc.. Maybe I 311299 would serve your Savage better. Just a thought.

Joe

[BruceB]

Joe;

I think your plan is far more practical than most "comparison tests".

You're using the same barrel, which is where most comparison testing falls apart. The barrel itself is the single largest variable, so when two or more rifles are compared, the conditions in the various rifles are very different. This does not apply in your proposal. GOOD idea!

In my experience, some of my rifles have given really excellent results with the bullet bases even below the SHOULDER, let alone the neck. If powder contact with the bullet is a concern, a mere wisp of dacron will eliminate that contact.

I'll be very interested to see your results.

[Ricochet]

It won't settle the question of whether the base below the neck affects accuracy. You're also changing the "freebore" distance the boolit travels when you change the depth of seating.

[joeb33050]

Joe,

On that Savage 10 in 308, are you sure that the fat nose of the 314299 isn't allowing it to enter the bore thus requiring deep seating. Try a bullet nose in the muzzle. If it is very tight or hard to push it, then the nose is too fat. Remember the 314299 was made for fatter bores, 303 British, etc.. Maybe I 311299 would serve your Savage better. Just a thought.

Joe
The 314299 nose engraves nicely in this gun, the STOP is the top of the top band, sized .3095", that runs into the ?throat? thing and is clearly marked.
Thanks;
joe b.

[StarMetal]

The 314299 nose engraves nicely in this gun, the STOP is the top of the top band, sized .3095", that runs into the ?throat? thing and is clearly marked.
Thanks;
joe b.

Ok got it Joe. Sounds like the same problem with my 7mm-08 Sako...very short throat. On another note my AR15 in 6.5 Grendel has the shortest throat I've ever seen. Since the AR15 doesn't have a lot of camming power it makes the problem worse. I was able to find a bullet to fit from Saeco. Perhaps if you search around you can find a more suitable bore rider since you have a short tight throat.

Joe

[joeb33050]

It won't settle the question of whether the base below the neck affects accuracy. You're also changing the "freebore" distance the boolit travels when you change the depth of seating.
I don't think so, although I may be wrong. I'll ask Pat to throat the barrel such that the base of the bullet moves into the neck. This is something like .150". What will happen is that the cylindrical part of the throat, just ahead of the case neck, will be reamed from .3092" currently to .310" or so, allowing the top band at .3095" to go forward. I think there's nothing happening to the freebore. N'est ce pas?
Thanks;
joe b.

[Ricochet]

I thought you were saying you'd throat the barrel longer, then try it with the boolit seated below the neck or in the neck. That certainly changes the boolit travel before it hits the rifling. If you're talking about comparing best groups before and after rethroating it, even more has changed. Not much validity to the test, IMO.

[Nrut]

Joeb33050
I must be missing something...
I just run the boolit into a smaller tapered "push thru die" and taper the nose or top drive band to get the gas check into the neck..
For the .30 cal. I use a nose taper die made by Don Eagan..
But you probably know all this so that's why I am scratching my head..
Don is deceased I wish someone would pick up making those dies again.. They are super handy..

[joeb33050]

I thought you were saying you'd throat the barrel longer, then try it with the boolit seated below the neck or in the neck. That certainly changes the boolit travel before it hits the rifling. If you're talking about comparing best groups before and after rethroating it, even more has changed. Not much validity to the test, IMO.
I guess I'm having trouble gettijng this clear. Now, the MAX OAL is controlled by the throat just ahead of the case neck. The bullets are ~.3095", the throat, there, is ~.3092" The nose engraves nicely, the front of the front band hits this throat area and is clearly deformed and stopped. After throating, this cylindrical throat section will be enlarged from ~.3092"to ~.310", and the front band will then slide into the throat, the nose will still engrave nicely, and the GC will be inside the case. All samo samo, except the GC is in the neck, not hanging below the neck-shoulder junction.
Does that work?
joe b.

[StarMetal]

I guess I'm having trouble gettijng this clear. Now, the MAX OAL is controlled by the throat just ahead of the case neck. The bullets are ~.3095", the throat, there, is ~.3092" The nose engraves nicely, the front of the front band hits this throat area and is clearly deformed and stopped. After throating, this cylindrical throat section will be enlarged from ~.3092"to ~.310", and the front band will then slide into the throat, the nose will still engrave nicely, and the GC will be inside the case. All samo samo, except the GC is in the neck, not hanging below the neck-shoulder junction.
Does that work?
joe b.

Have you tried an actual .309 bullet? I mean the 314299 sized to .309?

Joe

[Nrut]

Ok joeB I see..
A nose taper die would alter your nose to the point were it wouldn't engrave..

[joeb33050]

Joeb33050
I must be missing something...
I just run the boolit into a smaller tapered "push thru die" and taper the nose or top drive band to get the gas check into the neck..
For the .30 cal. I use a nose taper die made by D. Eagan..
He is deceased I wish someone would pick up making those dies again.. They are super handy..
Joe Wiest made me a very nice nose-first taper die. Unfortunately, the die-gun-bullet combination don't allow me to get the bullet up into the neck. Not the problem with the Joe Wiest die, which is perfect for many gun-bullet combinations.
Here's another way to explain it. The front band at ~.3095" is too big for the rear section of the throat. I don't like to make the bullet dia. .308"; too small. Then I'm stuck getting the throat bigger.
Does that make sense?
joe b.

[Nrut]

Yep makes sense JoeB..
I clued in on your post #10

[joeb33050]

Have you tried an actual .309 bullet? I mean the 314299 sized to .309?

Joe
Sort of. My measurements of ~.3095" for the bullet and ~.3092" for the throat are approximate, as all these are. I've never had a sizing die that sized a bullet round to a tenth on one pass. If I repeatedly size and turn and size and......, the bullet base gets a bit smaller. If I do it to exhaustion, I can get a bullet smaller than .3092". I size, turn ~90 degrees, and size again as a rule. 2 passes for every bullet, no matter the sizing die size. Just my rule.
In 4 times slugging the chamber, I repeatedly get .3092" in front of the case mouth, and groove diameter of .3065". The land = bore diameter is smaller than .300" because .300" noses engrave, this after swaging the nose in the Joe Wiest die. We're fiddling with tenths here, and I don't want to size smaller than my current ~.3095" as a normal process. I don't have a .309" die, do have .308", etc, up to .312".
I don't think a .3090" bullet will go in the .3092" chamber, but don't know. If you or anyone else has a sizing die that will size these to .3090" I'll send bullets immediately, a dozen should tell the tale.
I recognize that another bullet might solve the problem, but I have two 311299 molds and one 2 cavity 314299 mold giving me a choice of 5 cavities/bullets to choose from, and one of these works in every 30 cal I've tried them in.
Anyone want to size some 314299s to .3090?
Thanks;
joe b.

[badgeredd]

Joe Wiest made me a very nice nose-first taper die. Unfortunately, the die-gun-bullet combination don't allow me to get the bullet up into the neck. Not the problem with the Joe Wiest die, which is perfect for many gun-bullet combinations.
Here's another way to explain it. The front band at ~.3095" is too big for the rear section of the throat. I don't like to make the bullet dia. .308"; too small. Then I'm stuck getting the throat bigger.
Does that make sense?
joe b.

Joe,

IMHO, I believe your premise is totally correct & would be a valid test. When I had my barrel for my 35/30-30 chambered, Jesse asked me what boolit I intended to use and cut the throat accordingly. It seems logical to me that you would have an honest comparison. The only thing I can think of that would change besides the boolit base location is the case volume with your chosen powder. I say "Go for it" and see what you get for results. :bigsmyl2:

Another thought, if you chrono your loads before and after you'd also have a measure of the effect of the boolit's intrusion effect on combustion. Maybe important, maybe not.

Edd

[madsenshooter]

Joe Weist made me a die to size the front band on a 308329 so that I could use it in K31. It doesn't size anything but the front band. If you let him know what you got, I'm sure he can make what you need, seems easier than rethroating. Maybe not, don't know about you, but I got enough operations in making a boollit anyway. G David Tubb seems to think seating the bullet above the neck shoulder junction makes a difference for j-words, says the bullet forms a donut above said junction and pushing one through it makes for variations in neck tension. But who's he?

[rhbrink]

j boe I have a lee push through .309 if interested, I just saw this thread and am very interested as I am looking at buying a Model 10 Compact for the new CBA light production class but have been wondering about the very short throat that Savage uses because you cannot modify the chamber or throat and keep it legal for computition. I have in the past put a .308 die on my lubricator and inverted a bullet and pushed the first band or two into the die, this will put a slight taper on the leading edge of the first band and size it down to .308 allowing you to seat the bullet a little farther out in the case. Maybe this will help some, if interested let me know.

[joeb33050]

j boe I have a lee push through .309 if interested, I just saw this thread and am very interested as I am looking at buying a Model 10 Compact for the new CBA light production class but have been wondering about the very short throat that Savage uses because you cannot modify the chamber or throat and keep it legal for computition. I have in the past put a .308 die on my lubricator and inverted a bullet and pushed the first band or two into the die, this will put a slight taper on the leading edge of the first band and size it down to .308 allowing you to seat the bullet a little farther out in the case. Maybe this will help some, if interested let me know.

I thought that this sizing the top band to .308" would solve the problem. It didn't. My .308" die sizes to .3085" when just the top band is sized. The further down I go, the smaller the first band. And, the bigger the nose gets. So I sized the noses, and bumped up the top band. so I sized the noses, then sized the front band. The unsized nose, in front of the top band, got bigger.
Eventually I got the nose and base bands to the size where the ctg. would go in the gun, but it went in hard, too hard. I've given up for now, if I can think of another way I'll try it.
I figured that sizing the top band to .308" would allow the ctg. to have the bullet out and the base above the neck. I'm disappointed.
Now, someone suggested chronographing the bullets when I do the test. Maybe, but I can't shoot for group and chronograph at the same time, doesn't work for me.
Thanks;
joe b.

[joeb33050]

I've got 3 sets of ctgs loaded with Rem 2 1/2, 314299 @ .3095", and OAL of 2.786" which leaves ~1/32" of the top band above the case neck-everything else sticking out is nose. Bottom groove lubed only, Lyman super moly. These require some pushing on the bolt handle to get in the chamber.
IMR4227, 19, 20, 21 gr.
All I have is a 4X scope, another 6-24 on the way. I use Lyman STS on other rifles.
Tomorrow, at Markham Park in Ft. Lauderdale, may tell if this shoots or not.
joe b.

[joeb33050]

The 6-24 BSA scope showed up, so I put it on. My first time shooting this rifle. The Choate stock is a nightmare from the bench, the slots in the bottom of the stock make shooting from bags about impossible. So, between adjusting the scope for focus and parallax and working out how to handle the stock, and getting sighted in, I only shot 4 groups with the lightest load.
19/IMR4227: 2.375, 1.575, 2.15, 1.15 Avg. 1.812"
20/IMR4227:1.6, 1.5, 1.875, 1.1, 1.375 Avg. 1.49"
21/IMR4227:2.225, 1.9, 1.15, 1.85, 1.05 Avg. 1.635"
These are 5 shot 100- yard groups, 314299 @.3095", Lyman Super Moly in the bottom grease groove only. Cartridges require a hard push to get them in the gun. All have GC+ below the case neck.
It looks like having the base of the bullet below the case neck doesn't GREATLY affect accuracy.
joe b.

[shotman]

well many jacket match bullets are below case neck. I dont like a GC below because under recoil it may come off, there could be problems. Maybe not but what would happen if the check just happen to be near the primer and ended up half way down the barrel? It may never happen but IT COULD and that is enough for me. If check is in the neck It will go out the barrel

[joeb33050]

Shot again today, 10-27-09, 100 yards, 5 shot groups
17/A#9, 314299, .3095", WLP
2.95", 1.45", 1.45", 2.05, 1.775, AVG: 1.935"
20/IMR4227, 31141, .3095, WLP
1.1", 1.0", 1.4", .85", 1.775", AVG: 1.225"
20/IMR4227, 314299, .3095, WLP
1.325, .9, 2.275, 2.0, .975, AVG: 1.495"
It seems that having the GC+ below the case neck does not greatly affect accuracy.
joe b.