Tell me what you know about neck tension and accuracy.

I'm loading .223 for a Rem. 700 PSS and can't quite extend the Win. 55 gr. BT FMJ out to reach the lands. The bullet sits a bit forward of the cannalure. I'm getting flyers.

Seating with a standard RCBS die. Neck sized, fire-formed brass. We're not cranking the die down on the neck, and there's no crimp to speak of.

I'm wondering if I shorten the OAL and seat to the cannalure if this will increase my neck tension and maybe provide a more accurate load. I'm getting 2" groups at 100 yds. -- and then some flyers that are out maybe 3" or more. That seems WAY out of spec for what this gun should be doing.

My bench technique is good, using a 14x scope. So that's not the problem.

Any ideas? Thanks . . .

------------------
PowderBurns Black Powder / Muzzle Loading Forum:

www.hotboards.com/plus/plus.mirage?who=powderburns

I would agree that the accuracy or lack thereof is pretty bad. I can't see neck tension being the problem. When a rifle shoots that bad it's more than that.
Just for fun try full length sizing taking care not to bump the shoulder. You will find that cartridge concentricity is actually better. What is the twist in that rifle? if it is a 14 it may not stabilize the 55fmj. Regards, Bill.

Rifling is 1:9"

I've full length sized a lot of Win. brass with this 55 gr. bullet. That's not doing it.

My OAL measurement from a Sinclair gauge is 2.375" or thereabouts. With the bullet seated in a case trimmed to 1.758" I'm loading to an OAL of about 2.288" -- .87" off the lands.

Rem. 700 these days has a long throat. I shot some Win. factory loads in 55 gr. BT FMJ and got the same results -- 2" plus groups.

I wonder about a heavier bullet . . .

------------------
PowderBurns Black Powder / Muzzle Loading Forum:

www.hotboards.com/plus/plus.mirage?who=powderburns

Try the 55 gr. and 69 grain Sierra Match Kings.

Check the crown after firing to see if you have a symmetrical smoke pattern. May need re-crowning.

Check that the barrel is in fact free floating.

Pull the action out of the stock and check for any high points in the composite that would keep it from fitting down into the aluminum bedding block. Retighten the screws holding the action back so that the recoil lug is against the aluminum face. Tighten in stages. The 308 gets 65 in lbs, I don't know about the 223.

What velocity are you getting?

Don

I think your rifle may be twisted for the heavier bullets and that may be the reason you cann't touch anything. Your long throat is for the heavier bullets and not a factory problem. I would try the sierra 69 or 77 gr bullet before I started to worry about bedding,crown, etc. If you had a 1/12 twist and couldn't touch anything with a 55 gr bullet I'd say you need a new barrel the throat would probably be gone or a bad chambering job.

Crown looks virginal under 5x magnification. I'll check after shooting. The gun looks virginal.

I removed infintesimal bits of composite from the rear tang area block and from the screw pillar at the rear block where the trigger assy. bolts into the stock. Tightened to 65 in/lb with a Husky, high tech wrench -- not the "shaft bender" type, the "breaker joint" model.

Receiver looks like it's sitting flush on the pillar block -- good indicators of metal to metal contact.

I've gone over Boyd Mace's "The Accurate Varmint Rifle" -- nothing obviously binding or rubbing. Barrel is free floating.

I'm shooting 25.0 gr. of H-335/55 gr. Win. BT. Hodgdon rates this at about 31,500 or so in a 26" bbl. Mine is 24".

I'm going to try some longer bullets. That makes a lot of sense to me.

This forum is a damn fine resource! Thanks.

------------------
PowderBurns Black Powder / Muzzle Loading Forum:

www.hotboards.com/plus/plus.mirage?who=powderburns

[This message has been edited by PowderBurns (edited 04-21-2001).]

[This message has been edited by PowderBurns (edited 04-21-2001).]

I think you need a 1:8 to go up to the 80 grain bullet, so try the 69 first.

The rifle was designed to work with off-the-shelf match or tactical ammo. If it won't shoot 1 inch with Federal Match it won't shoot it with much of anything.

My 308 PSS had a rough chamber from the factory. They replaced the barrel. In neither barrel could a bullet be seated to touch the lands - except a 220 grain SMK, which tumbled!

In both barrels the chamber was too long. In the one I have now, you can start to close the bolt on a field gage (+.008), before you get a slight contact. The PSSs back then had the military finish (my brain won't dredge up the name!) In mine the inside of the barrel was finished also!

I firelapped it and got it down to 1.5 inches, then skim bedded it and it now shoots .5-.75 with anything. I used Brownells Steel Bed. I roughed up the surface of the bedding block with 80 grit sandpaper, washed it with toluene, put in the bedding and tightened to 20 in lb, then backed off and came back to 5 in lb. other than that follow the Brownells directions.

I use an old-fashioned heating pad wrapped around the action when curing the bedding. It seems to make the finished product last longer.

Good luck,

Don

Back to neck tension and accuracy - - -I tried quite a few experiments with neck tension in a .338 Win Mag, and a few with a .338 Jamison. There is definitely an effect. Annealing the necks also has an effect on accuracy as that also affects the neck tension.

The end result of my experiments was that the lighter the tension down to .001" grip on the bullet, the better the accuracy and SD's of the load. I did this with 225g Nosler bullets using two different loads. There was a disparity in the velocity of the two loads, one using N160 being about 100fps faster than a load using RL22. Optimum for accuracy for hunting use in this particular rifle was .002" grip on the bullet. .001" grip was slightly more accurate but recoil drove the bullets in the magazine back into the case. At .003" grip the SD's got larger as did the groups, and with more than .003" grip, groups were erratic, some OK and others with shots significantly out of the group with inconsistent shot pattern. With newly annealed cases .003" grip on the bullets was a bit better, but I finally settled on .002" grip for hunting loads and accuracy.

I've never experimented with the smaller calibers to any extent but in a 22-250, the lighter the neck tension, the better accuracy appeared. I'll probably be looking at that aspect more closely soon. I do know that for a long time it was fashionable for many benchrest shooters to have extremely light tension on their loads, but then they are shooting tight necked chambers. Bob

I would be very suspect of the bullets themselves. I would try another type of good hunting or match bullet before I did anything else.

quote:

---

Originally posted by PowderBurns:
Tell me what you know about neck tension and accuracy.

I'm loading .223 for a Rem. 700 PSS and can't quite extend the Win. 55 gr. BT FMJ out to reach the lands. The bullet sits a bit forward of the cannalure. I'm getting flyers.
PB/ Part of the problem maybe the bullets, canalouvered
Seating with a standard RCBS die. Neck sized, fire-formed brass. We're not cranking the die down on the neck, and there's no crimp to speak of.

I'm wondering if I shorten the OAL and seat to the cannalure if this will increase my neck tension and maybe provide a more accurate load. I'm getting 2" groups at 100 yds. -- and then some flyers that are out maybe 3" or more. That seems WAY out of spec for what this gun should be doing.

My bench technique is good, using a 14x scope. So that's not the problem.

Any ideas? Thanks . . .

---

PB/ Part of the problem may be those fmj cannalure bullets, I use nearly the same load, a little hotter, with 52 Berger fbhp or 55 Hornady V-Max and Federal or Remington 7 1/2 primers in br prepped cases and am using a 700vssf with Leupold scope and at 100yds off bags/prone get .5 groups all day and several high.2 low.3 groups on good wind days, I use commerical RP brass/Winchester comm brass/ Win military type brass NOT IN ONE GROUP but for testing and use a Stoney point setup to seat the bullets about .010 off the lands, I use a RCBS die set for full length sizing to fireform and then use a Redding Competition bushing neck sizing die for resizing the fireformed loads and a straightline seater to seat bullets, as another post states the factory glass/aluminum stock is great but does react badly to mis torque of the action screws/bolts, start at 50inlbs and if that don't work go to 55/60/65, I use the standard length allen wrench and put the long leg in the screw and tighten with the short leg firm finger tight and this fixed a grouping problem that appeared the first time i took the gun apart to clean it and reassembled it without knowing about the sensitive bolt tightening, found out and redid screws and back to 1/2in groups, as to origional question, some BR shooters use necks so loose that they don't even resize them just finger install the bullet and let the rifling seat the bullet, but I prefer a firmer hold on my loads for field use and such, good luck and good shooting!!!

Update:

I just loaded 50 pcs of Lake City fire-formed once fired brass, and 50 pcs. Win. factory brass full-length sized. Trimmed to 1.758".

Bought some Varget powder. Loading 26 gr. --which is right up into the neck.

I too suspect the bullets. Weights vary by 0.5 gr. Purchased some Sierra Match King 69 gr. and measured OAL with a Sinclair gauge. Seating 0.02" off the lands my OAL is a lanky 2.40" -- too long to get into a standard plastic ammo case. The feed in the mag just fine.

Other than sizing the neck with the ball on the decapper (polished), there's no neck tension to speak of, no crimping.

I will probably run a field test on this stuff tomorrow. My "consultant" at the local reload shop notes that the Rem. Police has a long throat for shooting the heavy bullets and that it's fussy about OAL and bullet quality. Here's hoping I got it right.

I'll keep this crew updated . . .

------------------
PowderBurns Black Powder / Muzzle Loading Forum:

www.hotboards.com/plus/plus.mirage?who=powderburns