Ignition - another accuracy issue.

Some time ago I acquired an used Schultz and Larsen "Legacy" in 223. It's the neatest rifle to hunt with, and quickly became my "go-to".

But it has only ever been medioce in the accuracy dept, quite acceptable for deer and goats, but not "minute of rabbit" that's for sure. I tried all the normal tricks to improve it. Careful checking of all basic things mechanical such as scope and mounts, bedding, crown. And load development, I tried a lot of combinations.

The rifle occasionally misfired right from the get go but I "forgave it" because of its other qualities. However it seemed the misfires were getting worse, and this combined with its poor accuracy should have been a "red flag". I was getting a bit sick of it and started looking a bit deeper. The light primer strikes prompted an investigation of the rifles headspace. Sure enough, this rifle has headspace at the outer end of the tolerance limit, it closes on a go guage as it should, and not on the no-go, as it should. But using "my comparator" the no-go guage measures 1.501" and fired brass from the rifle 1.496-1.497. A lot of my brass and factory ammo measures 1.492" to 1.494". I reset my dies to minimally resize the brass (at this stage I was hoping to be able to use any of my 223 reloads in any of my 223s) but the misfires continued even though the sized brass was coming out at 1.495"/1.496" . Loads at this length were also noticeably tighter fitting in my other 233 chambers.

After getting dedicated brass for the S&L and trying different primers the misfires continued. I contacted S&L, who responded promptly. After an exchange of photos they reckoned the firing pin strike was light and it needed polishing where it ran inside the cocking piece. Their engineer also commented that the main spring also looked short, but for some reason "we" both passed by this, they seemed fixated on the polish job, I was focused on the headspace. After yet more misfires (using factory ammo) I had a really good look at the mainspring, and sure enough some Muppet had shortened it, there was no way one of its ends was factory "dressed". Two attempts later at finding a substitute that was more powerful (wire diameter 1.5mm versus 1.4mm on the original) and fitted in the bolt body without binding I had bolt lift on cocking that was noticeably heavier, and a "warp speed" noise from the firing pin. "Warp speed" was the S&L engineers expression, English not being his first language possibly . . .

Back at the range . . . The rifle was firing everything, including rounds that had already resisted two strikes.

But the real kicker . . . Accuracy was measurably improved with cheap factory stuff. So I tried my favorite 223 deer reload and BINGO, the 77 TMKs that were previously struggling to do 40-50mm for 5 shots are now snuggling up at 25mm (and with an MR of less than 1.0cm) for 10 shot groups.

I should have cottoned onto this sooner, consistent ignition is a key accuracy factor. For example quite a few top rimfire guys replace the mainspring in their Annie match rifles annually. So if you have checked everything else on an otherwise quality rifle, then keep moving on.

S&L are sending a new mainspring, and I have very unkind thoughts towards the Muppets who previously messed with this rifle.

You improved the lock time. Something that made the 788s so accurate

Lock time doesn't improve accuracy, it's an aid to shooting the rifle with more precision . . . Or if you prefer, it rewards poor shooter consistency.

Consistency is part of the accuracy equation in my opinion...... thats just me tho

Interesting. I suppose it's to thr other side now if primers are a bit hot the pressure may go up, maybe blowing out patterns.
22 hornets can be quite primer sensitive

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Originally Posted by csmiffy

Interesting. I suppose it's to thr other side now if primers are a bit hot the pressure may go up, maybe blowing out patterns.
22 hornets can be quite primer sensitive

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The little hornet is sensitive to everything. That's what makes it so frustrating to hand load for until you understand that.

@Tentman one thing I stumbled across, if there is any oil on the chamber end of the barrel and the receiver then accuracy suffers. I found this with my wife's Classic DL in 22-250 which would shoot 1" 5 shot groups but I thought it should do better. S&L told me to remove all oil and once done the rifle would shoot 1/2" 5 shot groups. We own 6 S&L rifles and they all shoot very well as long as there is no oil in that area.

Just put a new mainspring in my cz 527 as a “last resort” to tightening groups up (seems I’ve done everything I can think of to fix it). Hoping to shoot after work this week so this post is very comforting

There are possibly other things mechanical besides mainspring that impact ignition. Many years ago there was a Savage Lightweight 6.5 CM floating round on the forum as "in-accurate, won't shoot" . After a while it came my way. I shot it and sure enough, it wouldn't shoot. All the basics were checked, the bedding had been gone over by a previous owner and looked fine (this was one of the walnut stocked lightweights) and there was nothing else awry that I could fine . . . . It did indeed point to a dud barrel.

But on pulling it to bits for the umpteenth time I was peering down into the stock and noticed a wee mark in the trigger area. Sure enough on checking the trigger area you could see a rub mark on the sear - which is extended outside the trigger mechanism on Savages to form the bolt stop/release function, and on this model of Savages, had been revised so the bolt release was on the bottom . ...

All it took was one swipe with a chisel to take a tiny chip out of the trigger well on the stock and that rifle shot extremely well after that. I always thought of it as a bedding issue, but looking back it was probably variable ignition as the sear dropped. Sear drag is a known accuracy issue, especially in 22s.