44 mag rifle vertical stringing

[GhostHawk]

Listen to it!

[kenyerian]

Better slug your barrel.The SAAMI specs for 44 Magnum are different for pistols and rifles. The lands and grooves dimensions for a rifle, is 424" bore, .431" groove vs a revolver at .417" bore, .429" groove. My grandson's handi-rifle likes .432 sized boolits.

[waksupi]

I remember Felix stating that vertical stringing is too much powder, horizontal, too little.

[CIC]

Here is my recipe for success. .432 LBT cast and un-sized with a medium load of Universal. The bullet is plain base. One hole groups at 50 yards. Maybe that will be of some help. Oh by the way, I can get similar results from commercial cast if they are no smaller than .432.

[T-Bird]

Thanks for all the help! Went back today and shot the 15gr AA#7 load that I chronographed at 50, but never shot at 100. I got a 21/4 in total round group for 5 shots with 4 being within 1". This looks GOOD. Only load that hasn't strung vertically (Felix may have been right) it's below the starting load for 44 mag (15.8gr) but at about 1500fps, will serve my needs. Will try tomorrow for repeat results, if it works, I'll wait till it's colder and be sure it still shoots that well. During some of this testing, I shot some unsized boolits that were around .432, got the same stringing.Based on my mental math, this load should be in the upper 20K level, so it isn't too low pressure even tho it's below starting load. I could be wrong.

[T-Bird]

Went back today, placed the same target I used yesterday, holes and all at 100 yds. Shot 5 more, all of them were within yesterday's group. The rifle likes this load and so do I. The first load I shot at 100 only had 1/2 gr more pwdr and it exhibited vertical stringing. Amazing how much difference a small amt of pwder can make.Thanks everyone! This kind of stuff is what's both maddening and rewarding about this hobby!

[303Guy]

Have you considered the possibility of ignition inconsistency? Small differences could be affected by differences in muzzle lift due to barrel time and degree of lift, both acting together for that particular load.

I've had an otherwise accurate rifle producing strong vertical stringing with a particular powder. Horizontal spread was very slight.

[John Boy]

Vertical string group in all instances is not the fault of the rifle or the reloads. Give this article a read and see if any of the causes are yours, not the rifle or the reloads ... http://www.6mmbr.com/verticaltips.html

[T-Bird]

Read it John Boy thanks. I don't know. This isn't a bench rest gun, it's a 300$ H+R single shot. The trigger is hard, it's not well balanced, etc. I did however have good luck with another load using AA#5 and the same rest set up and bullet. I just wanted another, slightly hotter load to use at longer distance if the opportunity presented itself. My vertical string wasn't like the ones in that article. It was 10"! Not resting the forearm on the front rest and holding it in my hand,seemed to shrink the string to 5". When I got to 17gr, in my load "development", it was WORSE! When I backed off to 15gr, I got a nice, tight round 10 shot group. In my case, I think it WAS the load.

[303Guy]

It was the load but why? Interesting that reducing the load tightened up the group. This would indicate barrel harmonics. I was suspecting ignition and or burn variances which it could still be. I need to retest my rifle that gave me a 10 inch vertical string. Two rifles have done it to me actually. The first one I put down to action stress due to a misfit forearm. It was swollen after boiling to get all the oil out. Now it fits fine. The other gun was the load - different powder.

[T-Bird]

I don't know, I was looking for a load that was 15-1600fps from the rifle, which would be (I estimated) about maybe1250-1300fps from a 6" pistol.The AA#5 load that I was "improving" was a 1350fps load from a rifle, and is a real nice soft, accurate load for kids. I shot the 15 gr load over the chrono , 3 shots that were between 1481 fps and 1501 fps. It was a small sample size admittedly, but seemed to be consistant velocity at least. It also shot well at 50yds, but for some reason, I didn't shoot it at 100, I Increased the load to 15.5, and got stringing. Stringing didn't get worse till I got to 17gr. It was interesting that the only way inaccuracy was expressed was by vertical string. There was very little horizontal spread in any of the loads.

[T-Bird]

It's hard to believe that as thick as those H+R bbls are that they vibrate at all but I know they do.

[303Guy]

My No4 that gave bad vertical stringing has a can on it and normally shoots sub-MOA. The vertical stringing with BL-C(2) was astounding. Recoil increased a lot, as did muzzle blast. With H4350 the recoil with the can is like a 223. Followed by a push. I assume the push is caused by the gases escaping like a rocket engine.

[Mr_Sheesh]

Barrels vibrate a lot; Lean a car antenna against the barrel after checking zero, you'll find the shots change POI an obnoxious amount. Same thing for a tree branch etc.