vertical stringing

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LLarry.parallaxscurioa...	vertical stringing	Lead	[-]
Posts: 1 (06/02/09 20:27:05) Reply Quote More My Recent Posts Message Me Connection Blocking Invite Ignore User's Posts	Tags : None I am having vertical stringing of two to three inches with a scoped K31. 180 grain spitzers with 40 grains IMR 4064. Any recommendations or causes? Tks Larry
RGRWJB		#1	[-]
Posts: 8950 (06/03/09 04:30:13) Director/OwnerDirector/Owner Reply Quote More My Recent Posts Message Me Connection Blocking Invite Ignore User's Posts	Bob should be along soon to answer that one. "We sleep safe in our beds because rough men stand ready in the night to visit violence on those who would do us harm." George Orwell.
jonkx		#2	[-]
Posts: 508 (06/03/09 06:23:23) Reply Quote More My Recent Posts Message Me Connection Blocking Invite Ignore User's Posts	Could be a few things. Are you hand weighing those charges? If not a weight difference could cause vertical stringing. You shooting from a bench or position? Range? If from position you could be shooting as you inhale/exhale causing the gun to bob. Could be a scope issue too, what sort of mount?
LLarry.parallaxscurioa...		#3	[-]
Posts: 2 (06/03/09 20:27:34) Reply Quote More My Recent Posts Message Me Connection Blocking Invite Ignore User's Posts	I am using the clamp on St Marie mount and shooting from a bench. Yes I weight each charge. Larry
CDR Xfire		#4	[-]
Posts: 155 (06/04/09 07:51:45) Moderator Reply Quote More My Recent Posts Message Me Connection Blocking Invite Ignore User's Posts	It's close to impossible to diagnose rifle and shooter problems over the internet; coaching can only be done in real life, with the coach examining the rifle and ammunition, and watching the shooter carefully as he shoots. If you are anywhere near Northern Virginia, I would invite you to some range time with me or a practice match at Quantico so I can see what's going on. The first question you need to ask yourself is why you think you and your rifle should be doing better. Despite all the internet hype you may read, these are surplus rifles; they are NOT minute-ofangle target rifles. Two to two and a half MOA is about what you should expect from an issued one without some expert tuning. The scope doesn't make it group any better, it only helps you see the target better. I will offer the following advice, though ... get off the bench and shoot from a good tight prone position. If the rifle is not rested at precisely the same spot every time; and if it is not restrained in recoil the same way everytime, it will "jump" differently for each shot, resulting in ... you guessed it ... vertical stringing. Resp'y, Bob S. USN Distinguished Marksman No. O-067
LLarry.parallaxscurioa...	vertical stringing	#5	[-]
Posts: 3 (06/04/09 22:18:01) Reply Quote More My Recent Posts Message Me Connection Blocking Invite Ignore User's Posts	Ahhh Bob you bent my dogtags when you said these are not MOA rifles. Okay I will try shooting prone. But one question...prone shooting means using the sling and doesn't that introduce bias? I would love to accompany you to a Quantico range. I have not been there since I was a young Marine back in the early 70s. I now live on Oahu and that is just too far. But we do have a great municipal range here if you get the urge for a stiff mai tai after shooting. I decided to go back to basics and check the recoil lug screw. It was almost a quarter turn loose. Hopefully that will help. Larry
bagbalm		#6	[-]
Posts: 53 (06/06/09 03:25:52) Reply Quote More My Recent Posts Message Me Connection Blocking Invite Ignore User's Posts	May I suggest you also make sure the barrel is free to move at the end and not clamped solid in the wood? If it is tight then a small change in how the rifle is brought back to rest on the support can be transmitted through the wood and press up or down on the end of the barrel. The fit can change if the wood absorbs moisture or dirt gets lodged in the gap. In the rear I added a screw to the tang ahead of the screw that is pulled down so that they can counter-brace each other. I am not as good a shooter as my rifle is capable of shooting, but occasionally I'll shoot a five round string under a half inch spread at 100 yards. It is completely free-floated at the muzzle with a muzzle weight. I tried the brake, but the plain unvented weight is more accurate. I'm off today to try some reduced loads of 110 grain M1 carbine bullets in front of IMR 4759 for my Swiss.
LLarry.parallaxscurioa...		#7	[-]
Posts: 4 (06/07/09 14:38:19) Reply Quote More My Recent Posts Message Me Connection Blocking Invite Ignore User's Posts	The barrel is clamped solid in the wood at the muzzle end. I will make a shim from a popsicle stick at each barrel band and take it to the range next weekend. I have not tried that previously as I discussed that with another swiss rifle shooter at the range and his reply was that he thought if the Swiss wanted a shim there they would have put one there. Question: What do you mean when you say your rifle is free floated by using a barrel weight at the muzzle? Thanks for the suggestions. Larry
Parashooter		#8	[-]
Posts: 2548 (06/07/09 20:43:15) Chief Moderator Reply Quote More My Recent Posts Message Me Connection Blocking Invite Ignore User's Posts	I suspect he means that it's free-floated and it has a muzzle weight. "With" is not being used in its causative sense here - only the associative.
CDR Xfire		#9	[-]
Posts: 157 (06/08/09 03:22:00) Moderator Reply Quote More My Recent Posts Message Me Connection Blocking Invite Ignore User's Posts	Without a competent translation of the original process instructions for the Waffenfabrik bedding procedures, it's difficult to discern what the Swiss intended for the treatment at the front end. Based on my engineering and rifle building experieince of 40 years, I'd go out on the proverbial limb and say that some contact between the barrel and the tip on the stock was intended, as there is nothing else in the bedding system that restrains the barreled action in the yaw axis. The front of the stock acts like a Vee block. The "issue" rifles are frequently decribed erroneously as "free floated". True free floating can work if some means of restaining the action from movement in yaw is put into the bedding system. Others here have descibed ways of doing that. Here is the bedding of my CISM rifle that was built by Grunig & Elmiger using a slightly altered military K31 action: Here's what the rifle looks like: The thing to avoid with an as-issued rifle (carbine) is a "trapped barrel". If the barrel is clamped tightly at the end, it cannot expand in the longitudinal direction as it heats up, and the POI will "wander", groups being erratic. The simplest solution for an "as-issued" rifle (carbine) that complies with the CMP rules is to just loosen the front band screw so that the barrel can be pushed up out of it's seat in the wood at the end of the stock. When it is released after pushing up, it should spring back to it's equilibrium position. Those who put the shims in between the stock and handguard at this point are accomplishing the same thing and making it a little more "permanent", but the shims are not allowed under the CMP rules. Putting the blob of metal at the muzzle (the "damper") is supposed to decrease the ampitude of vibrations in the barrel. It also alters the frequency response of the barrel. If tuned properly, it can significantly improve groups; it can also mess things up if the vibrations induced by the loads happen to find the new resonant point of the barrel/damper mass system. I have one of the dampers that I am going to try on a K31 that is in a modified "sporter" stock ... I bought it more to put some added weight out front for balance, but it will be a good test for the damping affect, too. When I get a roundtuit .... Resp'y, Bob S. USN Distinguished Marksman No. O-067 Last Edited By: CDR Xfire 06/08/09 09:43:50. Edited 1 times.
bagbalm		#10	[-]
Posts: 56 (06/08/09 09:22:12) Reply Quote More My Recent Posts Message Me Connection Blocking Invite Ignore User's Posts	Yes the weight and free floating are incidental. When I got my rifle and took it apart I noticed my barrel rubbed against the wood enough to wear the bluing off a spot in the two o'clock position looking from the rear. It did have a tendency to walk shots in a line of about two inches as it warmed up. I don't intend to ever use a bayonet with my rifle so I don't need a good mechanical support out there. Yet I had no desire to sporterize it. After I epoxy bedded the receiver very much like CDR Xfire documented so well with his pix I simply sanded the opening at the muzzle until I could slide a piece of paper between the wood and barrel when it is laid horizontally across a rest like I shoot it. With the barrel free to vibrate it shot groups like this - Note the two bottom holes are doubles. The end of the barrel was obviously vibrating in a mode that swung it in a triangular pattern. That is a three inch target at 100 yards. Now that I have a weight on the end it doesn't shoot a geometric pattern. This is how it shoots everyday: Those are one inch target dots at 100 yards. Sadly the limiting factor now seems to be ME. I can only sight and hold on a one inch dot so well at 100 yards and I get tired quickly. So I'm capable of shooting inch and a quarter to inch and a half groups. The rifle I'm sure with a better shooter could stay within an inch. Once in awhile when the wind is low and I'm fresh and the gods are looking the other way I'll shot a cluster under a half inch all touching each other. I can't count on it and it doesn't happen every range trip. Perhaps with a higher powered scope and one of those lead sled contraptions - but that's not real world to me. I might as well go ahead and buy a bench gun if I have to experience that. This I can do shooting over a log or braced on a tree out in the woods. Last Edited By: bagbalm 06/08/09 09:27:57. Edited 1 times.
RGRWJB		#11	[-]
Posts: 8953 (06/08/09 19:06:23) Director/OwnerDirector/Owner Reply Quote More My Recent Posts Message Me Connection Blocking Invite Ignore User's Posts	GREAT POSTS GUYS! "We sleep safe in our beds because rough men stand ready in the night to visit violence on those who would do us harm." George Orwell.

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