simgre Posted August 18, 2014 Report Share Posted August 18, 2014 I recently managed to find my Holy Grail, namely an RPA Interceptor multi-shot in .223. It had recently had it's RPA fitted Archer barrel replaced with a Lother Walther tube, with a 1 in 8" twist. The fella I bought it off, someone I know and trust, estimated it had had no more than 1000 rounds through the new barrel. Anyway, started with a load that my Savage 12BVSS loved. 69gn SMK and Vhit N140. Terrible. I had some Hornady 68gn HPBT and some 73gn Bergers. Loaded some with N140, H335, and Benchmark, all powders that I've always had great success with in this calibre. Nothing in any combination of bullet or powder would do anything more impressive than an inch and half to two inches at 100yds. However, light bullets in the 52gn HPBT of either Sierra or Hornady, it loves! Regardless of which powder and bullet combination I've had some brilliant performance. Either bullet with Benchmark has give an honest three round group of a quarter inch! I get over excited when this happens and generally put the other two outside stretching it to three quarters of an inch or so... An anomaly that's "fixable" to take it beyond 600 with confidence or, just take it for what it is? Fly's a liitle bit in the face of modern convention! Link to comment Share on other sites More sharing options...
gbal Posted August 18, 2014 Report Share Posted August 18, 2014 Hmmm....how did it shoot these heavier bullets with it's previous owner?Any data from him? Presumably,you have checked the barrel twist-it's possible it's actually a slow one,maybe mismarked? If it's shooting 3 into .25,then two 'fliers' only with the light bullets,and the heavies don't group three,just check the 'excitement factor' by shooting POI into a black zone where you can't see bullet holes....or shoot enough to get used to .25 as routine.....I'd check groups at some distances too. The alternate to 'excite' is 'lose concentration' with two 1/2 inchers,then end up with a 1+ 'group. How does it shoot with another known decent shooter? Does sound like a 'wrong twist' though,the simplest explanation-measure it? gbal Link to comment Share on other sites More sharing options...
simgre Posted August 18, 2014 Author Report Share Posted August 18, 2014 Definitely a 1 in 8"... Another mate shot it at the time and was punching 3/4" groups. The "potential" per se I am more than happy with as far as light bullets are concerned a bit more tweeking and sort the trigger as it's way too light, and I reckon I can expect 1/3" groups all day long.... But, a fast twist not liking heavy bullets is the bit than I don't get. I've emailed the guy I got it from, but he's away a lot with minimal access to comms. Link to comment Share on other sites More sharing options...
DW58 Posted August 18, 2014 Report Share Posted August 18, 2014 Sierra 69gr SMKs work fine for us in a 1:8 barrel with Vihtavuori N140. Link to comment Share on other sites More sharing options...
Bianchi Posted August 18, 2014 Report Share Posted August 18, 2014 A few mates of mine have had issues with the SMK 69s in 8" or 9" barrels (mostly LW) as well. After testing the SMK 77s with Viht N135 or N140 they observed a tremendous improvement in accuracy and are now all grinning again. One mate has even won the nationals at 300m here with his scoped AR15 (also with a LW 8" barrel) using this load at least twice. Could be that the groove/land dimensions are marginally different. I lknow that this is the case with Heym barrels. Have you checked the barrel with a borescope yet? Link to comment Share on other sites More sharing options...
gbal Posted August 18, 2014 Report Share Posted August 18, 2014 Simgre,thanks for the reply re twist.Of course it is very anomalous for a 1 in 8 not to shoot the heavier bullets pretty well,in a rifle with a good barrel,as evidenced by the lighter bullets groups. Likewise a light trigger helps,once you get used to it (BRs are down to 2oz),but again you are shooting the light bullets with it ok for 3 shots.And another shooter has groups opening up with heavier,too....same brass etc etc. Most 'variables' seem controlled,though it's possible the ammo isn't optimised for that rifle....though you have tried a range of,presumably not hot, loads or any pressure signs. If it won't shoot bergers,scenars,, pretty well with V140,or other powders, about 10thou off lands....(might not be optimal,but won't be far off)..no mag loading issues,like bullet tip bashing/too long-check is single load them...maybe someone will come up with a testable idea,but you are right,it's a puzzler so far.... Link to comment Share on other sites More sharing options...
forbie Posted August 18, 2014 Report Share Posted August 18, 2014 You may or may not know about Optimum Charge Weight. Look it up OCW on the web and try what he does. It lets you see very quickly what works and doesn't in a particular rifle as I have found out. Link to comment Share on other sites More sharing options...
simgre Posted August 18, 2014 Author Report Share Posted August 18, 2014 Sierra 69gr SMKs work fine for us in a 1:8 barrel with Vihtavuori N140. That's always been my benchmatk load in anything with a 1 in 9" twist or faster..... My 12BVSS loved that load. Turned into a five shot laser out to 800m.... Link to comment Share on other sites More sharing options...
gbal Posted August 18, 2014 Report Share Posted August 18, 2014 That's always been my benchmatk load in anything with a 1 in 9" twist or faster..... My 12BVSS loved that load. Turned into a five shot laser out to 800m.... Point taken-though lasers tend not to drop/drift 200/100 inches....it might have good precision,as the 12BVSS is quite well thought of,and drop them close together... But as you know,sometimes a commonly good load doesn't work for a particular rifle-though its not often a poor load-and always a sensible starter,at least-the puzzle remains-why don't anything tried so far shoot reasonably close to the light bullets? (strictly three of them,anyhow). :-) Link to comment Share on other sites More sharing options...
simgre Posted August 18, 2014 Author Report Share Posted August 18, 2014 You may or may not know about Optimum Charge Weight. Look it up OCW on the web and try what he does. It lets you see very quickly what works and doesn't in a particular rifle as I have found out. Yep, aware of OCW and I do in fact develop my loads along those lines. It's not the groups of the day that are causing me "issue", so to speak. Let's be honest, a genuine three shot, quarter inch group, consistantly, is outstanding! It was me that couldn't close the five round group down and it is it's apparent dislike of heavy bullets that's puzzled.... Link to comment Share on other sites More sharing options...
simgre Posted August 18, 2014 Author Report Share Posted August 18, 2014 -the puzzle remains-why don't anything tried so far shoot reasonably close to the light bullets? (strictly three of them,anyhow). :-) Exactly! But, this is just the start. For good measure I've just ordered some 77gn SMKs and 75gn Amax from my local shop for good measure! I'm going to head out again tomorrow with another myriad of loads! All of the previous were loaded to 2.260 so they fit the mag. Ten thou of the lands would give me a single load option only and not with the diminutive 52gn either. Then thou off the lands and there's not much shank left in the neck.... Now lets see if I can hold my excitement when I see those bullets start to print a group not much bigger than the bullet! LOL Link to comment Share on other sites More sharing options...
gbal Posted August 18, 2014 Report Share Posted August 18, 2014 OK,Tally ho! Don't get too concerned about seating depth,that's a fine tune issue-I was just trying to eliminate bullet tip damage in the magazine-something odd is occurring with these heavy bullets-damaged tips was a possible. I would not load up too many different powder weights-we need a good sample size group (s)-better ten shots from a loading about .5g short of the book max for that bullet ,than three 3 shotters at either extreme...by all means have a few loads,but the odds are high that your safe quite/very accurate load (or at least one such node) is about .5 from max...A couple of more good quality bullets is a good idea,though-hope the weather is conducive to shooting....stay cool,.3 is very good,but if the rifle can do that,you'll just have to get used to it-and it's not unprecedented,though very satisfying when repeated nearly every (three) shots...good luck-there has to be a resolution.... g Link to comment Share on other sites More sharing options...
bradders Posted August 18, 2014 Report Share Posted August 18, 2014 A friend and I experienced this exact thing with a batch of 1:8 Walthers several years ago, Wouldn't stabilise anything above a 69, but were great with 52's etc. Walther said they don't guarantee their barrels....and this is why I haven't used them since Link to comment Share on other sites More sharing options...
Mattnall Posted August 19, 2014 Report Share Posted August 19, 2014 A friend and I experienced this exact thing with a batch of 1:8 Walthers several years ago, Wouldn't stabilise anything above a 69, but were great with 52's etc. Walther said they don't guarantee their barrels....and this is why I haven't used them since Of the LW blanks I bought only about 60% would stabilise bullets as expected. LW said they sold me barrels of a certain twist (as asked for) not a guarantee that they would stabilise xxgn bullets. However these were 1:7" though, not 1:8". They were brilliant with lighter bullets but not the heavier ones they were intended for, and all the other barrels (different twists and calibres) I bought were great. Link to comment Share on other sites More sharing options...
NICK Posted August 19, 2014 Report Share Posted August 19, 2014 A friend and I experienced this exact thing with a batch of 1:8 Walthers several years ago, Wouldn't stabilise anything above a 69, but were great with 52's etc. Walther said they don't guarantee their barrels....and this is why I haven't used them since I have a Walther in .25cal. I will not be buying another. Very average. Nick. Link to comment Share on other sites More sharing options...
gunner Posted August 19, 2014 Report Share Posted August 19, 2014 I have a Walther in .25cal. I will not be buying another. Very average. Nick. Me neither - had an 8 twist 223 Ai that shot worse than the std R700 - even tho it had been properly blue printed , my new krieger - is in a different league alltogether . Link to comment Share on other sites More sharing options...
Murph Posted August 27, 2014 Report Share Posted August 27, 2014 I know if I bought a 1 in 8 twist barrel that did this I wouldn't be one bit happy lol Link to comment Share on other sites More sharing options...
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