foxpig Posted December 7, 2013 Report Share Posted December 7, 2013 Just wondered if someone could tell me what the advantage of having a tight neck chamber is. Ive started neck turning and will soon be having a rebarrel. Need to now what all this tight neck stuff means really and weather or not I need to get a ttihht chamber or something like .. Cheers as very confused foxpig Link to comment Share on other sites More sharing options...
The Gun Pimp Posted December 7, 2013 Report Share Posted December 7, 2013 If you're not going to shoot competitive benchrest there's not much point in a 'tight neck'. All my benchguns have tight necks but I don't run a tight neck for any other shooting - F Class, tactical etc. Link to comment Share on other sites More sharing options...
foxpig Posted December 8, 2013 Author Report Share Posted December 8, 2013 Thanks for the reply but can I ask what the actual benefit is of having a tight neck?? Link to comment Share on other sites More sharing options...
The Gun Pimp Posted December 8, 2013 Report Share Posted December 8, 2013 It's all about launching the bullet (under 50,000psi of pressure) as true as possible into the rifling. If the bullet enters the rifling absolutely true, it stands a good chance of coming out the other end in a similar manner. The 'tight neck' gives less opportunity for the bullet to be 'off line'. Not a good explanation I know. I'll try and think of a better one! Link to comment Share on other sites More sharing options...
foxpig Posted December 8, 2013 Author Report Share Posted December 8, 2013 No that makes perfect sense and was the answer I was looking for. Nice one tgp Link to comment Share on other sites More sharing options...
Hatzi Posted December 8, 2013 Report Share Posted December 8, 2013 The case neck has no room to expand beyond the elastic limit of the brass therefore returns to correct size with no plastic deformation consequently reducing the amount of work hardenening done to the brass. +what TGP said too as weel as all the consistency benefits of accurately turning the case neck to fit with the correct few thou allowance. Link to comment Share on other sites More sharing options...
brown dog Posted December 8, 2013 Report Share Posted December 8, 2013 It's all about launching the bullet (under 50,000psi of pressure) as true as possible into the rifling. If the bullet enters the rifling absolutely true, it stands a good chance of coming out the other end in a similar manner. The 'tight neck' gives less opportunity for the bullet to be 'off line'. Not a good explanation I know. I'll try and think of a better one! This is not my domain at all, so ready for correction....I understand tight neck chambers to be a requirement that arises from uniforming (ie thinning) case necks to a minimum uniform dimension. The dimension chosen being thin enough that all neck thickness variance has been removed from the ammunition. Link to comment Share on other sites More sharing options...
Tony.H Posted December 8, 2013 Report Share Posted December 8, 2013 This is not my domain at all, so ready for correction....I understand tight neck chambers to be a requirement that arises from uniforming (ie thinning) case necks to a minimum uniform dimension. The dimension chosen being thin enough that all neck thickness variance has been removed from the ammunition. i thought that it was both yours and tgp explanation rolled into one, basiclly so once the high spots are turned off of the brass and are gone, so more concentric then, the tight chamber is to suit your brass so, the expansion is minimum and you can use a consistant neck tension for consistancy. ive just got a reamer print for a .20tac and on the drawing it says no need to neck turn, with the thickness of the brass and the size of the overall neck once the bullet is seated it shows it will allow 1thou expansion, which sound nice and tight but, the brass is showing between 13-14 thou thickness, ive been told by all of the smiths ive spoken to, too not neck turn the brass as there is no need for this cal and chamber set up, although i am itching too i, would normaly of turned to 12thou but, i am just going to shoot the brass as is and play with neck tention instead, the rifle is only for fox but, iv time to prep brass so i just see it as part of the enjoyment of reloading....... tony Link to comment Share on other sites More sharing options...
gbal Posted December 8, 2013 Report Share Posted December 8, 2013 No that makes perfect sense and was the answer I was looking for. Nice one tgp Agreed-though the other posts do expand on it a bit. It is perhaps worth adding some context-100y BR is often decided by differences in aggregate for 25 shots that are only a few thousands of an inch different,as in !st .235,2nd .238,3rd .245....and so on.At that level of precision almost every small improvement is worth some investment-and tight neck chambers offer some. For general varmint shooting,accuracy is of course highly desirable-but not that level of repeatable precision-you won't often get 5 shots at a fox,with a perfectly clear aim mark on it's fur.Likewise stalking,(and even if you did ,you might not actually want a second or third etc shot to go down exactly the same wound channel that did not do the job with the first shot!) For these purposes,slick feeding-especially the first shot -is important (as it is for magazines full in tactical)-hence full length resizing (and for fast shots at 1000 y BR).Not that tight necks means fussy about chambering,but a very close fit is more vulnerable to dirt etc-hardly applies on a Bench! So,the sublime precision of BR and tight necks,are just not cost effective outside BR,nor really utilisable without a downside-just not very 'practical'. Gbal Link to comment Share on other sites More sharing options...
The Gun Pimp Posted December 8, 2013 Report Share Posted December 8, 2013 The origins of neck-turning and 'fitted' or 'tight' necks go back to the beginnings of benchrest where the brass was nowhere near up to the standard it is today in terms of uniformity. Shooters improved their brass by turning the necks but, to make this viable (in terms of increased accuracy), they needed to reduce the now larger 'neck to chamber' clearance - otherwise the benefit of more even brass would be largely negated. As a few of the posts have mentioned, it's easy to come unstuck with a tight neck. Under benchrest conditions, we are under cover with plenty of opportunity to clean. If you think of the fouling on the neck of a case after one shot - the same fouling will be on the chamber's neck. If you run a tight neck for say F Class, where a day's shooting could be 70 - 80 rounds without cleaning, would the build-up of fouling on the chamber neck be significant enough to 'remove' that one thou. tolerance? Link to comment Share on other sites More sharing options...
Laurie Posted December 8, 2013 Report Share Posted December 8, 2013 There do seem to be some extra issues over just case neck consistency and case to chamber clearance. There was a report many years back in 'Precision Shooting' magazine where somebody tried using a larger 6PPC chamber neck and reduced clearances by thickening the brass with some sort of metal spray on process. necks were 100% symmetrical but maybe 12 or 13 thou' thick instead of the usual heavily turned eight and half used in the PPC in benchrest. Clearances were as per normal in the benchrest game which back then was usually two thou' overall equating to a single thou' at any point around the neck. It didn't work - results were much poorer than with the normal way of doing things. So, it seems that having a thinner neck than normal - allied to consistent dimensions, minimal sizing and expansion, carefully controlled / light neck tension - provides a benefit in itself. The optimum neck thickness and case to chamber clearance is not one size fits all either it seems. All write-ups on 6.5-284 and straight 284 suggest that running a minimum clearance set-up is sub-optimal. Three thou' overall, better still three and a half top four is usually now recommended, and not just for the very valid safety and reliability in the field / F-Class type competition reasons that TGP mentions. Link to comment Share on other sites More sharing options...
gunner Posted December 8, 2013 Report Share Posted December 8, 2013 Just wondered if someone could tell me what the advantage of having a tight neck chamber is. Ive started neck turning and will soon be having a rebarrel. Need to now what all this tight neck stuff means really and weather or not I need to get a ttihht chamber or something like .. Cheers as very confused foxpig hi fp i agree with tgp and hatzi and others , if your neck turning then def get a tight neck chamber on yer new barrel ! it helps align the bullet to the lands and like one said your minimising working of your brass , so should last longer . ideally you need to make up a round thats neck turned and a bullet seated to get a precice measurement so that ideally you would have the reamer made to YOUR dummy round (with the right clearance ) i know its a pain in the botty sometimes to neck turn but once its done its done ! yippee . now go and take the eye out of a bluebottle Link to comment Share on other sites More sharing options...
Stonewall Posted December 9, 2013 Report Share Posted December 9, 2013 Benchrest Central forum Centerfire benchrest topic: Boy ! Was I ever wrong and read Jackies posts at the bottom of page one. I could not insert a link Glenn Link to comment Share on other sites More sharing options...
Stonewall Posted December 9, 2013 Report Share Posted December 9, 2013 woops ! Glenn Link to comment Share on other sites More sharing options...
Tony.H Posted December 9, 2013 Report Share Posted December 9, 2013 Benchrest Central forum Centerfire benchrest topic: Boy ! Was I ever wrong and read Jackies posts at the bottom of page one. I could not insert a link Glenn Benchrest Central forum Centerfire benchrest topic: Boy ! Was I ever wrong and read Jackies posts at the bottom of page one. I could not insert a link Glenn http://benchrest.com/showthread.php?88367-Boy!-Was-I-Ever-Wrong Link to comment Share on other sites More sharing options...
The Gun Pimp Posted December 9, 2013 Report Share Posted December 9, 2013 Well, like I said - I wouldn't bother unless you are shooting competitive benchrest. For everything else, I prefer what I call a 'no-turn' neck - loaded round plus three thou. However, once to stop neck-turning, you lose control over the loaded diameter so, if you do use a 'plus three thou' neck reamer, it's important to check your loaded rounds and NOT rely on the brass manufacturer's consistency (remembering the gold box/blue box 6BR brass from Lapua) - I like to keep a bushing handy to slip over each loaded round. Link to comment Share on other sites More sharing options...
(200x135).jpg.0fd0a94f065c6cb243fdff1b40e0819a.jpg)
.jpg.0972b4e2bdf0b5a4109eb96f2b1b62ad.jpg)
Recommended Posts
Archived
This topic is now archived and is closed to further replies.