Re: YHM 7.62 QD larger exit hole diameter?
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BGEFIVEFOURONE</div><div class="ubbcode-body">My YHM in 5.56 is the same way. The trapped gasses can offset the round (ie downrange POI shift) I think they do it as a safety as mentioned. </div></div>
This would not be correct, first, the projectile is long gone. Secondly, those designs that do deal with gas pathing that may effect ballistics have no correlation to bore diameter, the impact is due to isocentric gas redirect, non-timed, bore purge only baffles.
A full stack of large over bore points to:
1. A poor understanding of modern techniques to efficiently strip gas.
2. Poor craftsmanship as it relates to either stack alignment, potential sloppy final bore ream or an inability to hold tolerances.
3. A valid requirement based on ballistic trajectories present or anticipated having to do with the attachment method (QD). Here we can find graduated, trumpet, hour glass and a whole host of other bore set-ups. Just because end cap hole large does not necessarily mean the proceeding are as well. Should not be found through the whole stack.
4. Uncommon use of a "trash end cap," a technique where a sacrificial non functional final is used to protect the end of the can when extreme environments are anticipated, mostly concrete key-holing.
Lastly, if you saw that can at a show it may be a fake/show can and the end cap is just a any old hole they had in their pocket.
Matt, the jump your asking about is dependent on gas pressures as well, check with maker. Some cans do, most can't. YHM makes a .338 with wholly different specs.
http://yhm.net/index.php?main_page=product_info&cPath=14_18&products_id=318
