An idea on how to get better performance from sub-sonic bullets

[320pf]

Originally Posted by rumlover

Well, after 12 for 12 deer total being shot with subs (8/Hornady 220s and 4/SMKs of various weight) I'm confident their performance has been proven and results left buy the bullets match the results of those I've shot in to other media.

No argument from me. I am also quite happy with the Sierra 200 and 240 MK performance. I just made my original suggestion because this subject is brought up frequently on this site. You are correct, vertical cuts will likely have a negative impact on accuracy. But I did not suggest this! I suggested using a tube cutting tool to thin the jacket. The idea being that when the bullet tumbled in the target, the bullet would break at the score... increasing the permanent wound channel

After my original post I came across a cannelure tool by corbin. Using this tool to put a cannelure would not have a negative effect on accuracy, providing that one does not make the cannelure too deep.

A cannelure would do two things. Primarly, it would secure the bullet placement in the case. This could be desirable in an auto. Secondly, in would also increase the possibility that the bullet would fragment aften impact.

http://www.corbins.com/hct-1.htm

320pf

[rumlover]

I put up a post on a new bullet design. My thoughts were to create a high BC, stable bullet that would allow shooters with factory twist rated barrels to shoot sub loads all the while providing effective (not necessarily efficient) killing potential--AND safely be shot in the varying barrels found on the market. While I've passed the point of no return by spending booko cash on specialized barrels, I'd like to take what we've all learned and try to put it to good use for the masses.

My thoughts were a design with the following:
-BC over .5
-Reduced friction for safety reasons (a need I see when using factory guns to prevent the likelyhood of a barrel stoppage)
-hollow cavity up front (not necessarily a hollow point like the SMK, but that would be a good starting point)
-high sectional density looking for the heaviest alloys to pack into the shortest pill
-No exposed lead to vaporize and fill up the cans (problem found in sealed 22 cans)


What would you guys add?

[Night Shooter]

I'm having some serious issues shooting new 300 Whisper with 220 Gr. SMK HPBT in a 1 in 8 twist 16" barrel/upper from Model "1" Sales loaded with 9.2 grains of H-110...I think I can throw rock more accurate...they are even hitting the edge of my supressor and keyholing at 75 yards. They aren't shooting well without the supressor at the same distance...starting to keyhole but not as bad...4-6" groups ! Doesn't appear to be stablizing...comming out the barrel.
Any suggestions ?

[pug]

I believe I would check the twist just as a precaution. I usually use a 2 1/2 to 3" square patch in the cleaning rod loop. Insert the patch down the bore just a little and then put a piece of masking tape with a tail sticking up 8" down the rod from the muzzle. Start pushing the tight patch down the bore and the rod should start to rotate and make one full turn by the time the marker gets to the muzzle. Take a couple of readings to make sure. If it doesn't make one full turn then put the marker 10" from the muzzle and see if its a 1:10.

[rumlover]

I concur, wrong twist rate is probably the culprit. What powder/charge are you using? Have you cronyed the rounds? Also, there is the possibility of the threading for the suppressor being off center of the bore (as opposed to the barrel centerline). If your twist rate is the 1/8 advertised, take the can off and see if your prefered load still keyholes at 75+. If it doesn't, send the barrel to a more reputable smith, I'd suggest Noveske for AR work, and have the barrel threading re-done for the suppressor. If that's not the issue, find someone with a bore scope and look for burs in the rifling or throat (pay special attention to the gas port area and muzzle). If that isn't the issue, try some shorter pills and get the velocity up close to 1050--if you're not already there.

Outside of that, I'm not aware of anything else that could affect stability.