Forums
New posts
Search forums
What's new
Articles
Latest reviews
Author list
Classifieds
Log in
Register
What's new
Search
Search
Search titles and first posts only
Search titles only
By:
New posts
Search forums
Menu
Log in
Register
Install the app
Install
Forums
Hunting
Long Range Hunting & Shooting
IMPORTANT REQUEST
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Reply to thread
Message
<blockquote data-quote="Bart B" data-source="post: 105341" data-attributes="member: 5302"><p>[ QUOTE ]</p><p>Bart, were those comeups from a 20"gas gun?</p><p></p><p>[/ QUOTE ]No; standard 24-inch 7.62 NATO Garand barrel with 1:12 twist (I know, .30-06 ones had 1:10 twist but these were made to US Navy specs). They were custom made by Springfield Armory, MA but were tight; .2995" bore, .3076" groove, broach rifled and extremely uniform dimensions from throat to muzzle. They shot the same M118 ammo about 75 fps faster than the normal, larger bore &amp; groove diameters standard service barrels had. With good handloads, the best of them would stay inside 4 inches at 600 yards; not too shabby for a gas gun's ability to have all those moving parts (op rod and all) back into battery exactly the same for each shot - and a whippy barrel to boot!</p><p></p><p>That's gonna be the big error factor in what this guy wants. Without chronographing ammo from the acutal barrels, the muzzle velocity I use with the software may be 50 fps or more off from what they get. To say nothing of the powder temperature when the round's fired causing velocity changes. And different lots have different muzzle velocities. Whatever I come up with will be a SWAP; Scientific Wild *** Prediction.</p></blockquote><p></p>
[QUOTE="Bart B, post: 105341, member: 5302"] [ QUOTE ] Bart, were those comeups from a 20"gas gun? [/ QUOTE ]No; standard 24-inch 7.62 NATO Garand barrel with 1:12 twist (I know, .30-06 ones had 1:10 twist but these were made to US Navy specs). They were custom made by Springfield Armory, MA but were tight; .2995" bore, .3076" groove, broach rifled and extremely uniform dimensions from throat to muzzle. They shot the same M118 ammo about 75 fps faster than the normal, larger bore & groove diameters standard service barrels had. With good handloads, the best of them would stay inside 4 inches at 600 yards; not too shabby for a gas gun's ability to have all those moving parts (op rod and all) back into battery exactly the same for each shot - and a whippy barrel to boot! That's gonna be the big error factor in what this guy wants. Without chronographing ammo from the acutal barrels, the muzzle velocity I use with the software may be 50 fps or more off from what they get. To say nothing of the powder temperature when the round's fired causing velocity changes. And different lots have different muzzle velocities. Whatever I come up with will be a SWAP; Scientific Wild *** Prediction. [/QUOTE]
Insert quotes…
Verification
Post reply
Forums
Hunting
Long Range Hunting & Shooting
IMPORTANT REQUEST
Top