Hunting Washington Forum

Equipment & Gear => Guns and Ammo => Topic started by: hunter105 on April 04, 2012, 07:41:23 PM

Title: FPS between guns
Post by: hunter105 on April 04, 2012, 07:41:23 PM: OK all you smart guys, why does one gun shoot 3000fps and another shoot the same ammo 35fps slower? both guns are browning xbolts in .300WSM, same barrel lengths. Reloaded ammo with no more than 35fps between rounds in groups of three in each gun. Is it the head space tolerance between the guns? Really looking for an answer.
Title: Re: FPS between guns
Post by: FC on April 04, 2012, 07:45:57 PM: That would be my guess, a small variation in pressure in one gun vs. another.
Title: Re: FPS between guns
Post by: carpsniperg2 on April 04, 2012, 07:46:52 PM: Even thought they are the same gun most are not 100% the same. Small little differences such as head space and things like fowling and such could change the fps.
Title: Re: FPS between guns
Post by: JohnVH on April 04, 2012, 07:48:10 PM: interesting, now you know why they say no two guns are the same.
Title: Re: FPS between guns
Post by: Huntbear on April 04, 2012, 07:48:41 PM: There are a lot of variables. How sharp was the tool that cut both barrels rifling? Was there any burrs? Was the throating reamer slightly longer or shorter when it was used? Was the chamber reamer new or had it cut 100 chambers before it?
Are all the action screws torqued the same?

Could be a lot of things. Not any one of them definitive. My brother's custom Sako I built him will shoot the same round almost 50 fps faster than out of my gun... And I am the most anal retentive *censored* there is when it comes to my reloading...
Title: Re: FPS between guns
Post by: JimmyHoffa on April 04, 2012, 07:51:49 PM: any chance one is warmer (darker stock/left in the sun/different finish)? A slight temperature variation can also occur, warmer rounds have more pressure.
Title: Re: FPS between guns
Post by: bobcat on April 04, 2012, 07:59:27 PM: No two guns are alike, and 35 feet per second is actually a very small difference.
Title: Re: FPS between guns
Post by: Special T on April 04, 2012, 08:03:21 PM: ya like 1.1%
Title: Re: FPS between guns
Post by: demontang on April 04, 2012, 09:11:47 PM: Sounds normal to me because there are so many factors that could be different between the two rifles. It's just like two of the same bow's will shot the same arrow at different speeds.
Title: Re: FPS between guns
Post by: high country on April 05, 2012, 09:33:44 AM: I had a wby 257 ulw that had a 26" tube and a howa with a 24" tube.....same batch of ammo....the howa shot almost 100fps faster and better to boot. figure that one out.
Title: Re: FPS between guns
Post by: Mike450r on April 05, 2012, 02:37:30 PM: Quote from: high country on April 05, 2012, 09:33:44 AM
I had a wby 257 ulw that had a 26" tube and a howa with a 24" tube.....same batch of ammo....the howa shot almost 100fps faster and better to boot. figure that one out.

I have found that exact same thing. My . 24' 257 wby vangaurd is a faster more accurate shooter than my buddies 26" Mark V using the exact same ammo. Messed with him about it all the time because he thought he got the better rifle by buying the Mark V. Then he found a shooting article that said the .257 wby is one of if not the only magnum round that shoots better and faster out of a 24" -vs- a 26" barrel.
Title: Re: FPS between guns
Post by: Biggerhammer on April 05, 2012, 09:27:59 PM: It's all in the barrel. :tup:
Title: Re: FPS between guns
Post by: Killmore on April 06, 2012, 08:33:44 AM: Took my new 300 rum to a smith and one thing I had him do was a barrel break in. Hand lapped, so i shot Remington factoring 180 gr swift sciroccos and remy advertises 3250 fps and when I chrony them they clocked at 3295. IS that because the barrel being broke in and smoother?
Title: Re: FPS between guns
Post by: addicted on April 06, 2012, 08:35:47 AM: Quote from: Killmore on April 06, 2012, 08:33:44 AM
Took my new 300 rum to a smith and one thing I had him do was a barrel break in. Hand lapped, so i shot Remington factoring 180 gr swift sciroccos and remy advertises 3250 fps and when I chrony them they clocked at 3295. IS that because the barrel being broke in and smoother?

only if your chrony clocked them at 3250 before the lapping but if you didnt clock it we may never know
Title: Re: FPS between guns
Post by: high country on April 06, 2012, 09:06:22 AM: Quote from: Killmore on April 06, 2012, 08:33:44 AM
Took my new 300 rum to a smith and one thing I had him do was a barrel break in. Hand lapped, so i shot Remington factoring 180 gr swift sciroccos and remy advertises 3250 fps and when I chrony them they clocked at 3295. IS that because the barrel being broke in and smoother?

You will see that much in some es's. Shoot through the lights in the summer vs winter and you'll see the same.
Title: Re: FPS between guns
Post by: mazama on April 06, 2012, 09:18:34 AM: I have loaded ammo and sometimes it will very that much in same gun-try cleaning and not cleaning you may get a variance.