Stubby--Lapua

[philny1]

Purchased a Sako TRG-S 338 Lapua off internet. Spoke on the phone with the seller, asked all the right questions. Anyhow it arrived Fri and the barrel had been cut to 24". Any idea of the velocity loss those missing inches will cost??
Not the first time this has happen, one of the perils of dealing on the internet.

 

[jwp475]

I'd say about 25 FPS per inch.......I am building a 30" barreled Laupa as we speak..... a big cartridges and a long barrel just go together IMHO............

 

[britz]

If this is someone who will sell more than one item I hope you do your best to run down his name!!! That is just plain dirty. Good luck. I would guess that you would loose closer to 50 or more fps per inch because of the barrel diameter. Small bores are less affected by length than larger ones if memory serves. Good news is that at least you will get a little less barrel whip!

 

[jwp475]

[ QUOTE ]
Small bores are less affected by length than larger ones if memory serves.

[/ QUOTE ]

I believe that you have that backwards....

 

[philny1]

Rifle was bought from a listing on Guns America. Seller will not answer my e-mails. I find the vast majority of sellers to be honest, I have problems with 2-3% of the firearms bought.

 

[wildcat338]

Bearless,

Ive had that same problem from GunsAmerica thats why I mostly do stuff off of either gunbroker and auctionarms. Seems to be better on seller info etc.

I am thinking of selling my 338 lapua TRG-S as well with all I got for it we'll see though.

Goodluck on getting ahold of that seller.

Dave

 

[SamSpade]

Velocity loss chart: http://www.accuratereloading.com/223sb.html

 

[britz]

THis got me curious so I compaired two loading books w/ same twist same cal same powder same primer. The only cal that I could do this with was the 358 winchester from the Nosler #4 and the Speer #11 manuals. One had a 22" and one had a 23 " barrel. With the few same powder comparisons that could be made, it seems that for that cal, the difference was about 40 -80 fps per inch loss (Admittedly this isn't a good comparison).

However, it is no secret that when you get into the large Weatherby mags and STW's Dakota's RUM's, you need to get longer barrels to utilize the increased amount of slow burning powder. Also, my line of reasoning is that with the increase in caliber, there is an increase in the amount of area in the bore for gases to expand, wouldn't this denote that larger cal would make better use of a larger (longer) gas expansion chamber?

Not trying to pick an arguement, just curious and I admit that I sure could be wrong.

This was in respnose to jwp475 post.

 

[jwp475]

britz, When estimating velcity loss by shortening the barrel it is only an estimate..Take several barrels of the same caliber and shorten them and they will probable lose different amounts of velocity per inch.. Larger case capacity in general will lose less per inch in a larger bore diameter than a smaller diameter.I have chrongraphed enough different guns in the same caliber that I have on ocassion seen a shorter barrel have a higher velocity than the same caliber with a longer barrel on the same day with the same ammo....there are too many variables to be certain only by chronoing before and after shorting will you know for sure........

 

[philny1]

[ QUOTE ]
britz, When estimating velcity loss by shortening the barrel it is only an estimate..Take several barrels of the same caliber and shorten them and they will probable lose different amounts of velocity per inch.. Larger case capacity in general will lose less per inch in a larger bore diameter than a smaller diameter.I have chrongraphed enough different guns in the same caliber that I have on ocassion seen a shorter barrel have a higher velocity than the same caliber with a longer barrel on the same day with the same ammo....there are too many variables to be certain only by chronoing before and after shorting will you know for sure........

[/ QUOTE ]
I would guess 50-100 fps. Will be shooting it, probably later this week. Have an identical Sako with a 26" barrel.
Goodgrouper posted a load using RL-22 with the 225 Accubond, gonna give it a try. Will post results. Wouldn't it be something if it outperformed the longer barrel. Probably end up with a flame thrower.
I've bought quite a few guns off GA, this could happen on any site. Every once in awhile someone will take alot of liberties with their description. Doesn't seem to happen as often as it used to.
Thanks
Phil

 

[britz]

I am not familiar with the Lapua but if your results arn't satisfactory, you might wish to try some of the faster burning powders that are reccomended for that rifle. I have a hunch that they would be less affected by the barrel lenght.
good luck and good shooting.

 

[Fiftydriver]

Bearless,

I believe the factory barrel length for the TRG-S in 338 Lapua is only 25" to start with. In fact it may be less then that at 24 3/4" or something like that. I know that its shorter then the same rifle in the 7.62 Warbird or 30-378 because I have fitted muzzle brakes to alot of them and they are all very short compared to the other rounds.

As far as FPS loss per inch. Dan Lilja did a study on this with a larger 338 magnum, the 338-378 Wby and the 338-416 Improved.

In both cases, with the 300 gr SMK, velocity loss was around 20 to 22 fps per inch if I recall correctly cutting barrel length down to this class. Velocity loss was only around 18 fps with barrel lengths over 30" when loosing one inch of barrel.

The 338 bore is an amazingly effienct bore diameter. The reason is because you can get relatively heavy bullets in this bore diameter that are still relatively short in baring surface and the higher expansion ratio of this bore diameter allows the use of faster burning powder to be used.

It has been written that these larger bores would require a longer barrel to be effective, this is simply the opposite in fact. The larger the bore, the higher the expansion ratio of the round and as such they are less dependant on long barrels to produce top end velocity.

One glaring example of this is a couple of XP-100 pistols I made several years back. One was a 338 WSM wildcat, the other was a 300 WSM. Both had 15" 1-10 Lilja barrels with custom chambers built to similiar specs in relation to the rounds.

With the 180 gr Ballistic Tip loaded in both rounds, The 300 WSM topped out at around 2775 fps. In the 338 WSM however, it could drive the 180 gr Ballistic Tip to 2920 fps!!! Why?? Same powder capacity, same bullet weight, so why the large increase in velocity, easy!!

The baring surface on the 338 cal 180 is much less then the 30 cal 180. So there is less bore friction. Also, the powder that is appropriate for the two rounds is dramatically different.

The 300 WSM needed Rl-22 to get top velocity whereas the 338 WSM was very happy with the MUCH faster burning Rl-15.

Simply put, in my opinion, forget about whatever velocity lose you may have with the 1" shorter barrel, it is meaningless in every way. YOu are talking about 20 fps at the most in my opinion from a 25" barrel down to 24". Even from 26 to 24 it would be less then 50 fps.

There are so many factors that effect velocity potential that it is impossible to compare what is written in a loading manual and get any idea at all about what will happen in real world conditions.

I believe its the Hornday #5 manual that lists the 243 Win as producing the exact same velocity as a 6mm-284. Simply rubbish in the extreme and meaningless to be honest for comparision purposes.

Forget about your velocity loss if the rifle shoots well, you will never miss it.

Kirby Allen(50)

 

[philny1]

Hey, thanks for the post.
I have four Sakos, after reading your post out came the tape. The lapua that I been referring to as 24" is actually 22 7/8", measuring from the front of the receiver to the end of the barrel. The other Lapua is 24 3/8". I have a 30-378 that measures 24 3/8" and one that is 24 7/8". Also just taped the AM and what we been calling 30' is actually 29''. All measurements taken from the front of the receiver to the end of the barrel, is this the proper way to measure a barrel??
I would of thought the velocity loss to be somewhat greater. Mounted a scope on it yesterday, maybe get some rounds down it today.
Going to try some RL-22 and 225gr AB in both rifles. Less than pleased with the performance of the 26" lapua. Was shooting it last Jan and had no problem getting moa. Since then had shoulder surjery and now I'm forced to use a lead sled to shoot the Lapua. Is it possible the lapua does not like that rest, perhaps not recoiling properly. Just a thought. Been shooting a 338 RUM off the sled with good results.
Been meaning to drop you a line regarding the AM. Had to start from scratch, none of my old #s worked with the new throat. Then I ran out of 195s. TX Mike bailed me out with a very generous package of bullets. Got it shooting pretty fair, bout 2" at 300 yds. Will work on that.
Phil

 

[Fiftydriver]

Barrel length includes the amount of barrel inside the receiver as well. In most cases you can add 3/4" to 1" of barrel length to the measurement of the barrel length from the receiver. That will be your total barrel length.

Seems the barrel length on the Sakos is varying a bit????

Sounds like the AM is starting to shoot for you. I am sure you will find a load that will get you around 1/2 moa.

Keep me posted.

It is truely amazing what the 338 bore will do in a shorter barrel, even with large capacity magnums. I will be playing with a couple 375 cal wildcats here soon and suspect I will again be amazed by the next step in efficency with the even larger bore.

Kirby Allen(50)