.375H&H 25” Barrel cut to 23” - chronograph results

[deewayne2003]

So I recently had my BRNO 602 .375H&H customized by Tipton Burns of Texas Sporting Arms.

25” factory barrel - 5 rounds each of factory ammo & reloads chronograph results are averaged.

270gr Federal Blue box
Before 2620fps
After 2620fps

Odd - but it is what it is.

270gr BTSP reloads - A2700 & CCI mag primer.
Before 2,750fps
After 2,685

So a loss of 65fps by cutting 2” of barrel on the reloads - from same lot of ammo, factory ammo was all from same box.

 

[samson7x]

Interesting results. I cut an M70 from 25” to 20” and plan on making a thread with my results once I’m done collecting data.

 

[M70375!]

My thought is that the factory ammo was loaded with a faster burning powder and did not need the extra barrel length. The reloads were loaded with a heavier charge of slower powder, a more optimal load and a higher velocity which would suffer with a shorten barrel . Ammo companies sometimes will use a faster powder to save on powder expense, doesn't sound like much of a savings, but on a million rounds it adds up. It seems like many companies now are owned by large conglomerates that don't have their roots in the firearms industry like they did in the old days and are controlled by bean counters and their only concern is lowering cost. Just for fun pull a bullet from the factory load and compare it's weight to your reload.

 

[Rafiki]

General rule of thumb is 20fps/inch

 

[matt85]

Not a shock, most modern rifles have shorter barrels so most ammunition will likely be optimized for these.

 

[MShort]

I have cut 3 rifles over 375 and every time I’ve seen 20-25 fps per inch. Negligible loss for handier rifle

 

[Luvthunt]

I have cut 3 rifles over 375 and every time I’ve seen 20-25 fps per inch. Negligible loss for handier rifle

+1

 

[hoytcanon]

25" to 23" is hardly worth it... should have gone all the way back to 20"... everything you kill with the 23", you would kill with the 20." In the meantime, you will enjoy carrying and hunting with the 20" a whole heck of a lot more... 20 inches is where performance and convenience meet.

 

[double rifle newbie]

I have a 375 h&h a bolt stainless stalker in 26 inch and also one at 20. The 20 swings so much better for me. It feels great.

 

[hoytcanon]

I have a 375 h&h a bolt stainless stalker in 26 inch and also one at 20. The 20 swings so much better for me. It feels great.

Almost nobody regrets cutting down to 20" when they actually use it... that should say something.

 

[rookhawk]

So I recently had my BRNO 602 .375H&H customized by Tipton Burns of Texas Sporting Arms.

25” factory barrel - 5 rounds each of factory ammo & reloads chronograph results are averaged.

270gr Federal Blue box
Before 2620fps
After 2620fps

Odd - but it is what it is.

270gr BTSP reloads - A2700 & CCI mag primer.
Before 2,750fps
After 2,685

So a loss of 65fps by cutting 2” of barrel on the reloads - from same lot of ammo, factory ammo was all from same box.

Generic largebore rule of thumb is you lose 30fps per inch from published loads. This formula works well when you see original kynoch data with 28" test barrels and you're shooting a 24" rifle. (e.g. 470NE @2150FPS usually likes to regulate at 2030FPS from a 24" barrel)

 

[Boela]

Same here. I have x2 375's - one in H&H, the other in Ruger. Had them both chopped off at 20", and I am very pleased with the results. I would do it again in a heartbeat.

 

[Hornedfrogbbq]

How many of you shorter barrel chaps also are using a can?

 

[Red Leg]

Another option for shorter overall length is to apply the initial purchase and subsequent gun-smithing investment to a Blaser R8. With it you can maintain the original 25" barrel length (actually 25.5" with the standard .375 barrel), but have a rifle with the overall length of a Mauser actioned rifle with a 22" barrel.

 

[Daryl S]

Just a few years ago, I chronographed a ZKK 602 BRNO that had never been fired. The old box of 300gr. Winchester Silver Tips, chronographed 2,474fps at the muzzle, from it's almost 25" bl.
My .375/06IMP duplicates that velocity without ANY pressure signs.

 

[Doug Hamilton]

So I recently had my BRNO 602 .375H&H customized by Tipton Burns of Texas Sporting Arms.

25” factory barrel - 5 rounds each of factory ammo & reloads chronograph results are averaged.

270gr Federal Blue box
Before 2620fps
After 2620fps

Odd - but it is what it is.

270gr BTSP reloads - A2700 & CCI mag primer.
Before 2,750fps
After 2,685

So a loss of 65fps by cutting 2” of barrel on the reloads - from same lot of ammo, factory ammo was all from same box.

Interesting. Thanks for sharing your results.

 

[M70375!]

Just a few years ago, I chronographed a ZKK 602 BRNO that had never been fired. The old box of 300gr. Winchester Silver Tips, chronographed 2,474fps at the muzzle, from it's almost 25" bl.
My .375/06IMP duplicates that velocity without ANY pressure signs.

is a 375/06 a 30/06 necked up to375

 

[Daryl S]

Mine is a .30/06 case necked up to .375 and fireformed for an "Arch-type" chamber with .460" shoulder and .470" base dia. The case capacity is 78gr. in RP and Fed brass and 80gr. in WW brass.
Incidentally, I measured Sako and my own 9.3x62 brass having identical capacity, ie: 78gr.
I've been informed that modern powders in the standard .375/06 case will now duplicate these ballistics, which exceed .375H&H ballistics of 1912. My accuracy load with 270gr. TSX bullets is 2,650fps. This is likely identical or very close to modern factory H&H data. I did run it up to 2,750fps but when finally chronographing it, scared me. I backed the load off 3gr. This gave me a very decent 2,650fps.

 

[M70375!]

What is an arch type chamber and are your loads highly compress. Is this legal where 375 is minimum for DG

 

[Bonk]

How many of you shorter barrel chaps also are using a can?

It’s not exactly the same thing but I have a Ruger Guide Gun with a 20” threaded factory barrel that I use a can on.