Results: Cutting a 7mm-08 Barrel From 26" to 20"

[Another Casual]

Interesting information, easy to follow…thanks! SD & ES are lower in most cases with 20" barrel. Thoughts on reason for this?

With sample sizes of 3 shots I wouldnt put much weight in slight changes on ES/SD.

you might try a faster burning powder, my 30.06 only lost 33fps with a 150 gr Power Hammer Bullet using IMR8208 powder and it was cut from 24"to 18" very happy with the results

Faster powder has been on the to-do list for some time. Most of my powders are better suited to 6.5 creedmoor/PRC or 223. I've been on the look out locally for some 4064 or the like.

 

[LVJ76]

With sample sizes of 3 shots I wouldnt put much weight in slight changes on ES/SD.



Faster powder has been on the to-do list for some time. Most of my powders are better suited to 6.5 creedmoor/PRC or 223. I've been on the look out locally for some 4064 or the like.

Varget, CFE223 and RL17 will give you more speed vs IMR-4064 wIth the lighter bullets.. With heavier bullets RL16 and RL17 will also work well.

 

[JuddL]

GREAT data, thanks for sharing.

 

[JAYgs8163]

AA2460 will give you great speed on the lighter projectiles and it's easy to find and inexpensive. I shoot a 130 TTSX out of my 18" 308 right at 3100 fps with aa2460.

 

[jd palmer]

I like the facts ,even if they supprised me.

 

[Tulsa Reiner]

Thanks for the info, that's very helpful. Not the loss in fps I would've thought.

Nor the increase in SD and ES that I would have predicted.

 

[mechengr]

Thanks for sharing. I have a 280 Rem that I've been contemplating cutting down the 26" barrel to 20-22" and this is super helpful. Might just push me over the edge!

 

[Mark37082]

Very interesting and well documented. I wish I could cut down a newly purchased barrel, but that is one of the draw backs of CF. I may have to order a 20" CF now.

 

[Valek]

Interesting information, easy to follow…thanks! SD & ES are lower in most cases with 20" barrel. Thoughts on reason for this?

Didn't run a test for significance of difference in variability but, just eyeballing the statistics, the differences don't look significant to me in spite of the fact that there are absolute differences. Could be wrong (often am). Still, an interesting question.

 

[Buckys]

In my opinion, there's not enough threads with data from cutting down barrels!

I cut down my 26" 7mm-08 barrel to 20". I tested 7 loads before and after and wanted to share the data. Bullets and powders were picked based on what I have on hand. ***Disclaimer, all loads were max in my rifle and should not be attempted***

Why 20"? I figured it would be a good balance between too long to hunt with the can and too short to be tolerable from a noise perspective.

	Speer 130gr	50.2g H4350	Lost	Speer 145	48.0g H4350	Lost	Interlock 139	48.0g H4350	Lost	162 ELD-M	45.0g H4350	Lost	150 SPFB	45.9g IMR4451	Lost	162 ELD-M	45.1g IMR4451	Lost	162 ELD-M	46.0g IMR4831	Lost
	26"	20"		26"	20"		26"	20"		26"	20"		26"	20"		26"	20"		26"	20"
1	3126	2993		2986	2865		2972	2855		2730	2649		2765	2705		2710	2622		2660	2587
2	3108	2995		2980	2870		2974	2847		2717	2653		2820	2677		2688	2610		2660	2595
3	3126	2990		2980	2871		2982	2858		2723	2658		2772	2684		2731	2594		2648	2584
AVG	3120	2993	127	2982	2869	113	2976	2853	123	2723	2653	70	2786	2689	97	2710	2609	101	2656	2589	67
SD	10	3		3	3		5	6		7	5		30	15		22	14		7	6
ES	18	5		6	6		10	11		13	9		55	28		43	28		12	11

Average Lost: 100 FPS
Average per Inch: 16.63 FPS

Sadly my rifle prefers much lower charge weights than the max, but the FPS lost per inch was less than I expected. The difference in velocity won't be missed as the rifle is much more enjoyable to shoot with a silencer on it now and the speeds are still quite good. In many cases the choice in powder will have a larger impact on the velocity than having cut down the barrel. I still need to pick up some of the more traditional 7mm-08 powders to try, once supply improves.

Great post.

Not sure if you're planning to test new loads with the newly cut barrel but it would also be interesting to know - if you do, are you able to get good/better accuracy and reclaim any MV due to barrel harmonics, etc. working in favor of the shorter barrel...

 

[Shane Lindsey]

I have found similar results in 308 win. Heavier pills seem to lose less velocity than the lighter ones in my experience with the 215s.

 

[bamban]

I posted earlier in thread about my shortened factory 308s varmint synthetic fluted SS to 16-1/2. Suppressed. With 100 yatd I took it to our junior fund raising match at 600. No handloads just plain GI M118 LRs with 175 SMKs. I am more interested in the retained velocity at 600 yards. I figure with the right bullet it would make an excellent 400 yard hunter. Shot with bipod off the shoulder on the ground.

 

[CBH Australia]

Thanks for sharing. I have a 280 Rem that I've been contemplating cutting down the 26" barrel to 20-22" and this is super helpful. Might just push me over the edge!

The results of the OP are interesting.

I wonder if the .280 would show much difference in the velocity drop.

I've often read that an inch of barrel removed equates to between 25-50fps of velocity lost. The OP has lost around 20fps per inch .

120fps on game might not matter much but it's interesting to see real world results.

I own a 20" 7mm-08 and I have a 26" .280a.i. different rifles for different purposes. Can't quote the velocities or compare the cartridges .

I had to choose between a 20" and 26" because the CF wrapped barrels were what the the shop stock and pricing was in budget.

I went 26' because I wanted to use the potential of the 280a.i. cartridge but I would happily compromise 20fps per inch if i could have had 24" for the a happy medium.

We can't have suppressors so 26" is still manageable on a hunting rifle.

 

[Bob Wright]

In my opinion, there's not enough threads with data from cutting down barrels!

I cut down my 26" 7mm-08 barrel to 20". I tested 7 loads before and after and wanted to share the data. Bullets and powders were picked based on what I have on hand. ***Disclaimer, all loads were max in my rifle and should not be attempted***

Why 20"? I figured it would be a good balance between too long to hunt with the can and too short to be tolerable from a noise perspective.

	Speer 130gr	50.2g H4350	Lost	Speer 145	48.0g H4350	Lost	Interlock 139	48.0g H4350	Lost	162 ELD-M	45.0g H4350	Lost	150 SPFB	45.9g IMR4451	Lost	162 ELD-M	45.1g IMR4451	Lost	162 ELD-M	46.0g IMR4831	Lost
	26"	20"		26"	20"		26"	20"		26"	20"		26"	20"		26"	20"		26"	20"
1	3126	2993		2986	2865		2972	2855		2730	2649		2765	2705		2710	2622		2660	2587
2	3108	2995		2980	2870		2974	2847		2717	2653		2820	2677		2688	2610		2660	2595
3	3126	2990		2980	2871		2982	2858		2723	2658		2772	2684		2731	2594		2648	2584
AVG	3120	2993	127	2982	2869	113	2976	2853	123	2723	2653	70	2786	2689	97	2710	2609	101	2656	2589	67
SD	10	3		3	3		5	6		7	5		30	15		22	14		7	6
ES	18	5		6	6		10	11		13	9		55	28		43	28		12	11

Average Lost: 100 FPS
Average per Inch: 16.63 FPS

Sadly my rifle prefers much lower charge weights than the max, but the FPS lost per inch was less than I expected. The difference in velocity won't be missed as the rifle is much more enjoyable to shoot with a silencer on it now and the speeds are still quite good. In many cases the choice in powder will have a larger impact on the velocity than having cut down the barrel. I still need to pick up some of the more traditional 7mm-08 powders to try, once supply improves.

What's equally interesting is your ES/SD improved or stayed equal.
Head scratcher!